THE SMALLER THE HARD-WORKING MUSCLE MASS, THE GREATER IS THE DEPENDENCY ON CARBOHYDRATES AS A FUEL SOURCE
Yasuda, N., Ruby, B. C., & Gaskill, S. E. (2001). Substrate utilization during arm and leg exercise relative to the ventilatory threshold in men. Medicine and Science in Sports and Exercise, 33(5), Supplement abstract 871.
Males (N = 10) were studied for substrate utilization during 15 minutes of arm and leg exercise at 70 and 90% of ventilatory threshold for each exercise.
Ratings of perceived exertion were similar for both arm and leg exercise modes. At 70%, carbohydrate and fat oxidation were similar. At 90%, arm exercise invoked significantly greater carbohydrate oxidation than did the legs.
Implication. At high levels of exercise intensity, small working muscle masses (e.g., arms) are more dependent on carbohydrates as the main energy source than larger muscle masses (e.g., legs), which are less dependent on carbohydrate and continue to use a relatively greater amount of fat for fuel.
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