The immediate effects of robot-assistance on energy consumption and cardiorespiratory load during walking compared to walking without robot-assistance: a systematic review

Abstract

Purpose: The integration of sufficient cardiovascular stress into robot-assisted gait (RAG) training could combine the benefits of both RAG and aerobic training. The aim was to summarize literature data on the immediate effects of RAG compared to walking without robot-assistance on metabolic-, cardiorespiratory- and fatigue-related parameters.

Methods: PubMed and Web of Science were searched for eligible articles till February 2016. Means, SDs and significance values were extracted. Effect sizes were calculated.

Results: Fourteen studies were included, concerning 155 participants (85 healthy subjects, 39 stroke and 31 spinal cord injury patients), 9 robots (2 end-effectors, 1 treadmill-based and 6 wearable exoskeletons), and 7 outcome parameters (mostly oxygen consumption and heart rate). Overall, metabolic and cardiorespiratory parameters were lower during RAG compared to walking without robot-assistance (moderate to large effect sizes). In healthy subjects, when no body-weight support (BWS) was provided, RAG with an end-effector device was more energy demanding than walking overground (p > .05, large effect sizes).

Conclusions: Generally, results suggest that RAG is less energy-consuming and cardiorespiratory stressful than walking without robot-assistance, but results depend on factors such as robot type, walking speed, BWS and effort. Additional research is needed to draw firm conclusions. Implications for Rehabilitation Awareness of the energy consumption and cardiorespiratory load of robot-assisted gait (RAG) training is important in the rehabilitation of (neurological) patients with impaired cardiorespiratory fitness and patients who are at risk of cardiovascular diseases. On the other hand, the integration of sufficient cardiometabolic stress in RAG training could combine the effects of both RAG and aerobic training. Energy consumption and cardiorespiratory load during walking with robot-assistance seems to depend on factors such as robot type, walking speed, body-weight support or amount of effort. These parameters could be adjusted in RAG rehabilitation to make RAG more or less energy-consuming and cardiorespiratory stressful. Overall, short duration exoskeleton walking seems less energy-consuming and cardiorespiratory stressful than walking without robot-assistance. This might implicate that the exercise intensity is safe for (neurological) patients at risk of cardiovascular diseases. How this changes in extended walking time is unclear.

Keywords: Walking; cardiovascular physiological processes; end-effector; energy metabolism; exoskeleton device; respiratory physiological processes.