Abstract Title

Assessment of Arterial Occlusive Pressures for Blood Flow Restriction Exercise

Presenter Name

Jace Coon

RAD Assignment Number

404

Abstract

Introduction: Blood flow restriction exercise is a training technique that involves restricting blood flow to an active limb (i.e. arm or leg) during exercise, and can stimulate muscle hypertrophy. Application of this technique is limited, however, as the optimal occlusive pressure required for physiological benefit has not yet been clearly identified. A cuff pressure of 220 mmHg around the upper thighs has been used in a blood flow restriction exercise study in this laboratory, but the degree of arterial occlusion elicited by this pressure has not been investigated. The aims of this investigation were to 1) quantify the degree of blood flow restriction induced by this cuff pressure (220 mmHg); and, 2) assess the cuff pressure required for complete occlusion of arterial blood flow. We hypothesized that 220 mmHg cuff pressure would not result in complete arterial occlusion of the superficial femoral artery in all subjects.

Methods: 3 human subjects (1M/2F) underwent a protocol of progressively increasing cuff pressures applied to both upper thighs from 220 mmHg to 300 mmHg, in 10 mmHg increments every 60 s. Blood velocity and diameter of the superficial femoral artery was measured using duplex ultrasound during each stage. Superficial femoral artery blood flow was calculated as [time averaged mean velocity x [(radius)2 x π]]. Muscle oxygenation (SmO2) of the vastus lateralis was measured using near infrared spectroscopy, and mean arterial pressure (MAP) and stroke volume (SV) were calculated via finger photoplethysmography.

Results: 220 mmHg cuff pressure reduced superficial femoral artery blood flow by 30.9 ± 14.8%, accompanied by a 4.2 ± 2.3% reduction in SV, a 0.2 ± 0.3% reduction in SmO2, and a 2.0 ± 1.7 mmHg increase in MAP. Complete occlusion of the superficial femoral artery was not achieved, even at a maximal cuff pressure of 300 mmHg; superficial femoral artery blood flow was reduced by 20.1 ± 7.6%, SV decreased by 21.1 ± 5.8%, SmO2 decreased by 22.3 ± 6.3%, and MAP increased by 3.4 ± 4.2 mmHg.

Conclusions: In support of our hypothesis, 220 mmHg cuff pressure did not result in complete occlusion of the superficial femoral artery. This stimulus was sufficient to reduce venous return, however, as evidenced by the reduction in stroke volume. These findings could be relevant to future blood flow restriction exercise studies, as they provide insight into the degree of arterial occlusion achieved at rest by a standard cuff pressure of 220 mmHg.

Research Area

Cardiovascular

Presentation Type

Poster

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Assessment of Arterial Occlusive Pressures for Blood Flow Restriction Exercise

Introduction: Blood flow restriction exercise is a training technique that involves restricting blood flow to an active limb (i.e. arm or leg) during exercise, and can stimulate muscle hypertrophy. Application of this technique is limited, however, as the optimal occlusive pressure required for physiological benefit has not yet been clearly identified. A cuff pressure of 220 mmHg around the upper thighs has been used in a blood flow restriction exercise study in this laboratory, but the degree of arterial occlusion elicited by this pressure has not been investigated. The aims of this investigation were to 1) quantify the degree of blood flow restriction induced by this cuff pressure (220 mmHg); and, 2) assess the cuff pressure required for complete occlusion of arterial blood flow. We hypothesized that 220 mmHg cuff pressure would not result in complete arterial occlusion of the superficial femoral artery in all subjects.

Methods: 3 human subjects (1M/2F) underwent a protocol of progressively increasing cuff pressures applied to both upper thighs from 220 mmHg to 300 mmHg, in 10 mmHg increments every 60 s. Blood velocity and diameter of the superficial femoral artery was measured using duplex ultrasound during each stage. Superficial femoral artery blood flow was calculated as [time averaged mean velocity x [(radius)2 x π]]. Muscle oxygenation (SmO2) of the vastus lateralis was measured using near infrared spectroscopy, and mean arterial pressure (MAP) and stroke volume (SV) were calculated via finger photoplethysmography.

Results: 220 mmHg cuff pressure reduced superficial femoral artery blood flow by 30.9 ± 14.8%, accompanied by a 4.2 ± 2.3% reduction in SV, a 0.2 ± 0.3% reduction in SmO2, and a 2.0 ± 1.7 mmHg increase in MAP. Complete occlusion of the superficial femoral artery was not achieved, even at a maximal cuff pressure of 300 mmHg; superficial femoral artery blood flow was reduced by 20.1 ± 7.6%, SV decreased by 21.1 ± 5.8%, SmO2 decreased by 22.3 ± 6.3%, and MAP increased by 3.4 ± 4.2 mmHg.

Conclusions: In support of our hypothesis, 220 mmHg cuff pressure did not result in complete occlusion of the superficial femoral artery. This stimulus was sufficient to reduce venous return, however, as evidenced by the reduction in stroke volume. These findings could be relevant to future blood flow restriction exercise studies, as they provide insight into the degree of arterial occlusion achieved at rest by a standard cuff pressure of 220 mmHg.