THE ‘REAL WORLD’ APPLICATION OF POSTACTIVATION POTENTIATION IN A PHYSICAL TRAINING AND COMPETITION ENVIRONMENT. Nicholas Brink 9801974M A Thesis submitted to the Faculty of Health Science, University of the Witwatersrand, in fulfilment of the requirements for the degree of Doctor of Philosophy. Johannesburg, 2022. i Declaration I, Nicholas Brink declare that this thesis is my own, unaided work. It is being submitted for the Degree of Doctor of Philosophy at the University of the Witwatersrand, Johannesburg. It has not been submitted before for any degree or examination at any other University. Signature of candidate: 10/08/2022 ii Declaration: Student’s contribution to article(s) and agreement of co-author(s) I, Nicholas Brink, student number 9801974M, declare that this thesis is my own work and that I contributed adequately towards research findings published in the article(s) stated below which are included in my thesis. Signature of Student: Date 05/02/2022 Name of Primary Supervisor: Professor Demitri Constantinou Signature of Primary Supervisor Date_15/02/2022 Agreement by co-authors: By signing this declaration, the co-authors listed below agree to the use of the article by the student as part of his/her thesis. Article 1: Brink, N.J., Constantinou, D. and Torres, G., (2021). Postactivation performance enhancement (PAPE) of sprint acceleration performance. European Journal of Sport Science, pp.1-7. DOI: 10.1080/17461391.2021.1955012 Author Name Signature Date Comments: 1st Author Nicholas Brink 05/02/202 2nd Author Demitri Constantinou 15/02/202 3rd Author Georgia Torres 14/02/202 iii Article 2: Brink, N.J., Constantinou, D. and Torres, G., (Submitted in 2021). Postactivation Performance Enhancement (PAPE) using a vertical jump to improve vertical jump performance, Journal of Sport Medicine and Physical Fitness. DOI: 10.23736/ S0022-4707.22.12899-9 Author Name Signature Date Comments: Article 3: Brink, N.J., Constantinou, D. and Torres, G., (2022). Postactivation potentiation in healthy adults using a bodyweight conditioning activity: a systematic review and meta- analysis. Journal of Strength and Conditioning Research, (accepted) Author Name Signature Date 1st Author Nicholas Brink 05/02/2022 2nd Author Demitri Constantinou 15/02/2022 3rd Author Georgia Torres 14/02/2022 Comments: 1st Author Nicholas Brink 05/02/202 2nd Author Demitri Constantinou 15/02/202 3rd Author Georgia Torres 14/02/202 iv Dedication I dedicate this thesis to my wife, Sedisha and son, Zachary for their unwavering support and love and to my parents for raising me to believe in myself. George Brink 1942 - 2009 v Journal submissions and conference presentations arising from this research project. Published: Brink, N.J., Constantinou, D. and Torres, G., (2021). Postactivation performance enhancement (PAPE) of sprint acceleration performance. European Journal of Sport Science, pp.1-7. DOI 10.1080/17461391.2021.1955012 Accepted: Brink, N.J., Constantinou, D. and Torres, G., (Submitted in 2021). Postactivation Performance Enhancement (PAPE) using a vertical jump to improve vertical jump performance, Journal of Sport Medicine and Physical Fitness. DOI: 10.23736/S0022- 4707.22.12899-9 Accepted: Brink, N.J., Constantinou, D. and Torres, G., (Submitted in 2021). Postactivation potentiation in healthy adults using a bodyweight conditioning activity: a systematic review and meta-analysis. Journal of Strength and Conditioning Research, Conference: School of Therapeutic Sciences, Biennial Research Day. (2021) – Johannesburg, Gauteng Date: 14 September 2021 Title: Postactivation performance enhancement (PAPE) of sprint acceleration performance. Type: Oral platform presentation To be presented by: Nicholas Brink Authors: Brink, N.J., Constantinou, D. and Torres, G https://doi.org/10.1080/17461391.2021.1955012 vi Abstract Postactivation potentiation is a physiological concept that implies that a conditioning activity can enhance the outcome of a subsequent task. These tasks are normally power related activities like maximal sprinting or jumping. This study explored whether postactivation potentiation could be achieved in healthy adults using a bodyweight conditioning activity. Three original studies were conducted as part of this thesis. The researchers conducted study one and two to investigate whether a maximal intensity body- weight task could induce postactivation potentiation in a similar subsequent task. A randomised controlled trial was conducted in each case. The researchers used study three to investigate whether a body weight conditioning activity could improve the outcome of a subsequent task. A systematic review and meta-analysis were conducted which included the results of study one and two. Study one demonstrated that relative to the baseline there was a significant improvement in the maximal linear sprint group over 10 m and 20 m at two minutes of 0.12 m.s-1 and 0.11 m.s-1 and at six minutes of 0.11m.s-1 and 0.12m.s-1 respectively. There was also a significant improvement in the control group between two and six minutes post-intervention at 10 m and 20 m of 0.06 m.s-1 and 0.08 m.s-1 respectively. There was no significant difference between the intervention and control group. Based upon this finding a maximal sprint acceleration may enhance the outcome of a subsequent maximal sprint acceleration. The researchers demonstrated in study two that relative to the baseline there was a significant improvement in the maximal vertical jump group in jump height (1.89 cm) and power output (114.45 W) at two minutes. There was no change in control group across the experiment and no significant difference between the control group and the intervention group. These findings suggests that two maximal vertical jumps may enhance the outcome of a subsequent maximal vertical jump after two minutes. However, these enhancements were not sustained for a further four minutes. Study three demonstrated that there was a small overall effect of 0.30 (95% CI 0.14 to 0.46, p = 0.0003) in favour of using a bodyweight conditioning activity to improve the outcome of a subsequent vertical jump or linear sprint. The interpretation of these outcomes indicate that while the enhancement may be small to moderate in effect, they are in favour of using bodyweight conditioning activities to enhance the outcomes of a maximal vertical jump or maximal sprint. Vertical jump and sprint ability are highly associated with performance outcomes in many sports. Bodyweight conditioning activities allows for a simple, yet effective approach vii with minimal adverse consequences to achieve postactivation potentiation and an enhanced state of performance prior to participation in a ‘real world’ environment. Acknowledgments I would like to thank my supervisors Professor Demitri Constantinou and Dr Georgia Torres for all their help and advice with this PhD. I would also like to thank the Centre for Exercise Science and Sports Medicine for the loan of equipment. I would like to thank Bidvest Wits Football Club for the use of their facilities and access to their players to conduct this study. viii Table of Contents Declaration i Contributions of Authors to the Project ii Dedication iv Journal submissions and conference presentations arising from this thesis v Abstract vi Acknowledgments vii Table of Contents viii List of Figures xi List of Tables xii List of Abbreviations xiii Chapter 1 – Literature Review 1 Introduction to Postactivation potentiation 2 Postactivation potentiation using ballistic conditioning activities 5 Postactivation potentiation using a vertical jump to potentiate a vertical jump 10 Postactivation potentiation using a maximal sprint to potentiate a maximal sprint 13 Conclusion 15 Aims and objectives of the thesis 16 References 17 Chapter 2 – Study one: Brink, N.J., Constantinou, D. and Torres, G., (2021). Postactivation performance enhancement (PAPE) of sprint acceleration performance. European Journal of Sport Science, (published) 22 Abstract 23 Introduction 24 ix Methods ` 26 Results 29 Discussion 31 Conclusion 34 Acknowledgements 34 References 35 Chapter 3 – Study two: Brink N, Constantinou D, and Torres G (Submitted in 2021) Postactivation Performance Enhancement (PAPE) using a vertical jump to improve vertical jump performance, Journal of Sports Medicine and Physical Fitness (accepted) 39 Abstract 40 Background 41 Methods 43 Results 48 Discussions 50 Conclusions 52 Acknowledgments 53 References 53 Chapter 4 – Study three: Brink N, Constantinou D, and Torres G (Submitted in 2021) Postactivation potentiation in healthy adults using a bodyweight conditioning activity: a systematic review and meta-analysis., Journal of Sports Sciences (under review) 58 Abstract 59 Introduction 61 x Methods 62 Results 64 Discussion 66 Conclusion 70 References 70 Chapter 5 - Discussion 87 Introduction to the discussion 88 PAP using a vertically bias conditioning activity 90 PAP using a horizontally bias conditioning activity 93 PAP using bodyweight conditioning activities to improve performance 95 Strengths & limitations 98 Practical applications 100 Conclusion 101 References 101 Chapter 6 - Appendices 112 Appendix 1 – Ethical clearance certificate 113 Appendix 2 – Athlete coding sheet 114 Appendix 3 – Study one information document 115 Appendix 4 – Study two information document 117 Appendix 5 – Consent document 119 Appendix 6 – Data capture document 120 Appendix 7 – Study one data collection sheet 121 Appendix 8 – Study two data collection sheet 124 Appendix 9 - Article published in the European Journal of Sports Science 127 xi Appendix 10 - Turn-it-in report 134 List of Figures Chapter 1 Figure 1. Relationship between postactivation potentiation and fatigue. Adapted from Sale, D. Postactivation potentiation: role in human performance (Sale, 2002). Figure 2. Relationship between postactivation potentiation and postactivation performance enhancement. Adapted from Blazevich, A. and Babault, N. Postactivation Potentiation Versus Post-activation Performance Enhancement in Humans: Historical Perspective, Underlying Mechanisms, and Current Issues (Blazevich and Babault, 2019). Figure 3. Graphic representation of the size principle, according to which motor units that contain Type I (slow-twitch) and Type II (fast-twitch) fibres are organised based on some “size” factor. Adapted from Duncan French, Adaptations to anaerobic training programs, Chapter 5. Haff GG, Triplett NT, editors. Essentials of strength training and conditioning 4th edition. Human kinetics; 2015 Sep 23. Chapter 3 Figure 1. Test protocol for the control and experimental trials. Chapter 4 Figure 1. Flow chart of study selection for the analysis on whether a bodyweight conditioning activity can acutely improve the outcome of a subsequent task through postactivation potentiation. Figure 2. Risk of bias summary. The authors’ judgements about each risk of bias item are presented as percentages across all included studies. Figure 3. Primary analysis of studies measuring a bodyweight conditioning activity against a control. xii Figure 4. Funnel plot for assessing publication bias in studies measuring a bodyweight conditioning activity against a control. List of Tables Chapter 2 Table 1. Sprint velocity over 20 m mean ± SD values. Table 2. Sprint velocity over 10 m mean ± SD values. Chapter 3 Table 1. Vertical jump height mean ± SD values. Table 2. Peak power output mean ± SD values. Chapter 4 Table 1. Search strategy: Search of Medline PubMed Table 2. Characteristics of the included studies Table 3. The intervention and outcome protocols of the included studies Table 4. PRISMA checklist xiii List of Abbreviations C Control group, study one CA Conditioning activity cm Centimetre/s CON Control group, study two d Cohen’s d ES Effect size F F-value HRT Heavy resistance training kg Kilogram/s m Metre/s MJ Multiple jump series group, study