Correspondence between pelvic and ankle kinematics and wobble board tilt at bipedal stance - balance strategy in middle-aged women.

INTRODUCTION

Wobble boards are used in recreation, therapy, and ergonomics. Research is needed to determine the optimal control strategy in double-leg standing. The previous study concluded that pelvic and ankle range of motion in planes influence balance scores differently. So, this study aimed to assess the correspondence between temporary pelvic and ankle kinematics and board tilt.

METHODS

Seventeen healthy middle-aged women were tested on the wobble platform of sudden or gradually changed instability with their eyes open and closed. The study assessed correspondences of pelvic tilt, rotation, and ankle dorsi/plantar flexion related to antero-posterior platform tilt and pelvic obliquity, rotation, and ankle abduction/adduction related to medio-lateral platform tilt. These correspondences for each participant were evaluated with linear regression (slope) and correlation to observe their strength and homogeneity. Finally, the group of participants presenting statistically significant correspondences was summarized, results between legs and tests were compared, and dependence between regression parameters and the quality of balance maintenance was assessed.

RESULTS

The pelvic obliquity followed medio-lateral platform tilt (slope 0.79-0.88, correlation 0.88-0.98), and ankle dorsi-plantar flexion followed the antero-posterior one (slope 0.75-0.94, correlation 0.65-0.87) independently on balance quality or testing conditions. The anterior pelvic tilt decreased when the platform was anteriorly up but did not strictly follow the platform. The pelvic rotation and ankle abduction/adduction corresponded with platform tilt randomly.

CONCLUSION

The pelvis and ankles respond in a direction-dependent way to wobble instability. Wobble boards insist on simultaneous good pelvic medio-lateral and ankle antero-posterior motion, so they may also simultaneously stimulate them.