Impact of exercise to improve gait efficiency on activity and participation in older adults with mobility limitations: a randomized controlled trial

Abstract

Background: Definitive evidence that exercise interventions that improve gait also reduce disability is lacking. A task-oriented, motor sequence learning exercise intervention has been shown to reduce the energy cost of walking and improve gait speed, but whether the intervention also improves activity and participation has not been demonstrated.

Objective: The objective of this study was to compare the impact of a task-oriented, motor sequence learning exercise (TO) intervention and the impact of an impairment-oriented, multicomponent exercise (IO) intervention on activity and participation outcomes in older adults with mobility limitations. The mediating effects of a change in the energy cost of walking on changes in activity and participation also were determined.

Design: This study was a single-blind, randomized controlled trial. Setting The study was conducted in an ambulatory clinical research training center.

Participants: The study participants were 47 older adults (mean age=77.2 years, SD=5.5) with slow and variable gait. Intervention The intervention was a 12-week, physical therapist-guided program of TO or IO.

Measurements: Measures of activity (gait speed over an instrumented walkway; daily physical activity measured with an accelerometer; confidence in walking determined with the Gait Efficacy Scale; and physical function determined with the total, basic lower-extremity, and advanced lower-extremity components of the Late-Life Function and Disability Instrument [Late-Life FDI]) and participation (disability limitation dimension and instrumental role [home and community task performance] domain components of the Late-Life FDI) were recorded before and after the intervention. The energy cost of walking was determined from the rate of oxygen consumption during self-paced treadmill walking at the physiological steady state standardized by walking speed. An adjusted comparison of activity and participation outcomes in the treatment arms was made by use of an analysis of covariance model, with baseline and change in energy cost of walking added to the model to test for mediation. Tests were used to determine the significance of the mediating effects.

Results: Activity improved in TO but not in IO for confidence in walking (Gait Efficacy Scale; mean adjusted difference=9.8 [SD=3.5]) and physical function (Late-Life FDI basic lower-extremity component; mean adjusted difference=3.5 [SD=1.7]). Improvements in TO were marginally greater than those in IO for gait speed, physical activity, and total physical function. Participation improved marginally more in TO than in IO for disability limitations and instrumental role.

Limitations: The older adults were randomized to the intervention group, but differences in baseline measures had to be accounted for in the analyses.

Conclusions: A TO intervention that improved gait also led to improvements in some activity and participation outcomes in older adults with mobility limitations.

Trial registration: ClinicalTrials.gov NCT00177359.

Figure 1.

Between-group adjusted mean differences in activity and participation outcomes relative to small and moderate effect sizes for the variables. The radar graph provides an overall view of the between-group differences in the activity and participation variables. The adjusted between-group differences for each variable are plotted on separate spikes of the radar. The thick solid line connects the adjusted between-group differences for the variables. The estimated meaningful differences for each variable are represented as small meaningful changes (area enclosed by the dashed line) and moderate meaningful changes (area enclosed by the dotted line). The meaningful differences for each variable were estimated by calculating a small effect as 0.2 × baseline standard deviation of the sample mean of the variable and a moderate effect as 0.5 × baseline standard deviation of the sample mean of the variable. The values for gait speed and activity were adjusted by a multiple of 10 so that the same scale could be used in the axes for all of the variables. For gait speed, the actual value was the value shown times 10⁻²; for activity, the actual value was the value shown times 10. Asterisks indicate participation variables. cpm=counts per minute, GES=Gait Efficacy Scale, Instrumental=instrumental role, Late-Life FDI=Late-Life Function and Disability Instrument, LE=lower extremity, Limitations=disability limitations.

Figure 2.

Change in the estimates of the between-group adjusted mean differences explained by a change in gait efficiency. The black bars represent the between-group mean differences in the change in each variable from baseline to follow-up, adjusted for the covariates age, sex, and baseline value for the outcome variable. The gray bars represent the between-group mean differences in each variable from baseline to follow-up, adjusted for the covariates age, sex, baseline value for the outcome variable, baseline value of the energy cost of walking, and change in the energy cost of walking. A comparison of the gray bars with the black bars illustrates the mediating effects of the change in the energy cost of walking on changes in activity and participation outcomes. The values for gait speed and activity were adjusted by a multiple of 10 so that the same scale could be used in the axes for all of the variables. For gait speed, the actual value was the value shown × 10⁻²; for activity, the actual value was the value shown × 10. Asterisks indicate participation variables. cpm=counts per minute, GES=Gait Efficacy Scale, Late-Life FDI=Late-Life Function and Disability Instrument, LE=lower extremity.