two m.s-1 Metres per second n Number of individuals η2 Eta squared RCT Randomised control trial RLC Regulatory light chain p P-value P Plyometric group, study one PAP Postactivation potentiation PAPE Postactivation performance enhancement PRISMA Preferred reporting items for systematic reviews and meta-analyses S Sprint group, study one SD Standard deviation xiv VJ Vertical jump group, study two W Watt/s ̴ Approximately 1 CHAPTER 1 – Literature Review 2 Introduction to Postactivation potentiation Postactivation potentiation (PAP) is a physiological training principle which proposes that a muscle can be acutely optimised through its contractile history. This in turn affects the outcome of a subsequent task. The subsequent task is most often a power-based activity which requires high force production and a high rate of force development such as sprinting, jumping or throwing (Hodgson et al., 2005). Postactivation potentiation has been tested in a variety of sporting environments and different movement patterns with varying degrees of success (Borba et al., 2017). Traditionally, the conditioning activity for PAP was thought to require a heavy resistance isotonic preload stimulus (75-90% of one repetition maximum) to achieve a potentiated state (Hodgson et al., 2005). This required athletes to lift, push or pull heavy weights over a varying range of sets and repetitions to develop a combined effect of heightened muscle activation and consequential fatigue (figure 1). Theoretically, the fatigue dispels first, leaving the muscle in a state of acute enhancement (Rassier and Macintosh, 2000). This effect is referred to as PAP and should generate greater force production and an increase in the rate of force development in a subsequent power-based task. The primary mechanisms of PAP have been discussed in multiple studies (Hodgson et al., 2005; Tillin and Bishop, 2009). These include myosin regulatory light chains phosphorylation, changes in the pennation angle of the fascicle and higher order motor unit recruitment. As the most common theory, phosphorylation of myosin light chains produced an up-regulation in the rate of cross-bridge formation. This results in a faster rate of force development (Sale, 2002). Researchers have proposed that brief maximal voluntary contractions could produce a PAP response as this seems to be associated with an increase in peak rate of force development in a subsequent task (Blazevich and Babault, 2019). 3 Figure 1 Relationship between postactivation potentiation and fatigue. Adapted from Sale, D. Postactivation potentiation: role in human performance (Sale, 2002). Recent literature has discussed the association between the commonly used term, PAP, and the less well-known term; postactivation performance enhancement (PAPE) (figure 2). Over the last 20 years conventional concepts proposed that PAP is any acute enhancement lasting up to 20 minutes following a heavy resistance exercise or ballistic task (Wilson et al., 2013). It is proposed that a contraction-initiated increase in myosin regulatory light chain phosphorylation underpins the benefits observed in PAP, including an enhancement in voluntary contractile force (Vandenboom, 2011). However, correctly defined, the term PAP only refers to an enhancement of an evoked twitch response, which is relatively short lived and rapidly decreases after one minute (Vandervoort et al., 1983). In contrast, PAPE is associated with, among other things; voluntary contractions, increases in muscle temperature and several neural mechanisms unrelated to myosin regulatory light chain phosphorylation where muscle twitch has not been directly assessed (Blazevich and Babault, 2019; Cuenca-Fernandez et al., 2017; Prieske et al., 2018). This thesis does not intend to explore these terms in detail but will use postactivation potentiation or PAP in the traditional sense, to include all muscle enhancements while PAPE will only be used to refer to an acute bout of high intensity voluntary exercise followed by an enhancement in strength, speed or power production (Blazevich and Babault, 2019; Zimmermann et al., 2020). Figure 2 Relationship between postactivation potentiation and postactivation performance enhancement. Adapted from Blazevich, A. and Babault, N. Postactivation Potentiation Versus Post-activation Performance Enhancement in Humans: Historical Perspective, Underlying Mechanisms, and Current Issues (Blazevich and Babault, 2019). 4 Based upon the Henneman size principle, type I low-force muscle fibres are recruited before the type II high-force muscle fibres during activity (Wakeling, 2009). Therefore, to achieve an optimal state of preparation for a high intensity, power-based task, an athlete needs to progress through the type I fibres first (figure 3). This can be achieved through heavy resistance training under maximal exertion (Hodgson et al., 2005) whereby the large type II muscle fibres are activated through high load, low speed activities. The challenge lies in the narrow guidelines in which the PAP principle exists. An athlete’s strength and training age, the volume, intensity and recovery period of the conditioning activity, and possibly gender differences have all been reported to affect this outcome, with elite athletes showing the greatest benefits (Seitz and Haff, 2016; Wilson et al., 2013). This lack of irrefutable data makes PAP a questionable training aid rather than a definitive advantage. However, the possibility that a conditioning activity could maximise training practices long term, or acutely optimise an athlete’s competitive potential, drives this research forward. Although heavy resistance training has shown positive results, the nature of heavy lifting constrains coaches and athletes to use large pieces of heavy equipment. This coupled with the fact that the PAP effect using heavy resistance training has been reported to be most effective between five to eighteen minutes (Wilson et al., 2013) makes this strategy highly impractical. The goal is to make PAP a viable training and competitive aid to be utilised under ‘real world’ conditions without the use of laborious gym equipment, excessive space, and unreasonable time frames. This questions the usefulness and functionality of PAP using heavy resistance training and has forced investigators to challenge the narrow parameters and whether partial or full potentiation can occur by an alternative means. In this text, ‘real world’ is defined as under normal physical training and competition circumstances. 5 Figure 3 Graphic representation of the size principle, according to which motor units that contain Type I (slow-twitch), and Type II (fast-twitch) fibres are organised based on some “size” factor. Adapted from Duncan French, Adaptations to anaerobic training programs, Chapter 5. Haff GG, Triplett NT, editors. Essentials of strength training and conditioning 4th edition. Human kinetics; 2015 Sep 23. The following literature review explores other methods to achieve this potentiated state. Recently researchers have investigated the effects of using ballistic type exercises as the conditioning activity to induce maximal recruitment of the type II muscle fibres (Turner et al., 2015; Sharma et al., 2018). These would include high velocity, high power activities with and without an external resistance with a vertical or horizontal bias to achieve a potentiated state. This may highlight the benefits seen when using plyometrics as a chronic or acute training stimulus (Burkett et al., 2005; Hilfiker et al., 2007). This thesis will not separate the terms ballistic and plyometric. Much of the literature reports ballistic and plyometric interchangeably. For the flow of this thesis, the term ballistic will be used unless plyometric has been specifically reported and changes the meaning of the authors intent. Ballistic exercises have shown beneficial effects in achieving PAP and would negate the need to use heavy weights, excessive space, and technically challenging exercises (Maloney et al., 2014). This review will discuss the use of ballistic exercises to induce PAP from three viewpoints. Firstly, to assess the literature on whether ballistic activities with a focus on body-weight tasks have the potential to create a PAP effect. Secondly, to look at activities that use a vertical bias conditioning activity such as jumps or plyometrics. Whether these have the potential to induce a PAP effect in a subsequent task with a vertical bias. Lastly, to look at activities that use a horizontal bias conditioning activity, such as sprinting. Whether these have the potential to induce a PAP effect in a subsequent task with a horizontal bias. Evaluating the quality of the available studies to determine the reliability and the validity of the literature will be integral in determining a need for further investigation. The authors used this literature review to examine the study methods in the available literature to determine the reliability of the results. An essential part of this study will be to provide a practical solution for coaches and athletes on whether PAP using a bodyweight conditioning activity can be used as a performance enhancement tool in a ‘real world’ environment. 6 Postactivation potentiation using ballistic conditioning activities. Post-activation potentiation is a physiological concept which suggests that a conditioning activity can enhance the outcome of a subsequent power-based task (Sale, 2002). An athlete’s strength and training age, the volume, intensity and recovery period of the conditioning activity, and possibly gender differences have all been reported to affect this outcome, with elite athletes showing the greatest benefits (Seitz and Haff, 2016; Wilson et al., 2013).As previously mentioned, traditionally heavy resistance training has been used as the conditioning activity using a pre-loading stimulus of between 75 – 90% of one repetition maximum prior to a similar power-based task (Hodgson et al., 2005). The aim is to enhance the outcome of this subsequent task. The proposed effect involves greater muscle recruitment of the type II fibres but also an associated fatigue response. As both effects are present simultaneously, the sum of the effects are negated. However, the fatigue effect is reported to dispel first leaving the tissue in a state of acute enhancement (Rassier and Macintosh, 2000). This enhanced effect has been reported to occur anywhere between five and eighteen minutes post conditioning activity (Wilson et al., 2013). However, using heavy resistance training prior to training and especially in competition is impractical, requiring heavy weights (Kilduff et al., 2013) and unpredictable time frames which would be difficult to implement in a ‘real world’ competition environment. There is a need to investigate an alternative method to introduce PAP into the athlete’s preparation which can be implemented simply with minimal detrimental effects and within a reasonable time frame. There is growing interest in the PAP effects elicited by ballistic type exercises. These are defined as using maximal intensity with the intent to move an object or body as fast as possible (Maloney et al., 2014). This can be achieved with or without an external resistance using one or multiple repetitions where maximal intensity is achieved. This can take the form of activities using a vertical or horizontal bias. The intension is to move quickly rather than the velocity of the object or body which is the driving force behind the acute neural adaptations. These include; increased motor-unit recruitment, rate of force development, and intra- and inter-muscular coordination (Turner, 2009). Whilst ballistic exercises can be undertaken using external resistance, it is the absence of an external resistance which makes this form of exercise more favourable in inducing PAP in a competition