Intermuscular Adipose Tissue: A Brief Review of Etiology, Association With Physical Function and Weight Loss in Older Adults

Adipose tissue redistributes during aging resulting in increased intermuscular adipose tissue (IMAT), intramuscular, and intramyocellular lipid while subcutaneous fat decreases. IMAT has been associated with lower muscle strength, power, and quality, chronic inflammation, impaired glucose tolerance, and elevated total cholesterol in older adults. This review focused on trials investigating the role of age, physical activity and diet on IMAT. The studies agreed that IMAT increases with age and seems to be responsive to physical activity, particularly the combination of aerobic and resistance exercise. However, some reported this could occur with or without weight loss, and some reported that high IMAT at baseline may blunt the muscle quality adaptive response to physical training. Larger and longer trials are needed to differentiate the independent or synergistic effects of resistance and/or aerobic training, and obesity and weight loss combined with resistance, aerobic or combination of aerobic and resistance training on IMAT.