When performing squat exercises with restricted blood flow, using a higher level of fatigue during each set (40% velocity loss) leads to more muscle growth in the upper part of the thigh muscle...
Mechanism
Synthesis from 1 study
When you squat with your legs squeezed and push until you're extremely tired, your thigh muscles get bigger on the top side because waste products get trapped there and signal the muscle to grow. But this also makes your fastest muscle fibers slower and weaker, so you lose some explosive power even...
Most probable mechanism
When you push a muscle to extreme fatigue during a squat with restricted blood flow, waste products build up more in the upper part of the thigh because the blood can't flow out easily. This buildup tricks the muscle cells into thinking they're under stress, which turns on a growth signal that makes the muscle fibers get bigger, especially near the top where the pressure is highest.
Blood flow restriction during high-repetition squats limits venous outflow, causing metabolites such as lactate, hydrogen ions, and inorganic phosphate to accumulate within muscle fibers.
Metabolite accumulation induces cellular swelling and activates mechanosensitive and metabolic stress sensors, including mTORC1 and MAPK signaling pathways.
mTORC1 activation increases ribosomal biogenesis and translation initiation, elevating myofibrillar protein synthesis and leading to muscle fiber enlargement.
Metabolite retention and pressure gradients are greatest in proximal regions of the vastus lateralis due to anatomical positioning relative to the occlusion cuff, resulting in localized hypertrophy at these sites.
Less supported by current evidence, but not ruled out
Pushing a muscle to extreme fatigue can cause some of its fastest contracting fibers to become slower and less powerful, which reduces explosive strength even as the muscle gets bigger.
Chronic metabolic acidosis and elevated fatigue metabolites activate signaling pathways such as calcineurin/NFAT and AMPK that suppress expression of fast-twitch myosin heavy chain isoforms.
Reduced fast-twitch fiber content lowers maximum shortening velocity and rate of force development, diminishing explosive performance despite increased muscle size.
Evidence from Studies
Supporting (1)
Community contributions welcome
Effects of velocity loss with blood flow restriction in full squat on strength gains, neuromuscular adaptations, and muscle hypertrophy
Contradicting (0)
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