Comparing adaptations from blood flow restriction exercise training using regulated or unregulated pressure systems: a systematic review and meta-analysis

Key points

1. 0181 studies reviewed; 35 included in meta-analyses; regulated (n=47) and unregulated (n=34) systems both produced comparable training adaptations
2. 02Meta-analysis found no significant difference between system types for repetition maximum strength (p=0.62), dynamometry strength (p=0.88), muscle cross-sectional area (p=0.29), or muscle anthropometry (p=0.31)
3. 03Overall BFR exercise produced small effect size advantages over non-BFR exercise for repetition maximum strength (ES=0.27) and muscle cross-sectional area (ES=0.27)
4. 04Regulated systems can measure limb occlusion pressure and maintain more accurate pressures, which may improve safety and comfort, especially in older or clinical populations
5. 05Unregulated systems are cheaper, lighter, and more portable, making them more accessible in community and home settings

How it was conducted

Design

Systematic review and meta-analysis (PRISMA guidelines)

Databases

Medline, SPORTDiscus, CINAHL, Embase, SpringerLink; inception to 31 December 2023

Studies included

81 in systematic review; 35 in meta-analyses

Intervention duration

Greater than 2 weeks; range 12 days to 12 weeks across included studies

Participants

Adults aged 18-83 years; individual study samples ranged from 5 to 60 participants

Primary outcomes

Muscle strength (repetition maximum and dynamometry), muscle size (cross-sectional area and anthropometry), physical function

What they found

• Overall BFR vs non-BFR: repetition maximum muscle strength ES=0.27, 95% CI (0.13, 0.40), I2=63.34%
• Overall BFR vs non-BFR: muscle strength via dynamometry ES=0.13, 95% CI (0.07, 0.19), I2=0%
• Overall BFR vs non-BFR: muscle cross-sectional area ES=0.27, 95% CI (0.09, 0.45), I2=77.86%
• Overall BFR vs non-BFR: muscle anthropometry ES=0.03, 95% CI (-0.03, 0.10), I2=0%
• Regulated vs unregulated for repetition maximum strength: ES 0.23 vs 0.32, difference p=0.62
• Regulated vs unregulated for dynamometry strength: ES 0.13 vs 0.12, difference p=0.88
• Regulated vs unregulated for muscle cross-sectional area: ES 0.18 vs 0.50, difference p=0.29
• Regulated vs unregulated for muscle anthropometry: ES 0.05 vs -0.05, difference p=0.31
• BFR significantly increased repetition maximum strength in 85% of studies using that measure, dynamometry strength in 71%, muscle cross-sectional area or anthropometry in 90%, physical function in 77%, and endurance in 92%
• No evidence of publication bias: Egger's test p=0.20 (RM strength), p=0.56 (dynamometry), p=0.60 (CSA), p=0.14 (anthropometry)

Limitations

• No existing randomised controlled trial has directly compared regulated vs unregulated systems within the same study and protocol, so comparisons rely on subgroup analysis across different studies
• Other BFR prescription variables (cuff width, applied pressure, exercise intensity, participant characteristics) were not controlled across included studies and could confound comparisons
• Insufficient data to meta-analyse physical function, endurance, or aerobic capacity outcomes
• Blinding of participants and personnel was rated low risk in only 7% of included studies, which is an inherent limitation of exercise training research

Why it matters

For patients

Patients seeking BFR exercise rehabilitation or training can achieve similar muscle strength and size benefits regardless of whether their therapist uses an expensive regulated device or a simpler unregulated cuff.

For clinicians

Clinicians can select a BFR pressure system based on cost, portability, safety features, and patient comfort rather than expecting superior muscle outcomes from one system type; regulated systems may be preferred for vulnerable or novice populations due to individualisable pressures.

For readers

This is the first meta-analytic comparison of BFR system types, providing practitioners with evidence-based guidance for equipment selection decisions.