Low-Intensity BFR Cycling: Impact on VO₂Max and Muscle Adaptations

Overview

This study aims to investigate the effects of low-intensity cycling exercise combined with blood flow restriction (BFR) on maximal oxygen consumption (VO₂max), muscle strength, and muscle thickness in sedentary adult males. Participants will be randomly assigned to three groups: (1) a cycling exercise group performing 40 minutes of cycling at 40% VO₂max, (2) a cycling with blood flow restriction group performing 15 minutes of cycling at 40% VO₂max with limb occlusion pressure at 60-80%, and (3) a control group following a shorter cycling protocol. Muscle thickness, isokinetic knee strength, and VO₂max will be measured before and after the 9-week intervention. The study is designed to evaluate whether short-duration, low-intensity cycling with BFR can induce physiological adaptations comparable to traditional longer-duration cycling protocols.

This study is designed to examine the effects of low-intensity cycling exercise combined with blood flow restriction (BFR) on aerobic capacity (VO₂max), isokinetic knee strength, and muscle thickness in sedentary male adults. Traditional methods for improving aerobic capacity and muscle strength often involve high-intensity or long-duration training protocols. However, such protocols may not be feasible for all individuals, particularly during rehabilitation, periods of detraining, or in populations with limited exercise tolerance. Blood flow restriction training has gained attention as a promising strategy to elicit muscular and cardiovascular adaptations using lower intensities. The technique involves applying individualized limb occlusion pressure (LOP) via pneumatic cuffs during exercise to partially restrict arterial inflow and fully restrict venous outflow. This restriction is thought to create a hypoxic environment and increase metabolic stress, which may enhance the recruitment of fast-twitch muscle fibers and stimulate physiological adaptations. In this randomized controlled trial, participants are allocated to one of three groups: a standard cycling exercise group (40 minutes at 40% VO₂max), a BFR cycling group (15 minutes at 40% VO₂max with 60-80% LOP), and a control group (15 minutes at 40% VO₂max without BFR). All exercise sessions are performed three times per week for nine weeks. The LOP is adjusted across the training period to progressively increase the stimulus in the BFR group. Baseline and post-intervention assessments include measurements of body height and weight, ultrasound-based muscle thickness, isokinetic knee strength testing, and graded exercise testing for VO₂max. The goal is to determine whether low-intensity, short-duration cycling with BFR can serve as a practical and effective alternative to longer-duration exercise programs.