Physical Inactivity and Sedentary Behavior Negatively Impact Postural Balance and Gait

Background/Objectives: The benefits of physical activity (PA) do not depend on the PA level alone but also on sedentary behavior (SB). The interaction between PA and SB (i.e., PA–SB interplay) is important to determine one’s health status. This study explored the effect of PA–SB interplay on balance and gait in healthy young adults. Methods: Healthy young adults (n = 133, 18–35 yrs) were placed in four PA–SB interplay groups (according to their sitting duration and physical activity duration) using the American College of Sports Medicine PA guidelines (i.e., sedentary active [>6 h/day, >150 min/week], sedentary inactive [>6 h/day, <150 min/week], physically active [<6 h/day, >150 min/week], and physically inactive [<6 h/day, <150 min/week]). In this cross-sectional study, participants’ balance and gait were assessed with inertial measurement units placed on seven bodily sites. In this exploratory study, significance level was set at p < 0.1. Results: Sway acceleration RMS during the eyes closed on stable surface balance test showed a statistically significant difference among the PA–SB interplay groups (p = 0.055) which was found between sedentary active and physically inactive (p = 0.066). Anticipatory postural adjustment (APA) duration during gait showed a statistically significant difference (p = 0.010) which was found between sedentary inactive and physically active (p = 0.019) and between sedentary active and physically active (p = 0.026). Conclusions: PA–SB interplay influences static (sway acceleration RMS) and dynamic (APA duration) balance of healthy young adults. Findings suggest that somatosensory processing during balance and gait initiation are significantly impacted by PA–SB interplay.