The trunk's contribution to postural control under challenging balance conditions.

Area of Science:

• Biomechanics
• Human Movement Science
• Neuroscience

Background:

• The double inverted pendulum model has limitations in accurately assessing postural control.
• While multijoint analyses enhance balance understanding, the trunk's specific role remains unclear.

Purpose of the Study:

• To investigate the trunk's contribution to postural control relative to other joints.
• To determine how trunk muscles influence trunk kinematics during balance tasks.

Main Methods:

• Thirty-six athletes performed a dynamic tilting balance task.
• Center of Force (CoF), joint angles, and trunk-pelvis angles were measured using force platforms and inertial measurement units.
• Electromyography recorded trunk muscle activity (rectus abdominis, external obliquus, erector spinae).

Main Results:

• Joint kinematics explained 33-75% of CoF variance, with the ankle being the most significant predictor.
• The trunk was the second most important predictor, significantly influencing CoF sway path.
• Surface electromyography explained less than 35% of trunk kinematics variance, with erector spinae being the sole significant predictor.

Conclusions:

• The trunk plays a significant role in postural control, particularly in managing body sway magnitude.
• Surface electromyography alone is insufficient for fully characterizing the neuromuscular control of trunk movements.
• Incorporating trunk assessment and training is vital for enhancing overall postural control, relevant for rehabilitation and athletic training.