Why muscles grow after lifting weights, not during
Resistance exercise increases AMPK activity and reduces 4E‐BP1 phosphorylation and protein synthesis in human skeletal muscle
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
Surprising Findings
AMPK stayed high for up to an hour after exercise, yet muscle protein synthesis still increased by 32%.
Prior belief: AMPK shuts down muscle growth. This shows anabolic signals can overpower it—even when energy stress is still present.
Practical Takeaways
Consume 20–40g of protein within 1–2 hours after resistance training to maximize the 32% spike in muscle protein synthesis.
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
Surprising Findings
AMPK stayed high for up to an hour after exercise, yet muscle protein synthesis still increased by 32%.
Prior belief: AMPK shuts down muscle growth. This shows anabolic signals can overpower it—even when energy stress is still present.
Practical Takeaways
Consume 20–40g of protein within 1–2 hours after resistance training to maximize the 32% spike in muscle protein synthesis.
Publication
Journal
The Journal of Physiology
Year
2006
Authors
H. Dreyer, S. Fujita, J. Cadenas, D. Chinkes, E. Volpi, B. Rasmussen
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Claims (6)
Your muscles don't grow while you're lifting weights—they grow later, while you rest, because your body uses that time to repair and build new muscle tissue after the workout stresses them.
When you lift weights, your muscles temporarily stop building protein, but right after you finish, they kick into high gear to repair and grow—this happens because key signaling molecules in your muscles get activated during recovery.
Even though your muscles get a signal to slow down energy use after lifting weights, they still keep building protein—like your body’s repair crew is ignoring the ‘slow down’ sign because the ‘build up’ signal is stronger.
After a single workout with weights, your muscles temporarily slow down their protein-building process, and this might be because a specific energy-sensing molecule (AMPK) gets more active and tells the building machinery to take a break.
When you lift weights, a specific protein in your muscles (4E-BP1) temporarily stops being activated in one way, even though another related protein (mTOR) stays just as active as before—this suggests that mTOR might be controlling 4E-BP1 through a different, hidden method.