Effects of high-intensity interval training on adipose tissue lipolysis, inflammation, and metabolomics in aged rats

High-intensity interval training (HIIT) is a time-efficient alternative to moderate-intensity continuous training (MICT) to improve metabolic health in older individuals. However, differences in adipose tissue metabolism between these two approaches are unclear. Here, we evaluated the effects of HIIT and MICT on metabolic phenotypes in aged rats. HIIT significantly decreased fat mass, increased percent lean mass, decreased fat-to-lean ratio, reduced serum high-sensitivity C-reactive protein, increased serum interleukin-10 levels, and decreased perirenal adipose tissue leptin compared with rats in the sedentary (SED) group. HIIT also increased pregnenolone, cortisol, and corticosterone in both adipose tissue and serum. Both exercise modalities enhanced hormone-sensitive lipase and adipose triglyceride lipase expression compared with the SED group and decreased palmitic acid, stearic acid, octadecadienoic acid, urea, 1-heptadecanol, and α-tocopherol. MICT was related to glycerolipid metabolism, whereas HIIT was related to steroid hormone biosynthesis. Overall, HIIT showed more favorable regulation of anti-inflammatory activity than MICT.