Exercise as an Intervention for Frailty
Section snippets
Aerobic or endurance exercise training
There are 2 mechanisms by which aerobic exercise is thought to alter the frailty phenotype: improvement in the maximal oxygen uptake (Vo2max) and increased muscle mass. Vo2max is defined as the maximum rate of oxygen consumption measured during vigorous exercise and is closely related to submaximal endurance exercise capacity and exercise tolerance.
In an intervention study of 64 frail men and women, a 9-month program of strength training and walking that aimed at reaching 78% of peak heart
Resistance exercise training
There is well-documented evidence that muscle strength decreases with advancing age. Muscle strength decreases approximately 12% to 15% per decade after the age of 50 years18 in both men and women.19 In addition, muscle mass also decreases with increased age. In a cross-sectional study of healthy men of equal mass, muscle mass comprised 24% of total mass in those aged 20 to 29 years but decreased to 13% in subjects aged 70 to 79 years.20 Several studies have found that the decline in strength
Combined aerobic and resistance exercise
Given that aerobic or resistance exercise alone has beneficial results and that both types of exercise target specific distinct features of frailty, there has been recent interest in whether an intervention with both components is beneficial for frail older adults. In a randomized controlled trial of elderly subjects who had undergone surgical repair of a femur fracture, a 6-month intervention of aerobic activity and progressive resistance exercise was associated with a mean improvement of 19
Effect of exercise interventions on the adverse outcomes of frailty
Several studies have examined the effect of exercise on reducing the risk of falls, a common adverse outcome of frailty. After a single fall, the risk of skilled nursing facility placement in older adults increases 3-fold, after adjustment for cognitive, psychological, social, functional, and medical factors.38 In a study examining women undergoing resistance training for 25 weeks, risk of falls was reduced by 57% from baseline.39 A meta-analysis of 6 studies by Baker and colleagues40 showed
Effect on the phenotype of frailty
Although there have been multiple trials studying the effects of exercise on the various characteristics of frailty and the adverse outcomes of frailty, there have been few studies to determine whether exercise can alter or even reverse frailty status in older adults. In a study conducted with subjects who were frail or at high risk for frailty, a telephone intervention encouraging exercise decreased the proportion of frail elders by 18% at 6 months follow-up.47 At present, the Frailty
Adverse outcomes of exercise
Adverse outcomes with both aerobic and resistance training, although not uncommon, are rarely life threatening. In a study that examined resistance training in elderly women, most of the adverse outcomes were musculoskeletal complaints.39 Latham and colleagues49 found that the risk ratio for adverse events increased to 3.6 in those who underwent 10 weeks of resistance training. However, no reports of death or cardiovascular events were found in a systemic review of 62 trials of resistance
Future directions
Clearly, exercise and physical activity are promising interventions for frailty, and several studies are underway to examine their effect. However, there are several related areas that need further investigation before this intervention can be disseminated to frail older adults on a widespread basis. First, adherence to an exercise regimen is key to its beneficial effects, and strategies to overcome this barrier need to be developed before exercise as treatment modality is implemented on a wide
Summary: an exercise “prescription”
Although more investigation is still needed, most studies suggest that clinicians should recommend regular physical activity or exercise training to frail older adults. The current guidelines from the US Department of Health and Human Services state that all adults older than 65 years should participate in 150 minutes (ie, 2.5 hours) of moderate aerobic exercise per week.52 Although most trials studied resistance exercise training, frail older adults are encouraged to start with an aerobic
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Dr Liu was supported by a Health Resources and Services Administration grant from the Bureau of Health Professions (# D01 HP08796) and by Boston Medical Center, Boston, MA. Dr Fielding was supported by the Boston Claude D. Pepper Older Americans Independence Center (1P30AG031679). This material is based on work supported by the US Department of Agriculture, under agreement No. 58–1950–7–707.