and training environment. Heavy resistance training is completely 7 reliant on heavy weights, space and to a degree technique. An alternative solution to achieve PAP quickly and effectively without placing an excessive reliance on facilities and equipment highlights the potential that ballistic exercises have in the application of PAP in a competition and training environment. The Henneman size principle suggests that motor units are ramped from the smallest, type I, fatigue resistant fibres to the larger, most powerful type II fibres (Wakeling, 2009). Heavier loads activate a larger pool of the muscle tissue comprising of these type II muscle fibres. Activation of type II muscle fibres has been shown to have a larger capacity to produce a PAP response, indicating why heavier loads produce a greater PAP response in heavy resistance training (Hamada et al., 2003). As ballistic type exercises normally use less load than heavy resistance training, two theories are postulated for the benefits seen using these exercises to induce a PAP response. Firstly, due to the strong intention to move quickly, a ballistic contraction may provide a powerful, excitatory stimulus to activate all the muscle fibres extremely rapidly (Van Cutsem et al., 1998; Desmedt and Godaux, 1977). This is likely due to the lower threshold for motor unit recruitment seen during ballistic exercises compared to heavy resistance training (Van Cutsem et al., 1998; Desmedt and Godaux, 1977). The second theory proposes that selective recruitment exists as an exception to the size principle (Nardone and Schieppati, 1988; Nardone et al., 1989). By utilising high velocity, high power movements, the type I fibres can be surpassed, activating the type IIa and IIx fibres quickly. This form of recruitment may underpin the success seen in ballistic activities and PAP. An athlete’s preparation may play a role in highlighting which conditioning activities could be useful in competition. It is not uncommon for sprinters, jumpers and throwers to engage in some form of sprinting or jumping prior to competing. This is traditionally held to be the final preparation before maximal exertion. If this pre-activity phase can potentiate muscles either partially or fully, then an athlete would prioritise selecting a conditioning activity based on the specificity, and the convenience of this task. Research has demonstrated that using a conditioning activity similar to the subsequent task can enhance performances within specific populations (Smith et al., 2014). Karampatsos et al. (2013; 2017) observed that field event athletes achieved significantly greater throw distances after three vertical jumps or a 8 20 m sprint at maximal effort. These improvements were observed one minute post conditioning activity, indicating a reasonable time frame, post warm-up but pre-competition, in which PAP could be achieved, however these outcomes were not the athlete’s personal best performances in this study. Creekmur et al., (2017) observed that a weighted vertically bias plyometric intervention could improve the outcome of a 20 and 40 yard sprint by 1.15% and 1.24% respectively. This provides further evidence that ballistic activities have the capacity to potentiate power-based tasks. The study showed that using a weighted ballistic vertical jump can produce a potentiated effect which prior to sprinting can improve the performance outcome. This method may be more applicable in a training and competition environment compared to using heavy resistance training. However, this process still requires the use of a weighted plate but does show the potential for ballistic movements to produce a PAP effect. Smith et al. (2014) attempted to potentiate a 40 yard sprint by using a weighted sled push, a horizontally biased conditioning activity. The results indicated that the heaviest sled, 30% of the individuals body weight, produced the most enhancement in a subsequent 40-yard sprint. More interestingly was that the ‘control’, an unweighted sled push, produced an enhancement only marginally less that the heaviest intervention. Although the unweighted sled still provided an external resistance other than bodyweight, it could be the intent to move the sled quickly which was the association to producing a PAP effect. As the specific loading of the sled produces varied results, sled pushing may effect different kinematics compared to that of sprinting, bounding or towing (Young, 1992) which may be more specific compared to the subsequent task of a maximal 40 yard maximal sprint. This may suggest that the enhancement is not only to do with load but may also have a strong association to specificity and intensity of the task and the conditioning activity. The authors did acknowledge that this was not a true control which future studies should include. Research also indicates that jump performance can be improved by using variations of jumping as the conditioning activity (Burkett et al., 2005; Hilfiker et al., 2007). Burkett et al. (2005) reported that a conditioning activity using maximal weighted jump exceeded the outcome of a submaximal vertical jump and a stretching intervention. Although the authors pointed to the external resistance as the primary influencing factors, the maximal intensity 9 of the effective intervention could also have played a role in enhancing the outcome measurement. The submaximal jump and the stretching intervention both lacked the intention to move quickly. The weighted jumps only involved the participants holding dumbbells equivalent to 10% of the body while jumping on to a box. Load may be a contributing factor but the intention to produce a maximal intensity movement seems more likely to produce PAP in the subsequent task. Suchomel et al., (2016) suggest that the intensity and velocity of the conditioning activity need to closely mimic the levels achieved during competition or training as it was highly suggestive that this was an important component in achieving PAP. They demonstrated significant improvement in a vertical jump performance following a ballistic half squat compared to a non-ballistic half squat. As both interventions were loaded to 90% of the participants one repetition maximum and performed in either a ballistic or non-ballistic manner, it shows that weight alone is not the primary driver in PAP. This study included a control group who did not undergo the intervention. It could be concluded that the weight alone may have been detrimental to the outcome performance as both the control group and the non-ballistic group only showed trivial improvements. Lim and Kong (2013) found no PAP response following isometric knee extension and isometric squat. This indicates the associated importance attributed to the ballistic nature of the conditioning task as no benefit was found using isometric or a dynamic heavy slow resistance intervention on sprint outcomes. Seitz and Haff, (2016) found significant negative effects associated with maximal isometrics on performance outcomes. Burkett et al. (2005) also found that a maximal jump although weighted, was far superior to sub-maximal variations confirming the importance of velocity and intensity of the conditioning task in PAP. To this researcher’s knowledge, no systematic review has been done on the effects of PAP using bodyweight conditioning activities within a reasonable time frame to be useful in a competition environment. This lack of cohesion makes it difficult to create specific individualised programmes for athletes within the competition environment. For this reason, it is important to correlate the available information allowing for better understanding of this principle. This thesis investigated the effect of PAP through a systematic review and meta- analysis, linked with the hypothesised results of study one, PAP of sprint acceleration 10 performance and study two, PAP using a vertical jump to improve vertical jump performance. This is useful as it provides more insight into the potential effectiveness of bodyweight conditioning activities to potentiate subsequent tasks and provides coaches, trainers, and rehabilitation professionals clear options to improve training impulses and competition performances. Postactivation potentiation using a vertical jump to potentiate a vertical jump. There are indications that PAP can be achieved using both weighted and bodyweight ballistic tasks, which in the right circumstances can positively affect the outcome of a subsequent task (Dobbs et al., 2019; Seitz and Haff, 2016; Wilson et al., 2013). This suggests that PAP could be used as a long-term training aid and theoretically a competition enhancement within a ‘real world’ competition environment. Researchers advocate that ballistic type conditioning activities using bodyweight tasks to achieve PAP (Turner et al., 2015; Healy and Comyns, 2017; Smith et al., 2014) provide a practical training and competitive solution. The goal is to achieve PAP with minimal disruption to the athlete’s preparations within a reasonable time frame, while achieving positive outcomes which out- weigh any negative effects such as induced fatigue. This would allow athletes to specifically focus their warm-ups using minimal equipment, within reasonable space and time. Through testing and a developed protocol, athletes can maximise their ability to potentiate prior to training or competition. Mola, Bruce-Low and Burnet, (2014) investigated the recovery time for PAP in soccer players and found that heavy resistance training had a reduced global effect compared to the control group. This study provides some interesting reflections regarding bodyweight ballistic type exercises compared to heavy resistance training. The investigators assessed two groups, the control who did not participate in the intervention and the experimental group who did a three-repetition maximum squat intervention. Both groups undertook a vertical jump measurement at baseline and a vertical jump outcome measurement post intervention. Although no significant benefit was observed in either group, what is interesting is that the control group had no positive or negative feed-forward effect from the baseline testing to the post intervention testing which were ten minutes apart. As reported by Seitz and Haff (2016), voluntary movements undertaken at maximal intensity are likely 11 to induce a PAPE effect. Therefore, it is likely that the baseline testing would have a PAPE response for some time after the testing finished. Although this was not addressed in this study, it may indicate that bodyweight ballistic type exercises, the PAP effect is exposed sooner with less early post intervention fatigue deficits. Despite not discussed in this study, it was hypothesised that heavier load will induce a greater PAP response but with an associated greater fatigue response. This will create a longer latent period as the fatigue takes longer to dispel before the PAP effect is exposed. As ballistic type exercises use less load it is conceivable that there would be a smaller PAP effect but similarly a smaller fatigue effect. The fatigue effect dispels quicker with ballistic type exercises, so the PAP effect is exposed sooner with less early post intervention fatigue deficits. It has been reported that heavy resistance training and ballistic type exercises produce similar outcomes, but heavy resistance training takes longer (Seitz and Haff, 2016). Seitz and Haff, (2016) reported in a systematic review that traditional heavy resistance training produced a similar effect size (ES = 0.41) to a ballistic type conditioning activity (ES = 0.47). The authors did highlight that at the time of writing only a limited number of studies had published data on ballistic type conditioning activities, whereas extensive investigation had been done on heavy resistance training. Nevertheless, it appears that although the magnitude of improvement is similar, the PAP effect is observed earlier (<5min) in the ballistic group compared to the heavy resistance group (>5min). Tobin and Delahunt, (2014) and Sharma et al., (2018) used a similar methodology to compare a conditioning activity of a series of forty plyometric jumps on the performance of a vertical jump. Tobin and Delahunt (2014) demonstrated improvements at five time points (2.09cm – 2.87cm) post conditioning activity. There was no external resistance added to the participants. This highlights the improvements observed following a bodyweight ballistic intervention on a power-based outcome measure, a vertical jump. The outcome measurements demonstrated improvement at each time point post intervention. However as previous testing could have influenced the results, only the first outcome measurement at one minute could be directly attributed to the intervention. This provides evidence as to the early benefits observed by using a bodyweight conditioning activity to enhance the outcome in a similar power-based task. Other than the volume of jumps and equipment required like hurdles, the principle demonstrated promise as a PAP inducer for a competitive and training environment. 