The Effects of Running Speeds on Loading Rates in Individuals with Unilateral Transfemoral Amputation

Abstract

For individuals with lower limb amputation, participating in physical activities such as running is expected to positively impact their quality of life. However, individuals with lower limb amputation, especially unilateral transfemoral amputation, may be exposed to a higher risk for musculoskeletal injury during running. Although the loading rate is one of the indicators to estimate the risk of musculoskeletal injury, the loading rate in individuals with unilateral transfemoral amputation at various running speeds remains unclear. This study aimed to evaluate the risk of musculoskeletal injury across a range of running speeds in individuals with unilateral transfemoral amputation by using the loading rate. Fourteen individuals with unilateral transfemoral amputation and 10 non-amputees ran on a split-belt force-instrumented treadmill at 4 running speeds （30%, 40%, 50%, and 60% of each subject’s maximum speed）．Loading rates were calculated as the average and instantaneous slopes of the ground reaction force from touchdown to 50 ms. We found the loading rates in the unaffected limb were significantly greater than those in the affected and control limbs at all running speeds. In addition, the loading rates in the unaffected and affected limbs significantly increased with increasing running speed. The results of this study suggested that the risk for musculoskeletal injury during running in individuals with unilateral transfemoral amputation increased with increasing running speeds, especially in the unaffected limb.