Fig. 1

a Assessment of postural stability using the Biodex Stability System (BSS) (Biodex Medical Systems, Shirley, NY, USA). The static postural stability test instructed the subject to maintain the posture to level 12 platform (stable surface), whereas the dynamic postural stability test was measured on the same platform while decreasing platform stability gradually from level 12 (most stable) to level 1 (most unstable). b Assessment of isokinetic muscle strength using the Biodex multi-joint system 4 (Biodex Medical Systems). Each subject was seated on the device, with hips and knees flexed to 90° and trunk perpendicular to the floor. A strap was used to immobilize each subject’s thigh. The lateral femoral condyle of the knee joint was aligned with the rotational axis of the isokinetic machine