Effect of Physical Activity Versus Health Education on Physical Function, Grip Strength and Mobility

Editor's Note: Commentary based on Santanasto AJ, Glynn NW, Lovato LC, et al. Effect of physical activity versus health education on physical function, grip strength and mobility. J Am Geriatr Soc 2017;65:1427-33..

Rationale for Study/Background: Physical activity (PA) reduces the rate of mobility disability, compared with health education (HE), in at-risk older adults. It is important to understand aspects of performance contributing to this benefit.

Study Questions:

  1. How does PA affect 400 m walking speed, grip strength and total Short Physical Performance Battery (SPPB) score and its components: balance, 4 m gait speed and repeated chair stands, compared to HE?
  2. What is the potential mediating role of these performance measures in preventing major mobility disability in at risk older adults?

Funding: National Institutes of Health/National Institute on Aging Cooperative Agreement supplement from National Heart, Lung and Blood Institute; also sponsored in part by the Intramural Research Program, National Institute on Aging, NIH; the Claude D. Pepper Older Americans Independence Centers at the University of Florida (1P30AG028740), Wake Forest University, Tufts University, University of Pittsburgh, and Yale University and the NIH/NCRR CTSA at Stanford University; Tufts University is also supported by the Boston Rehabilitation Outcomes Center.

Study Design: The Lifestyle Interventions and Independence for Elders (LIFE) study was a multi-center, single-blind randomized trial of older adults.

Methods: Eligible participants from targeted mass mailings were randomized to PA (N = 818) or HE (N = 817) using a permuted block algorithm (with random block lengths) stratified by field center and sex. Inclusion criteria included: age 70-89 years; sedentary lifestyle (reported <20 min/week of regular exercise in the past month and <125 min/week of moderate PA); high risk for mobility disability (SPPB score <10 and 45% <8); able to walk 400 m in <15 minutes; no cognitive impairment (1.5 standard deviations below education and race-specific norms on the Modified Mini-Mental State Examination); and able to safely participate in the interventions based on medical history, physical examination, and resting electrocardiogram.

PA sessions were group-based and consisted primarily of over ground walking, with a goal of 150 min/week, supplemented with strength and balance training designed to be done at the center (twice per week) and at home. Resistance training used ankle weights adjustable up to 20 lbs. in 0.5 lb. increments. The balance regimen consisted of five levels that progressed in difficulty. Following each session, participants completed several flexibility/stretching exercises.

The HE group participated in weekly workshops for the first 26 weeks. From week 27 on, sessions were offered twice per month with required participation at least once per month. The topic of PA was purposefully avoided. The workshops concluded with 5-10 minutes of light, upper extremity stretching. Mean follow-up was 2.6 years.

Study Population: 1635 adults aged 70-89 (mean 78.9 ± 5.2) years, 67.2% women, at risk for mobility disability, as defined by a SPPB score <10.

Outcomes: Grip strength, SPPB score and its components (balance, 4 m gait speed, and chair-stands), as well as 400 m walking speed.

Statistical Analysis: Intervention adherence was defined as the percentage of scheduled center-based intervention sessions attended. Intervention effects were compared, using an intention-to-treat approach, on grip strength, 400 m walking speed, and the SPPB and its components, using repeated measures analysis of covariance (ANCOVA) with an unstructured parameterization matrix for longitudinal covariance. Models included the following variables: site, sex (both used to stratify randomization), baseline outcome variables, intervention, visit, and interaction between intervention and visit. These analyses were repeated in participants with baseline SPPB scores <8.

Results: Total SPPB score was higher in the PA group versus HE group across all follow-up times (overall P = 0.04), as was the chair stand component (overall P < 0.001). No intervention effects were observed for balance (overall P = 0.12), 4 m gait speed (overall P = 0.78) or grip strength (overall P = 0.62). However, 400 m walking speed was faster in PA versus HE group (overall P = <0.001). In separate models, 29% of the rate reduction of major mobility disability in the PA versus HE group was explained by change in SPPB score, while 39% was explained by change in the chair stand component.

Limitations: Improvements in lower extremity performance (SPPB) with PA, despite being statistically significant, were clinically modest and decreased over time in all patients except those at highest risk of mobility disability. More intense PA may confer more risk reduction and merits further study.

Conclusions: Lower extremity performance (SPPB) was significantly higher in the PA compared with the HE group. Changes in chair-stand score explained a considerable portion of the effect of PA on the reduction of major mobility disability, consistent with the concept that preserving muscle strength/power may be important for the prevention of major mobility disability.

Perspective: We humans know more than we do; it is difficult to do what we know is best for our health. Previous work by the LIFE study group showed that PA prevents mobility disability in older adults to a greater degree than HE.1 The present study sought to determine which performance measures were most improved by PA, in part to aid in tracking early benefits of future interventions and to improve them. The quality, availability, and financing of effective physical activity interventions for older populations in non-study settings continue to be a challenge. Older adults are often wrongly discouraged from exercising by their caregivers and doctors for various reasons, yet in the LIFE study the benefits of PA were most pronounced in older adults at highest risk (SPPB <8) for mobility disability. Mobility disabilities may be preventable through exercise,1 and the known associations of mobility disability with death and morbidity should inspire caregivers and doctors to promote older adult activity.2-3 As cardiologists, when we counsel our elderly patients on the benefits of exercise, we should also help facilitate identifying a time and place where they can exercise, e.g., through cardiac rehab or a geriatric physical activity program. Similarly, spouses and family members should be encouraged to become exercise advocates.

References

  1. Pahor M, Guralnik JM, Ambrosius WT, et al. Effect of structured physical activity on prevention of major mobility disability in older adults: The LIFE study randomized clinical trial. JAMA 2014;311:2387-96.
  2. Studenski S, Perera S, Patel K, et al. Gait speed and survival in older adults. JAMA 2011;305:50-8.
  3. Manini TM, Clark BC. Dynapenia and aging: an update. J Gerontol A Biol Sci Med Sci 2012;67:28-40.

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