PRESCRIBING BLOOD FLOW-RESTRICTED CYCLING USING RPE BALANCES THE PHYSIOLOGICAL AND PERCEPTUAL DEMANDS IN HEALTHY ADULTS

Abstract

INTRODUCTION Aerobic exercise is commonly prescribed using fixed heart rates or power/speed. These methods may not be suitable when incorporating blood flow restriction (BFR), as this technique can influence these measurements. Prescribing exercise via perception of exertion (RPE), which reflects overall psychophysiological stress, may present an alternative to overcome these issues. Aim: Describe physiological and perceptual responses during fixed-power and fixed-RPE cycling performed with blood flow restriction (BFR_{PWR} and BFR_{RPE}) and without (CON_{PWR} and CON_{RPE}). METHODS Following baseline testing, twelve active males cycled for ten minutes under four conditions. CON_{PWR} was performed first, then the remaining conditions in a randomised and counterbalanced order. BFR_{PWR} and CON_{PWR} were performed at the power equivalent to the first ventilatory threshold (161±38W). CON_{RPE} and BFR_{RPE} were prescribed at the RPE reported during CON_{PWR}. Continuous ventilatory and heart rate measurements were recorded as two-minute averages. Subjective RPE, effort, muscular discomfort, and cuff pain were recorded every two minutes. Blood lactate was measured pre-exercise, post-exercise, and two-minutes post-exercise. RESULTS BFR_{PWR} resulted in the greatest physiological and perceptual responses among all conditions. Power output was lower during BFR_{RPE} (119±48W) than CON_{RPE} (139±47W). Oxygen consumption during BFR_{RPE} (20.8±5.1mL·kg-1·min-1) was lower than CON_{PWR} (25.3±6.0mL·kg-1·min-1, p<0.001) and CON_{RPE} (22.3±5.9mL·kg-1·min-1, p=0.007). Heart rate during CON_{PWR} (143±22beats·min-1) was greater than BFR_{RPE} (133±26beats·min-1, p<0.001) and CON_{RPE} (131±25beats·min-1, p<0.001). Muscular discomfort was not different between BFR_{RPE} (2.5±1.3au) and CON_{PWR}(2.3±1.5au), yet both were greater than CON_{RPE} (p<0.001, 1.8±1.5au). Cuff pain was greater during BFR_{PWR} (3.3±1.7au) than BFR_{RPE} (2.2±1.1au, p<0001). Blood lactate was greater during fixed-power (4.9±3.5mmol·L-1) compared to fixed-RPE trials (3.6±2.7mmol·L-1, p<0.001). CONCLUSIONS BFR_{RPE} caused less discomfort and pain than BFR_{PWR} without compromising physiological stress compared to CON_{RPE}. BFR_{RPE} should be considered when high mechanical loads are contraindicated, or discomfort/pain is undesirable. These findings improve our understanding of aerobic BFR exercise prescription to healthy adults.