At first, your muscles might actually get a little smaller from this kind of training, but after doing it again later, they grow bigger than before — the growth just takes time to show up.

Scientific Claim

High-frequency, low-load blood flow-restricted resistance exercise is associated with a transient decrease in muscle fiber area by 6%–15% in type I and II fibers during the first training block, followed by a 6%–19% increase after the second block, indicating a delayed hypertrophic response.

Original Statement

“With the first block of BFRRE, ... type I and II MFA decreased by 6 ± 7% and 15 ± 11% (P < 0.05), respectively... muscle size increased by 6%–8%... MFA (type I: 19 ± 19%, type II: 11 ± 19%) peaked 10 days after the second block of BFRRE”

From study:Delayed myonuclear addition, myofiber hypertrophy, and increases in strength with high-frequency low-load blood flow restricted training to volitional failure.

Evidence Quality Assessment

Claim Status

overstated

Study Design Support

Design cannot support claim

Appropriate Language Strength

association

Can only show association/correlation

Assessment Explanation

The abstract describes observed changes but implies direct causation ('induced robust increases'). Without control group or randomization, these are associations, not proven effects.

Evidence from Studies

Supporting (1)

Delayed myonuclear addition, myofiber hypertrophy, and increases in strength with high-frequency low-load blood flow restricted training to volitional failure.

Cohort Study

Human

2019 Mar 1

This study found that doing lots of light leg exercises with restricted blood flow first made muscles slightly smaller for a bit, but then they grew bigger after a break — just like the claim says.

Contradicting (0)

No contradicting evidence found

Source Study

Delayed myonuclear addition, myofiber hypertrophy, and increases in strength with high-frequency low-load blood flow restricted training to volitional failure.

Score: 31

DOI: 10.1152/japplphysiol.00397.2018

Similar Assertions

Doing light weightlifting with a band that restricts blood flow for six weeks can make both slow and fast muscle fibers in older people grow bigger by about 20%, even without heavy lifting.

84%

Doing light weightlifting while restricting blood flow to the muscles can cause a big jump in special muscle repair cells, and this effect gets even bigger if you do it twice in a row.

82%

Even though muscles got bigger, the actual muscle fibers didn’t get thicker or change type—so the growth might be due to other factors like fluid or connective tissue.

76%

Even though the muscles got bigger after the exercise, the number of special repair cells and nuclei inside the muscle fibers didn’t go up — meaning the growth happened without these typical building mechanisms.

74%

This training makes your muscles grow and your strength go up — but not while you’re doing it. The best results show up weeks later, which means your body was under a lot of stress and needed time to recover.

74%