The fastest runner on artificial legs: different limbs, similar function?

Abstract

The recent competitive successes of a bilateral, transtibial amputee sprint runner who races with modern running prostheses has triggered an international controversy regarding the relative function provided by his artificial limbs. Here, we conducted three tests of functional similarity between this amputee sprinter and competitive male runners with intact limbs: the metabolic cost of running, sprinting endurance, and running mechanics. Metabolic and mechanical data, respectively, were acquired via indirect calorimetry and ground reaction force measurements during constant-speed, level treadmill running. First, we found that the mean gross metabolic cost of transport of our amputee sprint subject (174.9 ml O(2)*kg(-1)*km(-1); speeds: 2.5-4.1 m/s) was only 3.8% lower than mean values for intact-limb elite distance runners and 6.7% lower than for subelite distance runners but 17% lower than for intact-limb 400-m specialists [210.6 (SD 13.2) ml O(2)*kg(-1)*km(-1)]. Second, the speeds that our amputee sprinter maintained for six all-out, constant-speed trials to failure (speeds: 6.6-10.8 m/s; durations: 2-90 s) were within 2.2 (SD 0.6)% of those predicted for intact-limb sprinters. Third, at sprinting speeds of 8.0, 9.0, and 10.0 m/s, our amputee subject had longer foot-ground contact times [+14.7 (SD 4.2)%], shorter aerial [-26.4 (SD 9.9)%] and swing times [-15.2 (SD 6.9)%], and lower stance-averaged vertical forces [-19.3 (SD 3.1)%] than intact-limb sprinters [top speeds = 10.8 vs. 10.8 (SD 0.6) m/s]. We conclude that running on modern, lower-limb sprinting prostheses appears to be physiologically similar but mechanically different from running with intact limbs.

Força de Reação do Solo e atividade eletromiográfica da marcha de amputados transfemorais: uma série de casos

“…As a consequence of slow gait and the shorter ∆tstance (Table 1), the vertical GRF impulse was lower for the AL (Table 1), thereby mirroring previous studies 1,23 . The lowest vertical impulse facilitates balance control 24 .…”

Energy-efficacy comparisons and multibody dynamics analyses of legged robots with different closed-loop mechanisms

“…Another possible option of the energy regeneration of the energy is energy storage with passive compliance, which is obtained from spring and elastic materials [11]. The property of the energy storage is known in the artificial legs made of elastic materials, such as carbon fiber prostheses [65]. In this analysis, we used DAEs in the MBD analysis only with rigid bodies, which are treated by total differential equations, and the hybrid system composed of rigid bodies and elastic materials requires the extension of DAEs to involve calculations of a set of partial differential equations simultaneously, such as the finite element method.…”

Running-specific prostheses: The history, mechanics, and controversy

“…Weyand et al 13) compared contact length during treadmill running between one double-transtibial amputee runner and able-bodied runners.…”