After performing resistance exercise with restricted blood flow, the body releases more of a protein called irisin in untrained young men, but this release is smaller in older men and in those who...
Mechanism
Synthesis from 1 study
When you exercise with restricted blood flow, your muscles release a signal called irisin that tells them to grow by boosting a growth promoter and turning down a growth blocker. People who haven’t trained much or are younger respond more strongly, while trained or older people respond less because...
Most probable mechanism
When muscles are worked hard with restricted blood flow, they release a protein called irisin, which tells muscle cells to grow by increasing a growth signal called IGF-1 and reducing a brake on growth called myostatin. This makes muscle repair and growth more active. People who haven't trained much or are younger have a stronger response, while those who are trained or older have a weaker one because their muscles are already adapted or less responsive.
Resistance exercise under blood-flow restriction creates metabolic stress and mechanical strain in skeletal muscle fibers.
Stressed muscle cells release irisin into the bloodstream.
Irisin increases the expression of insulin-like growth factor-1 (IGF-1) in muscle tissue.
Irisin decreases the expression of myostatin, a protein that limits muscle growth.
Elevated IGF-1 and reduced myostatin enhance satellite cell activation, myoblast proliferation, and fusion into existing muscle fibers.
This cascade promotes muscle fiber hypertrophy and strength adaptation.
Less supported by current evidence, but not ruled out
Muscle stress from restricted blood flow also triggers the release of IL-6, which activates pathways that increase the number of muscle repair cells and boost protein production, helping muscles grow.
Resistance exercise under blood-flow restriction creates metabolic stress and mechanical strain in skeletal muscle fibers.
Stressed muscle cells release interleukin-6 (IL-6) into the bloodstream.
IL-6 activates the STAT3 signaling pathway in satellite cells, promoting their proliferation.
IL-6 enhances activation of the mTOR pathway, increasing muscle protein synthesis.
Increased satellite cell activity and protein synthesis contribute to muscle hypertrophy.
Muscle stress also causes the release of LIF, which activates repair cells and boosts protein building, but higher baseline levels may mean less room for improvement.
Resistance exercise under blood-flow restriction creates metabolic stress and mechanical strain in skeletal muscle fibers.
Stressed muscle cells release leukemia inhibitory factor (LIF) into the bloodstream.
LIF activates the JAK/STAT3 pathway in satellite cells, promoting their proliferation.
LIF enhances activation of the mTOR pathway, increasing muscle protein synthesis.
Higher baseline LIF levels correlate with smaller gains in muscle strength, suggesting reduced adaptive capacity.
Evidence from Studies
Supporting (1)
Community contributions welcome
Contradicting (0)
Community contributions welcome
Gold Standard Evidence Needed
According to GRADE and EBM methodology, here is what ideal scientific evidence would look like to definitively prove or disprove this specific claim, ordered from strongest to weakest evidence.