Muscle fiber type I influences lipid oxidation during low-intensity exercise in moderately active middle-aged men.
The simultaneous effects of body composition, cardiorespiratory fitness, physical activity, and muscle fiber characteristics on lipid oxidation at basal state and during exercise were studied in a population-based group (n = 70) of middle-aged men. Body composition, oxygen uptake, and lipid oxidation were determined in a volitional maximal exercise test, physical activity with a questionnaire, muscle fiber characteristics with muscle biopsy, and resting metabolic rate and lipid oxidation at basal state with indirect calorimetry. In regression analysis, type I muscle fibers contributed significantly to lipid oxidation at basal state (r = 0.30, r2 = 0.07, P<0.05) and during low-intensity exercise (r = 0.35, r2 = 0.10, P<0.05). ANOVA revealed 7.7% (P = 0.268) lower lipid oxidation at basal state, 14% (P<0.05) lower lipid oxidation in low-intensity exercise, and 10.5% (P = 0.088) lower lipid oxidation in moderate-intensity exercise in muscle fiber tertile I (type I muscle fiber count 28.8%) compared with muscle fiber tertile III (type I muscle fiber count 71.4%). In conclusion, the muscle fiber distribution contributed significantly to lipid oxidation during low-intensity exercise in moderately active middle-aged men.
Department of Internal Medicine and Biocenter Oulu, University of Oulu, Oulu, Finland. juha-pekka@turpeinen.fi
J-P
JP
Turpeinen
J
J
Leppävuori
O J
OJ
Heinonen
K
K
Kaila
J
J
Salo
M
M
Lilja
Y A
YA
Kesäniemi
D000704:Analysis of Variance; D001481:Basal Metabolism; D001706:Biopsy; D001823:Body Composition; D002153:Calorimetry, Indirect; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D006801:Humans; D050356:Lipid Metabolism / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D018657:Muscle Fibers, Slow-Twitch / Q000502:physiology*; D010084:Oxidation-Reduction; D010101:Oxygen Consumption / Q000502:physiology; D010809:Physical Fitness / Q000502:physiology*; D012044:Regression Analysis; D011795:Surveys and Questionnaires