Cardiac autonomic response to aerobic exercise with different levels of blood flow restriction in pre-hypertensive men

Purpose Cardiovascular safety of aerobic exercise with blood flow restriction (BFR) has been little studied in clinical populations. This study investigated the effects of different levels of BFR on cardiac autonomic response during and after walking tasks in pre-hypertensive men. Methods Twelve pre-hypertensive men performed three randomly assigned experimental sessions: (1) 20 min of walking at 40% of peak running velocity (V peak ) without BFR (CON); (2) 20 min of walking at 40% of V peak with BFR sets at 40% of the maximum cuff pressure that fully interrupted blood flow (BFR40); and (3) 20 min of walking at 40% of V peak with BFR sets at 80% of the maximum cuff pressure that fully interrupted blood flow (BFR80). The HR and HRV measurements were taken at rest, during exercise, and during the recovery period after constant load sessions. Results Heart rate was higher throughout the BFR80 session when compared to the CON condition ( p < 0.05). The time constant of heart rate recovery was higher in both BFR80 (73.2 ± 28.8 s) and BFR40 (49.8 ± 16.1 s) compared to CON (24.3 ± 7.8 s; p < 0.01). In addition, the cardiac vagal modulation during recovery was lower in the BFR80 than CON ( p < 0.05), but there was no significant difference between BFR40 and CON or between BFR80 and BFR40 ( p > 0.05). Conclusions Restricting blood flow imposes additional cardiovascular stress during and after exercise in pre-hypertensive men, with apparently greater stress as the level of BFR increases.