12 Sharma et al., (2018) demonstrated that multiple unweighted ballistic tasks had a greater effect on the vertical jump performance (3.87cm) compared to that of a 90% 1- rep max heavy resistance training (2.77cm) intervention at 10 minute post baseline testing. This indicates that bodyweight plyometrics may play a superior role in acutely potentiating muscle tissue. However, two potential flaws existed in this study. Firstly, the investigation conducted baseline testing within three minutes of the intervention. As this testing consisted of two maximal ballistic tasks, vertical jumps and a 20 m sprint, one or both of these activities could have had an effect on the intervention and the outcome measurements. Secondly, as the investigators considered two different baseline and outcome measurements, whichever one was conducted first would potentially influence the other measurement. This questions the validity of the study’s methodology and the reliability of the results. However, both groups participated in the same protocol with only the interventions differing. This may suggest that the ballistic intervention has potential to produce a greater PAP effect compared to a heavy resistance training. If benefits occur in vertical jumps with jump variations including drop jumps (Hilfiker et al., 2007) and depth jumps (Masamoto et al., 2003), then similar benefits are hypothesised with vertical jumps as the conditioning activity. Hilfiker et al., (2007) found that including a depth jump in a warm-up improved the outcome of a subsequent vertical jump. It is important to note that a bodyweight variation of a vertical jump can enhance the outcome of a subsequent jump without the need of an external resistance. This may indicate that specificity to the subsequent task and the intensity of the conditioning activity are key components in PAP. Coaches closely emulate the tasks and skills required in competition within the warm-up phase, both during training and competition to affect the specificity principle. There is a positive performance correlation between a sport and the warm-up processes (Russell et al., 2015). Similarly, the effectiveness of PAP is determined by how closely the conditioning activity relates to the subsequent task (Till and Cooke, 2009). Van den Tillaar, Lerberg and von Heimburg, (2019) demonstrated that specificity is an important constituent in the development of a potentiated outcome. A warm-up with activities similar to the subsequent task was used with significant benefit compared to an alternate non- specific warm-up. Burkett, Phillips and Ziuraitis, (2005) investigated the effect of intensity 13 and specificity of four warm-up tasks on the outcome of a vertical jump, and found a correlation between both the intensity and specificity of the conditioning activity on the subsequent task. The concept of the RAMP warm-up is well known and utilises a variety of similar exercise to potentiate athletes prior to maximal competition or training (Van den Tillaar, Lerberg and von Heimburg, 2019). Where this thesis diverges from the standard RAMP protocol is attempting providing evidence that an activity, like a vertical jump can potentiate the same subsequent activity as effectively as a range of similar conditioning tasks. Vertical power is an important attribute to athletic performance. If athletes and coaches are presented with a method to improve vertical jump performance without the use of external resistance equipment, while using a simple approach which is easy to administer with minimal negative effects, the benefit is evident. Researchers have shown that ballistic exercises can improve power-based activities. This evidence also highlights those ballistic tasks can produce an effect quickly (<5min) and with minimal negative consequences. The intensity and the specificity of the conditioning activity are important constituents in achieving PAP. There seems to be a general agreement that exercises which are similar in nature (Van den Tillaar et al., 2019) and intensity (Suchomel et al., 2016) provide a better response especially with the vertical jump. It is these components which this study investigated, with the purpose to expand the current pool of knowledge and broaden the existing parameters, with a view to translating to ‘real world’ applications. Postactivation potentiation using a maximal sprint to potentiate a maximal sprint. Sprinting, especially distances up to and including one hundred metres are almost exclusively anaerobic (Dufflield and Dawson, 2003), requiring high force production and rate of force development. Success or failure is measured in milliseconds, where even a partial enhancement could affect positioning, creating opportunities and success. There is a reasonable body of research; exclusively with individual athletes, to suggest that PAP could improve realistic competitive performances (Karampatsos et al., 2013; Karampatsos et al., 2017). The guidelines for PAP exist in narrow parameters with most studies suggesting individualisation of the conditioning activities to achieve the desired effect while the effects associated with team sports are as yet unavailable in competition and limited to isolated 14 testing scenarios in training (Tobin and Delahunt, 2014). Smith et al. (2014) attempted to potentiate athletes with loaded sled pulls over 20 m accelerations with some success, however the unloaded sled also showed significant benefits. This indicates that high intensity running without excess weight; less than 10% body weight, may achieve similar benefits observed in high intensity weighted runs with up to three times body weight. Turner et al. (2015) demonstrated how bodyweight bounding; a similar action to high intensity running (Young, 1992), acutely enhanced 10 m and 20 m sprint performance. This study compared two interventions against a control condition. One group performed bounding while the second group performed bounding with a weighted vest at 10% of the participants’ bodyweight. Both groups improved compared to the control. However, the bodyweight group showed improvement between two and four minutes while the weighted vest group only showed maximal improvement by eight minutes post intervention. Notable in this study is that a horizontal bias conditioning intervention in both weighted and bodyweight effected a positive change in a horizontal bias outcome measurement (maximal sprint). Issues pertaining to the study revolve around the application of multiple time points for outcome measurements. This effectively means that the latter results could not be directly attributed to the interventions as the participants have been exposed to earlier testing which may enhance or decrease the subsequent outcomes. Regardless, this does provide some evidence on the benefits of maximal intensity and specific conditioning activities on similar outcome measures. If athletes can achieve similar potentiated effects using simpler conditioning activities, then the benefit is evident. Van den Tillaar, Lerberg and von Heimburg, (2019) investigated the effect of a slower warm-up involving dynamic exercises and jogging to a similar warm-up with increasing intensity sprinting. The investigators intended to investigate whether the duration of the warm-up or the intensity and specificity of the warm-up was more influential in improving the outcome of a subsequent sprint. The outcome suggested that the longer, less specific warm-up had less influence on the sprint performance when compared to the longer specific and shorter specific warm-ups. Both involved a gradual increase in the velocity of the final warm-up runs culminating in a maximal effort prior to the outcome measurement. It was also reported that the participant’s perceived exertion was significantly less after the shorter specific warm-up compared to the longer specific warm-up. This is important as it highlights 15 the importance of developing warm-up practices which athletes are more likely to adopt and that potentially allow time to focus on other important aspects of the warm-up such as technical or tactical skills in team sports. The higher velocity warm-up showed significantly greater improvements over the timed distance. Watterdal (2013) exposed participants to a longer warm-up of 35 minutes which consisted of five maximal sprints prior to a 60 m sprint outcome measurement and a shorter warm-up of ten minutes with a single maximal sprint. A control condition was also included. Although no significant difference was found between the groups, possibly due to the small sample size (n=5), the result demonstrated that most of the participants ran the quickest 60 m following the shorter warm-up. The author discusses that the longer warm-up may induce fatigue prior to the outcome measurement. However, this does provide some indication that a maximal horizontal effort as part of a warm-up may be able to induce a PAP effect in a subsequent horizontal bias task, in this case sprinting. The participants also reported their satisfaction with each of the warm-ups and there was a clear approval rating of 6.9/10 for the shorter warm-up compared to a 5.9/10 for the longer warm-up and less for the control condition. This highlights that athletes may prefer to have a warm-up that is not only effective but also simple to implement which is perceived as not interfering with the competition or training preparation. The possibility that an athlete has the potential to compete at an elevated state of activation or to achieve a greater training stimulus drives PAP research forward. Silva et al. (2018) found that sprints at the end of a warm-up possibly improves athletic performance by 2-3% which is in line with the reported benefits of PAP using ballistic exercises (Creekmur et al., 2017). The challenge is to achieve these benefits within reasonable warm-up time frames. By using highly fatiguing or excessively long conditioning activities, the less likely athletes will incorporate these with their competition preparations. As PAP exists in narrow parameters, it is important that researchers challenge the current understanding and expand the pool of knowledge to make PAP a useful competition adjunct. PAP needs clear parameters and simple processes for athletes to achieve the benefits, while remaining in a state of focus prior to the event. 