Kinematic analysis of the ankle joint on the side‐hop test in subjects with ankle sprains

The side‐hop test (SHT) is useful functional performance test for ankle sprain. However, few research exists to investigate the relationship between the SHT and functional deficit in ankle. The objective of this study was to establish SHT as an evaluation criterion of functional deficits in ankle sprain. Twenty‐seven subjects with a history of ankle sprain participated. The time taken to perform SHT in the uninjured and injured limbs was measured. The angular displacements of the ankle joint were measured using the 3D motion analysis system. The muscle activities of the peroneus longus muscle (PL), tibialis anterior muscle (TA), and the medial and lateral gastrocnemius muscles (GM, GL) were measured using surface EMG. The time of SHT in the injured limb (9.22 ± 1.19 seconds) was significantly longer than that in the uninjured limb (8.71 ± 0.99 seconds). The range of the ankle inversion/eversion and dorsal flexion/plantar flexion in the injured limb was significantly greater than that in the uninjured limb. The injured limb showed a significant decrease in PL, TA, and GM integral EMG during SHT. Ankle motion and muscle activity caused the decline in SHT time in patients with injured limb.