Kenefick, R. W., Palombo, L. J., Ely, B. R., Goodman, D. A., Cheuvront, S. M., & Sawka, M. N. (2009). Impact of prior heat stress on subsequent aerobic exercise performance. ACSM 56th Annual Meeting, Seattle, Washington, Presentation Number 2430.

This investigation determined if prior heat exposure degrades subsequent aerobic exercise performance in the heat. Non-heat acclimated males (N = 18) established their baseline aerobic exercise performance in temperate conditions (four practice trials; 22°C) and then were divided into two (N = 8) groups. One group (EUHPH) was tested after 90 minutes of recovery (22°C) from three hours of intermittent light intensity (<30% VO2peak) exercise in the heat (50°C) where sweat losses were matched with fluid intake to maintain euhydration. The other group (EUH;) was tested while euhydrated without prior exercise-heat exposure. Aerobic performance was determined from a 30-minute cycling pre-load (50% VO2peak) followed by a 15-minute time-trial in 40°C. Total work in both conditions during the 15-minute performance time-trial was compared, as were the percentage changes from their best practice trial.

The 90-minute recovery was sufficient to recover from hyperthermia. Heart rate and core temperature were not different between groups at any time point during exercise. Total work was not different at baseline or between EUH and EUHPH exercise in the heat trials. The percent change in total work relative to baseline was not different between EUH and EUHPH.

Implication. If hydration and body temperature recover from prior exercise-heat exposure subsequent aerobic exercise performance in the heat is not compromised.

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