Effectiveness of short-term heat acclimation on endurance exercise with moderately trained males

Shaw, Jake

Abstract

Introduction – Exercising for an extended period in thermally demanding conditions places greater physiological and perceptual strain on the body than when exercising in temperate conditions (Galloway & Maughan, 1997; Moss et al., 2020; Tucker, Rauch, Harley, & Noakes, 2004). Heat acclimation (HA) has been suggested as one of the more effective interventions to be integrated into an athlete’s preparation to reduce physiological strain and improve exercise performance in hot conditions (C. J. Tyler, Reeve, Hodges, & Cheung, 2016). Many studies have explored studied hydration status of participants exercising in the heat and it is generally accepted that hydration status influences physiological and performance responses in the heat (Sekiguchi, Filep, Benjamin, Casa, & DiStefano, 2020). However, this is disputed. Aim - To explore the effectiveness of a STHA protocol with no fluid intake over 4 d.

Method – Twelve moderately trained, male participants completed this study (mean+SD; age: 35+15years; height: 175.3+4.5cm; body mass: 79.7+11.2kg; VO2peak: 47.2+9.9ml.kg.min). Control: Eleven of the 12 completed two 90-minute HST trials (35oC; 60%RH) on a cycle ergometer at 40% PPO followed by a 2% PPO incremental test to exhaustion post 10-minute passive recovery, taken a week apart with no intervention. Intervention: Twelve completed a 90-minute HST trial on a cycle ergometer at 40% PPO followed by a 2% PPO incremental test to exhaustion post 10-minute passive recovery pre and post four consecutive days of isothermic (40oC; 60%RH) HA with no fluid intake intervention.
Results – In the control trial, there was limited change for Tre , T s k , Tb , fc , %PV, and incremental performance trial. In the intervention trial, mean Tre lowered over time,

specifically at 70-min (P = 0.03). Mean HR decreased over time, specifically at 10 (P = 0.05), 20 (P = 0.03), and 30-min (P = 0.03). There were significant effects over time for RPE, TC, and TS. Mean incremental performance time increased by 142 s (P = 0.04) and mean PPO by 76 W (P = 0.03). 90-min steady state exercise completion rate improved post intervention from 7 to 12 with 11 performing the incremental exercise to exhaustion trial.

Conclusion – A 4 d isothermic STHA protocol with no fluid intake was effective at reducing physiological and perceptual strain and improving performance during exercise in hot conditions.

Citation

Shaw, J. Effectiveness of short-term heat acclimation on endurance exercise with moderately trained males. (Thesis). University of Hull. https://hull-repository.worktribe.com/output/4222648

• Thesis Type: Thesis
• Deposit Date: Sep 8, 2020
• Publicly Available Date: Feb 23, 2023
• Keywords: Sports science
• Public URL: https://hull-repository.worktribe.com/output/4222648
• Additional Information: Department of Sport, Health & Exercise Science, The University of Hull
• Award Date: Mar 1, 2020