The Influence of Chronotype on Strength Variables in Female University Students at different times of day: A Cross-Sectional Study

Background. Chronotype influences physical performance through circadian rhythms that vary across the day. Strength and power often peak in the evening, suggesting timing impacts training outcomes. This study explores these effects in female university students, a group which is underrepresented in chronobiological research. Objectives. This study aimed to examine how chronotype influences strength performance in female university students at different times of day. Specifically, it compared maximal strength, explosive power, and hand muscle strength between morning-type and evening-type individuals to identify optimal training or performance times based on chronobiological preference. Materials and methods. The Horne and Ostberg Morningness–Eveningness Questionnaire was used to classify 56 Indian female university students (mean age = 22.2 years; weight = 56 ± 4.31 kg; height = 158 ± 5 cm; BMI = 21 ± 1.5 kg/m²). Strength performance was assessed using three measures: one-repetition maximum (1RM) for maximal strength; countermovement jump (CMJ) for explosive power; and handgrip dynamometry for muscle strength. Testing was conducted under standardized conditions at each participant’s chronotype-aligned time (morning or evening). Independent samples t-tests were used for analysis, with the Shapiro–Wilk and Levene’s tests confirming the assumptions of normality and homogeneity. Results. It was observed that the evening-type individuals expressed much better scores on all variables of being tested than morning types. The evening group produced greater values in 1RM squat (78.3 ± 2.63 kg vs. 72.1 ± 3.11 kg; t (54) = -8.08, p < .001, d = 2.16), CMJ (30.1 ± 2.32 cm vs. 26.1 ± 2.32 cm; t (54) = -6.46, p < .001, d = 1. Conclusions. The findings of this study indicate that evening-type female university students have enhanced strength performance during evening hours, underscoring the need to consider chronotype when planning training and performance assessments in female athletes.