The Influence of Applied Pressure on the Perceptual Response to Blood Flow Restricted Exercise

Abstract

Some suggest basing the pressure used during blood flow restricted (BFR) exercise on the perceptual response, however, it is unknown if ratings differ across applied pressures. PURPOSE: To determine if the pressure applied during BFR exercise influences the perceptual response. METHODS: 14 participants completed 4 visits. 6 conditions were completed randomly and included elbow flexion exercise from 40-90% arterial occlusion at 30% of their one repetition maximum (1RM). The protocol included 1 set of 30 reps followed by 3 sets of 15 with 30s rest between. Ratings of perceived exertion (RPE) and discomfort were taken after each set. Friedman’s test was used to determine differences in RPE and discomfort between different pressures. Wilcoxon tests were used post-hoc if significance was found. A one way ANOVA was used to determine differences in total reps across applied pressures. RESULTS: Differences were found for sets 2-4 with RPE (p≤0.046), however, these differences were no longer significant following Bonferroni corrections. Median values ranged from 11-12 for Set 1, 13-15 for Set 2, 14-16 for Set 3 and 15-17 for Set 4. Differences were found for sets 1-4 with Discomfort (p≤0.002); however many of these differences were no longer significant following Bonferroni corrections. There were differences in discomfort between 50% (median of 4) and 90% (median of 6.5) arterial occlusion (p=0.03) and between 60% (median of 4) and 90% (median of 6.5) arterial occlusion (p=0.03). A one-way ANOVA found differences in reps completed across applied pressures (p<0.001). More reps were completed under 40% [64 (8) reps] compared to 70% [59 (8) reps, p=0.045], 80% [55 (9) reps, p=0.015], and 90% [47 (7) reps, p=0.015) arterial occlusion. In addition, more reps were completed under 50% [63 (9) reps] than 80% (p=0.03) or 90% (p=0.015) arterial occlusion. More reps were completed with 60% [61 (8) reps] than 80% (p=0.03) and 90% (p=0.015) arterial occlusion. Lastly, exercise under 70% completed more reps than 90% arterial occlusion (p=0.03). CONCLUSIONS: We wish to suggest that higher pressures may not augment the perceptual response to a large degree during exercise. These findings question using the perceptual response as an indicator for the amount of restriction given the similar ratings across pressures and higher volume at low pressure.