The Study
Isotonic Resistance Exercise Outperforms Eccentric Quasi-Isometric Resistance Exercise for Increasing Elbow Flexor Muscle Thickness and Estimated One-Repetition Maximum in Untrained Individuals: Exploring the Influence of Sex and Volume.
This study watched two groups of people do different kinds of arm exercises and saw that one group got a little stronger and their muscles grew a bit more. But we don’t know if the groups were picked fairly or if the people doing the measurements knew who did what, so we can’t say for sure that one exercise made the difference.
Analysis score
Maximum 90 for a randomized controlled trial.
Where the score came from
People who did regular weightlifting got stronger and their arms got thicker faster than those who did slow, held contractions — even though the slow ones took longer.
Where does this study sit?
Reviews of RCTs (Meta-analyses)
Max 100Randomized Trials
Max 90Reviews of Cohort Studies
Max 85Cohort Studies
Max 72Reviews of Case-Control Studies
Max 63Case-Control Studies
Max 58Cross-Sectional & Case Series
Max 50Expert Opinion
Max 545 / 100
Quality score
Participants are randomly assigned to treatment or control groups, minimizing bias. The gold standard for testing whether an intervention causes an effect.
Key takeaways
Summary
Based on the study abstract and findings.
- 1Yes — for beginners, regular lifting gives noticeably better arm growth and strength gains than slow holds, even if the slow method feels harder.
- 2Regular lifting: arms grew 6.7% thicker, strength up 19.6%.
- 3Slow holds: arms grew 4.0% thicker, strength up 12.8%.
- 4Women did more total work than men, but both genders improved equally.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
Applied physiology, nutrition, and metabolism = Physiologie appliquee, nutrition et metabolisme
Year
2025
Authors
Zachariah J. Henderson, Shizhen Wang, Stephen M. Cornish, Trisha Scribbans
Related Content
Videos (1)
Claims (7)
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.
Performing multiple sets of resistance exercise with sustained tension and fatigue leads to greater activation of muscle fibers and results in an increase in muscle size.
In people who have not previously trained, 8 weeks of traditional weightlifting exercises for the biceps leads to greater increases in muscle size and strength compared to a different type of resistance exercise that involves holding a static position under load.
In people who have not previously trained, performing 8 weeks of traditional weightlifting exercises for the biceps leads to greater increases in muscle size and strength compared to performing exercises that involve holding a weight in a stretched position without moving it.
Over an 8-week training program targeting the elbow flexors, untrained females performed more total resistance exercise volume than untrained males, but both groups showed similar increases in muscle thickness and strength.
In people who have not previously trained, performing 8 weeks of traditional weightlifting exercises for the biceps results in larger increases in muscle size and strength compared to performing exercises that involve slowly lowering weight without changing muscle length.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.