www.abertay.ac.u k
The Impact of Heat Acclimation on Physiological Response to Exercise and Performance at Hot and Temperate Conditions Ben Reid, MbR, School of Applied Science, Abertay University Email: b.reid1600@abertay.ac.uk Background
Methods
• There is ~0.3-0.9% performance decrease in every 1oC increase • Exercise in 25ºC has shown to significantly increase mean heart rate (~7 bpm) and core temperature (+0.8ºC) compared to cool conditions • Heat acclimation has shown to significantly improve performance in hot conditions and often in temperate conditions.
Results cont… 10
Distance Covered (km)
8
6 T1 T2 T3
4
2
0
Hot
Cool
Testing Period
18°C – 31°C – Low risk of heat strain 32°C – 40°C – Possibility of heat cramps 40°C – 51°C – Heat exhaustion likely 52°C+ - Heat stroke definite risk
• Each participant were included as part of both the control and intervention groups • 15-minute time trials completed on cycle ergometer at Abertay University • Yo-Yo Intermittent Recovery Test (Level 1) completed as field testing • 30-minutes pedaling at 60-70% HRmax following repeated sprints protocol
Study Overview
Aim • To analyse the effectiveness of a 3-week exercise heat acclimation intervention on performance and physiological response during exercise at 35ºC and 18ºC Hypothesis • Significant improvements in time trial (hot and cool) and Yo-Yo IR1 (cool) • Significant improvements in core, muscle and skin temperature, heart rate and sweat responses (hot only)
30.00
20.00
T1 T2 T3
10.00
0.00
Hot
Cool
Testing Period
Figure 5 – Exercising mean core temperature (°C) from T1, T2 and T3 in hot and cool conditions
Conclusions
Figure 1 – Impact of heat sensation on physiological strain (McCardle, Katch and Katch 2010)
Participants • 8 active males. Age - 24 ± 4.01 years. Height - 183 ± 6.20cm. Mass - 90.85 ± 17.22kg • No recent exposure to heat/altitude and injuries • ≥90 mins individual/team sport exercise per week
40.00
Core Temperature (°C)
Figure 2 – Participant study schedule
Figure 4 – 15- minute time trial distance covered (km) from T1, T2 and T3 in hot and cool conditions
Figure 3 – Acclimation repeated sprints protocol
Data Analysis Time Trials: • Distance covered • Heart rate (rest, exercise, recovery) • Core, skin and muscle temperature (rest, exercise, recovery) • Sweat rate ns Yo-Yo IR1: • Distance Covered • Estimated VO2 max
Results • Results shown are from 4 participants who have completed the entire study duration
• Early results encouraging. Improvements seen above, as well as sweat rate in the heat (T1 – 0.441g, T2 – 0.562g, T3 – 1.103g • Indication that heat acclimation protocol benefits performance and response in the heat. Temperate performance remains unclear • Promising results for Yo-Yo IR1 test, with some improvements observed in distance covered
References • •
• • •
McArdle, W.D., Katch, F.I. and Katch, V.L., 2010. Exercise physiology: nutrition, energy, and human performance. Lippincott Williams & Wilkins. Périard, J.D. and Racinais, S., 2015. Self-paced exercise in hot and cool conditions is associated with the maintenance of% VO2peak within a narrow range. Journal of Applied Physiology, 118(10), pp.1258-1265. McArdle, W.D., Katch, F.I. and Katch, V.L., 2006. Essentials of exercise physiology. Lippincott Williams & Wilkins. Brotherhood, J.R., 2008. Heat stress and strain in exercise and sport. Journal of Science and Medicine in Sport, 11(1), pp.6-19. Moss, J.N. et al. Short-term isothermic heat acclimation elicits beneficial adaptations but medium-term elicits a more complete adaptation. European journal of applied physiology, 120(1), pp.243-254.
Abertay University is an operating name of the University of Abertay Dundee, a charity registered in Scotland, No: SC016040.