16 In many sports, athletic potential is related to one’s ability to run fast. Where this thesis diverges for the standard warm-up protocol is providing evidence that an activity, such as a maximal sprint or vertical jump can potentiate the same subsequent activity as effectively and slightly better than a range of similar conditioning tasks. As this fall within the warm- up paradigm, it is understandable to consolidate these PAPE conditioning activities into this phase. However, as the sprint precedes the specific intent of undertaking a maximal sprint, then I would classify them as a conditioning activity. Many other factors influence an athlete’s success especially in a team sport setting. However, if a certain strategy can assist in acutely affecting an athlete’s performance outcomes with minimal effort, facilities, or time constraints, it seems worth considering. The evidence points to shorter, more specific, more intense warm-ups being preferred by athletes. It is also clear that doing more to induce a positive change may also be detrimental. This study intends to investigate the link between specificity and intensity with a participant’s ability to produce an enhanced outcome, specifically by using a sprint to potentiate a subsequent sprint. Conclusion Postactivation potentiation is a principle which suggests that an athlete can acutely enhance the potential of a subsequent task by undertaking some form of conditioning activity. This review has discussed the traditional approach to producing a PAP effect using heavy resistance training and has discussed why this is impractical in a ‘real world’ competition environment. The review highlighted the some of the potential benefits which ballistic type exercises hold in producing a full or partial PAP response. Along with requiring less equipment, space and time it was also preferred in many cases by the athletes themselves. It is for this reason that these studies will investigate whether ballistic tasks such as a vertical jump, a sprint or another sports specific conditioning activity can potentiate a similar subsequent task and whether this is a viable and practical intervention to introduce to coaches and athletes as part of their warm-ups in a ‘real world’ competition and training environment. Aims and objectives of the thesis. 17 This thesis aimed to provide an alternative, practical coaching solution for athletes to achieve PAP simply and quickly in a training and competition environment. Specifically, the thesis determined whether bodyweight, ballistic tasks can be used as conditioning activities to achieve PAP. Three studies were performed. Study one and study two used a randomised controlled trial methodology to investigate whether a vertical and horizontal bias bodyweight conditioning activity can affect an outcome measurement of a similar subsequent activity. This allowed for a comparison of not only the outcome measurement within the group relative to a baseline measurement but also between the groups, as a control condition was used. It was also important to determine the magnitude of the outcome. This was done firstly by introducing a third group which undertook an intervention previously investigated and shown to have a PAP benefit and secondly determined the effect size associated with both interventions compared to the control condition. The results were not only reliable as strong scientific rigour was applied but also valid. Study three used a systematic review and meta-analysis to investigate the effect of using a bodyweight conditioning activity and included the results obtained from study one and study two. This included strict inclusion criteria and followed the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines to evaluate these studies and other studies to synthesise and summarise the results. Aim To determine if bodyweight conditioning activities similar in type and intensity to the subsequent task result in a PAP response Objectives • To assess whether a maximal vertical jump can potentiate a subsequent vertical jump. • To assess whether a maximal sprint effort can potentiate a subsequent sprint effort. • To analyse the available data on PAP using bodyweight tasks through a systematic review and meta-analysis. • To make recommendations for the application of PAP in a ‘real world’ sporting environment. 18 References 1. Blazevich, A.J. and Babault, N., (2019). Post-activation Potentiation (PAP) versus Post- activation Performance Enhancement (PAPE) in Humans: Historical Perspective, Underlying Mechanisms, and Current Issues. Frontiers in physiology, 10, p. 1359. 2. Borba, D.d.A., Ferreira-Júnior, J.B., Santos, L.A.d., Carmo, M.C.d. and Coelho, L.G.M., (2017). Effect of post-activation potentiation in Athletics: a systematic review. Revista Brasileira de Cineantropometria & Desempenho Humano, 19(1), pp. 128-138. 3. Burkett, L.N., Phillips, W.T. and Ziuraitis, J., (2005). The best warm-up for the vertical jump in college-age athletic men. The Journal of Strength & Conditioning Research, 19(3), pp. 673-676. 4. Creekmur, C.C., Haworth, J.L., Cox, R.H. and Walsh, M.S., (2017). Effects of plyometrics performed during warm-up on 20 and 40 m sprint performance. J Sports Med Phys Fitness, 57(5), pp. 550-555. 5. Cuenca-Fernandez, F., Smith, I.C., Jordan, M.J., MacIntosh, B.R., Lopez-Contreras, G., Arellano, R. and Herzog, W., (2017). Nonlocalized postactivation performance enhancement (PAPE) effects in trained athletes: a pilot study. Applied Physiology Nutrition and Metabolism, 42(10), pp. 1122-1125. 6. Desmedt, J.E. and Godaux, E., (1977). Ballistic contractions in man: characteristic recruitment pattern of single motor units of the tibialis anterior muscle. The Journal of physiology, 264(3), pp. 673-693. 7. Dobbs, W.C., Tolusso, D.V., Fedewa, M.V. and Esco, M.R., (2019). Effect of Postactivation Potentiation on Explosive Vertical Jump: A Systematic Review and Meta-Analysis. J Strength Cond Res, 33(7), pp. 2009-2018. 8. Dufflield, B. and Dawson, B., (2003). Energy system contribution in track running. New Studies in Athletics, 18(4), pp. 47-56. 19 9. Hamada, T., Sale, D., MacDougall, J. and Tarnopolsky, M., (2003). Interaction of fibre type, potentiation and fatigue in human knee extensor muscles. Acta physiologica scandinavica, 178(2), pp. 165-173. 10. Healy, R. and Comyns, T.M., (2017). The Application of Postactivation Potentiation Methods to Improve Sprint Speed. Strength and Conditioning Journal, 39(1), pp. 1-9. 11. Hilfiker, R., Hubner, K., Lorenz, T. and Marti, B., (2007). Effects of drop jumps added to the warm-up of elite sport athletes with a high capacity for explosive force development. Journal of Strength and Conditioning Research, 21(2), pp. 550-555. 12. Hodgson, M., Docherty, D. and Robbins, D., (2005). Post-activation potentiation - Underlying physiology and implications for motor performance. Sports Medicine, 35(7), pp. 585-595. 13. Karampatsos, G., Terzis, G., Polychroniou, C. and Georgiadis, G., (2013). Acute effects of jumping and sprinting on hammer throwing performance. Journal of Physical Education & Sport, 13(1), pp. 3-5. 14. Karampatsos, G.P., Korfiatis, P.G., Zaras, N.D., Georgiadis, G.V. and Terzis, G.D., (2017). Acute effect of countermovement jumping on throwing performance in track and field athletes during competition. The Journal of Strength & Conditioning Research, 31(2), pp. 359-364. 15. Kilduff, L.P., Finn, C.V., Baker, J.S., Cook, C.J. and West, D.J., (2013). Preconditioning Strategies to Enhance Physical Performance on the Day of Competition. International Journal of Sports Physiology & Performance, 8(6), pp. 677-681. 16. Lim, J.J. and Kong, P.W., (2013). Effects of isometric and dynamic postactivation potentiation protocols on maximal sprint performance. J Strength Cond Res, 27(10), pp. 2730-2736. 17. Maloney, S.J., Turner, A.N. and Fletcher, I.M., (2014). Ballistic exercise as a pre- activation stimulus: a review of the literature and practical applications. Sports Med, 44(10), pp. 1347-1359. 20 18. Masamoto, N., Larson, R., Gates, T. and Faigenbaum, A., (2003). Acute effects of plyometric exercise on maximum squat performance in male athletes. The Journal of Strength & Conditioning Research, 17(1), pp. 68-71. 19. Mola, J.N., Bruce-Low, S.S. and Burnet, S.J., (2014). Optimal recovery time for postactivation potentiation in professional soccer players. J Strength Cond Res, 28(6), pp. 1529-1537. 20. Nardone, A., Romano, C. and Schieppati, M., (1989). Selective recruitment of high‐ threshold human motor units during voluntary isotonic lengthening of active muscles. The Journal of physiology, 409(1), pp. 451-471. 21. Nardone, A. and Schieppati, M., (1988). Shift of activity from slow to fast muscle during voluntary lengthening contractions of the triceps surae muscles in humans. The Journal of physiology, 395(1), pp. 363-381. 22. Prieske, O., Maffiuletti, N.A. and Granacher, U., (2018). Postactivation Potentiation of the Plantar Flexors Does Not Directly Translate to Jump Performance in Female Elite Young Soccer Players. Frontiers in Physiology, 9. 23. Rassier, D. and Macintosh, B., (2000). Coexistence of potentiation and fatigue in skeletal muscle. Brazilian Journal of Medical and Biological Research, 33(5), pp. 499-508. 24. Russell, M., West, D.J., Harper, L.D., Cook, C.J. and Kilduff, L.P., (2015). Half-Time Strategies to Enhance Second-Half Performance in Team-Sports Players: A Review and Recommendations. Sports Medicine, 45(3), pp. 353-364. 25. Sale, D.G., (2002). Postactivation potentiation: role in human performance. Exercise and sport sciences reviews, 30(3), pp. 138-143. 26. Seitz, L. and Haff, G., (2016). Factors Modulating Post-Activation Potentiation of Jump, Sprint, Throw, and Upper-Body Ballistic Performances: A Systematic Review with Meta-Analysis. Sports Medicine, 46(2), pp. 231-240. 27. Sharma, S.K., Raza, S., Moiz, J.A., Verma, S., Naqvi, I.H., Anwer, S. and Alghadir, A.H., (2018). Postactivation Potentiation Following Acute Bouts of Plyometric versus 21 Heavy-Resistance Exercise in Collegiate Soccer Players. Biomed Res Int, 2018, p. 3719039. 28. Silva, L.M., Neiva, H.P., Marques, M.C., Izquierdo, M. and Marinho, D.A., (2018). Effects of warm-up, post-warm-up, and re-warm-up strategies on explosive efforts in team sports: A systematic review. Sports Medicine, 48(10), pp. 2285-2299. 29. Smith, C.E., Hannon, J.C., McGladrey, B., Shultz, B., Eisenman, P. and Lyons, B., (2014). The effects of a postactivation potentiation warm-up on subsequent sprint performance. Human Movement, 15(1), pp. 33-41. 30. Suchomel, T.J., Sato, K., DeWeese, B.H., Ebben, W.P. and Stone, M.H., (2016). Potentiation effects of half-squats performed in a ballistic or nonballistic manner. Journal of strength and conditioning research, 30(6), pp. 1652-1660. 31. Till, K.A. and Cooke, C., (2009). The effects of postactivation potentiation on sprint and jump performance of male academy soccer players. J Strength Cond Res, 23(7), pp. 1960-1967. 32. Tillin, N.A. and Bishop, D., (2009). Factors Modulating Post-Activation Potentiation and its Effect on Performance of Subsequent Explosive Activities. Sports Medicine, 39(2), pp. 147-166. 33. Tobin, D.P. and Delahunt, E., (2014). The acute effect of a plyometric stimulus on jump performance in professional rugby players. J Strength Cond Res, 28(2), pp. 367-372. 34. Turner, A.N., (2009). Training for power: Principles and practice. Professional Strength & Conditioning, (14), pp. 20-32. 35. Turner, A.P., Bellhouse, S., Kilduff, L.P. and Russell, M., (2015). Postactivation potentiation of sprint acceleration performance using plyometric exercise. J Strength Cond Res, 29(2), pp. 343-350. 36. Van Cutsem, M., Duchateau, J. and Hainaut, K., (1998). Changes in single motor unit behaviour contribute to the increase in contraction speed after dynamic training in humans. The Journal of physiology, 513(1), pp. 295-305. 22 37. Van den Tillaar, R., Lerberg, E. and von Heimburg, E., (2019). Comparison of three types of warm-up upon sprint ability in experienced soccer players. Journal of Sport and Health Science. 8(6), pp. 574-578. 