Title

The effect of post-resistance exercise water immersion on muscular adaptation and performance in athletes

Author Identifiers

Barry G. Horgan

https://orcid.org/0000-0002-6436-8950

Date of Award

2022

Degree Type

Thesis

Degree Name

Doctor of Philosophy

School

School of Medical and Health Sciences

First Advisor

G. Gregory Haff

Second Advisor

Dale W. Chapman

Third Advisor

Shona L. Halson

Fourth Advisor

Eric J. Drinkwater

Fifth Advisor

Nicholas West

Abstract

High training load and reduced well-being increase the risk of injury, illness and performance decrements. Post-exercise recovery strategies (e.g., water immersion) are used in Olympic and teamsport training settings to induce recovery and enhance subsequent performance. Recent suggestions that cold water immersion negatively affects short- (e.g., protein synthesis, hypertrophy signalling pathways) and long-term (e.g., muscular hypertrophy and strength) responses to resistance exercise are concerning. In this thesis, post-exercise cold (CWI), contrast water therapy (alternating hot and cold) (CWT) and hot water immersion (HWI) strategies were utilised to elucidate their effects on the inflammatory, anthropometric, performance and perceptual responses to resistance exercise in athletes. Outcomes will inform the prescription of post-exercise water immersion to reduce risks of injury, illness, or performance decrements. In Chapter 2, the ±7 and ±28-day relationships between perceived recovery, training load, injury and illness in athletes (n=536) were explored. In Chapters 4 and 5, the acute ( ≤ 48-h) effects of CWI, CWT, or HWI on responses to resistance exercise in athletes (n=18) were examined. In Chapter 6, the long-term (4-week) responses to CWI versus HWI following resistance exercise in athletes (n=18) were investigated. In Chapter 2, perceived recovery resulted in an absolute risk (AR) of 0.9-5.9% and 0.9-20% for injury and illness, respectively. Factoring training load, injury and illness demonstrated bi-directional (increases and decreases) associations with perceived recovery (i.e., physical [soreness], physiological [sleep duration and quality]); while illness also had negative (mood, motivation) and positive (stress) associations with psychological variables. In the 48-h period prior to an occurrence, low sleep duration was associated (p=0.005) with increased injury risk (AR=4%), while ‘very poor’ sleep quality (AR=7.83%) or extremes of too little ( < 5-h, AR=3.1-14.3%) and too much ( > 10-h, AR=~2.6-11%) sleep were associated (p < 0.001) with increased illness. In Chapters 4 and 5, creatine kinase was reduced (g=0.02-0.30) following CWI (p=0.007), CWT (p=0.006) or HWI (p < 0.001) vs. CON, while significant increases (g=0.50) were observed following CWI vs. HWI. CWT resulted in significantly higher (g=0.56) interleukin-6 vs. HWI, as well as increased testosterone (HWI > CWT: p=0.038, g=0.24). Participant belief in a post-exercise intervention strategy was associated with HSP72 (“believer” > “non-believer”, p=0.026), soreness (“believer” > “non-believer”, p=0.002) and interleukin-4 (“non-believer” > “believer”, p=0.002). HWI reduced (treatment effect) fatigue perceptions (HWI > CWT: p=0.05, g=0.43) and improved sleep quality (HWI > CON: p < 0.001, g=1.15; HWI > CWI: p=0.017, g=0.70; HWI > CWT: p=0.018, g=0.51). There were trivial to small (p < 0.001-0.039, g=0.02-0.34) improvements (treatment effect) in jump performance following all water immersion strategies, compared to CON. In Chapter 6, squat jump height increased (g=0.08-0.19) following CON (p=0.004) and CWI (p=0.003), compared to HWI. Lean mass (p=0.960) did not change between interventions. Acute post-resistance exercise HWI accrues small to large improvements in perceived sleep quality and reductions in next-day fatigue. Practitioners should consider athlete belief and individual responses when prescribing water immersion to reduce acute perceptions of muscle soreness. Repeated post-resistance exercise CON or CWI provides trivial increases in SJ, compared to HWI. Following reviews on post-resistance exercise CWI, these data may support use of CWI and HWI during in-season competition phases in high-performance athletes.

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Access to this thesis is embargoed until 22 April 2027. At the expiration of the embargo period, access to the thesis will be restricted to current ECU staff and students.

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