The acute cardiorespiratory response to blood flow restriction interval cycling in patients with COPD: a randomized crossover trial

<bold>Introduction:</bold> Endurance training with blood flow restriction (BFR-EN) can improve muscular function and aerobic capacity. We investigated the acute cardiorespiratory response between BFR-EN and traditional interval endurance exercise (TRA-EN). <bold>Methods:</bold> We conducted a randomized crossover study in patients with COPD. The protocol involved three cycling intervals interspersed by 1 min resting periods. Respiratory parameters were collected by breath-by-breath. Rate of perceived exertion (RPE, scale from 0 to 10) for dyspnea and leg fatigue were assessed. TRA-EN intervals lasted 2 min at an intensity of 65% incremental peak power output (iPPO). BFR-EN intervals lasted 2 min at an intensity of 50% iPPO. 50% arterial occlusion pressure (AOP) was continuously applied during the BFR-EN condition on both legs. Linear mixed models were used to analyze all respiratory, and RPE data adjusted for multiple measurements and reported as mean differences [95% confidence interval]. <bold>Results:</bold> Nine participants (male/female: 5/4), Gold (1/2/3/4: 1/2/4/1), mean (SD) age: 66 (8.4) yrs., VO_2peak: 13.5 (9.9) mL/kg/min, VE_max: 36.5 (7.1) L/min, completed the study. BFR-EN elicited significantly lower VE (−2.8 L/min [−4.15 to -1.44]), oxygen consumption (−0.06 L/min [−0.08 to -0.03]), breathing rate (−1.24 breaths/min [−2.34 to -0.14]), and RPE Dyspnea (−0.08 [−0.62 to 0.47]) compared to TRA-EN. RPE Leg (0.73 [0.07 to 1.4]) was significantly higher in BFR-EN. <bold>Conclusion:</bold> BFR-EN at 50% iPPO and 50% AOP resulted in lower VE compared to TRA-EN at 65% iPPO. For people with COPD, BFR-EN could provide an endurance training method with less respiratory effort while augmenting leg muscle effort.