The Influence of Muscular Tightness of Gastrocnemius on the Ankle Joint Reaction Force during Gait

Objective. The muscular tightness is a common clinical musculoskeletal problem and is postulated as an intrinsic risk factor for the development of muscle injuries. The purpose of this study was to investigate the influence of the muscular tightness of gastrocnemius on the ankle joint reaction force during gait in order to inform the clinical management of patients with muscular tightness of lower legs. Method. Ten adult subjects (5 males and 5 females) with the muscle tightness of gastrocnemius participated in this study. The motion analysis system and two force plates were applied to capture the gait motions with the standard Helen Hayes marker set. The ground reaction forces and ankle joint reaction forces during the walking trails were compared between the affected (n=10) and unaffected limbs (n=10). Results. Although the kinematic data of gait analysis were quite similar between affected and unaffected limbs, the kinetic findings revealed significantly increased ankle loadings in the affected limbs during gait cycle. The significantly increased peak vertical ground reaction forces [1.85 ± 0.46 times body weight (B.W.) vs 1.30 ± 0.21 B.W., P= 0.003], peak joint compression force in ankle [1.79 ± 0.44 B.W. vs 1.25 ± 0.20 B.W., P= 0.001] were demonstrated in the affected limbs during walking. Conclusion. The results of gait analysis indicated that the muscular tightness of gastrocnemius muscles had an effect on ankle-foot complex. Adequate mobility of ankle-foot joints was necessary for normal attenuation of forces transmitted from the ground to the weight-bearing extremity. The quantitative gait analysis was valuable to clarify the influence of the muscle tightness on the ankle joint reaction forces in the lower extremities.