Did muscles grow by getting bigger or by making new fibers?
Muscle fiber hypertrophy, hyperplasia, and capillary density in college men after resistance training.
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
Surprising Findings
Some individuals with less fiber hypertrophy showed evidence of increased fiber number.
The overall group showed no hyperplasia, but the abstract notes that those who didn’t grow fibers as much may have added new ones—hinting at individual variability long thought impossible in humans.
Practical Takeaways
Focus on consistent, progressive resistance training to maximize muscle fiber growth.
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
Surprising Findings
Some individuals with less fiber hypertrophy showed evidence of increased fiber number.
The overall group showed no hyperplasia, but the abstract notes that those who didn’t grow fibers as much may have added new ones—hinting at individual variability long thought impossible in humans.
Practical Takeaways
Focus on consistent, progressive resistance training to maximize muscle fiber growth.
Publication
Journal
Journal of applied physiology
Year
1996
Authors
G. McCall, W. Byrnes, A. Dickinson, P. Pattany, S. Fleck
Related Content
Claims (6)
When you lift weights, your muscles get bigger not because you're growing new muscle fibers, but because the ones you already have are getting thicker. Scientists don't think you actually create new muscle fibers from training.
Lifting weights for three months makes the muscle fibers in young men's biceps get bigger — both the endurance-type and power-type fibers.
Lifting weights for three months increases the number of tiny blood vessels in arm muscles of young men, and the growth keeps up with how much the muscle fibers get bigger.
If college guys who've lifted weights before do a specific 12-week workout plan—3 times a week, 8 exercises, 3 sets each—they'll get 25% stronger in their arms, based on how much they can lift in one go on a curl machine.
Lifting weights for three months can make the upper arm muscle about 13% bigger in young college guys.