Relationship between Upper Body Mass and Trunk Segment Control for Stability during Single-Leg Standing

Abstract

[Purpose] The trunk is extremely important for postural control because it has the largest body mass ratio. This study aimed to clarify the relationship between upper body center of mass (UCoM) control, including the trunk, and one-leg standing balance. [Methods] Ten healthy adult males were subjected to a left-right one-leg standing task. The center of mass total locus length (CoM-TLL), center of pressure total locus length (CoP-TLL), CoP-frequency (CoP-Freq), UCoM deviation (UCoM-Dev), trunk lateral flexion angle of the stance leg side, and hip abduction angle of the stance leg side were analyzed. Pearson's correlation analysis was performed on each parameter to examine the relationship. [Results] ​​Significant correlations were found between the CoM-TLL and UCoM-Dev (r = 0.53, p = 0.02), the CoM-TLL and lateral trunk flexion angle to the stance side (r = 0.47, p = 0.04), CoM-TLL and hip abduction angle (r = 0.45, p = 0.04), and CoP-Freq and trunk lateral flexion angle to the stance side (r = −0.64, p = 0.002) in the one-leg standing position.​ [Conclusion] In postural control, some postural parameters were associated with CoM and CoP sway. Postural parameters that contribute to CoM deviation were found to be related to the amount of body sway. Postural parameters that decrease CoM deviance were found to be related to decreases in the amount of body sway and body sway frequency. Therefore, these suggested that different upper body segmentation and mass control strategies were associated with CoM and CoP.