Even if you do a lot of heavy weight training for 6 weeks, your muscle fibers don’t actually get more of the main building proteins—so the idea that your muscles grow by diluting those proteins with...
Mechanism
Synthesis from 1 study
Doing lots of high-rep lifts makes muscle cells swell with calcium, which tells the cell to build more of the non-muscle stuff — like energy tools and fluid — instead of the actual contractile parts. That’s why the muscle gets bigger without changing the amount of its main building proteins.
Most probable mechanism
When someone does a lot of high-rep weight training, their muscle cells get flooded with calcium each time they contract. This calcium triggers a chain reaction inside the cell that tells it to make more of the non-muscle-building proteins — like those involved in energy production and fluid balance — rather than the main contractile proteins. As a result, the muscle gets bigger from adding more of these non-contractile components, not from making more of the actual muscle fibers.
Repeated high-repetition muscle contractions during high-volume training increase intracellular calcium flux in muscle fibers
Elevated intracellular calcium activates MAPK signaling pathways, such as ERK1/2
Activated MAPK signaling preferentially upregulates translation of non-myofibrillar proteins, including metabolic and sarcoplasmic enzymes
Increased synthesis of non-myofibrillar proteins leads to accumulation of sarcoplasmic components without proportional increase in myofibrillar protein abundance
Evidence from Studies
Supporting (1)
Community contributions welcome
Effects of High-Volume Versus High-Load Resistance Training on Skeletal Muscle Growth and Molecular Adaptations
Contradicting (0)
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