Optimizing Heat Acclimation for Endurance Athletes: High- vs Low-Intensity Training

We sought to determine the effect of high- vs. low-intensity training in the heat and ensuing taper period in the heat on endurance performance.

Nineteen well-trained triathletes undertook 5 days of normal training and a 1-week taper, including either low- (HA-L, n=10) or high-intensity (HA-H, n=9) training sessions in the heat (30°C, 50% of relative humidity). A control group (n=10) reproduced their usual training in thermoneutral conditions. Indoor twenty-kilometre cycling time-trials (35°C, 50% RH) were performed before (Pre) and after the main heat exposure (Mid) and after the taper (Post).

Power output remained stable in the control group from Pre to Mid (ES: -0.10 ± 0.26) and increased from Mid to Post (0.18 ± 0.22). The HA-L group demonstrated a progressive increase in performance from Pre to Mid (0.62 ± 0.33) and from Mid to Post (0.53 ± 0.30), alongside typical physiological signs of HA (reduced core temperature and heart rate, increased body mass loss). While the HA-H group presented similar adaptations, increased perceived fatigue and decreased performance at Mid (-0.35 ± 0.26) were evidenced and reversed at Post (0.50 ± 0.20). No difference in power output was reported at Post between the HA-H and the control groups.

HA-H can quickly induce F-OR in non-acclimatized endurance athletes. Since it was associated with a weak subsequent performance supercompensation, coaches and athletes should pay particular attention to training monitoring during a final preparation in the heat and reduce training intensity when early signs of F-OR are identified.

Autor / Fonte:Cyril Schmit, Rob Duffield, Christophe Hausswirth, Jeanick Brisswalter, Yann Le Meur International Journal of Sports Physiology and Performance 2017 September 5, : 1-24
Link: http://journals.humankinetics.com/doi/10.1123/ijspp.2017-0007