Incline curls and preacher curls are two of the most popular biceps exercises for good reason. They stretch and load the elbow flexors — biceps, brachialis, and forearms — crucial for hypertrophy. Which is better for growing the biceps?
- Incline Curl: Performed on an inclined bench, typically 45 degrees, positioning the arms behind the torso to fully stretch the upper elbow flexors at the shoulder joint.
- Preacher Curl: Using a preacher bench, place the arms forward in arm flexion, emphasizing the lower elbow flexors.
Several studies have compared them against each other and other biceps exercises. The House of Hypertrophy (HoH) broke down the results:
[Related: What Should You Drink to Stay Legit Hydrated]
Study 1: Growth Across the Biceps
The most recent study comparing incline curls versus preacher curls recruited 63 previously untrained women and split them into two groups. One group performed incline curls, and the other trained preacher curls twice weekly for eight weeks. (1)
Range of motion was 0 to 120 degrees of arm flexion. Participants completed three sets of eight to 12 reps until muscle failure. Loads were increased throughout the study’s duration to remain in the same rep range.
Since the brachialis muscle, which sits underneath and alongside the outer biceps, also grows from curls, it’s factored into the measurements.
The Results
Upper arms were measured at three points:
- 50% of arm length, or mid-biceps region: Incline curls elicited greater growth.
- 60% of arm length, just below mid-biceps: Growth was similar between exercises.
- 70% of arm length, closer to the elbow: Preacher curl elicited greater growth.
Study 2: Brachialis & Brachioradialis
A second study involved 21 untrained adults who performed incline curls with one arm, and preacher curls with the other for 12 weeks:
- Biceps brachii: Greater growth in the incline curl group, between 20-40% (upper half) of the biceps length.
- Brachioradialis (outer forearm): The preacher curl group experienced more growth, around 60% of muscle length.
- Brachialis: More growth from preacher curls, particularly at 70-80% of muscle length.
Study 3: Conflict and Nuances
A 2023 study with 31 trained women concluded that preacher curls might be superior to incline curls for overall growth. (2) However, differences between the exercises were not statistically significant, largely due to the small sample size.
Study 4: Blood Flow Restriction & Arm Gains
Blood flow restriction (BFR) has been suggested to enhance hypertrophy in specific muscle regions. A fourth study had 21 men with two years of training experience train one arm with incline curls and the other with preacher curls, using BFR. (3)
No significant differences were found over the three weeks. However, the short trial duration may have limited the outcomes.
Incline Curls: King of Biceps Exercises?
In another experiment, detrained men were separated into two groups and prescribed full-body workouts three times weekly. One group performed the same exercises each session, with barbell curls as the only isolation movement for the elbow flexors. The other group was assigned varied exercises each session, including barbell curls, preacher curls, and incline curls on different days.
Elbow flexors grew more in the varied group at 50% percent muscle length, similar to the latest study, suggesting incline curls as the culprit.
This study indirectly further supports the effectiveness of incline curls…being better than standing barbell curls.
—House of Hypertrophy
The last study compared cable curls with the arms behind the body and cable curls with the arms in the standard position. Elbow flexor growth was similar in the middle and lower arm.
While the results differ from the previous findings, both exercises were the hardest at the starting position. The results are likely to change with different resistance profiles.
Incline vs. Preacher Curls: Which is Better?
Based on these studies, HoH posits that incline curls are the better biceps exercise, but any exercise with the arms behind the body should cause similar gains. Meanwhile, preacher curls may grow the brachialis and brachioradialis better.
More research comparing a wider variety of curls will help advance the data.
More In Research
- What Should You Drink to Stay Legit Hydrated
- Fructose: Friend or Foe?
- Creatine Monohydrate vs. Hydrochloride — What’s the Difference?
Featured image: @markottobre on Instagram
