Does a hormone rush make your arms bigger?
Elevations in ostensibly anabolic hormones with resistance exercise enhance neither training-induced muscle hypertrophy nor strength of the elbow flexors.
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
Surprising Findings
Massive hormone spikes (testosterone, GH, IGF-1) had zero effect on muscle growth or strength gains—even though they were statistically significant (p < 0.001).
For decades, fitness gurus and even textbooks claimed that post-workout hormone surges were essential for hypertrophy. This study directly contradicts that with controlled, within-subject data.
Practical Takeaways
Skip the leg-day-before-arm-day routine. Focus on progressive overload, full range of motion, and sufficient volume for your target muscles—no need to chase hormonal surges.
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
Surprising Findings
Massive hormone spikes (testosterone, GH, IGF-1) had zero effect on muscle growth or strength gains—even though they were statistically significant (p < 0.001).
For decades, fitness gurus and even textbooks claimed that post-workout hormone surges were essential for hypertrophy. This study directly contradicts that with controlled, within-subject data.
Practical Takeaways
Skip the leg-day-before-arm-day routine. Focus on progressive overload, full range of motion, and sufficient volume for your target muscles—no need to chase hormonal surges.
Publication
Journal
Journal of applied physiology
Year
2010
Authors
Daniel W D West, N. Burd, Jason E. Tang, D. Moore, Aaron W. Staples, A. Holwerda, S. Baker, Stuart M Phillips
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Claims (6)
Even if your testosterone, growth hormone, or IGF-1 levels spike right after a workout, you don’t need those spikes to grow muscle — your muscles can still get bigger without them.
If young men lift weights for 15 weeks, their arm muscles get bigger—about 10–12% for the whole muscle and 9–24% for the individual muscle fibers—no matter if their body’s hormone levels spike during workouts or stay normal.
Even though lifting weights makes young men’s hormones spike temporarily, those spikes don’t make their biceps grow bigger or stronger over 15 weeks—what really matters is what’s happening right inside the muscle itself.
When young men do intense leg workouts, their body releases more lactate and cortisol—stress and energy chemicals—but that doesn’t mean they’ll grow bigger muscles or get stronger faster than if those chemicals stayed low.
If young men lift weights for 15 weeks, their biceps get significantly stronger—by about 20%—no matter if their body releases extra muscle-building hormones during the workout or not.