Effects Of Overground-based Versus Treadmill-based Exoskeleton Training Protocols On Human-exoskeleton Performance

To increase soldiers’ physical capability with the usage of exoskeletons, it is essential to develop a training protocol that can enhance user-exoskeleton performance in the real-world setting. As opposed to the typical treadmill-based (TR) training protocol focusing on practicing walking with exoskeleton assistance at the constant speed and flat surface, an overground-based (OG) training protocol was developed to include simulated real-world conditions, such as walking on uneven terrains, during transition states or while making turns. PURPOSE: To compare the effects of OG and TR training protocols on user-exoskeleton proficiency in performing army-relevant tasks and field conditions. METHODS: 14 male subjects (22.2 ± 3.1 years) received 2 sessions of OG or TR training to walk with a powered ankle exoskeleton. Subjects performed a battery of evaluation tasks before (PRE) and after the training (POST), with and without a 75 lb. carried load, and while wearing regular boots (NoEXO) or Exoboots (EXO-powered). Outcome measures included oxygen consumption rate (VO2), cost of transport (CoT), and task completion time. Subjects were classified as “non-adept”, or “adept” users based on their baseline adaptation performance. RESULTS: Compared to PRE, both groups had lower CoT for Flat terrain walking with EXO-powered at POST (15.0 ± 2.2 vs. 13.2 ± 2.9 ml/m, p < 0.05). However, both groups had greater CoT for the loaded, uneven terrain walking (31.5 ± 3.2 vs 34.5 ± 4.8 ml/m, p < 0.05), and this increase in CoT was larger in non-adept than adept users (by 18.4 vs 4.1 %, p < 0.05). OG group shortened the loaded, balance beam walking time at POST more than the TR group (-11.8 vs +2.1%, p < 0.05). For the 20-min ruck march, adept users reduced VO2 at POST more than non-adept users (-6.1 vs +4.7%, p < 0.05). For the split-belt treadmill walking, OG group had less increase in VO2 compared to TR group when the belt speeds were untied (+50.0 vs +87.9%, p < 0.05) and became tied again (+3.7 vs +24.7%, p < 0.05). CONCLUSION: OG and TR training showed similar performance of treadmill-based tasks and overground tasks on flat terrain. For the tasks challenging agility/coordination, OG training showed more improvement or better performance than TR training. Adept exoskeleton users can be benefited by either training protocol. Supported by W911QY-18-2-0006