Intermuscular Adipose Tissue Is Muscle Specific and Associated with Poor Functional Performance

Lori J Tuttle,David R Sinacore,Michael J Mueller

doi:10.1155/2012/172957

Abstract

Purpose. People with obesity, diabetes, and peripheral neuropathy have high levels of intermuscular adipose tissue (IMAT) volume which has been inversely related to physical function. We determined if IMAT is muscle specific, if calf IMAT is different between a healthy obese group (HO), a group with diabetes mellitus (D), and a group with diabetes mellitus and peripheral neuropathy (DN), and if IMAT volume or the ratio of IMAT/muscle volume is related to physical function in these groups. Methods. 10 healthy obese people, 11 with type 2 diabetes, 24 with diabetes and peripheral neuropathy, had assessments of muscle morphology, physical function and muscle performance. Results. The gastrocnemius muscle had a higher ratio of IMAT/muscle volume than any other muscle or compartment. There were no differences between groups in calf muscle or IMAT volumes. Calf IMAT was inversely related to physical performance on the 6-minute walk test (r = −0.47) and physical performance test (r = −0.36). IMAT/muscle volume was inversely related to physical performance (PPT, r = −0.44; 6 MW r = −0.48; stair power, r = −0.30). Conclusions. IMAT accumulation varies in calf muscles, is highest in the gastrocnemius muscle, and is associated with poor physical performance.

Highlights

Previous research has shown that people with obesity, diabetes, and peripheral neuropathy have significantly greater amounts of intermuscular adipose tissue (IMAT) in the calf compared to a nonobese control group and that this calf IMAT was associated with poor physical performance [1]
This study is the first to report that the amount of IMAT/ muscle volume in the calf is muscle and compartment specific in the pathologies of obesity, diabetes, and diabetes combined with peripheral neuropathy
The gastrocnemius muscle had the largest ratio of IMAT/muscle volume compared to any of the calf muscles and compartments, which was contrary to what we expected and to what has been reported in obese animal models [9, 10]

Summary

Introduction

Previous research has shown that people with obesity, diabetes, and peripheral neuropathy have significantly greater amounts of intermuscular adipose tissue (IMAT) in the calf compared to a nonobese control group and that this calf IMAT was associated with poor physical performance [1]. The gastrocnemius muscle is considered predominantly a fast twitch muscle and is used more for large force production, while the soleus muscle is considered more slow twitch and is a postural muscle that is better suited for using lipids as a fuel source [8] It has been shown in animal models that there is a difference in fatty acid transport in muscles with different fiber type distributions (type I/red muscles are more oxidative than type II/white) and that fatty acid transport and triacylglycerides in muscle are impacted by insulin resistance and diabetes [9]. We hypothesized that calf IMAT volume would be inversely correlated with measures of physical performance

Methods and Procedures

Assessments

Results

Discussion