To investigate the effects of high-intensity contractions and low-intensity contractions with and without blood flow restriction on changes in blood pressure and hemodynamic parameters. A total of 179 participants (18-35 years) were randomly assigned to one of three training groups that exercised 3 times per week for six weeks or a non-exercise control group. The groups are as follows: 1) Control [CON, n = 44]; 2) completed 4 sets of two-minute isometric contractions at 30% maximal voluntary contraction [LI, n = 47]; 3) completed 4 sets of two-minute isometric contractions at 30% maximal voluntary contraction with a 12 cm cuff inflated to 50% of arterial occlusion pressure [LI+BFR, n = 41]; or 4) completed 4 maximal isometric contractions lasting 5 seconds [MAX, n = 47]. Blood pressure, vascular resistance, and reactive hyperemia were measured at pre and post. Data are presented as means (SD). There was no evidence that SBP (BF10: 0.066), DBP (BF10: 0.057), vascular resistance (BF10: 0.085), or peak reactive hyperemia changed (BF10: 0.044) or A.U.C. (BF10: 0.074). Change scores for SBP were 1.1 (6.7), 0.7 (5.8), -0.4 (6.5), and -0.9 (6.3) mmHg for CON, LI, LI+BFR, and MAX, respectively. DBP change scores were 1.5 (6.6), 1.5 (7), -0.7 (5.9), and 0.3 (6.3) mmHg for CON, LI, LI+BFR, and MAX, respectively. Although recommended as a non-pharmacological method of blood pressure control, isometric exercise with or without BFR did not lower blood pressure. Future work could examine the inclusion of a daily strength test prior to the low intensity protocol.
Keywords: Hypertension; isometric exercise; reactive hyperemia; vascular resistance.