Kinesiology of the Hip: A Focus on Muscular Actions


The hip joint serves as a central pivot point for the body as a whole. This large ball-and-socket joint allows simultaneous, triplanar movements of the femur relative to the pelvis, as well as the trunk and pelvis relative to the femur. Lifting the foot off the ground, reaching towards the floor, or rapidly rotating the trunk and pelvis while supporting the body over one limb typically demands strong and specific activation of the hips’ surrounding musculature.

Pathology that affects the strength, control, or extensibility of the hip muscles can significantly disrupt the fluidity, comfort, and metabolic efficiency of many routine movements involving both functional and recreational activities. Furthermore, abnormal performance of the muscles of the hip may alter the distribution of forces across the joint’s articular surfaces, potentially causing, or at least predisposing, degenerative changes in the articular cartilage, bone, and surrounding connective tissues.

Physical therapy diagnosis related to the hip and adjacent regions often requires a solid understanding of the actions of the surrounding muscles. This knowledge is instrumental in identifying when a specific muscle or muscle group is weak, painful, dominant, or tight (ie, lacks the extensibility to permit normal range of motion). Depending on the particular muscle, any one of these conditions can significantly affect the alignment across the lumbar spine, pelvis, and femur, ultimately affecting the alignment throughout the entire lower limb. Furthermore, understanding the actions of the hip muscles is fundamental to interventions used to specifically activate, strengthen, or stretch certain muscles.

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