Predictors of cardiovascular fitness in sedentary men.
The relative contribution of anthropometric and skeletal muscle characteristics to cardiorespiratory fitness was studied in sedentary men. Cardiorespiratory fitness (maximal oxygen consumption) was assessed using an incremental bicycle ergometer protocol in 37 men aged 34-53 years. Vastus lateralis muscle biopsy samples were used to assess fiber type composition (I, IIA, IIX) and areas, capillary density, and activities of glycolytic and oxidative energy metabolic pathway enzymes. Correlations (all p < 0.05) were observed between maximal oxygen consumption (L.min-1) and body mass (r = 0.53), body mass index (r = 0.39), waist circumference (r = 0.34), fat free mass (FFM; r = 0.68), fat mass (r = 0.33), the enzyme activity of cytochrome c oxidase (COX; r = 0.39), muscle type IIA (r = 0.40) and IIX (r = 0.50) fiber area, and the number of capillaries per type IIA (r = 0.39) and IIX (r = 0.37) fiber. When adjusted for FFM in partial correlations, all correlations were lost, with the exception of COX (r = 0.48). Stepwise multiple regression revealed that maximal oxygen consumption was independently predicted by FFM, COX activity, mean capillary number per fiber, waist circumference, and, to a lesser extent, muscle capillary supply. In the absence of regular physical activity, cardiorespiratory fitness is strongly predicted by the potential for aerobic metabolism of skeletal muscle and negatively correlated with abdominal fat deposition.
Division of Kinesiology, Laval University, Quebec, QCG1K7P4, Canada.
Marie-Eve
ME
Riou
Etienne
E
Pigeon
Josée
J
St-Onge
Angelo
A
Tremblay
André
A
Marette
S John
SJ
Weisnagel
Denis R
DR
Joanisse
D050154:Adiposity; D000328:Adult; D001706:Biopsy; D015992:Body Mass Index; D002196:Capillaries / Q000503:physiopathology; D002319:Cardiovascular System / Q000503:physiopathology*; D003430:Cross-Sectional Studies; D003576:Electron Transport Complex IV / Q000378:metabolism; D004734:Energy Metabolism; D006801:Humans; D008019:Life Style; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D009119:Muscle Contraction; D009765:Obesity / Q000378:metabolism / Q000503:physiopathology*; D010101:Oxygen Consumption; D010809:Physical Fitness; D052097:Quadriceps Muscle / Q000098:blood supply / Q000378:metabolism / Q000503:physiopathology*; D055105:Waist Circumference
D003576:Electron Transport Complex IV