STRENGTH TRAINING IN THE PREVENTION AND TREATMENT OF FRAILY IN THE ELDERLY





William J. Evans*

Donald W. Reynolds Center on Aging, University of Arkansas for Medical Sciences and Central Arkansas Veterans Healthcare System, Little Rock, AR




Advancing age is associated with profound changes in body composition, which includes the loss of skeletal muscle mass (referred to as Sarcopenia) and an increase in fat mass. . The excretion of urinary creatinine, reflecting total muscle mass, decreases by nearly 50% between the ages of 20 and 90. Computed tomography of individual muscles shows that after age 30, there is a decrease in cross-sectional areas of the thigh along with decreased muscle density associated with increased intramuscular fat. These changes are most pronounced in women. Sarcopenia may result from a gradual and selective loss of muscle fibers. The number of muscle fibers in the midsection of the vastus lateralis of autopsy specimens is lower by about 110,000 in elderly men (age 70-73) than in young men (age 19-37), a 23% difference. The decline is more marked in Type II muscle fibers, which fall from an average 60% in sedentary young men to below 30% after the age of 80, and is significantly related to age-related decreases in strength (r = 0.54, P < 0.001). Skeletal muscle is the largest reservoir of protein the body. Sarcopenia is a direct cause of the age related decrease in muscle strength. While there is some indication that muscle function is reduced with advancing age, the overwhelming majority of the loss in strength results from Sarcopenia. Previous research has demonstrated a significant negative correlation between strength and chosen normal walking speed and among very elderly people leg power is closely associated with functional performance. Leg power, which represents a more dynamic measurement of muscle function, may be a useful predictor of functional capacity in the very old. When the intensity of resistance exercise training is low, elderly subjects achieve only modest increases in strength. Our studies and that of others have demonstrated that at an exercise intensity sufficiently high (we have used 80% of 1 RM) large improvements in strength, muscle mass, and functional capacity can be realized. We have demonstrated that even in extremely old and frail individuals, a high intensity strength-training program can triple muscle strength, and increase muscle area. In addition, increased strength in very old nursing home residents has been associated with increased balance, gait speed, stair climbing power, and spontaneous activity. We have also demonstrated that strength training greatly improves nitrogen balance in elderly people. This effect may be particularly important among elderly individuals consuming marginal or inadequate amounts of protein.







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