Muscle Oxygenation and Metabolic Regulations During Low and Moderate Intensity Exercise with Blood Flow Restriction

Abstract

A number of studies have shown that low-intensity exercise with blood flow restriction (BFR) increases oxygen uptake and heart rate during exercise compared to normal exercise without BFR. However, it is currently unknown about the influence of moderate-intensity exercise with BFR on systemic and peripheral metabolic regulations. PURPOSE: To investigate the effect of endurance exercise with BFR under either low (25% of VO2max) or moderate (40% of VO2max) intensities on muscle oxygenation, energy metabolism and endocrine responses. METHODS: Ten male subjects conducted three trials on different days (with a cross over design). All subjects performed three different trials consisting of moderate intensity (40% of VO2max) exercise without BFR (NORMAL) or with BFR (MOD) and low intensity (25% of VO2max) exercise with BFR (LOW). The exercise was designed as a 15 min of pedaling exercise. During the exercise in MOD and LOW, 2 min of cuff pressure (160mmHg) was applied repeatedly for proximal cites of both legs followed by 1 min of release. Muscle oxygenation for vastus lateralis muscle was evaluated using near-infrared spectroscopy (NIRS). Respiratory and venous blood samples were also collected during exercise. RESULTS: The oxygen consumption (VO2) did not differ significantly between NORMAL and MOD, but LOW revealed significantly lower VO2. Carbohydrate oxidation rate was significantly elevated in MOD (Mean±SD, 25.6 ± 8.6 mg/kg/min), with no difference between NORMAL and LOW (10.6 ± 4.8 and 8.7 ± 2.8). There were no significant differences among three trials for blood glucose and serum growth hormone levels. Blood lactate and serum cortisol levels were significantly higher in MOD than those in the other two trials. Oxyhemoglobin (oxy-Hb) for vastus lateralis muscle was significantly lower in MOD than the other two trials. In addition, deoxyhemoglobin (deoxy-Hb) was significantly increased in both MOD and LOW (vs. NORMAL), and MOD showed highest value of total hemoglobin among three trials. CONCLUSION: Moderate intensity (40% of VO2max) exercise with BFR caused profound elevations of deoxy-Hb with lower oxy-Hb and augmented carbohydrate oxidation. Furthermore, carbohydrate oxidation during low-intensity (25% of VO2max) exercise with BFR was similar moderate intensity exercise without BFR.