Resistance Training Reduces Skeletal Muscle Work Efficiency in Weight-reduced and Non-weight-reduced Subjects

OBJECTIVE: To determine whether resistance training is similarly effective in reducing skeletal muscle efficiency and increasing strength in weight-reduced and maximal weight subjects. METHODS: We examined the effects of supervised resistance exercise on skeletal muscle in 14 overweight and obese individuals sustaining a 10% or greater weight loss for over 6 months, and a phenotypically similar group of 15 subjects who were nonweight-reduced and weight stable at their maximal lifetime body weight. We assessed skeletal muscle work efficiency and fuel utilization (bicycle ergometry), strength (dynamometry), body composition (dual energy x-ray absorptiometry), and resting energy expenditure (indirect calorimetry) before and after 12 weeks of thrice weekly resistance training. RESULTS: Non-weight-reduced subjects were significantly (10–20%) stronger before and after the intervention than reduced weight subjects and gained significantly more fat-free mass with a greater decline in % body fat than weight-reduced subjects. Resistance training resulted in similar significant decreases (~10 %) in skeletal muscle work efficiency at low level exercise and ~10–20% increases in leg strength in both weight-reduced and non-weight-reduced subjects. CONCLUSION: Resistance training similarly increases muscle strength and decreases efficiency regardless of weight loss history. Increased resistance training could be an effective adjunct to reduced-weight maintenance therapy.