Saskia Baltrusch

101 Chapter 4 3.2 Walking Metabolic costs For walking, metabolic cost increased by 12% and 17% when wearing the exoskeleton in speed conditions PWS and PWSX, respectively (Figure 7). For both speed conditions this effect was significant (PWS: p=0.002 and PWSX: p=0.002). Kinematics The preferred walking speed without exoskeleton (PWS) and the preferred walking speed with exoskeleton (PWSX) were slightly, but significantly different. Participants preferred to walk faster without the exoskeleton than with the exoskeleton (mean (sd): 1.27m/s (0.16) vs. 1.22m/s (0.14); p=0.05). A reduction in stride length was found when walking with exoskeleton compared to without (Figure 8). This effect was, however, only significant at the preferred walking speed determined without exoskeleton (mean (sd): 1.42m (0.13) vs. 1.40m (0.13); p=0.013). Figure 7: Metabolic costs of walking in preferred walking speed without exoskeleton (PWS) and preferred walking speed with exoskeleton (PWSX). Values are normalized for bodyweight and walking speed. N=13; Error bars indicate standard deviations. *Significant change in metabolic costs between control condition (without) and exoskeleton condition (with exo/low cam). Figure 8: Stride length when walking with and without exoskeleton in the preferred walking speed without exo (PWS) and in the preferred speed with exo (PWSX). N=10; Error bars indicate standard deviations. *Significant change in stride length between control condition (without) and exoskeleton condition (with exo/low cam). 4