Robotic resistance/assistance training improves locomotor function in individuals poststroke: a randomized controlled study

Abstract

Objective: To determine whether providing a controlled resistance versus assistance to the paretic leg at the ankle during treadmill training will improve walking function in individuals poststroke.

Design: Repeated assessment of the same patients with parallel design and randomized controlled study between 2 groups.

Setting: Research units of rehabilitation hospitals.

Participants: Patients (N=30) with chronic stroke.

Intervention: Subjects were stratified based on self-selected walking speed and were randomly assigned to the resistance or assistance training group. For the resistance group, a controlled resistance load was applied to the paretic leg at the ankle to resist leg swing during treadmill walking. For the assistance group, a load that assists swing was applied.

Main outcome measures: Primary outcome measures were walking speed and 6-minute walking distance. Secondary measures included clinical assessments of balance, muscle tone, and quality of life. Outcome measures were evaluated before and after 6 weeks of training and at 8 weeks' follow-up, and compared within group and between the 2 groups.

Results: After 6 weeks of robotic training, walking speed significantly increased for both groups, with no significant differences in walking speed gains observed between the 2 groups. In addition, 6-minute walking distance and balance significantly improved for the assistance group but not for the resistance group.

Conclusions: Applying a controlled resistance or an assistance load to the paretic leg during treadmill training may induce improvements in walking speed in individuals poststroke. Resistance training was not superior to assistance training in improving locomotor function in individuals poststroke.

Keywords: Gait; Hemiplegia; Recovery of function; Rehabilitation; Robotics; Walking.

Fig 1

Experimental setup. The cable-driven robotic gait system works with the treadmill and body weight support system. Four cables driven by 4 motors, pulleys, and cable spools were used to apply controlled resistance/assistance loads to the legs. A personal computer was used to control the coordinated movement of the 4 motors. In this study, 1 cable was used to provide controlled force to the paretic leg during the swing phase of gait. Abbreviation: 3D, 3-dimensional.

Fig 2

Self-selected and fast overground walking speed, before and after 6 weeks of robotic resistance (A) and assistance (B) treadmill training with the cable-driven robotic gait training system, and 8 weeks after the end of training. An instrumented walkway (GaitMat II) was used to measure overground gait speed. Data shown in the figure are the mean and SD of gait speed across subjects. *P<.05.

Fig 3

Six-minute walking distance (A) and BBS score (B) before and after 6 weeks of robotic resistance and assistance training, and 8 weeks after the end of training. Data shown in the figure are the mean and SD of walking distance and BBS score across subjects. *P<.05.

Fig 4

Improvements in self-selected (A) and fast walking (B) overground gait speed before and after 6 weeks of robotic resistance and assistance treadmill training, and 8 weeks after the end of training. Three trials were tested for each condition. The bar and error indicate the mean and SD of the functional gains in gait speed across subjects.