Perfusion distribution between and within muscles during intermittent static exercise in endurance-trained and untrained men.

We have recently shown that muscle perfusion varies between different quadriceps femoris muscles during submaximal exercise in humans. In animals, endurance training changes perfusion distribution between muscles during exercise. Whether the same is observed in humans is currently unknown. Therefore, we compared perfusion levels between different parts of the quadriceps femoris muscle group during one-legged intermittent static exercise in seven endurance-trained and seven untrained men. Muscle perfusion was measured using positron emission tomography with [ 15O]-H 2 O. In addition, relative dispersion of perfusion (standard deviation within a region/mean within a region x 100 %) within each muscle region was calculated as an index of perfusion heterogeneity within the muscles. Muscle perfusion tended to be lower in endurance-trained men (p = 0.16) and it was also different between the regions (p < 0.001). However, perfusion distributed similarly between the groups (p = 0.51). Relative dispersion of perfusion within the muscles was lower in endurance-trained men (p = 0.01) and it was also different between muscles (p < 0.001). These results suggest that endurance training does not alter perfusion distribution between muscles, but it decreases perfusion heterogeneity within the muscles.