Effects of Back-Support Exoskeleton Use on Lower Limb Joint Kinematics and Kinetics During Level Walking

We assessed the effects of using a passive back-support exoskeleton (BSE) on lower limb joint kinematics and kinetics during level walking. Twenty young, healthy participants completed level walking trials while wearing a BSE (backX (TM)) with three different levels of hip-extension support torque (i.e., no torque, low, and high) and in a control condition (no-BSE). When hip extension torques were required for gait- initial 0-10% and final 75-100% of the gait cycle-the BSE with high supportive torque provided similar to 10 Nm of external hip extension torque at each hip, resulting in beneficial changes in participants' gait patterns. Specifically, there was a similar to 10% reduction in muscle-generated hip extension torque and similar to 15-20% reduction in extensor power. During the stance-swing transition, however, BSE use produced undesirable changes in lower limb kinematics (e.g., 5-20% increase in ankle joint velocity) and kinetics (e.g., similar to 10% increase in hip flexor, knee extensor, and ankle plantarilexor powers). These latter changes likely stemmed from the need to increase mechanical energy for propelling the leg into the swing phase. BSE use may thus increase the metabolic cost of walking. Whether such use also leads to muscle fatigue and/or postural instability in long-distance walking needs to be confirmed in future work.

Automated summary

This study assessed the effects of using a passive back-support exoskeleton (BSE) on lower limb joint kinematics and kinetics during walking. The results showed that the BSE, particularly with high supportive torque, provided beneficial changes in gait patterns. However, it also produced undesirable changes in lower limb kinetics and may increase the metabolic cost of walking.