The Perceived Tightness Scale Does Not Provide Reliable Estimates Of Blood Flow Restriction Pressure

Abstract

When completing blood flow restriction, use of a perceived tightness scale is recommended as a method for setting sub-occlusive pressures. However, whether or not participants can consistently rate a similar pressure using this scale is unknown. PURPOSE: To determine the reliability of a perceived pressure when asking participants to rate a 7 out of 10, considered a moderate pressure with no pain, during blood flow restriction. METHODS: Participants (12 men, 12 women) were tested over 3 visits, involving measurements for arterial occlusion and the relative pressure at which participants deemed a 7 out of 10. Participants arrived to the lab and proceeded to lie supine for a 10-minute rest period. Measurements were completed in one limb for the upper and lower body. A repeated measures analysis with a between subject factor of sex was used to compare relative arterial occlusion pressures across days and sex with a default prior of 0.5 for the fixed effects and 1 for the random effects. An independent samples t-test was used to determine if there were sex differences in %CV with a default prior of 0.707. A Bayes factor (BF10) of 3 and 0.33 was considered evidence for the alternative and null hypotheses, respectively. RESULTS: The %CV for the measurement in the upper body was 12%, with no effect of sex (men: 12.3% vs. women 12.2%; BF10: .403; median δ (95% credible interval): .016 (-.741, .752)). The %CV for relative arterial occlusion pressure in the lower body also did not differ between sexes (men: 13.7% vs. women 10.3%; BF10: .509; median δ (95% credible interval): .266 (-.396, .999)). Participants’ rated a 7/10 pressure above the arterial occlusion pressure for the upper body and below for the lower body. At the group level, participants rated a 7 out of 10 at a higher relative pressure on day 1 compared to days 2 (BF10: 4.482, median δ (95% credible interval): -.694 (-1.307, -.130)) and 3 (BF10: 10.2, median δ (95% credible interval): -.838 (-1.468, -.189)) for the lower body but no differences in the upper body. There was no effect of sex. CONCLUSIONS: The use of a perceived tightness scale does not appear to provide a reliable method for the prescription of blood flow restriction pressure. Future work should consider alternative methods or modifications to the scale for improving reliability when setting sub-occlusive pressures.