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

Not Applicable

Completed

• Conditions: Aerobic Capacity; VO2max; Blood Flow Restriction (BFR) Training Effects; Blood Flow Restriction Exercise; Muscle Strengh; Isokinetic

• Registration Number: NCT07114835
• Lead Sponsor: Kahramanmaras Sutcu Imam University

Brief Summary

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.

Detailed Description

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.

Study Timeline

• Study Start: 2023-12-01
• Primary Completion: 2024-03-05
• Study Completion: 2024-03-05
• Study First Submitted: 2025-06-30
• Status Verified: 2025-08
• Study First Submitted QC: 2025-08-06
• Last Update Submitted: 2025-08-06
• Study First Posted: 2025-08-11
• Last Update Posted: 2025-08-11

Recruitment & Eligibility

• Status: COMPLETED
• Sex: Male
• Target Recruitment: 24

Inclusion Criteria

• Individuals aged between 18-24 years,
• Individuals without any health problems,
• Individuals who do not actively participate in sports,
• Individuals who marked all items as no on the H+cuff participant information form,
• Individuals who have not had a sports injury that would prevent them from participating in sports in the last 6 months,

Exclusion Criteria

• history of lower extremity injury, respiratory disorders and refusal to participate

Study & Design

• Study Type: INTERVENTIONAL
• Study Design: CROSSOVER

Primary Outcome Measures

Name	Time	Method
Change in Maximal Oxygen Consumption (VO₂max, L/min)	Baseline and Post-test (Week 9)	Absolute VO₂max will be measured during a graded cycling exercise test using a breath-by-breath gas analyzer.
Change in Relative VO₂max (ml/kg/min)	Baseline and Post-test (Week 9)	VO₂max will also be reported relative to body weight using standard calculation: (VO₂max ÷ body weight).

Secondary Outcome Measures

Name	Time	Method
Change in Respiratory Exchange Ratio (RER)	Baseline and Post-test (Week 9)	RER will be recorded during the maximal exercise test as the ratio of carbon dioxide output to oxygen uptake (VCO₂/VO₂).
Change in Muscle Thickness (Rectus Femoris, Vastus Lateralis, Biceps Femoris)	Baseline and Post-test (Week 9)	Muscle thickness will be measured using B-mode ultrasonography with linear probe at specified anatomical landmarks.
Change in Peak Torque (Isokinetic Knee Strength, 60°/s and 180°/s)	Baseline and Post-test (Week 9)	Isokinetic knee extension and flexion strength will be measured using an isokinetic dynamometer at angular velocities of 60°/s and 180°/s.
Change in Maximal Heart Rate (MHR)	Baseline and Post-test (Week 9)	Maximal heart rate will be recorded during the graded exercise test.

Trial Locations

Locations (1)

Faculty of Sport Science; 🇹🇷 Kahramanmaraş, Onikişubat, Turkey