Effect of time of day on blood lactate and anaerobic thershold level in submaximal and maksimal running speed among female volleyball players

The aim of the study was to examine the effect of time of day on blood lactate and anaerobic thershold level in submaximal and maksimal running speed among female volleyball players. 12 female volleyball players with 5 years of volleyball licence and aged 15-29 years voluntarily participated into the study. Each subject peformed an incremental treadmill running protocol at different times on alternate days (09:00-13:00-17:00) in School of Physical Education and Sports Laboratory in Abant Izzet Baysal University. Before each test height, weight, fat percentage, body temperature, diastolic and systolic blood pressures, resting heart rate and resting blod lactate levels of subjects were taken. The incremental treadmill running protocol was started at speed of 7 km/hr and the speed was increased by 1 km/hr each 3 minutes to measure lactate levels and anaerobic thresholds of subjects. Test was continued until the subjects exhausted. During the incremental treadmill test protocol after each 3 minutes, a minute break was given to take blood sample from subject?s earlobe. Then the blood samples were analyzed in YSI 1500 SPORT? Lactate Analyzer (Columbia, USA).Statistical analyses were performed by using SPSS 17.0 for Windows. Values were reported as means ± SD. For the analysis of effect of circadian variations on each parameters one-way ANOVA with repeated measures was applied. Bonferroni post hoc analysis were used when there was significant statistical difference in any parameters. Statistical significance was set at p <0.05.In conclusion, there was no significant difference within all measured parameters except body temperature at different times of day. Although blood lactate levels were less at 09:00 and 17.00, the difference was not reported as significant (p>0.05). Moreover, the effect of time of day on heart rates at each speed level, total running duration and distance were not significantly different (p>0.05). Effect of time of day on body temperature was found significantly different between 09:00 and 17:00 (p<0.05) Keywords: Circadian rhythm, anaerobic threshold, blood lactate level, female volleyball players