Impact of Walking with Leg Blood Flow Restriction on Central Blood Pressure and Subendocardial Viability

Abstract

PURPOSE: Walking exercise with limb blood flow restriction (BFR) has been shown to increase muscular mass and strength even if it is performed at low intensities. Despite mounting evidence for its efficacy and the increasing popularity, the safety of BFR exercise in relation to cardiac loads has not been established. We measured central blood pressure in order to more accurately assess blood pressure load imposed on the left ventricle during the BFR exercise. Additionally, as restricted venous return expectedly induced smaller increase in stroke volume and greater tachycardia (i.e., shorter diastolic duration), subendocardial viability ratio, an index of myocardial perfusion relative to left ventricular workload, was derived. METHODS: Fifteen apparently healthy adults (10 men and 5 women, 27±1 years) underwent five bouts of 2-minute treadmill walking at 2 miles/hour with 1-min interval either with or without BFR on both proximal thighs. Beat-by-beat peripheral blood pressure and hemodynamics were measured using the Portapres. Central arterial hemodynamics was evaluated with pulse wave analysis via general transfer function. RESULTS: Peripheral systolic blood pressure (SBP) increased during walking more substantially with BFR (43±5% vs. baseline) than without during BFR (12±4% vs. baseline). Although aortic SBP did not change significantly during walking without BFR, there was a substantial elevation in aortic SBP during walking with BFR (41±4% vs. baseline). Compared with the non-BFR session, significantly smaller increase in stroke volume and shorter diastolic duration were observed during the BFR session. Thus, despite greater hypertensive response, subendocardial viability ratio was significantly lower in the BFR session compared with the non-BFR session (P<0.05). CONCLUSIONS: These findings suggest that even during slow-speed walking, leg BFR induces a greater hypertensive response in the aorta and a lower myocardial perfusion. These central hemodynamic responses might force a circulatory challenge, particularly for those with compromised cardiovascular function.