A randomised controlled trial of physical activity and health messages on anthropometric and cardiometabolic outcomes amongst South African university professional staff

Abstract

Background: Physical inactivity among the adult population is increasing. The workplace is identified as an appropriate setting to promote physical activity. Emerging research suggests high-intensity interval training (HIIT) is time-efficient compared to the traditional moderate-intensity continuous training (MICT). Health messages intervention grounded on behaviour change techniques may improve healthy lifestyle choices. South Africa is experiencing an increasing prevalence of overweight and obesity, physical inactivity, and cardiovascular diseases. There is limited research on the effect of HIIT, MICT, and health messages intervention in improving body composition and cardiometabolic outcomes among adults employed in a South African setting.

Aim: To investigate the effects of high-intensity interval training (HIIT), moderateintensity continuous training (MICT), and health messages interventions on body composition and selected cardiometabolic outcomes amongst university professional staff employed at the University of the Witwatersrand.

Setting: University of the Witwatersrand.

Methods: The study used a mixed methods approach that used a parallel randomised controlled (RCT) design and focus group discussions (FGDs). A total of 54 professional staff were randomly assigned to 12-week high-intensity interval training (HIIT), moderate-intensity continuous training (MICT), or the control group. The HIIT exercise protocol included 18 to 31 minutes of cycling for 3 days per week at three near-maximal (80-90% HRmax) intervals of up to 30 seconds interspersed with a recovery (65%-75% HRmax). The MICT exercise protocol included cycling for 30 to 55 minutes, 3 days per week at 55-70% HRmax. There was no intervention in the control group. HIIT and MICT training sessions were supervised at 1:1 at the workplace gym. Both MICT and HIIT groups received the health messages intervention that included receiving text health messages through SMS messaging to motivate them to improve their lifestyle behaviour. Messages were sent 5 times per week over the 12-week intervention at random times. Employee perceptions of the intervention were explored in postintervention focus group discussions (FGDs). Anthropometric variables and selected cardiometabolic outcomes were measured at baseline and follow-up.

Results: Eleven participants (20.37%) were lost upon follow-up. Most of those lost to follow-up were in the control (35.29%) followed by the MICT (21.05%) and the HIIT (5.56%). The analysis was done for participants who had both baseline and follow-up data (n=43). A within-group comparison showed a decrease in anthropometry variables (body weight, waist circumference (WC), and body mass index (BMI), and selected cardiometabolic outcomes; systolic blood pressure (SBP), pulse pressure (PP), random blood glucose (RBG), and estimated VO2max) in both the HIIT and MICT health messages group and these observed changes were statistically significant (p˂0.05). There was an increase in anthropometric variables (body weight, WC, and BMI), cardiometabolic outcomes (SBP, RBG), and a decrease in estimated VO2max (p˂0.05) in the control group. The between-group comparison shows that there was no significant difference in change in anthropometry (WC, BMI), cardiometabolic outcomes (SBP, DBP, RBG), RHR, PP, MAP, and VO2max) between the HIIT group and the MICT group. Furthermore, there was a significant difference change in WC, BMI, MAP, RBG, and VO2max between the HIIT and MICT groups compared to the control group. No injuries were reported as a result of the intervention in both the HIIT and MICT groups. Participants expressed the view that time constraints, lack of interest/motivation, high workload, and fatigue/burnout were barriers to participation. While guidance through health messages, instructor-led exercise sessions, and a conveniently accessible location in the workplace facilitated their participation.

Conclusion: The 12-week supervised HIIT and health messages in the workplace setting was more time-and volume-efficient in significantly improving anthropometric and selected cardiometabolic outcomes compared to MICT. The supervised HIIT and health messages may be an effective protocol for promoting physical activity, improving anthropometric and cardiometabolic outcomes among professional staff. Addressing potential barriers and promoting facilitators in the workplace physical intervention may promote increased participation in employee wellness programmes.