Exercise but not diet-induced weight loss decreases skeletal muscle inflammatory gene expression in frail obese elderly persons

Many obese elderly persons have impaired physical function associated with an increased chronic inflammatory response. We evaluated 12 wk of exercise (aerobic and resistance) or 12 wk of weight loss (∼7% reduction) on skeletal muscle mRNAs for toll-like receptor-4 (TLR-4), mechanogrowth factor (MGF), TNF-α, and IL-6 in 16 obese (body mass index 38 ± 2 kg/m ²) older (69 ± 1 yr) physically frail individuals. Vastus lateralis muscle biopsies were obtained at 0 and 12 wk and analyzed by real-time RT-PCR. Body composition was assessed by dual-energy x-ray absorptiometry. Body weight decreased (-7.5 ± 1.2 kg, P = 0.001) in the weight loss group but not in the exercise group (-0.3 ± 0.8 kg, P = 0.74). Fat-free mass (FFM) decreased (-2.9 ± 0.6 kg, P = 0.010) in the weight loss group and increased (1.6 ± 0.6 kg, P = 0.03) in the exercise group. Exercise resulted in a 37% decrease in TLR-4 mRNA (P < 0.05) while weight loss had no significant effect. Additionally, exercise led to a significant (50%) decrease in IL-6 and TNF-α mRNA (P < 0.05) while weight loss had no effect. Exercise increased MGF mRNA (∼2 fold, P < 0.05), but weight loss had no effect. In conclusion, exercise but not weight loss had a beneficial effect on markers of muscle inflammation and anabolism in frail obese elderly individuals.