Effects of bag holding with one hand on lower leg muscles and postural control

Abstract

This study examined the influence of holding a load with one hand on the tissue oxygenation kinetics in the flexor digitorum superficialis muscle of the forearm, the electromyographic responses in the lower leg antigravity muscles, and the center of foot pressure (COP) sway. Ten healthy young men participated in this study. They kept an upright standing posture while holding a load with the dominant hand under four load weight conditions (0%, 15%, 30%, and 45% of maximal voluntary contraction (MVC) of the jerk strength). Sway factors were mainly significantly higher at 45% MVC than the other conditions. There was little relationship between tissue oxygenation kinetics in the forearm and COP sway during upright standing posture. Holding a load below 30% MVC did not affect postural stability. When holding a 45% MVC load, activities of the antigravity muscles of the lower leg on the side holding bag largely increased, fatigue in antigravity muscles of both legs was induced, and these phenomena increased wiggling and quick body sway.