The Effects of High-Intensity Interval Training on Skeletal Muscle Morphological Changes and Denervation Gene expression of Aged Rats

Muscle denervation is one of the most critical pathological factors involved in muscle atrophy as a result of ageing. This study aims to investigate the chronic effect of high-intensity interval training (HIIT) on cross-sectional areas and muscle denervation genes, interpreted in the plantaris muscle atrophy of aged rats. Twenty-eight aged and young rats were divided into four different groups, including exercise and control. The training protocol included six weeks of HIIT. Animals were sacrificed 48 hours after the last training session, and the plantaris muscle was removed. To measure Gadd45a mRNA and NCAM1mRNA, we used a real-time PCR technique. The cross-sectional area was measured with photomyography using an H&E technique. The results showed that ageing significantly decreased NCAM1 mRNA in the aged control group (p=0.0001) and exercise leads to a significant increase (interaction effect) of it (p=0.003). Gadd45a mRNA was significantly increased due to ageing (p=0.009), and exercise resulted in a significant decrease in that in the aged exercise group (p=0.04). The cross-sectional area in the aged control group was significantly smaller than in the young control group (p=0.046). In contrast to young groups, exercise could increase the cross-sectional area in the aged exercise group compared with the aged control group, but it was not significant (p=0.069). It seems that HIIT could improve ageing-induced muscular atrophy, although denervation-involved gene modification leads to an increase in the muscular cross-sectional area; therefore, it improves muscular atrophy due to ageing.