Heat adaptation in triathlon

  • JAMES, Carl (PI)
  • Willmott, Ashley G.B. (CoI)
  • Gibson, Oliver R. (CoI)

Project: Research project

Project Details


PURPOSE Heat acclimation (HA) kinetics often necessitates that the intervention is conducted in the weeks immediately preceding athletic competitions, potentially interfering with a training taper. Therefore, we investigated the efficacy of a mixed-method HA protocol, superimposed over planned external training loads, during the 3-weeks prior to the 2022 U23 World Triathlon Championships.

METHODS Six international triathletes completed eight pre-competition HA sessions (5 active: running/cycling, 3 passive: hot water immersion [HWI]), across 2-weeks. Outdoor high-intensity training sessions were followed by 30-60-min HWI, whilst low-intensity cycling/running sessions were completed in a hot, humid environmental chamber. To assess heat adaptations, participants completed three 25-min heat stress tests (HST) involving iso-speed treadmill running (session 1 = HST1, session 5 = HST2, and session 8 = HST3). Physiological, haematological and wellbeing monitoring were conducted throughout HA.

RESULTS Reduced heart rate (~-6 b.min-1) was observed within HST3 (p=0.01, ηp2= 0.64), versus HST1 and HST2. No changes in core temperature were observed across HSTs (p=0.055, ηp2=0.44). Sweat sodium concentration was lower by HST2 at the arm (-23±16 mmol.L-1, p=0.02) and back (-27±17 mmol.L-1, p=0.01). White blood cell count reduced from baseline to the end of HA (p=0.02, ηp2=0.27), but no changes were found in any other haematological markers (all p>0.05). Perceptual wellbeing measures did not change across HA (all p>0.05).

CONCLUSION By HST3, seven prior mixed-method HA sessions improved markers of heat adaptation (exercising HR and sweat concentration) within international triathletes. Mixed-method HA may be implemented without modifying training load, with no apparent detrimental effects on athlete health or training stress markers.
Effective start/end date1/11/22 → …


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