The role of the muscle metaboreflex on cardiovascular responses to submaximal resistance exercise with different pressures and modes of blood flow restriction.

Abstract

This study investigated the role of muscle metaboreflex on cardiovascular responses to submaximal resistance exercise using different pressures and modes of blood flow restriction. Fifty-three adults completed six visits. The first visit involved a performance test (2 sets of unilateral knee extension exercise until task failure at 30% 1RM) with continuous blood flow restriction (80% arterial occlusion pressure). In subsequent visits, participants performed 1) a non-exercise control (Control), 70% of the repetitions completed in the performance test with the cuff inflated to 2) continuously 80% arterial occlusion (LL+80%), 3) continuously 40% arterial occlusion (LL+40%), 4) intermittently 80% arterial occlusion during exercise (LL+80%Int), and 5) 0 mmHg (LL), in a randomized order. Three minutes of post-exercise circulatory occlusion was employed to assess the muscle metaboreflex activation. Blood pressure and heart rate were measured at various time points. The pre-post increase in systolic blood pressure was not greater with LL+80%Int (p=0.987) but was greater with LL+80% and LL+40% (LL+80%>LL+40%, p=0.005) than LL by 7 [95%CI: 4, 9] and 4 [95%CI; 2, 6] mmHg, respectively. Heart rate increased only with LL+80% over LL and Control (p<0.001). The changes in systolic blood pressure (p>0.468) and heart rate (p>0.543) did not differ among exercise conditions from immediate post-exercise to the end of the circulatory occlusion. Systolic/diastolic blood pressure returned to a similar level as Control (~120 mmHg, ~70 mmHg, respectively) immediately after the cuff deflation. Continuous blood flow restriction, especially with higher pressure, accentuates muscle metaboreflex activation, resulting in amplified cardiovascular responses to the exercise.