The Study
Type 1 Muscle Fiber Hypertrophy after Blood Flow–restricted Training in Powerlifters
This study is like a test where athletes were randomly put into two groups to compare exercises. It suggests that one type of exercise might make certain muscles bigger, but because we only have a short summary, we can't be totally sure it wasn't just luck or other factors.
Analysis score
Maximum 90 for a randomized controlled trial.
Where the score came from
When powerlifters used special bands to restrict blood flow during light weight training, it made their slow-twitch muscle fibers grow bigger.
Where does this study sit?
Reviews of RCTs (Meta-analyses)
Max 100Randomized Trials
Max 90Reviews of Cohort Studies
Max 85Cohort Studies
Max 72Reviews of Case-Control Studies
Max 63Case-Control Studies
Max 58Cross-Sectional & Case Series
Max 50Expert Opinion
Max 542 / 100
Quality score
Participants are randomly assigned to treatment or control groups, minimizing bias. The gold standard for testing whether an intervention causes an effect.
Key takeaways
Summary
Based on the study abstract and findings.
- 1Yes, these are meaningful changes in muscle size that would be noticeable.
- 2Type I muscle fibers grew 12% bigger with blood flow restriction training but didn't change with regular training.
- 3The muscle overall grew 7.7% bigger with blood flow restriction vs 0.5% with regular training.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
Medicine & Science in Sports & Exercise
Year
2019
Authors
Thomas Bjørnsen, M. Wernbom, Alexander Kirketeig, G. Paulsen, Lars Samnøy, L. Bækken, D. Cameron-Smith, S. Berntsen, T. Raastad
Related Content
Claims (5)
Lifting lighter weights with more reps might make your slow-twitch muscles grow bigger than lifting heavier weights with fewer reps.
When top powerlifters do a special type of exercise that limits blood flow to their muscles, their thigh muscle size grows almost 8% bigger—way more than the tiny growth from normal workouts.
When powerlifters do squats with restricted blood flow using lighter weights, it makes their slow-twitch muscle fibers grow bigger by 12%, while regular training doesn't change muscle fiber size.
When top powerlifters do a special type of weight training that restricts blood flow, it makes their slow-twitch muscle fibers grow more cell nuclei by 18%, but normal weight training doesn't do this.
For top powerlifters, two types of weight training—one that restricts blood flow and one that doesn't—both leave fast-twitch muscle fibers the same size after training.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.