38. Vandenboom, R., (2011). Modulation of skeletal muscle contraction by myosin phosphorylation. Comprehensive Physiology, 7(1), pp. 171-212. 39. Vandervoort, A., Quinlan, J. and McComas, A., (1983). Twitch potentiation after voluntary contraction. Experimental neurology, 81(1), pp. 141-152. 40. Wakeling, J.M., (2009). Patterns of motor recruitment can be determined using surface EMG. Journal of Electromyography and Kinesiology, 19(2), pp. 199-207. 41. Watterdal, Ø., (2013). The impact of warm up intensity and duration on sprint performance. 42. Wilson, J.M., Duncan, N.M., Marin, P.J., Brown, L.E., Loenneke, J.P., Wilson, S.M., Jo, E., Lowery, R.P. and Ugrinowitsch, C., (2013). Meta-analysis of postactivation potentiation and power: effects of conditioning activity, volume, gender, rest periods, and training status. The Journal of Strength & Conditioning Research, 27(3), pp. 854- 859. 43. Young, W., (1992). Sprint bounding and the sprint bound index. NSCA J, 4(6), pp. 44- 44. 44. Zimmermann, H.B., MacIntosh, B.R. and Dal Pupo, J., (2020). Does postactivation potentiation (PAP) increase voluntary performance? Applied Physiology Nutrition and Metabolism, 45(4), pp. 349-356. 22 CHAPTER 2 – Study one: Brink N, Constantinou D, and Torres G (2021) Postactivation performance enhancement (PAPE) of sprint acceleration performance, European Journal of Sports Science. DOI: 10.1080/17461391.2021.1955012 (published) At the time of this thesis submission, study one was published in the European Journal of Sports Science, as an original article (Appendix 9). The original content has not been altered but figures, tables, and captions as well as referencing style have been adapted and are presented in line with the thesis format. Postactivation performance enhancement (PAPE) will be used in this study to refer to an acute bout of high intensity voluntary exercise followed by an enhancement in strength, speed or power production. 23 1. Original study Title: Postactivation performance enhancement (PAPE) of sprint acceleration performance Authors: Nicholas Brink, Demitri Constantinou, Georgia Torres Abstract Postactivation performance enhancement (PAPE) is a principle that an acute bout of high intensity voluntary exercise is followed by an enhancement in strength, speed, or power production. As an integral part of the warm-up, this study intended to show a direct correlation between intensity, specificity, and the outcome of a maximal task of sprint accelerations compared to a previously defined weighted plyometric intervention. In a randomised controlled, double-blind trial, adult professional footballers undertook 20 m maximal sprint accelerations at a baseline and at two and six minutes post-intervention after one of three interventions; two repetitions of 20 m sprint accelerations (S), 3x10 alternative leg weighted bounding (P) and control (C). All the baseline outcomes were similar between the groups. Relative to the baseline there was a significant improvement for S over 10 m and 20 m at two minutes of 0.12 m.s-1 and 0.11 m.s-1 and at six minutes of 0.11 m.s-1 and 0.12 m.s-1. Relative to the baseline P also had a significant improvement over 10 m and 20 m at two minutes 0.09 m.s-1 and 0.09 m.s-1 and at six minutes of 0.11 m.s-1 and 0.09 m.s-1 There was also a significant improvement in C between two and six minutes post-intervention at 10 m and 20 m of 0.06 m.s-1 and 0.08 m.s-1. There was no significant difference between the interventions and C. This finding suggests that a maximal sprint acceleration may enhance the outcome of a subsequent maximal sprint acceleration at two minutes, but the latter results could not be directly attributed to the interventions as previous testing is likely to have influenced these outcomes. Key words: PAPE; intensity; PAP; specificity; plyometric; sprinting. 24 Introduction Sprinting requires a high rate of force production that is linked to acceleration, speed, change of direction and power and relates directly to training effect and competition outcomes (Colyer et al., 2018; van den Tillaar et al., 2019). The warm-up plays an important role in enhancing or diminishing this desired effect so even small deviations; especially evident in isolated sprinting events, can influence success or failure (Gil et al., 2019). When preparing for maximal exertion, maximal sprinting is often incorporated as the apex of the warm-up sequence (Silva et al., 2018). There is evidence that high velocity, high intensity tasks at the end of a warm-up can acutely enhance an athletes’ potential which exceeds the enhancement attained by a submaximal warm-up alone (van den Tillaar et al., 2019). In this study, postactivation potentiation (PAP) will refer to enhancements in muscle twitch response while postactivation performance enhancement (PAPE) will refer to an acute bout of high intensity voluntary exercise followed by an enhancement in strength, speed or power production (Blazevich and Babault, 2019; Zimmermann et al., 2020). Postactivation performance enhancement is a physical training principle which proposes that a muscle can be acutely optimised by its contractile history, which in turn affects the outcome of a subsequent task (Hodgson et al., 2005; Lorenz, 2011). There is a plethora of evidence linking heavy resistance training (HRT) with a PAPE response using a heavy resistance isotonic preload stimulus (75-90% 1RM) to achieve this enhanced state (Hodgson et al., 2005; Matthews et al., 2004; Wilson et al., 2013). Although HRT has shown effective results, the nature of heavy lifting constrains coaches and athletes to use equipment and requires individualised time frames to dispel the associated fatigue consequence, making this strategy impractical in a training and competitive environment (Wilson et al., 2013). These effects are untested in a competition environment especially in team sports and limited to isolated testing scenarios in training (Bevan et al., 2010; Tobin and Delahunt, 2014). The guidelines for PAPE using HRT exist within narrow parameters with a high proportion of non-responders prompting cautionary recommendations from investigators to individualise the delay times after the conditioning activity (CA) to achieve the desired effect (Wilson et al., 2013). However, there seems to be a proportional association between the specificity and the intensity of the CA and PAPE which has been similarly defined in many warm-up practices (Burkett et al., 2005; Russell et al., 2015; van den Tillaar et al., 2019). This concept suggests that athletes could optimize prior to performing a maximal activity by using a CA similar in nature and intensity to the expected outcome (Suchomel et al., 2017). 25 There is a growing interest in the PAPE effects elicited by ballistic movements and plyometrics. By utilising high velocity, high power movements, the larger muscle fibers can theoretically be recruited extremely quickly, underpinning the success seen with plyometrics and PAPE (Maloney et al., 2014). Although much of the research associated with PAPE and plyometrics involves a weighted CA, (Piper et al., 2020) unweighted activities have also shown improvements (Turner et al., 2015). Research suggests that using an unweighted CA very similar to the final task can enhance performances within specific populations as much as a comparable weighted CA (Smith et al., 2014). Karampatsos et al. (2013; 2017) observed that field event athletes achieved significantly greater throw distances 1 minute after a 20 m sprint at maximal effort in training. Sharma et al (2018) showed that multiple unweighted plyometric tasks had a greater effect on a 20 m sprint performance compared to that of HRT, suggesting that unweighted plyometrics may play an important role in acutely enhancing muscle tissue, a concept reiterated by Creekmur et al. (2017). Smith et al. (2014) found that unloaded sled pull improved athletes 20 m sprint times as much as weighted sled pulls. This indicates that high intensity running without excess weight may have similar benefits to high intensity weighted runs. Turner et al. (2015) demonstrated how body-weighted bounding; an action similar to high intensity running (Young, 1992) acutely enhanced 10 m and 20 m sprint accelerations. Common aspects associated with PAPE seem to include the specificity to the outcome task and the intensity of the CA. Coaches would closely emulate the tasks and skills required in competition within the warm-up phase to affect this specificity principle. There is a positive performance correlation between a sport and its warm-up processes (Russell et al., 2015). Similarly, a common theme relating to the effectiveness of PAPE, is how closely the CA relates to the outcome task (Till and Cooke, 2009). Van den Tillaar et al. (2019) found that specificity is an important constituent in the development of an enhanced outcome. A warm- up with activities similar to the subsequent task were used with significant benefit compared to an alternate non-specific warm-up. Van den Tillaar et al. (2019) also investigated the effect of a slower warm-up involving dynamic exercises and jogging to a similar warm-up with increasing intensity sprinting. The higher velocity warm-up showed significantly greater improvements over the timed distance. Silva et al. (2018) found that sprints at the end of a warm-up improves athletic performance by 2-3% which is in line with the reported benefits of PAPE using plyometrics (Creekmur et al., 2017) 26 This study intended to demonstrate how a CA similar in specificity and intensity to a sprint acceleration could be used to improve a subsequent sprint acceleration over 10 m and 20 m. It was hypothesised that this sprint acceleration intervention would improve a subsequent sprint acceleration as much as a previously defined weighted, plyometric PAPE intervention, and more than that of a control group. Methods Study design A randomised, double-blinded controlled study design was used to compare the effects of a maximal sprint accelerations in relation to a weighted plyometric activity and a control condition on the outcome of 20 m sprint accelerations. Although a crossover design might have been better, testing professional athletes can be a challenging undertaking due to their hectic training and match schedule allowing for a small window of opportunity. For this reason, a single testing session was selected. Ethics approval for the study was granted by the University of the Witwatersrand’s Human Research Ethics Committee (Medical) (approval number M190623). Participants and sampling Male, professional soccer players were invited to participate in this study from the first and reserve squad linked to a team in South Africa’s Premier Soccer League (age: 24 ± 5 years; mass: 69.2 ± 9.8 kg; height: 1.74 ± 0.06 m; relative squat strength [absolute squat strength/body mass]: 1.85 ± 0.19). The participants were invited on the basis that they were match fit and in full training participation. Seventy-two participants consented to participate in the study, with three participants excluded based on being unfit to train. The remaining (n=69) participants were randomly and uniformly allocated to either; the sprint acceleration group (S), the plyometric group (P) or the control group (C) by an independent assessor to prevent selection bias. All the participants were informed about the study parameters but were blinded to the study’s objectives to prevent bias and signed a consent document to acknowledge this. A minimum sample of 69 (effect size = 0.54, power = 0.95 and significance level = 0.05); was determined from a sample size calculation using G∗Power software (version 3.1.9.2; Heinrich-Heine-Universität Dusseldorf, Germany), effect size specification as in Cohen (1988) and the sprint velocity over 20 m influenced by time x condition interaction from Turner et al (Turner et al., 2015). 