Which workout makes muscles bigger: heavy weights or lots of reps?
The effect of myofibril and sarcoplasmic hypertrophy training on muscle hypertrophy and strength
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
Two groups of young men did different workouts for 8 weeks: one lifted heavy weights with few reps, the other lifted lighter weights with many reps. Scientists measured their muscles and strength before and after.
Surprising Findings
Muscle grew on scans but not on tape measure
Most people assume muscle growth means bigger arms or chest circumference. But here, ultrasonography detected growth while traditional measurements like arm girth didn’t change — suggesting visual progress lags behind cellular changes.
Practical Takeaways
Prioritize heavy compound lifts (like bench press and deadlift) with low-to-moderate reps (e.g., 4–8) for maximum muscle and strength gains.
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
Two groups of young men did different workouts for 8 weeks: one lifted heavy weights with few reps, the other lifted lighter weights with many reps. Scientists measured their muscles and strength before and after.
Surprising Findings
Muscle grew on scans but not on tape measure
Most people assume muscle growth means bigger arms or chest circumference. But here, ultrasonography detected growth while traditional measurements like arm girth didn’t change — suggesting visual progress lags behind cellular changes.
Practical Takeaways
Prioritize heavy compound lifts (like bench press and deadlift) with low-to-moderate reps (e.g., 4–8) for maximum muscle and strength gains.
Publication
Journal
Sport Sciences for Health
Year
2025
Authors
Haci Tunahan Gezer, H. Sözen, Ali Aslan, Hilal Altaş, Olgu Küçan
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Claims (2)
If young guys lift heavy weights with fewer reps, they’ll likely build more chest and back muscle than if they lift lighter weights with more reps — at least over 8 weeks.
If young guys lift weights for eight weeks—whether they go heavy or do more reps—they’ll likely build muscle in their upper body and back, and that can be seen with ultrasound scans.