Effects of progressive resistance training on body composition in frail older adults: results of a randomized, controlled trial

Abstract

Background: Progressive resistance exercise training (PRT) has been shown to increase muscle strength and fat-free mass (FFM) in elderly persons. Limited information is available regarding the effects of PRT on lean and fat mass in frail elderly persons.

Methods: Ninety-one community-dwelling sedentary men and women, 78 years and older with physical frailty (defined using standardized objective criteria) were enrolled in a 9-month trial of exercise training (ET). Physical frailty was defined as having 2 of the 3 following criteria: modified Physical Performance Test score between 18 and 32, peak aerobic power between 10 and 18 ml/kg/min, or self-report of difficulty or assistance with two instrumental activities of daily living or one basic activity of daily living. Participants were randomly assigned to either a control (CTL) group that performed a low intensity home exercise program or a supervised ET group that performed 3 months of low intensity exercise and 3 months of PRT.

Results: After completion of PRT, ET participants had greater improvements than did CTL participants in maximal voluntary force production for knee extension (mean Delta +5.3 +/- 13 ft/lb vs +1.1 +/- 11 ft/lb, p =.05), measured using isokinetic dynamometry. Total body FFM (measured using dual energy x-ray absorptiometry) increased in the ET group, but not in the CTL group (mean Delta +0.84 +/- 1.4 kg vs +0.01 +/- 1.5 kg, p =.005). Total, trunk, intra-abdominal, and subcutaneous fat mass (measured using dual energy x-ray absorptiometry and (1)H-magnetic resonance imaging) did not change in response to PRT.

Conclusions: Three months of supervised PRT induced improvements in maximal voluntary thigh muscle strength and whole body FFM in frail, community-dwelling elderly women and men. This supervised exercise program may not be sufficient to reduce whole-body or intra-abdominal fat area in this population.