Affiliations: Department of Exercise and Sport Sciences, Faculty of Sport Sciences, Hacettepe University, Ankara, Turkey
Correspondence:
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Corresponding author: Evrim Ünver, Department of Exercise and Sport Sciences, Faculty of Sport Sciences, Hacettepe University, Ankara, Turkey. E-mail: evrimunver@hotmail.com.
Abstract: BACKGROUND: The circadian rhythm (CR) is a 24-hour cyclic period that influences a wide array of physiological systems and performance sports. However, its specific effect on drop jump (DJ) scores have not been studied. OBJECTIVE: To investigate the effect of circadian rhythm on DJ performances. METHODS: Thirty-three healthy university students (men, n= 16, age: 23.47 ± 2.9 years; fewomen, n= 17, age: 22.25 ± 2.27 years) participated in this study. Subjects were tested twice, over two separate days, once in the morning and once in the evening. Subjects started from a drop height of 20 cm and continued until the height where the reactive strength index (RSI) started to decrease. This height was recorded as the optimal drop height (ODH). Ground contact time (GCT) and jump height were also recorded. RESULTS:The ODH values were similar between testing sessions for both genders (p> 0.05). A significant increase in jump height during the evening session was observed in men (p= 0.005, d= 0.80). The RSI values increased significantly in men (p= 0.006, η2 = 0.77) while GCT was similar in both genders (p> 0.05). CONCLUSION: In men, the optimal time of day for DJ explosive training is the evening. Women may benefit from this type of training both during morning and evening sessions.
Keywords: Circadian rhythm, drop jump, reactive strength index, optimal drop height, jump height, ground contact time
