High-fat diet overrules the effects of training on fiber-specific intramyocellular lipid utilization during exercise

J Appl Physiol (1985). 2011 Jul;111(1):108-16. doi: 10.1152/japplphysiol.01459.2010. Epub 2011 May 5.

Abstract

In this study, we compared the effects of endurance training in the fasted state (F) vs. the fed state [ample carbohydrate intake (CHO)] on exercise-induced intramyocellular lipid (IMCL) and glycogen utilization during a 6-wk period of a hypercaloric (∼+30% kcal/day) fat-rich diet (HFD; 50% of kcal). Healthy male volunteers (18-25 yrs) received a HFD in conjunction with endurance training (four times, 60-90 min/wk) either in F (n = 10) or with CHO before and during exercise sessions (n = 10). The control group (n = 7) received a HFD without training and increased body weight by ∼3 kg (P < 0.001). Before and after a HFD, the subjects performed a 2-h constant-load bicycle exercise test in F at ∼70% maximal oxygen uptake rate. A HFD, both in the absence (F) or presence (CHO) of training, elevated basal IMCL content by ∼50% in type I and by ∼75% in type IIa fibers (P < 0.05). Independent of training in F or CHO, a HFD, as such, stimulated exercise-induced net IMCL breakdown by approximately twofold in type I and by approximately fourfold in type IIa fibers. Furthermore, exercise-induced net muscle glycogen breakdown was not significantly affected by a HFD. It is concluded that a HFD stimulates net IMCL degradation by increasing basal IMCL content during exercise in type I and especially IIa fibers. Furthermore, a hypercaloric HFD provides adequate amounts of carbohydrates to maintain high muscle glycogen content during training and does not impair exercise-induced muscle glycogen breakdown.

Publication types

  • Comparative Study
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • AMP-Activated Protein Kinases / metabolism
  • Acetyl-CoA Carboxylase / metabolism
  • Adolescent
  • Adult
  • Analysis of Variance
  • Belgium
  • Dietary Carbohydrates / administration & dosage
  • Dietary Carbohydrates / metabolism
  • Dietary Fats / administration & dosage
  • Dietary Fats / metabolism*
  • Energy Intake*
  • Energy Metabolism*
  • Exercise Test
  • Exercise*
  • Fasting / metabolism
  • Fatty Acids, Nonesterified / blood
  • Gene Expression Regulation, Enzymologic
  • Glycogen / metabolism
  • Humans
  • Lipid Metabolism*
  • Male
  • Muscle Fibers, Skeletal / metabolism*
  • Oxygen Consumption
  • Phosphorylation
  • Physical Endurance*
  • Protein-Serine-Threonine Kinases / genetics
  • Pyruvate Dehydrogenase Acetyl-Transferring Kinase
  • RNA, Messenger / metabolism
  • Time Factors
  • Weight Gain
  • Young Adult

Substances

  • Dietary Carbohydrates
  • Dietary Fats
  • Fatty Acids, Nonesterified
  • Pyruvate Dehydrogenase Acetyl-Transferring Kinase
  • RNA, Messenger
  • Glycogen
  • Protein-Serine-Threonine Kinases
  • AMP-Activated Protein Kinases
  • Acetyl-CoA Carboxylase