Intermuscular Adipose Tissue And Muscle Function In Adults With And Without Obesity

This is the authors' abstract. We don't add key points for this paper.

Intermuscular adipose tissue (IMAT) has been linked to metabolic dysfunction in aging and obesity. However, IMAT and its relationship to muscle function is largely unresearched. PURPOSE: To determine if IMAT influences muscle function (strength [ST], power [PW], relative strength [RS], and relative power [RP]) in adults of varying body composition. METHODS: Forty-five individuals (age 32.9 ± 7.4 years, 62% female) with (n=32) and without (n=13) obesity were recruited to take part in strength and power testing using unilateral leg extension. Anatomical MR images were used to identify muscle cross sectional area (mCSA) and IMAT content using semi-automated techniques across serial MRI segments of the thigh. RS and RP were calculated by normalizing ST and PW to mCSA. Obesity was classified as having a body fat % >30% in males and >42% in females, measured by DEXA. RESULTS: IMAT was elevated in individuals with obesity compared to without (148.62 ± 47.24 vs. 256.10 ± 70.54 mm 2 ; p< 0.001). There were no differences in total lean mass, leg lean mass, and mCSA between groups. IMAT relative to mCSA (IMAT/mCSA) was elevated with obesity (0.012 ± 0.005 vs. 0.021 ± 0.005; p< 0.001). There were no differences in measures of muscle function between groups. In individuals without obesity, IMAT/mCSA was inversely associated with ST (r= -0.654; p=0.015) and PW (r= -0.632; p= 0.021). With obesity there was no association between IMAT/mCSA and any measure of muscle function. CONCLUSION: IMAT/mCSA was associated with decreased muscle function in individuals without obesity. This relationship was not observed in individuals with obesity despite having higher concentrations of IMAT. There appears to be a divergent relationship between IMAT and muscle function in individuals with and without obesity. Future research is needed to understand how IMAT may affect muscle function in adults of varying body composition.