Perceptual And Blood Pressure Responses To Submaximal Exercise With Blood Flow Restriction

Blood pressure and discomfort responses to low-load resistance exercise are amplified by the application of blood flow restriction (BFR). However, since failure (i.e., high effort) itself is also a potent stimulator of blood pressure and discomfort, it is important to account for proximity to failure when assessing the effect of submaximal BFR exercise. PURPOSE: To assess the effects of BFR on blood pressure and discomfort, using submaximal resistance exercise protocols accounted for proximity to failure. METHODS: Forty-four participants (22 SD 3 years) completed five visits. The initial visit included 1RM tests and two sets of unilateral knee extensions to failure at 30% 1RM with BFR (i.e., 80% of arterial occlusion) on dominant leg and without BFR (i.e., free flow) on non-dominant leg. Participants were then randomly assigned to perform four experimental conditions: 1) 70% maximal blood flow restricted repetitions with BFR (LL + BFR) or 2) without BFR (LL); 3) 70% maximal free flow repetitions (LL + EFFORT); 4) time-matched, non-exercise control (CON). Blood pressure was assessed pre-and post-exercise, and discomfort levels were measured after each of two sets. Data are presented as mean [SD]. RESULTS: Systolic (BFinclusion: 1.959x10+11) and diastolic pressure (BFinclusion: 2.328x10+22) exhibited differential changes across conditions. Systolic pressure increased in every condition, with greater elevations observed for LL + BFR compared to LL (difference: 11.0 [9.7] mmHg), LL + EFFORT (difference: 6.0 [14.0] mmHg) and CON (difference: 15.5 [10.4] mmHg). The increases in diastolic pressure for LL + BFR were greater than LL (difference: 11.7 [5.8] mmHg), LL + EFFORT (difference: 12.0 [8.4] mmHg) and the CON (difference: 11.7 [7.6] mmHg). For discomfort, there was evidence for a condition x set interaction (BFinclusion: 9.213x10+8). Discomfort increased from set 1 to set 2 in LL + BFR (change: 4.3 [11.0] AU), whereas discomfort decreased in LL (change: -15.1[13.9] AU) and LL + EFFORT (change: -6.6 [16.6] AU). CONCLUSIONS: BFR provided an additional stimulus to both systolic and diastolic blood pressure when combined with submaximal low-load resistance exercise, regardless of proximity to failure. The slight elevation in discomfort with BFR may be attributed to enhanced metabolite accumulation or cuff pressure.