Date of Award
Ph.D. in Health and Kinesiology
Health, Exercise Science, and Recreation Management
Jeremy P Loenneke
Mark J. Loftin
Paul D. Loprinzi
Blood flow restriction (BFR) with low load exercise increases muscular size and strength. Little is known of vascular adaptations to this training modality, and nothing was known at very low loads. These studies examined cardiovascular responses to high load (70% of one-repetition maximum (1RM)) and very low load (15%1RM) exercise, alone or at two levels of BFR. Study 1: Participants performed unilateral biceps curls using either 15%1RM with no BFR (15/00), 40% of arterial occlusion pressure (AOP) (15/40), or 80%AOP (15/80), or 70%1RM (70/00). Systolic and diastolic blood pressure (SBP, DBP) and blood flow (BF) were measured in the arms during four sets performed to voluntary failure. BF increased in 15/00 (+470.8 (257.6) ml·min-1), 15/40 (325.3 (174.9) ml·min-1), and 70/00 (445.6 (249.3) ml·min-1) following the 2nd set, but not in 15/80. One minute following the 4th set, BF increased in 15/80 (+300.6 (206.4) ml·min-1), with no differences between conditions. SBP rose across all conditions (+10 (11) mmHg), whereas DBP rose in 15/00 (+8 (5) mmHg), 15/40 (+9 (7) mmHg), and 15/80 (+3 (7) mmHg) only. Study 2: Participants trained twice weekly, with one of the four conditions in each arm. Forearm blood flow (FBF), vascular conductance (VC), maximum venous outflow (MVO), venous volume variation (VVV), and venous compliance (CV) were examined before and after training. FBF and VC increased in 15/80 (+0.520 (0.218) ml·min-1·100ml-1; +8.286 (2.66) ml·mmHg-1) and 70/00 (+0.616 (0.212) ml·min-1·100ml-1; +8.595 (2.60) ml·mmHg-1). MVO increased for all conditions at 60 mmHg (+4.020 (1.416) ml·min-1·100ml-1), and for 15/00 (+6.52 (3.02) ml·min-1·100ml-1) and 15/80 (+11.468 (2.965) ml·min-1·100ml-1) at 80 mmHg. VVV increased at 20 mmHg (+0.075 (0.030) %), 40 mmHg (+0.162 (0.069) %), and 80 mmHg (+0.310 (0.103) %) for all conditions, but decreased for 15/00 (-0.632 (0.200) %) at 60 mmHg. CV increased across all conditions following training (+0.003 (0.002) %·mmHg-1). Rating of perceived exertion decreased halfway through training and remained depressed, while discomfort at first decreased at 4 weeks but returned to baseline at 8 weeks. High BFR pressures combined with very low loads result in similar vascular adaptations as high loads with eight weeks of training.
Mouser, J. Grant, "Acute and Chronic Vascular Responses to Blood Flow Restriction in the Upper Body" (2018). Electronic Theses and Dissertations. 1406.
Available for download on Thursday, July 23, 2020