Lower trunk muscle activity-induced alignment and cop position during single-leg standing.

Area of Science:

• Biomechanics
• Kinesiology
• Human Movement Science

Background:

• Single-leg standing is crucial for various activities.
• Lower trunk muscle activation influences postural control.
• Understanding muscle contraction effects on balance is vital.

Purpose of the Study:

• To investigate the impact of specific lower trunk muscle contractions on single-leg standing.
• To analyze changes in center of pressure (COP) and body alignment.
• To determine the effects of Abdominal Expansion (AE), Abdominal Bracing (AB), and Abdominal Cave-in (AC).

Main Methods:

• Ten healthy males performed single-leg standing with maximal single-leg raise (SLR).
• COP alignment and position were measured during three trunk muscle contraction types: AE, AB, and AC.
• Trunk and lower limb kinematics were analyzed.

Main Results:

• Abdominal Cave-in (AC) significantly increased the SLR angle during single-leg standing.
• AC also led to a backward shift in the center of foot pressure (COP).
• Posterior trunk tilt angle and cross-step distance were reduced with AC.

Conclusions:

• Abdominal Cave-in (AC) during the wind-up phase of movement enhances lower limb elevation.
• AC effectively decreases posterior trunk tilt and reduces cross-step distance.
• This suggests AC improves dynamic balance and postural stability during single-leg tasks.