Metabolic Stress & Hypertrophy: do metabolites create muscle growth ?

Metabolic Stress & Hypertrophy: do metabolites create muscle growth ?⭕️ ⁣

In the current model of hypertrophy, and the mechanisms behind it, 3 are the “main” ways through which hypertrophy occurs: ⁣
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1) Mechanical Tension⁣
2) Metabolic Stress⁣
3) Muscle Damage (which we’ve already seen it actually doesn’t cause muscle growth by itself) [1]⁣
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But if point 3 is “out” of the triade, let’s see whether or not metabolic stress is actually a separate (or different ?) way through which muscle growth occurs. ⁣
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When we’re performing a long training set and our muscle fibers fatigue, metabolites accumulate within our muscles. Generally motor unit recruitment increases, but NOT because the lower-threshold motor units stop working or because metabolite accumulation causes it by itself [2] but rather because our CNS *responds* to this fatigue mechanism by increasing the level of effort perceived, and thus increasing motor unit recruitment [3]: ⁣
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This causes higher threshold motor units to be recruited and muscle fibers to be activated: as fibers keep working, they experience greater level of mechanical tension, which is what ultimately leads to muscle growth, over time. ⁣
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Therefore, in reality, Mechanical Tension is the main driver of muscle growth and we never see hypertrophy when the other mechanisms happen *alone* (without Mechanical Tension, which is what actually matters!)⁣
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References:⁣
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1) https://pubmed.ncbi.nlm.nih.gov/11668355/⁣
2) https://pubmed.ncbi.nlm.nih.gov/32830552/⁣
3) https://pubmed.ncbi.nlm.nih.gov/7929794/⁣