Can Resistance Or Aerobic Exercise Training Attenuate The Decrease In Muscle Mass Induced By Weight-loss In Overweight Older Adults?

Abstract

Aging is associated with a loss of muscle mass and increased body fat. The effects of diet-induced weight-loss, alone or in combination with exercise, on muscle mass in older adults are not clear. PURPOSE: To examine the ability of both resistance and aerobic exercise to counteract the loss of skeletal muscle induced by calorie restriction in overweight older adults. METHODS: Twenty-seven overweight to obese (BMI = 32.2 ± 3.0 kg/m2) older (66.4 ± 4.2 years) men (n = 6) and women (n = 21) completed a 4-month intervention consisting of diet-induced weight-loss (WL, n = 9), aerobic exercise and weight-loss (AWL, n = 9) or resistance training and weight-loss (RWL, n = 9). The WL intervention (all subjects) consisted of a 10% reduction in total body weight through a caloric restriction of 500-1000 kcal/day. The AWL exercised 3-5 times a week for 35-45 min at ∼70% VO2 max. The RWL consisted of lower body progressive resistance training 3 days a week. Whole body fat mass and fat free mass were determined by DEXA scan. CT images were taken of the mid thigh to measure muscle cross sectional area (CSA). Type 1 and type 2 fiber CSA was determined histologically within percutaneous muscle biopsies of vastus lateralis. Between-group change in muscle variables was determined by one-way ANOVA. RESULTS: Mean body weight (-9.5 ± 1.0 %) and total body fat (-15.3 ± 1.0 %) decreased significantly in all subjects with no between-groups difference observed. Fat free mass significantly decreased in the WL group (-5.07 ± 1.35 %) and remained unchanged in the AWL (0.57 ± 1.35 %) and RWL groups (-1.55 ± 1.35 %). Thigh muscle CSA decreased in the WL group (-5.02 ± 1.33 %) and remained unchanged in the AWL (-2.52 ± 1.33 %) and RWL groups (1.43 ± 1.33 %). Type 1 fiber CSA decreased with WL (-19.71 ± 8.72 %), increased in the AWL group (-19.71 ± 8.72 %) and remained unchanged in the RWL group (1.44 ± 8.72 %). Type 2 fiber CSA remained unchanged in all groups, but there was a trend for an decrease in the WL group and an increase in the RWL group. The decreases with weight-loss were consistently and significantly attenuated by both aerobic and resistance exercise. CONCLUSION: Aerobic and resistance training can both attenuate the negative effects of diet-induced weight-loss on muscle mass in older overweight adults.