We aimed to determine the effects of 8 weeks of aerobic exercise on obesity in mice induced by high-fat diet-feeding and the mechanisms involved. Forty-six male C57BL/ 6 mice were randomly allocated to a normal diet group and high-fat diet group, then to a Control Sedentary group (CS group), a Control Exercise group (CE group), an Obese Sedentary group (OS group), and an Obese Exercise group (OE group). The exercise groups underwent moderate-intensity aerobic exercise at 60% of maximum exercise intensity for 8 weeks. Before and after this exercise intervention, the maximum exercise ability of each group was determined, and the dietary energy intake and body mass of the mice were measured regularly during the intervention. The mice were euthanized and both gastrocnemius muscles were removed 48 hours after the last exercise bout. The desmin distribution in the muscles was assessed following immunofluorescence staining, and the cross-sectional area and inflammatory cell infiltration in skeletal muscle were assessed following hematoxylin and eosin staining. Western Blot was used to measure the expression of proteins related to atrophy and inflammation in skeletal muscle. The energy intake, body mass, and expression of atrogin-1, muscle ring finger (MuRF1), and tumor necrosis factor (TNF) -α protein was significantly higher in the OS group than in the CS group (P< 0.05); whereas the exercise ability, cross-sectional area of muscle fibers, and interleukin ( IL) - 10 protein expression were significantly lower (P< 0.05). In addition, desmin protein expression was disordered. After aerobic exercise, there was no significant difference in energy intake between the OS and OE groups. However, the body mass and protein expression of atrogin-1, MuRF1, TNF-α, and IL-1β were significantly lower in the OS group (P< 0.05) and the exercise ability, cross- sectional area of muscle fibers, and IL-10 protein expression were significantly higher (P< 0.05). In addition, the protein expression of atrogin-1, MuRF1, TNF-α, and IL-1β in the CE group was significantly lower than in the CS group (P< 0.01), whereas the IL-10 protein expression was significantly higher (P< 0.05). In conclusion, high-fat diet-induced obesity is associated with chronic inflammation in skeletal muscle, which leads to skeletal muscle atrophy and a decline in exercise capacity. Conversely, aerobic exercise ameliorates this skeletal muscle atrophy, which improves exercise ability, and a reduction in local inflammation may play a key role in this effect.