The effect of cold water immersion on electrocardiogram recordings in healthy male rugby union players
Date
2021
Authors
Palmer, Brandon
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Abstract
Introduction: Although cold water immersion therapy (CWI) is a popular recovery therapy used
to accelerate the recovery process in rugby players, the cardiovascular response to cold water
immersion places strain on the heart. However, little is known about the cardiac electrical effects
due to cold water temperatures. The aim of this study, therefore, was to investigate the effects of
cold water immersion therapy at two different water temperatures on cardiac electrical activity in
male university rugby players.
Methods: A prospective, randomised crossover study design was used to investigate the effects of
CWI therapy at two different water temperatures (8ºC and 14ºC) measuring cardiac electrical effects
and heart rate variability of male university rugby players. An electrocardiogram (ECG) was used
to measure the cardiac electrical effects and a Zephyr™ BioHarness™ was used to measure heart
rate variability in the participants. Heart rate variability, blood pressure, and heart rate data were
tested for normality. Continuous data were analysed using Statistica 12 and presented as means and
standard deviations. Electrocardiogram data was assessed and presented as frequencies and
proportions. Significance was set at p<0.05.
Results: Significant lower root mean square of successive RR interval differences (RMSDD) (P
<0 .00001), and standard deviation of normal-to-normal RR intervals (SDNN) (P<0 .00001) were
observed during the cold water immersion period at both 8ºC and 14ºC compared to pre-immersion
period. Additionally, the stress index was significantly lower during the cold water immersion
period compared to the pre-test values (P=0.000754) at both cold water temperatures. This indicates
that there was a greater parasympathetic response during the cold water period. With regards to
systolic blood pressure, the initial cold water immersion readings were significantly higher
compared to pre-tests for both water temperatures. During the post cold water immersion period (or
the post-test period), recorded measurements returned to baseline measures. Importantly, no ECG
abnormalities were detected during the cold water immersion tests.
Conclusion: These findings showed no cardiac electrical activity abnormalities with cold water
immersion therapy in rugby players. Heart rate variability during cold water immersion is
significantly higher compared to the non-immersion pre-test period, due to a larger parasympathetic
response. This study showed that the parasympathetic system has a predominant effect on the body
compared to the sympathetic nervous system during cold water immersion therapy
Description
A dissertation submitted in fulfilment of the requirements for the degree of
Master of Science (Medicine) in the field of Sport and Exercise Science to the Faculty of Health Sciences, School of Therapeutic Sciences, University of the
Witwatersrand, Johannesburg, 2021