How dietary fat affects muscle energy use, metabolism, and performance in athletes

Intramyocellular lipid content was significantly increased after a high-fat diet, reaching 1.54 +/- 0.27% compared to 0.69 +/- 0.09% after a low-fat diet.

• Oxidative capacity in the muscle was similar after both high-fat and low-fat diets, with no significant difference in mitochondrial volume.
• Glycogen levels were lower after the high-fat diet, but the difference was not statistically significant.
• Maximal power output and oxygen consumption during exercise tests did not differ between the two diet periods.
• Total work output during a 20-minute all-out time trial was comparable for both diets.
• Endurance performance times for a half-marathon did not significantly differ between high-fat and low-fat diets.
• Blood lactate levels and respiratory exchange ratios were lower after the high-fat diet at rest and during submaximal exercise.

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