Effect of Hot Environment on Repetitive Sprint Performance and Maximal Accumulated O2 Deficit of Cyclists

Abstract. This study was undertaken with a view to compare the effect of hot environment on repeated sprint performance and maximal accumulated oxygen deficit (MAOD) during continuous sub-maximal exercise. Eight male cyclists aged 22.5 ± 2.1 yr, weight 63.4 ± 4.5 kg and VO2max of 58 ± 5.2 ml/kg/min participated in this study. The method of measuring MAOD was adopted from Medbø et al., (1988). In phase 1 the VO2max of the cyclists were measured on cycle ergometer following a graded exercise protocol. In phase 2, the cyclists did sub-maximal exercise for 10 min at 60, 70, 80, 90%VO2max, on separate days. The linear regression determined from the VO2 – power relationship was used to estimate supra-maximal power output at 120 % VO2max. In phase 3, the subjects performed AOD test with maximal sprint (120%VO2max) until exhaustion followed by a continuous cycling for 60 min (60%VO2max). The subjects performed another 3 sprints (120%VO2max) after every 20 min. The exercise was conducted in thermo-neutral (25.7 ± 0.4oC) condition. In phase 4 the exercise was conducted in hot condition (31.4 ± 0.1oC) with the same protocol. Results indicated there was no difference in MAOD, sprint performances, core temperature, plasma lactate and plasma ammonia between the hot and thermo-neutral conditions (p<0.05). However, MAOD and sprint performance deteriorated in subsequent sprints (p<0.05) irrespective of hot and thermo-neutral conditions. This study highlighted that hot environment did not impart any significant change in the anaerobic capacity of the cyclists measured on the basis of maximal accumulated O2 deficit, all out repeated sprint performance, plasma lactate and plasma ammonia levels. Key Words: MAOD, cyclists, sprint performance, hot environment 1