Effect of intense strength training on standing balance, walking speed, and sit-to-stand performance in older adults

Background. Muscle size and strength decrease with aging, and the resultant muscle weakness has been implicated in increased risk of falls in older adults. These falls have large economic and functional costs. Methods. The purpose of this randomized, controlled study was to determine if an 8-week, 3-day per week intense (77.8 +/- 3.4% of 1-repetition maximum [1RM]) strength training program could improve functional ability related to the risk of falling in subjects aged 61-87 years (mean 72, SD 6.3). Twelve strength-training-naive subjects performed two sets of 10 repetitions for six lower body exercises while 12 subjects served as nonintervention controls. Subjects were tested pre-, mid-, and postintervention for strength gain and on three tests of functional ability. Results. Postintervention strength was significantly better (p < .017) in all training subjects across all exercises, and no injuries were reported as a result of either training or 1RM testing. After controlling for preintervention differences, repeated measure analysis of covariance (ANCOVA) found a significant difference between experimental and nonintervention control subjects for postintervention maximal walking speed [F(1,19) = 5.03, p < .05]. There were no significant between-group differences for 1-leg blind balance time or 5-repetition sil-to-stand performance [F(1,19) = .082; F(1,19) = .068, respectively, p > .05]. Conclusions. These findings suggest that strength training alone does not appear to enhance standing balance or sit-to-stand performance in active, community-dwelling older adults but that it may improve maximal walking speed. The relationship between strength gain and risk of falls remains unclear. The data do reinforce the notion that intense strength training is a safe and effective way to increase muscle strength in this population.