Muscle torque of the hip joint flexors and extensors in physically active and inactive amputees

Study aim: The aim of this study was to assess proportion and symmetry between torque in muscles that affect the hip joint in the non-amputated and the amputated limb in persons both engaged in and not engaged in sports.

Material and methods: Study participants comprised 12 persons with above-knee leg amputation. The group of participants was divided into two subgroups: persons engaged in sports and physically inactive persons. The strength and the speed capacity of hip joint flexors and hip joint extensors were measured using a Biodex System 4 dynamometer. The measurement was conducted at two angular velocities (60°/s and 120°/s) and during isometric activity of the non-amputated and the amputated limb.

Results: Maximal torque of hip joint flexors in the amputated limb of physically active persons constituted 65.3% of the corresponding value in persons without amputation and was higher than in physically inactive persons (55.9%). Similar values were obtained for extensors. The time to reach maximal muscle torque in the amputated limb during the extension of the hip joint at 60°/s equalled 400 ms in physically active persons and 900 ms in physically inactive persons and during flexion, equalled 400 ms and 600 ms, respectively.

Conclusions: Physically active persons showed greater dynamics in generating maximal muscle torque, especially during the extension of the hip joint. Physical activity benefits the strength and speed capacity of muscles that affect the hip joint in persons with above-knee amputation, thus decreasing asymmetry and disproportion between limbs.