If you want to build bigger biceps, preacher curls might be your ticket to the gun show. Preacher curls were popularized by the first Mr. Olympia Larry Scott back in the 1960s. Scott's hard work at the preacher bench built him an amazing set of arms. They were also a favorite of the late strength coach Charles Poliquin who also had great biceps. Early EMG research by Tudor O. Bompa and Lorenzo Cornacchia in their book “Serious Strength Training” showed that preacher curls caused the most electrical activity in the biceps. Now, recent research shows how to get the most out of this powerful biceps builder.
In this study (Pedrosa et al., 2023), researchers took 19 untrained, young women and measured their biceps size and full range of motion strength. They had the ladies train one arm in the bottom half of the preacher curl (0-68 degrees) and the other arm in the top half of the preacher curl (68-135 degrees). A band was set up to mark the starting position for the top half curl and the ending point of the bottom half curl.
The subjects trained three times a week for 8 weeks. They started with 3 sets of 8 reps for the first 4 weeks then moved to 5 sets for weeks 5-8. When the subject could do 10 reps, their weight was increased by 1kg. After the program, the researchers re-tested arm size and a full range of motion. The arm that was trained in the bottom half of the preacher curl had greater gains in muscle size and strength.
Critique
It is always nice to have more subjects, a mix of men and women, subjects with more training experience, and longer duration. However, training studies are expensive, time consume, and difficult to conduct so we need to be realistic.
Having each subject train one arm in the top half and one in the bottom half is a great study design. With each style of training done on the same subject, you rule out the impact of genetics. For example, if half the subjects did training style A and got better results than the other subjects who did training style B, it might be that the subjects in the first group had superior genetics. The downside with this design (which the authors wisely acknowledged) is the training effect on one side might influence the other side.
You would expect a full range of motion strength gains to be greater when training the bottom vs. the top range of motion on a preacher curl. The bottom is the hardest part. If you are strong enough to get through the bottom part, the rest is easy – even if you don’t train it.
Although this is a good study, I would disagree with the authors’ conclusions. You cannot use this study to claim that training the biceps in a lengthened position is superior to training it in a shortened position from this research (i.e., I’m not saying this is not true, but simply that this study doesn't "prove" it). To substantiate the claim of the superiority of the lengthened position, you would have to compare the bottom half preacher curl to an exercise that places maximum tension on the biceps in the shortened position (e.g., incline chest-supported curls). In this exercise, you could do partial reps in the top half of the range of motion for comparison.
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| This curl would place max biceps tension in the top half of the range of motion (shortened position) |
What this study really shows is that if you are doing preacher curls with a free weight, there is no point in using a range of motion that has you moving a free weight mostly sideways and losing a lot of tension - the primary driver of muscle growth.
The main takeaway should be that with a free weight exercise, stay in the range where there is the most tension. For decades when coaching the preacher curl, I’ve had clients and students stop where the tension starts to fall off instead of coming all the way up and resting.
The idea of staying in the range with the most tension is supported by another study by Goto et al., who compared lying triceps extensions through a full range of motion (0-120 degrees) to stay in a partial range (45-90 degrees). The group that stayed in the partial range of motion had almost double the amount of triceps growth as the full range of motion group. The authors suggest that the benefit of a partial range of motion group might be more intramuscular hypoxia (lack of oxygen to the working muscle which might stimulate muscle growth). Note: the standard lying triceps extension exercise does not place your triceps (at least the long head) into a fully lengthened position at the bottom.
It is easier to make the claim about the superiority of the lengthened position when using a machine that allows for high levels of tension throughout the range of motion. For example, a study comparing various ranges of motion on leg extensions found greater quadriceps (front thigh) hypertrophy when training in the initial range of motion (Pedrosa et al., 2022). This was especially evident in the distal (lower portion) of the quads.
Practical Applications: Your Best Preacher Curl for Bigger Biceps
- Use an incline bench instead of a preacher curl bench. This is more practical and accessible for many people (especially those training at home) and allows you to adjust the angle.
- Most preacher curl benches are not steep enough (usually they are closer to a 45-degree angle). As a result, you place a ton of stress on your biceps tendon at the bottom and then the resistance falls off about halfway up.
- Set the incline higher. If you want to get your protractor out, you can go about 70-80 degrees. Ultimately play to find the angle that gives you the best biceps recruitment.
- If you experience any elbow pain, stop and use another exercise.
- Doing this exercise one arm at a time lets you focus all your attention on that one bicep. It also helps to reduce your risk of left-to-right imbalances. If you have a weaker and/or smaller arm, do that side first and then match the weight and reps on your stronger side – even if it is easy.
- By using a dumbbell, the dumbbell plates will hit the bench at the bottom. This stops you from overextending your elbow at the bottom and risking injury.
- When doing preacher curls, stop curling when you lose tension at the top of the movement.
- Remember, this is an accessory exercise. Don’t load it up to max weight. By using a moderate weight and a steeper incline, you can avoid tearing your biceps tendon's like this guy in the video below.
References
Bompa, T. O., & Cornacchia, L. J. (2002). Serious strength training. Human Kinetics.
Goto, M., Maeda, C., Hirayama, T., Terada, S., Nirengi, S., Kurosawa, Y., Nagano, A., & Hamaoka, T. (2019). Partial Range of Motion Exercise Is Effective for Facilitating Muscle Hypertrophy and Function Through Sustained Intramuscular Hypoxia in Young Trained Men. Journal of strength and conditioning research, 33(5), 1286–1294. https://doi.org/10.1519/JSC.0000000000002051
Pedrosa, G. F., Lima, F. V., Schoenfeld, B. J., Lacerda, L. T., Simões, M. G., Pereira, M. R., Diniz, R. C. R., & Chagas, M. H. (2022). Partial range of motion training elicits favorable improvements in muscular adaptations when carried out at long muscle lengths. European journal of sport science, 22(8), 1250–1260. https://doi.org/10.1080/17461391.2021.1927199
Pedrosa, G. F., Simões, M. G., Figueiredo, M. O. C., Lacerda, L. T., Schoenfeld, B. J., Lima, F. V., Chagas, M. H., & Diniz, R. C. R. (2023). Training in the Initial Range of Motion Promotes Greater Muscle Adaptations Than at Final in the Arm Curl. Sports (Basel, Switzerland), 11(2), 39. https://doi.org/10.3390/sports11020039
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