Beck Owen N, Taboga Paolo, Grabowski Alena M
Department of Integrative Physiology, University of Colorado, Boulder, Colorado; and
Department of Integrative Physiology, University of Colorado, Boulder, Colorado; and.
J Appl Physiol (1985). 2017 Apr 1;122(4):976-984. doi: 10.1152/japplphysiol.00587.2016. Epub 2017 Jan 19.
Inspired by the springlike action of biological legs, running-specific prostheses are designed to enable athletes with lower-limb amputations to run. However, manufacturer's recommendations for prosthetic stiffness and height may not optimize running performance. Therefore, we investigated the effects of using different prosthetic configurations on the metabolic cost and biomechanics of running. Five athletes with bilateral transtibial amputations each performed 15 trials on a force-measuring treadmill at 2.5 or 3.0 m/s. Athletes ran using each of 3 different prosthetic models (Freedom Innovations Catapult FX6, Össur Flex-Run, and Ottobock 1E90 Sprinter) with 5 combinations of stiffness categories (manufacturer's recommended and ± 1) and heights (International Paralympic Committee's maximum competition height and ± 2 cm) while we measured metabolic rates and ground reaction forces. Overall, prosthetic stiffness [fixed effect (β) = 0.036; = 0.008] but not height ( ≥ 0.089) affected the net metabolic cost of transport; less stiff prostheses reduced metabolic cost. While controlling for prosthetic stiffness (in kilonewtons per meter), using the Flex-Run (β = -0.139; = 0.044) and 1E90 Sprinter prostheses (β = -0.176; = 0.009) reduced net metabolic costs by 4.3-4.9% compared with using the Catapult prostheses. The metabolic cost of running improved when athletes used prosthetic configurations that decreased peak horizontal braking ground reaction forces (β = 2.786; = 0.001), stride frequencies (β = 0.911; < 0.001), and leg stiffness values (β = 0.053; = 0.009). Remarkably, athletes did not maintain overall leg stiffness across prosthetic stiffness conditions. Rather, the in-series prosthetic stiffness governed overall leg stiffness. The metabolic cost of running in athletes with bilateral transtibial amputations is influenced by prosthetic model and stiffness but not height. We measured the metabolic rates and biomechanics of five athletes with bilateral transtibial amputations while running with different prosthetic configurations. The metabolic cost of running for these athletes is minimized by using an optimal prosthetic model and reducing prosthetic stiffness. The metabolic cost of running was independent of prosthetic height, suggesting that longer legs are not advantageous for distance running. Moreover, the in-series prosthetic stiffness governs the leg stiffness of athletes with bilateral leg amputations.
受生物腿类似弹簧动作的启发，专门设计的跑步假肢旨在使下肢截肢运动员能够跑步。然而，制造商关于假肢刚度和高度的建议可能无法使跑步性能达到最佳。因此，我们研究了使用不同假肢配置对跑步代谢成本和生物力学的影响。五名双侧胫骨截肢运动员在测力跑步机上以2.5或3.0米/秒的速度各进行了15次试验。运动员使用3种不同的假肢模型（Freedom Innovations Catapult FX6、Össur Flex-Run和奥托博克1E90 Sprinter）中的每一种，以及5种刚度类别（制造商推荐的和±1）和高度（国际残奥委会的最大比赛高度和±2厘米）的组合进行跑步，同时我们测量代谢率和地面反作用力。总体而言，假肢刚度[固定效应(β)=0.036；P=0.008]而非高度（P≥０.０８９）影响了净运输代谢成本；刚度较小的假肢降低了代谢成本。在控制假肢刚度（以千牛顿每米为单位）的情况下，与使用Catapult假肢相比，使用Flex-Run（β=-0.139；P=0.044）和1E90 Sprinter假肢（β=-0.176；P=0.009）可使净代谢成本降低4.3%-4.9%。当运动员使用能降低水平制动地面反作用力峰值（β=2.786；P=0.001）、步频（β=0.911；P<0.001）和腿部刚度值（β=0.053；P=0.009）的假肢配置时，跑步的代谢成本有所改善。值得注意的是，运动员在不同假肢刚度条件下并未保持整体腿部刚度。相反，串联假肢刚度决定了整体腿部刚度。双侧胫骨截肢运动员的跑步代谢成本受假肢模型和刚度影响，但不受高度影响。我们测量了五名双侧胫骨截肢运动员在使用不同假肢配置跑步时的代谢率和生物力学。通过使用最佳假肢模型并降低假肢刚度，可使这些运动员的跑步代谢成本降至最低。跑步的代谢成本与假肢高度无关，这表明腿更长对长跑并无优势。此外，串联假肢刚度决定了双侧腿部截肢运动员的腿部刚度。
