The evidence from numerous studies of recent years makes it clear that resistance training produces significant benefits to the health and remaining life expectancy of older adults. To put it another way, most people do too little to maintain strength and their health suffers for it. The effects here seem to partially overlap with and partially be distinct from the benefits of aerobic exercise. But the benefits are broad, as indicated in this open access position paper on the subject.
Age-related loss of muscle mass (originally termed sarcopenia) has an estimated prevalence of 10% in adults older than 60 years (538), rising to greater than 50% in adults older than 80 years. Prevalence rates are lower in community-dwelling older adults than those residing in assisted living and skilled nursing facilities. Loss of muscle mass is generally gradual, beginning after age 30 and accelerating after age 60. Previous longitudinal studies have suggested that muscle mass decreases by 1.0-1.4% per year in the lower limbs, which is more than the rate of loss reported in upper-limb muscles. Sarcopenia is considered part of the causal pathway for strength loss, disability, and morbidity in older adult populations. Yet, muscle weakness is highly associated with both mortality and physical disability, even when adjusting for sarcopenia, indicating that muscle mass loss may be secondary to the effects of strength loss.
The rate of decline in muscle strength with age is two to five times greater than declines in muscle size. As such, thresholds of clinically relevant muscle weakness have been established as a biomarker of age-related disability and early mortality. These thresholds have been shown to be strongly related to incident mobility limitations and mortality. Given these links, grip strength (a robust proxy indicator of overall strength) has been labeled a "biomarker of aging". Losses in strength may translate to functional challenges because decreases in specific force and power are observed. Declines in muscle power have been shown to be more important than muscle strength in the ability to perform daily activities. Moreover, a large body of evidence links muscular weakness to a host of negative age-related health outcomes including type 2 diabetes, disability, cognitive decline, osteoporosis, and early all-cause mortality.
Resistance training is considered an important component of a complete exercise program to complement the widely known positive effects of aerobic training on health and physical capacities. There is strong evidence that resistance training can mitigate the effects of aging on neuromuscular function and functional capacity. Various forms of resistance training have potential to improve muscle strength, mass, and power output. Evidence reveals a dose-response relationship where volume and intensity are strongly associated with adaptations to resistance exercise.
Despite the known benefits of resistance training, only 8.7% of older adults (older than 75 years of age) in the United States participate in muscle-strengthening activities as part of their leisure time. When performed regularly (2-3 days per week), and achieving an adequate intensity and volume (2-3 sets per exercise) through periodization, resistance exercise results in favorable neuromuscular adaptations in both healthy older adults and those with chronic conditions. These adaptations translate to functional improvements of daily living activities, especially when power training exercise is included. In addition, resistance training may improve balance, preserve bone density, independence, and vitality, reduce risk of numerous chronic diseases such as heart disease, arthritis, type 2 diabetes, and osteoporosis, while also improving psychological and cognitive benefits.