In healthy young men, two different types of weight training programs—high-intensity lifting and high-intensity lifting with blood flow restriction—produce similar increases in thigh muscle size...
Mechanism
Synthesis from 1 study
Lifting heavy or light weights until you can't do another rep both make your muscles grow because they turn on the same growth signals inside your muscle cells. Even if you use bands to restrict blood flow, the buildup of waste and swelling does the same thing—so it’s not how heavy the weight is,...
Most probable mechanism
When you lift weights until you can't do another rep, your muscles get stretched and squeezed hard, which sends a signal to make more muscle protein. Even if you lift light weights with bands around your legs, the buildup of waste products and swelling in the muscle does the same thing. Both ways turn on the same molecular switch that tells your muscle cells to grow bigger.
Training to muscular failure recruits high-threshold motor units, generating high mechanical tension across muscle fibers regardless of load
Mechanical tension activates intracellular signaling pathways including mTOR and MAPK, increasing muscle protein synthesis
Blood flow restriction causes metabolite accumulation (lactate, H+, inorganic phosphate) and cellular swelling, independently activating mTOR and MAPK pathways
Sustained activation of anabolic signaling leads to net positive muscle protein balance and myofibrillar accretion
Less supported by current evidence, but not ruled out
As muscles grow, the tough connective tissue wrapping around them also thickens, which may help hold the muscle in place and improve how force is transferred during movement.
Repetitive mechanical loading during resistance training applies strain to the fascia surrounding the vastus lateralis
Mechanical strain activates fibroblasts in the fascia, stimulating collagen synthesis and extracellular matrix deposition
Increased fascial thickness may provide structural support for expanding muscle fibers and influence force transmission
Evidence from Studies
Supporting (1)
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