title: Effect of dietary fat on metabolic adjustments to maximal VO2 and endurance in runners.
abstract: The present study examined the effects of dietary manipulations on six trained runners. The percent energy contributions from carbohydrate, fat, and protein were 61/24/14, 50/38/12, and 73/15/12 for the normal (N), fat (F), and carbohydrate (C) diets, respectively. Expiratory gases and blood responses to a maximum (VO2max) and a prolonged treadmill run were determined following 7 d on each diet. Free fatty acids (FFA), triglycerides, glycerol, glucose, and lactate were measured. Dietary assessment of subjects' N diet indicated that they were consuming approximately 700 kcal.d-1 less than estimated daily expenditures. Running time to exhaustion was greatest after the F diet (91.2 +/- 9.5 min, P < 0.05) as compared with the C (75.8 +/- 7.6 min, P < 0.05) and N (69.3 +/- 7.2 min, P < 0.05) diets. VO2max was also higher on the F diet (66.4 +/- 2.7 ml.kg-1 x min-1, P < 0.05) as compared with the C (59.6 +/- 2.8 ml.kg-1 x min-1, P < 0.05) and N (63.7 +/- 2.6 ml.kg-1 x min-1, P < 0.05) diets. Plasma FFA levels were higher (P < 0.05) and glycerol levels were lower (P < 0.05) during the F diet than during the C and N diets. Other biochemical measures did not differ significantly among diets. These data suggest that increased availability of FFA, consequent to the F diet, may provide for enhanced oxidative potential as evidenced by an increase in VO2max and running time. This implies that restriction of dietary fat may be detrimental to endurance performance.
authors.affiliation: Department of Physiology, State University of New York at Buffalo, School of Medicine and Biomedical Sciences 14214.
authors.forename: D M
authors.initials: DM
authors.lastname: Muoio
authors.forename: J J
authors.initials: JJ
authors.lastname: Leddy
authors.forename: P J
authors.initials: PJ
authors.lastname: Horvath
authors.forename: A B
authors.initials: AB
authors.lastname: Awad
authors.forename: D R
authors.initials: DR
authors.lastname: Pendergast
mesh_terms: D000704:Analysis of Variance; D004040:Dietary Carbohydrates / Q000008:administration & dosage*; D004041:Dietary Fats / Q000008:administration & dosage*; D004734:Energy Metabolism; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008297:Male; D010101:Oxygen Consumption / Q000502:physiology*; D010807:Physical Endurance / Q000502:physiology*; D015656:Respiratory Mechanics / Q000502:physiology; D012420:Running / Q000502:physiology*
chemical_list: D004040:Dietary Carbohydrates; D004041:Dietary Fats