Regional muscle blood flow capacity and exercise hyperemia in high-intensity trained rats

Abstract

The purpose of this study was to determine the effects of high-intensity treadmill exercise training on 1) the regional distribution of muscle blood flow within and among muscles in rats during high-intensity treadmill exercise (phase I) and 2) on the total and regional hindlimb skeletal muscle blood flow capacities as measured in isolated perfused rat hindquarters during maximal papaverine vasodilation (phase II). Two groups of male Sprague-Dawley rats were trained 5 days/wk for 6 wk with a program consisting of 6 bouts/day of 2.5-min runs at 60 m/min up a 15% grade with 4.5-min rest periods between bouts. After training, blood flows were measured with the radiolabeled microsphere technique (phase I) in pair-weighted sedentary control and exercise-trained rats while they ran at 60 m/min (0% grade). In phase II of the study, regional vascular flow capacities were determined at three perfusion pressures (30, 40, and 50 mmHg) in isolated perfused hindquarters of control and trained rats maximally vasodilated with papaverine. The results indicate that this exercise training program produces increases in the vascular flow capacity of fast-twitch glycolytic muscle tissue of rats. However, these changes were not apparent in the magnitude or distribution of muscle blood flow in conscious rats running at 60 m/min, since blood flows within and among muscles during exercise were the same in trained and control rats.

Arteriolar Endothelial Dysfunction Is Restored in Ischaemic Muscles by Chronic Electrical Stimulation

“…The angiogenic effects of muscle activity on the microvascular bed therefore depend on the total time for which the stimulation is applied. This has been shown many times with respect to exercise training which must continue for several weeks before increases in muscle capillary supply [56]or blood flow [57]are seen. It was also true for the stimulated ischaemic muscles in the current study, in accord with previous observations [13].…”

Endurance, interval sprint, and resistance exercise training: impact on microvascular dysfunction in type 2 diabetes

“…Importantly, EX alters relationships among muscle fiber type, recruitment patterns, and blood flow (11,82,110,139) by modifying vascular structure, endothelium (37,38,40,71,81,85,96,98,107,120,137,142,150), and vascular smooth muscle (VSM) of skeletal muscle arteries/arterioles (77,80,81). Although many EXinduced vascular adaptations are concentrated in the muscle tissue, having the greatest relative increase in activity during training sessions (11,15,22,55,56,82,84,92,131,138,139), the relative amount of adaptation is not distributed uniformly for any of these parameters (84), and these adaptations are not the same for different types of EX (11,81,82,109,110,139). Thus different intensities and types of exercise activities require different fiber-recruitment patterns, which subsequently influence the spatial distribution of adaptations within skeletal muscle induced by the EX.…”

Adaptation of Skeletal Muscle Microvasculature to Increased or Decreased Blood Flow: Role of Shear Stress, Nitric Oxide and Vascular Endothelial Growth Factor

“…Endurance training involves oxidative muscles, increasing blood flow to this fibre type 5–6 fold and leading to associated capillary growth (15–20% increase in capillary:fibre ratio). In contrast, with high-intensity sprint training, blood flow is increased 3–4 fold in muscles composed of white glycolytic fibres and a 20% increase in capillary supply occurs specifically in relation to these fibres, whereas these parameters are not changed in oxidative muscles in this type of training [4,5,6,7]. The onset of capillary growth is dependent on the intensity of training and is much faster in animals trained by running to exhaustion [8].…”