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Acute Muscular, Metabolic, Cardiovascular, and Perceptual Responses to Low Cuff Pressure-small Cuff Width Blood Flow Restricted Exercise Prescription

Kyle J Hackney, Ben M Olson, Austin J Schmidt, Ashlyn H Nelson and Evan L Zacharias

Low-load blood flow restricted (BFR) exercise represents a novel method of rehabilitative exercise, however, little is known about variables that may influence the acute physiological response to BFR exercise prescription. This study explored the muscular, metabolic, cardiovascular, and perceptual responses to acute blood flow restricted exercise and compared it to traditional exercise using a Biodex dynamometer. Fourteen resistance trained, male participants (age: 22.1 ± 3.3 years; height: 177.8 ± 6.4 cm; body mass: 85.8 ± 11.9 kg) were randomized to complete 4 sets of isotonic knee extension-flexion resistance exercise under two conditions: 1) control; and 2) BFR exercise. Both control and BFR exercise used training loads of 20% of maximal voluntary contraction, however, control had free limb blood flow and BFR exercise was implemented using a 5 cm external cuff around the proximal thigh inflated to 140 mmHg. Muscle cross-sectional area (an index of muscle swelling) was significantly increased from baseline by 11.3% and 12.4% in control and BFR, respectively (p = 0.001). Similarly compared to baseline, lactate (control = 6.1 ± 1.3; BFR = 5.9 ± 0.9 mmol; p < 0.001), heart rate (control = 140.1 ± 18.8; BFR = 144.2 ± 12.6 bt â�?�? min-1; p < 0.001), RPE (control = 5.8 ± 2.8; BFR = 6.3 ± 2.4 arbitrary units; p < 0.001), and pain (control = 6.71 ± 18.4; BFR = 16.8 ± 29.2 mm; p = 0.003) significantly increased, however no differences could be detected between exercise types. Low cuff pressure-small cuff width BFR exercise does not result greater muscular swelling or alter metabolic, cardiovascular, or perceptual responses relative to low-intensity exercise alone. If rapid strength and mass gains can be achieved using low cuff pressure-small cuff width BFR methods it represents an intriguing rehabilitation strategy for disuse, injury, and some muscular disease treatments with less concern for patient safety.