Influence of simulated hip muscle weakness on hip joint forces during deep squatting

Abstract

This study aimed to determine the effects of simulated hip muscle weakness on changes in hip joint forces during deep squat motion. Ten healthy individuals performed squat motion at three different positions (0° foot angle [N-squat], 10° toe-in [IN-squat], and 30° toe-out [OUT-squat]). A scaled musculoskeletal model for each participant was used to calculate the muscle and hip joint forces. For each hip muscle, models of full strength, mild muscle weakness (15% decrease), and severe muscle weakness (30% decrease) were created. The muscles affecting the hip joint forces were identified, and the rate of change in the joint forces was compared among the three squat conditions. The anterior hip joint force was increased in the muscle weakness models of the inferior gluteus maximus (iGlutMax) and iGlutMax+deep external rotator (ExtRot) muscles. With 30% muscle weakness of these muscles, statistically significant differences in the rate of increase in the anterior joint force were observed in the following order: IN-squat (iGlutMax, 29.5%; iGlutMax+ExtRot, 41.4%), N-squat (iGlutMax, 18.3%; iGlutMax+ExtRot, 27.8%), and OUTsquat (iGlutMax, 5.6%; iGlutMax+ExtRot, 9.3%). OUT-squat may be recommended to minimize the increase in hip joint forces if accompanied by hip muscle weakness.

The effect of experimentally induced gluteal muscle weakness on joint kinematics, reaction forces, and dynamic balance performance during deep bilateral squats

“…Weakness of gluteal muscles might alter the magnitude and direction of JRFs of the hip due to compensatory mechanisms, specifically an increase of muscle forces in other synergistic muscles 46 . Tateuchi et al 9 using individualized, scaled musculoskeletal models of 10 healthy volunteers, simulated mild (15%) and severe (30%) muscle weakness during squats and reported an increase of the anterior hip JRF by 18.3% during a severe weakness of the inferior gluteus maximus and 27.8% during a severe weakness of inferior gluteus maximus/deep external rotators of the hip, due to compensatory increase in quadriceps, hamstrings, and superior gluteus maximus, whereas the medial hip JRF decreased in the inferior gluteus maximus/deep external rotators weakness model. In this study, no change of the hip JRFs in AP and ML direction was observed, but a decrease of the superior JRF following SGN and IGN block in the affected hip and superior overloading of the contralateral unaffected hip.…”

“…7 Incorrect squatting execution could induce increased compressive and shear forces at the hip, knee, and ankle joints. 7,8 Several conditions such as chronic hip muscle weakness/ insufficiency, 9 fatigue, 10 pain, 11 and osteoarthritis 12 might influence squat performance 13 and therefore, should be considered when assessing and training patients with these pathologies. In the presence of lower extremity muscle weakness, abnormal movements, and compensation mechanisms might be observed in an attempt to complete the task.…”

Criteria-Based Rehabilitation Following Revision Hip Arthroscopy: A Clinical Commentary

“…Maximized strengthening of both internal and external rotator muscle groups is important in the homeostasis of the hip, with particular research supporting the deep external rotators, although a specific ratio has not been confirmed. Tateuchi et al 61 showed increased anterior hip joint forces in the deep squat when weakness in the deep external rotators was present. Meinders and colleagues showed that maximal activation of the deep external rotators resulted in decreased hip contact force angles and reduced acetabular loading.…”