Maximal oxygen uptake, ventilatory thresholds and mechanical power during cycling in Tropical climate in Guadeloupean elite cyclists

The Tropical climate imposes a high level of physiological stress which could modify the target heart rate in training load prescription as the recommendations are often determined by maximal oxygen uptake testing in temperature-neutral laboratories To test this hypothesis 7 high-level cyclists performed two randomised maximal tests in neutral (19 2 +/- 0 9 degrees C 51 7 +/- 1 3% RH) and Tropical environment (25 8 +/- 1 1 degrees C 63 7 +/- 2 3% RH) Neither maximal oxygen uptake nor ventilatory threshold was influenced by the environmental conditions However ventilation (p<0 005) and the respiratory equivalent in O-2 (p<0 05) were significantly higher in the Tropical environment whereas maximal power output and the time to attain maximal oxygen uptake were significantly lower (p<0 05 for both) Moreover, the ventilatory cost of cycling (expressed in LW-1) was significantly greater in the Tropical condition (0 40 +/- 0 03 LW-1 vs 0 32 +/- 0 05 LW-1 in Tropical vs Neutral condition effect p<0 005 condition x time p<0 001) Rectal temperature was influenced by neither the environmental conditions nor exercise (36 7 +/- 0 1 and 37 0 +/- 0 1 degrees C vs 36 8 +/- 0 1 and 37 1 +/- 0 2 degrees C in Tropical vs Neutral before and after exercise) but was influenced by condition x time (p<0 05) The heart rate (HR) values usually used for training prescription were not significantly different (154 +/- 5 bpm vs 156 +/- 4 bpm and 172 +/- 4 bpm vs 167 +/- 4 bpm in Tropical vs Neutral climate for the first and second thresholds respectively) We concluded that the usual parameters measured during maximal exercise to establish training programs are not impaired in moderate Tropical environment Nevertheless the thermal stress attested by the increased ventilatory cost of cycling could have prevented the cyclists from performing a true maximal test in Tropical conditions (C) 2010 Sports Medicine Australia Published by Elsevier Ltd All rights reserved