Similar to nonamputees, female athletes with unilateral transtibial amputation (TTA) using running-specific leg prostheses (RSPs) may have worse running economy and higher rates of running-related injury than male athletes. These authors hypothesized that optimizing RSP configuration for female athletes could improve running economy and minimize biomechanical asymmetry, which has been associated with running-related injury.
Nine females with a TTA ran at 2.5 m/s while we measured metabolic rates and ground reaction forces. The runners used an RSP with a manufacturer-recommended stiffness category, 1 category less stiff and 2 categories less stiff than recommended.
Use of an RSP 2 categories less stiff resulted in 3.0% lower net metabolic power (P = 0.04), 7.8% lower affected leg stiffness (P = 6.01 × 10−4), increased contact time asymmetry (P = 0.04), and decreased stance average vertical ground reaction force asymmetry (P = 0.04) compared with a recommended stiffness category RSP.
Lower RSP stiffness (kN/m) values were associated with lower net metabolic power (P = 0.02), lower affected leg stiffness (P = 1.36 × 10−4), longer affected leg contact time (P = 1.46 × 10−4), and similar affected leg peak and stance-average vertical ground reaction force compared with higher RSP stiffness values.
The runners then used the RSP stiffness category that elicited the lowest net metabolic power with 100 g, 200 g, and 300 g added distally. No significant effects of added mass on net metabolic power, biomechanics, or asymmetry were found.
The authors concluded that females with unilateral transtibial amputation can improve running performance through reductions in net metabolic power by using an RSP that is less stiff than manufacturer-recommended. Lower RSP stiffness values are associated with greater leg stiffness and contact time asymmetry, and lower stance-average vertical ground reaction force asymmetry.
Source: Ashcraft KR, Grabowski AM. Effects of prosthetic stiffness and added mass on metabolic power and asymmetry in female runners with a leg amputation. J Appl Physiol (1985). 2024;137(1):85-98. doi: 10.1152/japplphysiol.00522.2023. © 2024 the American Physiological Society; all rights reserved.
