Validity of an exercise test based on habitual gait speed in mobility-limited older adults

Abstract

Objective: To evaluate whether a customized exercise tolerance testing (ETT) protocol based on an individual's habitual gait speed (HGS) on level ground would be a valid mode of exercise testing older adults. Although ETT provides a useful means to risk-stratify adults, age-related declines in gait speed paradoxically limit the utility of standard ETT protocols for evaluating older adults. A customized ETT protocol may be a useful alternative to these standard methods, and this study hypothesized that this alternative approach would be valid.

Design: We performed a cross-sectional analysis of baseline data from a randomized controlled trial of older adults with observed mobility problems. Screening was performed using a treadmill-based ETT protocol customized for each individual's HGS. We determined the content validity by assessing the results of the ETTs, and we evaluated the construct validity of treadmill time in relation to the Physical Activity Scale for the Elderly (PASE) and the Late Life Function and Disability Instrument (LLFDI).

Setting: Outpatient rehabilitation center.

Participants: Community-dwelling, mobility-limited older adults (N=141).

Interventions: Not applicable.

Main outcome measures: Cardiac instability, ETT duration, peak heart rate, peak systolic blood pressure, PASE, and LLFDI.

Results: Acute cardiac instability was identified in 4 of the participants who underwent ETT. The remaining participants (n=137, 68% female; mean age, 75.3 y) were included in the subsequent analyses. Mean exercise duration was 9.39 minutes, with no significant differences in durations being observed after evaluating among tertiles by HGS status. Mean peak heart rate and mean peak systolic blood pressure were 126.6 beats/min and 175.0 mmHg, respectively. Within separate multivariate models, ETT duration in each of the 3 gait speed groups was significantly associated (P<.05) with PASE and LLFDI.

Conclusions: Mobility-limited older adults can complete this customized ETT protocol, allowing for the identification of acute cardiac instability and the achievement of optimal exercise parameters.

Trial registration: ClinicalTrials.gov NCT00158119.

Copyright © 2012 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

Figures

Fig 1

Graphical depiction of the submaximal ETT protocol based on HGSs.

Fig 2

Survival analysis between the duration of the ETT results and the 3 groups classified by HGS (N = 137).