EFFECTS OF HIGH-INTENSITY, LOW-INTENSITY AND LOW-INTENSITY WITH BLOOD FLOW RESTRICTION EXERCISE TO VOLUNTARY MUSCULAR EXHAUSTION ON METABOLIC AND IONIC HOMEOSTASIS AND VENOUS VASCULAR FUNCTION IN HEAL

INTRODUCTION:
Training under blood flow restriction causes faster muscular fatigue than training under free flow conditions. However, the remaining issue is whether the metabolic and ionic changes of BFR exercise differ from high mechanical intensity (HI) or light intensity (LI) exercise when the exercise is performed to voluntary muscular fatigue. In addition, the effects of BFR-induced venous hypertension or HI and LI exercise on venous vascular function are still unknown. Therefore, the present project investigated metabolic and ionic alterations as well as venous function during and after BFR, HI and LI exercise to voluntary muscular exhaustion by intravascular catheter measurements.
METHODS:
In a randomized cross-over design, ten healthy male subjects underwent three trials of unilateral leg extension exercise. These trials were differentiated into a high intensity (HI, 75% 1RM), low intensity (LI, 30% 1RM) and LI with BFR trial (LI-BFR). The exercise protocol consists of 4 sets to voluntary failure. The additive BFR protocol involved the proximal occlusion of the exercising thigh by a blood pressure cuff system at a pressure of 50% of the individual arterial occlusion pressure. For analysis of changes in intravascular pressures, blood gases, oximetry and electrolytes, a venous catheter (Rete venosum dorsale pedis) were placed at the exercising leg before exercise. Venous blood gases and intravascular pressures were analyzed before, during and 5 min after exercise. In order to determine the functionality of the venous system, a phlebodynamometry was performed before and after the exercise.
RESULTS:
The total workload was significantly lower in the LI-BFR condition compared to LI- and HI-condition (p < 0.05). The peripheral venous pressure increased significantly during the exercise (p < 0.001), with no difference between conditions (p = 0.33). Additionally, there were no significant changes in venous function assessed by phlebodynamometry all forms of training (p = 0.56). Analyses of the BGAs showed that venous pCO2 increased significantly during the exercise (p < 0.001), with no difference between conditions (p = 0.64). At the same time, the analyses of pO2 showed a significant reduced oxygen availability for working muscle during the exercise regardless of conditions (p < 0.001). Regardless of conditions, venous [K+], [Na+], [La-] showed a periodic increase during exercise (p < 0.001) which decreased to baseline levels 5 min post exercise, respectively.
CONCLUSION:
This is the first study investigating venous vascular function before and after BFR, LI and HI exercise to voluntary muscular exhaustion. Based on the obtained data, there is no acute adverse effect on venous function after BFR or HI and LI training in young male subjects. Similarly, the data from this study shows that although BFR training leads to accelerated muscle fatigue compared to LI, the metabolic and ionic changes are equivalent to HI or LI condition, when the exercise is performed to voluntary muscular exhaustion.