Biceps EMG ranking held across sessions: concentration curl first, hammer curl last
In short
When 15 adults performed concentration, dumbbell, hammer and incline curls for 7 reps at about 33% of peak isometric force across four sessions, the biceps surface EMG ranking was stable (Kendall's W = 0.90): concentration curl first, dumbbell and incline curls tied, hammer curl last. Concentration curls produced significantly higher amplitudes than hammer curls, but closely ranked exercises did not keep a consistent order, and one-third of participants showed only fair-to-moderate individual agreement.
The curl that lit up the biceps most was the concentration curl, and the lowest was the hammer curl. That order barely changed across four testing days. Because raw EMG amplitudes drift from session to session, the researchers asked whether the ranking, rather than the raw value, would hold.
How was it measured?
- Participants: 15 adults (8 trained, 7 untrained), mean age 37
- Exercises: concentration, dumbbell, hammer and incline curls
- Load: about 33% of peak isometric force, 7 reps per exercise
- The same protocol repeated on four separate days
How reliable is the ranking?
At the group level, rank agreement was high: Kendall's W was 0.90 (p = 0.0013). The concentration curl ranked first, the dumbbell and incline curls tied, and the hammer curl ranked last. Normalizing EMG to a peak isometric contraction was more reliable than normalizing to the dumbbell curl.
Only pairs with clear amplitude gaps, such as concentration versus hammer, kept a stable order. Similar exercises like the dumbbell and incline curl swapped places between days. Individually, one-third of participants showed only fair-to-moderate agreement in their own rankings across sessions.
How should this guide exercise choice?
If the biceps themselves are the target, the concentration curl earns a spot. The hammer curl shows lower biceps signal because it shifts work to the brachialis beneath it, so it serves a different purpose (see the hammer curl form guide). These data cannot separate the dumbbell and incline curl, so pick whichever one you can progress steadily in your log.
EMG estimates muscle activation; it does not directly measure muscle growth. The study tested 15 people at light-to-moderate loads, so individual results should be checked before applying the group ranking to heavy training or personal programming.
Frequently asked questions
Which curl activates the biceps the most?
In a study that tested 15 adults on four days, the concentration curl produced the highest biceps surface EMG, the dumbbell and incline curls were similar, and the hammer curl was lowest. The difference between the concentration and hammer curl was statistically significant.
Is the dumbbell curl or the incline curl better for the biceps?
In this study the two were tied, and their order changed from day to day, so neither came out ahead. Rankings between exercises with small EMG differences are not reliable.
Is the hammer curl a poor biceps exercise?
It produced the lowest biceps EMG of the four curls, but that does not make it ineffective. The neutral grip shifts more work to the brachialis beneath the biceps, so it serves a different purpose.
Can I apply EMG rankings directly to my own program?
The group ranking was stable, but one-third of participants showed only fair-to-moderate agreement in their individual rankings across days. The loads were also light, about 33% of peak isometric force, so individual checks are warranted.
Source: PubMed