27 Procedures All participants had height in meters (Charder, portable height measure unit; Fizique, Johannesburg, RSA) and mass in kilograms (Charder, electric scale; Fizique, Johannesburg, RSA) measurements recorded prior to the testing. Testing occurred 48-hours after the most recent training session. Each randomised group was separated from the other groups allowing for blinding to the different interventions. A designated member of the coaching staff (UEFA A-licensed), familiar with the testing procedure was selected to administer the warm-up, intervention, pre- and post-intervention testing. He was instructed by the primary investigator on the procedures but not informed of the objectives of the study allowing for blinding to prevent bias. Participants reported to training as normal and undertook a standardised preparation football warm-up of approximately 20 minutes consisting of jogging, dynamic stretching, body preparation exercise, submaximal sprints; up to ~90%, submaximal plyometrics and six vs two, five minute rondos (small-sided possession games). The warm-up and testing occurred on a football pitch, with football boots which the participants were accustomed to using. After the warm-up, the participants progressed to the maximal baseline testing; 2 x 20 m pre-intervention sprint accelerations, with timing gates at the start, 10 m, and 20 m. This was followed by low intensity ball related games (head tennis) for 20 minutes to maintain an estimated elevated body temperature but expel any potential PAPE effects accrued during the baseline testing (Maloney et al., 2014). After 20 minutes S, P and C performed their individual interventions. Intervention To account for the possible PAPE and fatiguing consequences of the intervention testing, C participated in the pre-intervention testing and the post-intervention testing while omitting the intervention. A 20 minute period between the pre-intervention testing and the intervention was used to ensure that any PAPE effects incurred during the pre-intervention testing were completely dispelled prior to performing the interventions, a consequence not previously discussed in previous studies (Vandenboom, 2011; Turner et al., 2015). The S group participants performed two maximal sprint accelerations over 20 m at 95% or above of their baseline maximum to account for specificity and intensity. The P group 28 participants undertook 3 sets of 10 weighted alternative leg bounds as defined by Turner et al. (2015) using 10% body mass weighted vests (Fit for Life, adjustable weighted vest; Fizique, Johannesburg, RSA). It is worth noting that the investigators used this intervention exactly as described by Turner et al. (2015), however the pre- and post-intervention protocol differed allowing for this studies objectives to be investigated. The C group participants continued to walk during the intervention period to maintain estimated elevated muscle temperature. The total time for intervention period was ∼90 sec and was comparable between all participants. Following the interventions, the participants completed two maximal sprints accelerations at two and six minutes respectively post-intervention (Gołaś et al., 2016). Participants completed the four post-intervention test sprint accelerations with the aim to achieve the best outcome. Measurements The sprint accelerations were measured using speed gates (Fusion Sport, SmartSpeed, v.1.5.2) at 0 m, 10 m, and 20 m. The participants started 0.3 m behind the first gates (Russell et al., 2015) on their own time following a ready command. They were instructed to sprint with maximal effort past the final gate. The participants performed two maximal sprints at the pre-intervention and post-intervention tests with the goal of achieving the fastest outcome. The sprint acceleration intervention was compared to the baseline to assess for intensity as one of the highly influential factors in achieving PAPE. The S group participants who did not achieve 95% or above of the baseline testing during the intervention testing were recorded and compared to the within group participants who achieve 95% or above compared to the pre-intervention testing. Statistical analysis Statistical analysis was performed using SPSS software (Version 26; SPSS, Inc, Chicago, IL, USA). The data were tested for normality using the Shapiro-Wilk test. The data are presented as a mean ± standard deviation. A 3x3 mixed design analysis of variance with a within-between interaction was used to investigate the 10 and 20 m sprint accelerations. The between group factor being the groups (S, P and C) and the within subject factor being time (pre-intervention, two minutes post-intervention and six minutes post-intervention). Mauchly’s test was consulted and Greenhouse-Geisser correction was applied if sphericity was violated. Significant main events observed in the within subject factor for each time 29 point was compared to the baseline and were investigated further with a Bonferroni pairwise comparison. Where significant p values were identified for the interaction effect (time x group), posthoc testing used Cohen’s d for each pairwise comparison. The magnitude of effect size was evaluated and considered trivial (<0.2), small (0.2–0.50), moderate (0.50– 0.80), and large (>0.80) as proposed by Cohen. Individual performances were recorded and monitored for significant differences from before and after the CA as well as the percentage of individuals who displayed change. A paired t test was used to compare the baseline and the sprint intervention. The level of significance was set at p < 0.05. Results The mean ± SD values for the between and within group results are reported in table 1. The pre-intervention baseline testing also showed good test-retest reliability of (0.81) and (0.85) for 10 and 20 m, respectively. The 20 m sprint acceleration was influenced by a significant interaction between time x group, (F4, 132 = 3.19, p < 0.05, partial η2 = 0.09) and time (F2, 132 = 23.76, p < 0.001, partial η2 = 0.27). There was no significant difference between the groups at baseline (p = 0.894) and the control group did not change between the intervention. Relative to the baseline there was a significant difference for S (F2, 44 = 20.14, p < 0.001, partial η2 = 0.49), at two minutes (6.73 m.s-1 ± 0.19, p < 0.001) and six minutes (6.73 m.s-1 ± 0.19, p < 0.001) and for P (F2, 44 = 6.61, p = 0.003, partial η2 = 0.23) at two minutes (6.73 m.s-1 ± 0.15, p = 0.038) and six minutes (6.74 m.s-1 ± 0.17, p < 0.001) over 20 m. Although C showed no mean difference between the pre-intervention baseline and post intervention at two minutes, there was a significant mean difference between two minutes post- intervention and six minutes post-intervention (6.71 m.s-1 ± 0.17, p = 0.003). There was no significant difference between the groups at any time point. However, S and P were 1.47% and 1.44% faster than C at two minutes, respectively. Table 1. Sprint velocity over 20 m mean ± SD values. Groups Pre-intervention baseline Post-intervention two minutes Post-intervention six minutes 20 m sprint velocity (m.s-1) Sprint Plyometric 6.62 ± 0.15 6.63 ± 0.13 6.73 ± 0.19* 6.73 ± 0.15* 6.73 ± 0.19* 6.74 ± 0.17* 30 Control 6.64 ± 0.15 6.63 ± 0.16 6.71 ± 0.17† p-value (ES) ES assessment Sprint compared to control 1.00 (0.13) Trivial >0.05 (0.57) Moderate 1.00 (0.11) Trivial p-value (ES) ES assessment Plyometric compared to control 1.00 (0.07) Trivial >0.05 (0.64) Moderate 1.00 (0.17) Trivial * Significantly different from pre-intervention baseline, ES = Effect size, p-value = significant level. † Significantly different from post-intervention time point two minutes. No significant between group differences observed. The mean ± SD values for the between and within group results are reported in table 2. The 10 m sprint acceleration was influenced by a significant interaction between time and group, (F4, 132 = 2.53, p < 0.05, partial η2 = 0.07) and time (F2, 132 = 22.07, p < 0.001, partial η2 = 0.25). There was no significant difference between the groups at baseline (p = 0.776) and the control group did not change between the intervention. Relative to the baseline there was a significant difference for S (F2, 44 = 16.40, p < 0.001, partial η2 = 0.43), at two minutes (5.82 m.s-1 ± 0.17, p = 0.001) and six minutes (5.80 m.s-1 ± 0.18, p < 0.001) and P (F2, 44 = 6.02, p = 0.005, partial η2 = 0.22) at two minutes (5.81 m.s-1 ± 0,15 p < 0.05) and six minutes (5.81 m.s-1 ± 0.16, p < 0.05) over 10 m. Although C showed no mean difference between the pre-intervention baseline and post intervention at time point two minutes, there was a significant mean difference between two minutes post-intervention and six minutes post- intervention (5.80m.s-1 ± 0.16, p < 0.05). There was no significant difference between the groups at any time point. However, S and P were 1.44% and 1.22% faster than C at two minutes, respectively. Table 2. Sprint velocity over 10 m mean ± SD values. Groups Pre-intervention baseline Post-intervention two minutes Post-intervention six minutes 10 m sprint velocity (m.s-1) Sprint Plyometric Control 5.70 ± 0.15 5.72 ± 0.11 5.72 ± 0.15 5.82 ± 0.17* 5.81 ± 0.15* 5.74 ± 0.14 5.80 ± 0.18* 5.81 ± 0.16* 5.80 ± 0.16† 31 p-value (ES) ES assessment Sprint compared to control 1.00 (0.13) Trivial >0.05 (0.51) Moderate 1.00 (0.17) Trivial p-value (ES) ES assessment Plyometric compared to control 1.00 (0.09) Trivial >0.05 (0.48) Small 1.00 (0.06) Trivial * Significantly different from pre-intervention baseline, ES = Effect size, p-value = significant level. † Significantly different from post-intervention time point two minutes. No significant between group differences observed. Eighteen (78%) and 19 (83%) of the 23 participants in S did their fastest 10 m sprint acceleration at two and six minutes respectively, while 20 (87%) of the participants did their fastest 20 m sprint acceleration at two and six minutes compared to their baseline sprint acceleration. All 23 participants within this group achieved > 95% of the baseline velocity during the intervention over both the 10 m and 20 m. There was no significant difference between the baseline velocity and the intervention velocity in S over 10 m (p = 0.23) or 20 m (p = 0.22) Discussion The outcome of this study supports the hypothesis that a maximal sprint acceleration intervention may improve the outcome of a subsequent maximal sprint acceleration. When compared to a previously tested PAPE effect (Turner et al., 2015); using a weighted plyometric intervention, the sprint acceleration group showed improvements in sprint velocity within a similar range over two and six minutes post-intervention. Furthermore, following a standardised football warm-up, some improvements were observed following a maximal sprint acceleration intervention compared to no intervention. Although this between group outcome was not significant, a medium effect size of d = 0.57 and 0.51 for 20 m and 10 m was found at two minutes between group S and group C indicating a moderate difference in magnitude. Group C demonstrated a significant improvement during the post- intervention testing between two and six minutes. Additionally, groups S and P significantly improved their within group times relative to their baselines. This shows that a maximal sprint acceleration intervention may improve the outcome of a subsequent maximal sprint acceleration. 