The effect of circadian rhythmicity on lower extremity strength and balance in female athletes
CHRONOBIOLOGY INTERNATIONAL, vol.43, no.2, pp.277-288, 2026 (SCI-Expanded, Scopus)
- Publication Type: Article / Article
- Volume: 43 Issue: 2
- Publication Date: 2026
- Doi Number: 10.1080/07420528.2025.2597962
- Journal Name: CHRONOBIOLOGY INTERNATIONAL
- Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, BIOSIS, EMBASE, Environment Index, MEDLINE, Psycinfo, SportDiscus, Zoological Record, Academic Search Ultimate (EBSCO), Biomedical Reference Collection: Corporate Edition (EBSCO)
- Page Numbers: pp.277-288
- Ondokuz Mayıs University Affiliated: Yes
Abstract
The aim of this study was to investigate the effect of circadian rhythmicity (CR) on lower extremity strength and balance performance in 22 female athletes (19-24 y). Participants underwent isokinetic knee strength, Single Leg Hop Tests (SLHT), Y Balance Test (YBT), and isokinetic static/dynamic balance tests. All measurements were randomized and performed at 9:00, 14:00, and 19:00 to assess CR variation. In total, 3 angular strength, 5 jump, and 2 balance tests were analyzed. When comparing results across time zones, body temperature, isokinetic 60 degrees/sec extension (Ext) strength, and several bipedal static balance parameters Forward-Backward Standard Deviation (SBFD), Average Forward-Backward Speed (AFBS), and Ellipse Area (EA)) showed statistical significance (p>0.05). No significant differences were found in other isokinetic strength tests, all SLHTs, Y balance, or dynamic balance tests (p>0.05). Significant CR effects on lower extremity strength were observed only in the 60 sec extension, with overall strength peaking at 14:00. Strength asymmetry remained similar across time points. These findings suggest that time-sensitive performance parameters like strength and static balance are influenced by CR, while balance and coordination parameters appear more stable. Accordingly, scheduling strength-based training during midday hours may optimize performance by leveraging CR-related variations.