the diurnal variation on cardiovascular endurance performance of secondary school athlete student

Background: the previous investigations in diurnal variation of endurance sports performance did not reach a consensus and have been limited. this study would be a valuable resource for endurance sports trainers and event managers to plan their training and competition in a specific time of day. objectives: the aim of this study is to find out the diurnal variation in cardiovascular endurance performance in the young athletes. materials and methods: thirty five athlete students (15.17 ± 1.62 years) participated in this study. maximal oxygen uptake (vo2max), post-exercise percentage of maximal heart rate (mhr% post-ex), post-exercise body temperature (btemppost-ex), and post exercise blood lactic acid level (lapost-ex) were measured in this study. three non-consecutive testings: a) morning (09:00-10:00; am), b) noon (12:00-13:00; nn) and c) afternoon (16:00-17:00; pm) were conducted. participants were required to follow the meal plan and resting schedule for all testing days. results: vo2max was significantly higher at nn (f2. 68 = 3.29, p < 0.05, η2 = 0.088) in comparison with pm. the mhr%post-ex, btemppost-ex, lapost-ex was not significantly different among three times of day. conclusions: diurnal effect on endurance performance was found and the highest exercise vo2max was identified at noon. secondary school students or young athletes are recommended to have sports training related to vo2max at noon for the purpose of maximizing training effectiveness.