The performance of ankle kinetics in individuals with gastrocnemius tightness during fast walk following the static stretch
目的：快走常被推薦為有氧運動。腓腸肌柔軟度不足可能影響走路動作。利用牽拉可改善肌肉柔軟度不足，因此本研究目的在探討靜態牽拉對腓腸肌緊縮者快走動作的立即影響。方法：本研究徵召24位腓腸肌緊縮者並隨機分成緊縮組和牽拉組，和12位健康且腓腸肌柔軟度正常者為控制組。其中牽拉組接受20分鐘的靜態牽拉。三組皆進行腓腸肌柔軟度測試和快走試驗。快走試驗是用動作分析系統和測力板測量，以計算快走時踝關節的運動學和動力學資料。腓腸肌拉緊程度是參考過去文獻建立腓腸肌長度的數學模型推算。結果：腓腸肌柔軟度測試顯示控制組的柔軟度最大、牽拉組次之、緊縮組最小 (p < .001)。緊縮組在快走時的腓腸肌最大拉緊程度為最大、牽拉組次之、控制組最小 (p < .001)。當快走的腓腸肌拉緊程度達最大時，三組在踝關節蹠屈力矩、關節功率和縱向壓縮力有顯著差異 (p值分別為 .005, .015, 和 .021)。相較控制組，牽拉組和緊縮組皆有較大的蹠屈力矩、較多的吸收功率和較大的縱向壓縮力。牽拉組和緊縮組間無明顯差異。結論：靜態牽拉可改善緊縮腓腸肌的柔軟度。腓腸肌緊縮者在牽拉後仍較正常人有較大的蹠屈力矩、較多的踝關節吸收功率和較大的踝關節縱向壓縮力等不正常的動作表現。
Purpose: Fast walking is one of the recommended aerobic exercise. Insufficient gastrocnemius flexibility may affect the movement of ankle during fast walking. Stretching improves the muscle flexibility. Therefore, the purpose of the study is to determine the acute effects of static stretching on the ankle movement of patient with tight gastrocnemius during fast walking. Methods: The 24 participants with tight gastrocnemius were randomly assigned to either tight group or stretch group, and 12 healthy volunteers with normal gastrocnemius flexibility were assigned to control group. Gastrocnemius flexibility test and fast walking measurements were performed in all participants. The stretch group received 20 min of static stretching before the measurement. The kinematic and kinetic data of ankle joint during fast walking is calculated and analyzed by motion analysis system and two force plates. The regression model for gastrocnemius length proposed by the previous studies was used to estimate the tensile level of gastrocnemius during fast walking. Results: The healthy control group showed the greatest gastrocnemius flexibility, followed by the stretch group, and the tight group had the worst gastrocnemius flexibility (p < .001). The maximal tensile level of gastrocnemius during fast walking was greatest in the tight group, then in the stretch group, and it is smallest in the control group (p < .001). The plantar flexor torque , joint power and vertical joint force at the maximal tensile level of gastrocnemius were significantly different among three groups (p = .005, .015, and .021, respectively). Compared with control group, the tight and stretch groups have a larger plantar flexor torque, power absorption and compression force at ankle joint. There were no significant differences between stretch and tight groups. Conclusion: The flexibility of tight gastrocnemius can be improved by the static stretching. Compared with the control group, the subjects with tight gastrocnemius demonstrated a larger plantar flexor torque, greater power absorption and greater compression force at the ankle joint after static stretching during fast walking.