Incline curls vs preacher curls: which is best for bigger biceps?

A bigger set of biceps is on many gym-goers' agendas, and while there are plenty of bicep exercises to choose from, the incline curl and preacher curl are time-tested favourites.

The former has arguably become even more popular lately, due to the increase in research around lengthened-bias training. However, does that mean it stands out on top as the best? Are old-school preacher curls a waste of our time? A new study put both exercises to the test.

The study

In the study, researchers compared the changes in elbow flexor muscle size and strength while performing preacher and incline curls.

Here’s a quick breakdown of the study:

• 63 untrained women completed either preacher or incline curls on a 30-degree inclined bench, twice a week for three sets of 8-12 reps per workout over an eight-week period
• Muscle thickness was measured at different points of the elbow flexors, before and after the eight weeks
• A three rep-max test for each exercise was also completed at the start and end of the eight weeks

So, which turned out on top? Both, in their own right.

The incline curl and preacher curl both led to growth in proximal elbow flexor thickness (that's the upper portion of the bicep, close to the shoulder joint). Although, the incline curl came out on top with more growth.

The preacher curl, however, led to more growth than the incline curl in distal elbow flexor thickness (that's the lower portion of the bicep, closest to the elbow joint).

In regard to strength, both the incline curl and preacher curl groups saw strength improvements in their three rep max test for their assigned exercise. So, the group performing incline curls got stronger at doing incline curls, and the group doing preacher curls, got stronger at preacher curls.

So, which should you be including in your training? The researchers concluded: “Our findings can be used to guide exercise selection in resistance training progams aiming to optimize muscle hypertrophy and strength gains.

“Given the apparent complementarity of the two exercise induced adaptations, it is reasonable to recommend that strength and conditioning professionals and practitioners consider both biceps curl resistance exercises, particularly when the objective is to optimize the hypertrophy of different muscle sites and strength improvements in both tasks.”

In simple terms, include both exercises in your training (if you can), or rotate between the two. There’s no point splitting hairs here, both types of curls are effective for strength and muscle growth, they just target slightly different portions of the bicep moreso than the other.