Metabolism: clinical and experimentalFeb 6, 2008

Short-term effects of dietary fat on muscle fat in sprinters and endurance runners

Circadian Biology Weekly Brief ↗PubMed ↗DOI ↗

Updated Apr 4, 2026

Abstract

Endurance runners showed 1.7 times higher intramyocellular lipid (IMCL) levels in tibialis anterior muscle after normal-fat diet compared to low-fat diet.

In sprinters, intramyocellular lipid levels in tibialis anterior and soleus muscles were similar across different dietary fat protocols.
Endurance runners exhibited increased TA-IMCL levels of 1.7 times and 3.0 times higher after normal-fat and high-fat diets, respectively, compared to low-fat diet.
Soleus IMCL values in endurance runners were 1.5 times and 1.6 times higher after normal-fat and high-fat diets compared to low-fat diet.
TA-IMCL levels after high-fat diet were significantly higher than those after normal-fat diet in endurance runners.
The response to dietary fat loading on IMCL varied by muscle type in endurance runners.

Simplified

The effect of short-term fat loading on intramyocellular lipid (IMCL) in different types of muscle in endurance runners and sprinters has not been fully elucidated yet. The purpose of this study was to investigate the effect of dietary lipid on IMCL in soleus muscle (SOL) and tibialis anterior muscle (TA) during training period in endurance runners and sprinters. Seven male endurance runners and 7 male sprinters were selected to participate in the study. We measured TA- and SOL-IMCL levels after 3-day course of isocaloric normal- (25%), high- (60%), and low-fat (10%) diet during training period by (1)H-magnetic resonance spectroscopy in each subject. In sprinters, TA- and SOL-IMCL levels were comparable after each diet protocol. However, in endurance runners, TA-IMCL levels after normal-fat and high-fat diets were 1.7 times and 3.0 times higher than that after low-fat diet, respectively. The SOL-IMCL values after normal-fat diet and high-fat diet were 1.5 times and 1.6 times higher than that after low-fat diet, respectively. In addition, the TA-IMCL level after high-fat diet, but not SOL-IMCL, was significantly higher compared with that after normal-fat diet. Our data suggested that short-term dietary fat challenge during training period significantly altered IMCL level in endurance runners, but not in sprinters. In addition, response to fat loading on IMCL was influenced by variation of muscle type in endurance runners. These phenotypic and regional differences might be explained by differences in type of exercise training and muscle fiber composition.

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Short-term effects of dietary fat on muscle fat in sprinters and endurance runners

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