Physiological responses and perceived exertion during robot-assisted treadmill walking in non-ambulatory stroke survivors

Abstract

Purpose

To examine physiological responses and perceived exertion during robot-assisted treadmill walking in non-ambulatory stroke survivors; compare these outcomes with aerobic exercise recommendations; and investigate the effect of robotic assistance.

Materials and methods

Twelve non-ambulatory stroke survivors (67 ± 11 years-old, 84 ± 38 d post-stroke) participated. Subjects walked three times 20 min (1 session/day) in the Lokomat: once with conventional exercise parameters, once with 60% robotic assistance and once with 100% robotic assistance. Gas exchange and heart rate were monitored continuously. Perceived exertion was assessed every 3 min during walking.

Results

During conventional robot-assisted treadmill walking, net perceived exertion (0–14 scale) significantly increased between minute 6 (median = 2, interquartile range = 4) and 18 (median = 5, interquartile range = 4). Net physiological responses did not significantly change over time. Throughout exercise, percentage of predicted heart rate reserve was significantly below the 40% threshold (medians: 11–14%) and percentage of predicted maximum heart rate reached the 55% threshold (medians: 59–60%). Perceived exertion reached the 11-point threshold halfway. Net physiological responses and perceived exertion did not significantly differ between 60% and 100% robotic assistance.

Conclusions

The assistance level that non-ambulatory stroke survivors require at their highest tolerable walking speed seems too high to sufficiently stress the cardiorespiratory system during robot-assisted treadmill walking.

Implications for rehabilitation

• The exercise intensity of 20-minute conventional robot-assisted treadmill walking can be low, and might be too low to challenge the cardiorespiratory system of non-ambulatory stroke survivors.

• Lowering the level of robotic assistance from 100% to 60% does not seem to increase the exercise intensity of 20-minute robot-assisted treadmill walking.

Keywords:

• Energy metabolism
• aerobic exercise
• walking
• exoskeleton devices
• stroke

Acknowledgments

The authors would like to thank the patients of the Jessa Hospital campus Sint-Ursula (Herk-de-Stad, Belgium) and the Neurorehabilitation Units 1 and 4 of Fondazione Santa Lucia (Rome, Italy) for participating in this trial, and the therapists for managing the Lokomat system and recruiting participants.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

The authors disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: Nina Lefeber and Emma De Keersmaecker are Strategic Basic Research fellows funded by the Research Foundation – Flanders (FWO).