Joint moment-angle properties of the hip abductors and hip extensors

Purpose: Strengthening of hip joint musculature is common in the rehabilitation of the lower extremity. However, strength curves for hip abduction and extension have not been assessed when varying the position of the knee. The force-length properties of the biarticular muscles can be affected when altering the position of the knee during the production of hip moments. Methods: Maximum isometric joint moments were measured at four different angles of hip abduction and hip extension, at the two knee positions (0° and 90°). Results: The hip abduction and extension moments decreased as the hip moved from an adducted position and flexed position to an abducted position and extended position, respectively, resulting in a descending joint moment angle curve for each. Conclusion: The results indicate that position of the knee does not significantly change the normalized peak hip abduction joint moment, but the position of the knee does significantly change the normalized peak hip extension joint moment. This provides a baseline reference of hip joint moment production and can be utilized when assessing a population with a pathology or prescribing rehabilitative exercises.