The Study
Single-Joint Exercise Results in Higher Hypertrophy of Elbow Flexors Than Multijoint Exercise
This study is like comparing two different ways to exercise your arm muscles using the same person for both exercises. It found that curling a dumbbell (single-joint) made arm muscles grow about 11% while doing rows (multi-joint) only made them grow about 5%. But here's the catch: the researchers didn't say they randomly decided who did which exercise - they just assigned people. Without that random assignment, we can't be sure the exercise type actually caused the difference, or if something else might have caused it. So we can only say these exercises seem to be linked to different amounts of muscle growth, not that one definitely makes muscles grow more than the other.
Analysis score
Maximum 90 for a randomized controlled trial.
Where the score came from
Researchers compared two types of arm exercises - biceps curl (single-joint) and dumbbell row (multi-joint) - to see which builds more arm muscle.
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 531 / 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 - the biceps curl produced more than double the muscle growth compared to the dumbbell row
- 2Biceps curl: 11.06% muscle growth | Dumbbell row: 5.16% muscle growth
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
Journal of Strength and Conditioning Research
Year
2019
Authors
P. Mannarino, T. Matta, J. Lima, R. Simão, Belmiro Freitas de Salles
Related Content
Claims (5)
Doing both compound movements like pull-ups and isolation exercises like dumbbell curls is the best way to build bigger biceps and the underlying brachialis muscle.
When you train one specific exercise, you get stronger mainly at that exact exercise - doing bicep curls doesn't make you much better at doing dumbbell rows, and vice versa.
When men who hadn't trained before did bicep curls (a single-joint exercise) for 8 weeks, their arm muscles grew about 11%. But when they did dumbbell rows (a multi-joint exercise) instead, their muscles only grew about 5%.
When people want to build bigger biceps, they should focus on bicep curls rather than compound movements like pull-ups that work multiple muscle groups at once.
When you do compound exercises like dumbbell rows that work multiple muscles at once, they might build muscle in some parts of your arm about the same as isolation exercises like dumbbell curls that focus on just one muscle. But in other parts of your arm, the two types of exercises might build muscle differently.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.