32 A sprint acceleration intervention can improve a subsequent sprint acceleration within two minutes and these improvements can be maintained for at least six minutes. However, these improvements at six minutes cannot be directly attributed to the intervention effect and may be influenced by the initial post-intervention testing evident in group C. This is an important consideration when preparing athletes for competition or training. Many studies have discussed the implication of the enhancement/fatigue factor with previous studies having shown a delay in this improvement especially after using a heavy CA (Hodgson et al., 2005; Matthews et al., 2004; Wilson et al., 2013). This is likely due to an initial heightened fatigue effect which is less evident when ballistic or plyometric CA’s were used (Sharma et al., 2018). This suggests that a heavier CA induces more fatigue and thus requires longer recovery until PAPE is reached. Studies assessing heavier CA’s; >75% 1RM, compared to plyometric CA’s have shown similar outcomes with marked differences in time between CA and maximal improvements (Maloney et al., 2014). Along with the cumbersome nature of using weights it is challenging to find out when the fatigue has dispelled and an athlete has achieved an enhanced state, linked to the individualisation of the PAPE effect. Most studies that use body weight or plyometric tasks compared to heavier CA’s show quicker recovery times post CA while in this study, neither S nor P showed diminished performance post- intervention (Maloney et al., 2014; Seitz and Haff, 2016). This has been demonstrated in previous studies where interventions like body weight activities; sprints, jumps and plyometric activities show quick improvements with minimal early fatiguing effects, while more weighted the interventions, the longer the period between diminished performance to the enhancement (Seitz and Haff, 2016; Wilson et al., 2013). Blazevich and Babault, (2019) suggest that using a submaximal warm-up results in the CA producing a more extreme PAPE effect while a maximal or complete warm-up prior to the CA tend to produce more varied outcomes. Large parts of the literature indicate that the warm-up processes for PAPE studies are submaximal (Smith et al., 2014; Sharma et al., 2018; Tobin and Delahunt, 2014), effectively allowing the testing and intervention to produce an exaggerated PAPE effect. Part of this study revealed that a standardised football warm-up is not sufficient to fully enhance athletes as indicated by their pre-intervention baseline sprint velocities compared to the post-intervention sprint velocities. It was only the 33 addition of the maximal intervention which allowed the participants to exceed the baseline level evident in the S and P. Group C who did not receive either intervention and were allowed ∼25 minutes to dispel any PAPE effects incurred during the pre-intervention testing had no significant change from the baseline to two minutes post-intervention. This study attempted to reduce any effect that baseline testing may have had on the subsequent results. The length of PAPE is reported in different studies as lasting anything up to 20 minutes post- intervention (Blazevich and Babault, 2019). This investigation attempted to reduce any PAPE effects from the pre-intervention baseline testing by allowing each group 20 minutes to dispel any fatigue and or enhanced effects incurred during the baseline testing. This coupled with the C group not participating in the intervention demonstrated that the intervention was directly attributed to the subsequent improvements observed in the S and P groups at two minutes. What was not initially considered was what effect the subsequent post-intervention testing would have on the next post-intervention test. The C group had a significant change post- intervention from two minutes post-intervention to six minutes post-intervention. This improvement was attributed to the testing impulse at two minutes as their previous impulse was ∼25 minutes previously allowing for sufficient time to dispel any PAPE effects which was highlighted in the pre-intervention baseline test and post-intervention test at two minutes, showing no significant difference. This indicates a maximal sprint acceleration at two minutes during post-intervention testing was sufficient in nature to achieve a PAPE state. This also suggests that the maintained enhancement for S and P between two minutes and six minutes post-intervention cannot be directly attributed to the intervention either and that the results during the second post-intervention testing were affected by the initial post- intervention testing. This shows that in this study the results at six minutes post-intervention cannot be directly attributed to the effect of the intervention and were also affected by the sprint acceleration at two minutes post-intervention. This makes previous findings questionable where multiple post-intervention tests are undertaken and suggests caution when reviewing literature where significant change is reported with multiple post- intervention testing scenarios administered. Future consideration needs to be given to the effect testing protocols have on subsequent testing protocols when investigating PAPE. 34 This study demonstrated that the majority (>75% over 10 m and >80% over 20 m) of the participants in S improved their velocity at the two and six minutes post-intervention compared to their pre-intervention baseline outcome. In contrast P showed an improvement in >65% of the participants over the same distances and time points. An unexpected outcome of this study was that approximately 75% of the participants in the C group showed significant improvements over both the 10 m and 20 m, between the two and six minutes post-intervention tests. This may suggest that within this population and this environment, more participants overall will elicit improvements doing a sprint acceleration rather than a weighted bounding intervention, up to six minutes post-intervention. This supports the claim that specificity and intensity may be highly influential in producing an early PAPE response in more participants within a group. Achieving this PAPE response may help to mitigate the individual response effect as even if some individuals are non-responders or partial responders the odds of this are reduced. Conclusion The findings of this study have important implications for coaches looking to take advantage of the PAPE conundrum. This study proposes that a sprint acceleration; specifically, two sets of 20 m maximal intensity runs, may induce a PAPE response in a subsequent maximal 10 m and 20 m maximal sprint acceleration at two minutes. The improvements observed from a sprint acceleration CA are of a similar magnitude to a weighted plyometric CA with a horizontal bias. Comparable to other plyometric CA’s utilizing body weight, sprint accelerations seem to exhibit immediate enhancements without the associated fatigue effects commonly observed with PAPE and HRT. Future consideration needs to be given to the effect testing protocols have on subsequent testing protocols when investigating PAPE. This format of inducing a PAPE response promotes a practical warm-up solution for athletes and coaches seeking to achieve performance enhancement without using laborious equipment, determining individual response times, or eliciting a dominant initial fatigue consequence. In conclusion the implementation of a CA or preload stimulus similar in nature and intensity to the subsequent task may be effective in delivering an enhancement to competitive athletes and teams. Acknowledgments 35 Funding No external funding was sourced for this study. Conflicts of interest The authors declare no conflict of interest. References 1. Bevan, H.R., Cunningham, D.J., Tooley, E.P., Owen, N.J., Cook, C.J. and Kilduff, L.P., (2010). Influence of postactivation potentiation on sprinting performance in professional rugby players. J Strength Cond Res, 24(3), pp. 701-705. 2. Blazevich, A.J. and Babault, N., (2019). Post-activation Potentiation (PAP) versus Post- activation Performance Enhancement (PAPE) in Humans: Historical Perspective, Underlying Mechanisms, and Current Issues. Frontiers in physiology, 10, p. 1359. 3. Burkett, L.N., Phillips, W.T. and Ziuraitis, J., (2005). The best warm-up for the vertical jump in college-age athletic men. The Journal of Strength & Conditioning Research, 19(3), pp. 673-676. 4. Colyer, S.L., Nagahara, R., Takai, Y. and Salo, A.I., (2018). Kinetic factors differentiating mid-to-late sprint acceleration performance in sprinters and soccer players. ISBS Proceedings Archive, 36(1), p. 674. 5. Creekmur, C.C., Haworth, J.L., Cox, R.H. and Walsh, M.S., (2017). Effects of plyometrics performed during warm-up on 20 and 40 m sprint performance. J Sports Med Phys Fitness, 57(5), pp. 550-555. 6. Gil, M.H., Neiva, H.P., Garrido, N.D., Aidar, F.J., Cirilo-Sousa, M.S., Marques, M.C. and Marinho, D.A., (2019). The Effect of Ballistic Exercise as Pre-Activation for 100 m Sprints. International Journal of Environmental Research and Public Health, 16(10). 7. Gołaś, A., Maszczyk, A., Zajac, A., Mikołajec, K. and Stastny, P., (2016). Optimizing post activation potentiation for explosive activities in competitive sports. J Hum Kinet, 52, pp. 95-106. 36 8. Hodgson, M., Docherty, D. and Robbins, D., (2005). Post-activation potentiation - Underlying physiology and implications for motor performance. Sports Medicine, 35(7), pp. 585-595. 9. Karampatsos, G., Terzis, G., Polychroniou, C. and Georgiadis, G., (2013). Acute effects of jumping and sprinting on hammer throwing performance. Journal of Physical Education & Sport, 13(1), pp. 3-5. 10. Karampatsos, G.P., Korfiatis, P.G., Zaras, N.D., Georgiadis, G.V. and Terzis, G.D., (2017). Acute effect of countermovement jumping on throwing performance in track and field athletes during competition. The Journal of Strength & Conditioning Research, 31(2), pp. 359-364. 11. Lorenz, D., (2011). Postactivation potentiation: An introduction. International journal of sports physical therapy, 6(3), p. 234. 12. Maloney, S.J., Turner, A.N. and Fletcher, I.M., (2014). Ballistic exercise as a pre- activation stimulus: a review of the literature and practical applications. Sports Med, 44(10), pp. 1347-1359. 13. Matthews, M.J., Matthews, H.P. and Snook, B., (2004). The acute effects of a resistance training warmup on sprint performance. Research in Sports Medicine, 12(2), pp. 151- 159. 14. Piper, A.D., Joubert, D.P., Jones, E.J. and Whitehead, M.T., (2020). Comparison of Post- Activation Potentiating Stimuli on Jump and Sprint Performance. International Journal of Exercise Science, 13(4), pp. 539-553. 15. Russell, M., West, D.J., Harper, L.D., Cook, C.J. and Kilduff, L.P., (2015). Half-Time Strategies to Enhance Second-Half Performance in Team-Sports Players: A Review and Recommendations. Sports Medicine, 45(3), pp. 353-364. 16. Seitz, L.B. and Haff, G.G., (2016). Factors Modulating Post-Activation Potentiation of Jump, Sprint, Throw, and Upper-Body Ballistic Performances: A Systematic Review with Meta-Analysis. Sports Med, 46(2), pp. 231-240. 17. Sharma, S.K., Raza, S., Moiz, J.A., Verma, S., Naqvi, I.H., Anwer, S. and Alghadir, A.H., (2018). Postactivation Potentiation Following Acute Bouts of Plyometric versus 37 Heavy-Resistance Exercise in Collegiate Soccer Players. Biomed Res Int, 2018, p. 3719039. 18. Silva, L.M., Neiva, H.P., Marques, M.C., Izquierdo, M. and Marinho, D.A., (2018). Effects of warm-up, post-warm-up, and re-warm-up strategies on explosive efforts in team sports: A systematic review. Sports Medicine, 48(10), pp. 2285-2299. 19. Smith, C.E., Hannon, J.C., McGladrey, B., Shultz, B., Eisenman, P. and Lyons, B., (2014). The effects of a postactivation potentiation warm-up on subsequent sprint performance. Human Movement, 15(1), pp. 33-41. 20. Suchomel, T.J., Comfort, P. and Lake, J.P., (2017). Enhancing the force-velocity profile of athletes using weightlifting derivatives. Strength & Conditioning Journal, 39(1), pp. 10-20. 21. Till, K.A. and Cooke, C., (2009). The effects of postactivation potentiation on sprint and jump performance of male academy soccer players. J Strength Cond Res, 23(7), pp. 1960-1967. 22. Tobin, D.P. and Delahunt, E., (2014). The acute effect of a plyometric st