Performing strength exercises until muscle fatigue, with 8 to 12 repetitions per set, results in an increase in muscle size in people who have not previously trained regularly.
Mechanism
Synthesis from 4 studies
When you lift weights until you can't do another rep, your muscles work so hard that every fiber gets activated. This creates strong internal tension and builds up chemical byproducts, which together trigger signals that tell your muscles to make more proteins. Over time, this makes the muscle...
Most probable mechanism
When you lift weights until you can't do another rep, your muscles keep working harder until all the muscle fibers are activated. This creates strong physical tension inside the muscle cells and builds up waste products like lactic acid. These two things together turn on signals inside the cells that tell the body to build more muscle proteins, making the fibers thicker over time.
Resistance training to muscular failure progressively recruits all available motor units, including high-threshold units innervating fast-twitch muscle fibers, due to fatigue of initially activated low-threshold units.
Sustained mechanical tension across muscle fibers, particularly when held at longer sarcomere lengths, activates mechanosensitive proteins such as integrins and titin, initiating intracellular signaling cascades.
Metabolic stress from prolonged contraction and accumulation of metabolites (e.g., lactate, hydrogen ions, cellular swelling) enhances anabolic signaling and amplifies mechanotransduction pathways.
Mechanotransduction and metabolic stress converge to activate mTORC1 and MAPK signaling pathways, increasing ribosomal biogenesis and translation of myofibrillar proteins.
Net muscle protein synthesis exceeds breakdown over repeated training sessions, leading to accretion of contractile proteins and enlargement of muscle fibers.
Less supported by current evidence, but not ruled out
Intense muscle training can cause muscle cells to absorb more testosterone from the blood, making it appear lower in circulation — but this doesn't stop muscle growth because the hormone is still being used locally where it's needed.
Mechanical and metabolic stress from training to failure increases expression of androgen receptors on muscle cell membranes.
Increased receptor density enhances binding of circulating testosterone, reducing its free concentration in plasma and saliva.
Local testosterone binding within muscle tissue supports anabolic signaling without requiring elevated systemic hormone levels.
Evidence from Studies
Supporting (4)
Community contributions welcome
Resistance training beyond momentary failure: the effects of past-failure partials on muscle hypertrophy in the gastrocnemius
Muscle Hypertrophy, Strength, and Salivary Hormone Changes Following 9 Weeks of High- or Low-Load Resistance Training
The Effects of Low-Load Vs. High-Load Resistance Training on Muscle Fiber Hypertrophy: A Meta-Analysis
Contradicting (0)
Community contributions welcome
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