Progressive Resistance Training Improves Torque Capacity and Strength in Mobility-Limited Older Adults

Abstract

Background: Progressive resistance training (PRT) is consistently shown to improve muscle strength in older adults. The efficacy of PRT to improve muscle fatigue in older adults with demonstrated mobility limitations remains unclear.

Methods: Mobility-limited (Short Physical Performance Battery [SPPB] ≤ 9) older adults (age 70-92 years) were recruited for this study and randomized to either PRT or home-based flexibility (FLEX) 3 d/wk for 12 weeks. Muscle fatigue and strength outcomes were assessed at baseline and 12 weeks. The primary outcome was torque capacity, a composite measure of strength and fatigue, defined as the sum of peak torques from an isokinetic fatigue test.

Results: Seventy participants were randomized (mean [SD] age 78.9 [5.4] years; 60% female; mean [SD] SPPB 7.5 [1.6]). At follow-up, the PRT group improved significantly in torque capacity, mean between-group difference (95% confidence interval) 466.19 (138.4, 793.97) Nm (p = .006), and maximal strength 127.3 (60.96, 193.61) Nm (p = .0003), when compared with FLEX group. Neither group demonstrated significant changes in muscle fatigue or torque variability.

Conclusion: Twelve weeks of PRT improved torque capacity, as well as strength in mobility-limited older adults. These results demonstrate PRT improves multiple age-related muscular impairments.

Trial registration: ClinicalTrials.gov NCT03083275.

Keywords: Exercise; Function; Power; Torque.

© The Author(s) 2018. Published by Oxford University Press on behalf of The Gerontological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Figures

Figure 1.

CONOSRT diagram of study recruitment, enrollment, and randomization. SPPB = Short Physical Performance Battery; 6MWT = 6-min walk test.

Figure 2.

Progressive resistance training (PRT) and home-based flexibility (FLEX) groups. Peak torque for all contractions performed during the fatigue test before and after the intervention period in FLEX (A) and PRT (B) groups. Absolute change (± SE) in summed torque in the PRT and FLEX groups (C). *Significant change between groups: p = .006.

Figure 3.

Progressive resistance training (PRT) group only. (A) Percent change (± SE) in peak torque at rest (average of pre-fatigue and fatigue test peak torque), at fatigue (average of repetitions 116–120), and at 2, 5, and 10 min after the fatigue test in the PRT group. (B) Percentage of peak torque at rest achieved (± SE) during fatigue and at 2, 5, and 10 min post the fatigue test before and after the intervention.

Figure 4.

Box plots of change in torque variability after 12 wk of home-based flexibility (FLEX; gray) or progressive resistance training (PRT; white). Positive and negative values indicate an increase or decrease, respectively. Plots generated using BoxPlotR (PMID: 24481215).