Acute effects of physical exercise with different levels of blood flow restriction on vascular reactivity and biomarkers of muscle hypertrophy, endothelial function and oxidative stress in young and elderly subjects - A randomized controlled protocol

Abstract

Background: Gains in muscle mass and strength have been documented in exercise training with blood flow restriction (BFR). However, the impact of retrograde blood flow during BFR training on vascular health remains unclear. The present study designed a protocol to evaluate the acute effects of exercise performed with different levels of BFR on vascular reactivity and biomarkers of endothelial function, oxidative stress, and muscle hypertrophy in young and older individuals.

Methods and study design: Sixty-eight physically inactive eutrophic men [34 young (18-25-yrs old) and 34 elderly (≥65-yrs old)] will be included in the study. Subjects will undergo three experimental protocols: a) control (ExCON) - handgrip exercise with intensity of 30% of the maximum voluntary contraction (MVC); b) blood flow restriction (ExBFR) - handgrip exercise with a resistance of 30% of the MVC with low level of BFR [80% of arterial occlusion pressure at rest (rAOP)]; and c) arterial occlusion pressure (ExAOP) - handgrip exercise with a resistance of 30% of the MVC with high level of BFR (120% of rAOP). Primary outcomes will be: a) vascular reactivity assessed by venous occlusion plethysmography; b) endothelial function (nitric oxide and apoptotic endothelial micro particles; c) oxidative stress (thiobarbituric acid reactive substances). Growth hormone and lactate concentration will be measured as secondary outcomes reflecting the hypertrophic drive and metabolic stress, respectively.

Discussion: The findings of the present study may help to elucidate the age-related impacts of BFR training on the vascular health.

Keywords: Aging; Blood pressure; Health; Muscle mass; Muscle strength.

Fig. 1

Flowchart of the experimental design. ExCON – Control group; ExBFR – Blood flow restriction group; ExAOP – Arterial occlusion pressure; IPAQ – International physical activity questionnaires; LABSAU – Laboratory of Physical Activity and Health Promotion; BIOVASC – Laboratory for Clinical and Experimental Research on Vascular Biology.

Fig. 2

Experimental sessions. ExCON – Control group; ExBFR – Blood flow restriction group; ExAOP – Arterial occlusion pressure; GH – Growth Hormone; TBARS – Thiobarbituric acid reactive substances; PCO₂ – Carbonic gas pressure; PO₂ – Oxygen gas pressure; TCO₂ – Total carbon dioxide; HCO3 – bicarbonate; BEecf – Base excess of the extracellular fluid; sO₂ – saturation of oxygen; MVC - maximal voluntary contraction; *: The duration of the exercise will vary according to the time to exhaustion of volunteer in each protocol.