Impact Of Time Of Day On Neuromuscular Performance Of The Star Excursion Balance Test In Young Women

How time of day affects cognitive performance is well established, but its influence on neuromuscular performance remains underexplored. We seek to extend our understanding through the Star Excursion Balance Task (SEBT), which combines multiple dimensions of neuromuscular performance, including strength, coordination, mobility, and postural control, and has previously been related to lower extremity injury risk. As women face higher rates of musculoskeletal injury than men, we hope to quantitatively assess the impact of time-of-day on women’s SEBT performance. PURPOSE: To understand the impact of time of day on neuromuscular performance in young, healthy women using the SEBT. METHODS: Young, healthy women (N: 45, age: 23.8 ± 3.0 y, BMI: 23.4 ± 3.7 kg/m2) performed the SEBT eight hours after habitual wake time (daytime) and three hours before habitual wake time (nighttime), in randomized order with sessions separated by three days. OpenCap, a video-based motion capture software, was used to measure joint positions and kinematics. Maximum reach distance, used in clinical scoring assessment, and path length were computed. Linear mixed-effects models examined the impact of leg (dominant/non-dominant), timing (day/night), and reach direction (anterior, anterolateral, lateral, posterolateral, posterior, posteromedial, medial, anteromedial) on maximum reach distance and path length. RESULTS: Maximum reach distance was impacted by leg in specific directions (shorter in the medial and anteromedial directions when standing on dominant leg, F(7,3466) = 2.56, p = 0.01). Maximum reach distance was not impacted by time of day. Path length was impacted by time of day (longer at night, F(1,3466) = 15.8, p < 0.01) and leg in specific directions (shorter in the posterior, medial, and anteromedial directions when standing on dominant leg, F(7,3466) = 4.28, p < 0.01). CONCLUSION: Our data indicate that while maximum reach distance is not impacted by time of day, path lengths were longer at night. The longer path lengths could indicate less efficient movement, possibly due to decreased postural stability during nighttime. Future work will examine changes in kinematics during the day and night. Wu Tsai Human Performance Alliance, NeuroTech Training Program (This material is based upon work supported by the National Science Foundation under Grant No. 1828993.)