Biceps curl
Curls reliably build the elbow flexors, and in a direct comparison they grew them about twice as much as rows did. Beginners already doing pulldowns and rows may get little extra from curls at first, but for anyone who wants bigger arms they are the most direct tool. The lower, stretched half of the rep seems to matter most.
What the science says
- Curls build the elbow flexors Strong evidence
Curl training increased biceps size in every trial cited here: Mannarino et al. (2021) found 11.1% elbow flexor growth with curls versus 5.2% with dumbbell rows in 8 weeks, and Pedrosa et al. (2023) found biceps cross-sectional area grew with preacher curls in young women. Many other curl studies show the same.
- Beginners may not need them at first Moderate evidence
Gentil et al. (2013) found that untrained men doing only lat pulldowns and bench press grew their elbow flexors about as much as those who also did curls and triceps work over 10 weeks. In trained men, de França et al. (2015) also found no significant extra arm growth from adding single-joint work, measured by circumference. Curls matter more once pulling volume alone stops working.
- The stretched part of the rep counts most Moderate evidence
Pedrosa et al. (2023) trained one arm in the first half of the preacher curl (arm near straight) and the other in the last half: the first-half arm grew more in the lower biceps and gained more full-range strength. Use a full range and don't cut the bottom of the rep.
How to do it
Muscles trained: biceps, brachialis, brachioradialis
- Stand tall, upper arms by your sides
- Curl the weight without letting the elbows drift forward much
- Keep the torso still; no swinging the hips to start the rep
- Lower slowly to fully straight arms
- Turn the palms up (supinate) if using dumbbells
How to apply it
Do curls with a full range of motion, close to failure, after your back work; 6–12 weekly sets for the biceps is enough for most people when rows and pulldowns are also in the program.
Who should be careful
Curls are low-risk for healthy adults. Elbow or forearm pain that persists is a reason to reduce load and volume, try a neutral (hammer) grip or an EZ bar, and see a physician or physical therapist if it does not settle.
Frequently asked questions
Do I need curls if I already do pull-ups and rows?
At first, maybe not: in untrained men, pulldowns and bench press grew the elbow flexors about as much as adding curls. Over time, curls grow the biceps about twice as much as rows do, so add them if arm size matters to you.
Should I do full or partial reps?
Full reps, with emphasis on the bottom. Training the stretched first half of the curl produced more lower-biceps growth and more strength than training only the top half.
How many sets of curls per week?
About 6–12 direct sets close to failure, on top of your back training, is enough for most people.
Scientific references
- Single-Joint Exercise Results in Higher Hypertrophy of Elbow Flexors Than Multijoint Exercise
- Effect of adding single-joint exercises to a multi-joint exercise resistance-training program on strength and hypertrophy in untrained subjects
- The effects of adding single-joint exercises to a multi-joint exercise resistance training program on upper body muscle strength and size in trained men
- Training in the Initial Range of Motion Promotes Greater Muscle Adaptations Than at Final in the Arm Curl
More exercises
- Back squat Strong evidence
The barbell back squat reliably builds the quadriceps, glutes and adductors and is one of the best-studied lower-body exercises in training research.
- Front squat Moderate evidence
The front squat holds the bar on the front of the shoulders, which keeps the torso more upright and loads the knees less than the back squat while recruiting the thigh muscles about as much.
- Bulgarian split squat Moderate evidence
The Bulgarian (rear-foot-elevated) split squat trains one leg at a time and builds the quads and glutes with far less load on the bar than a back squat.
- Leg press Strong evidence
The leg press builds the quadriceps about as well as free-weight squats and also grows the glutes and adductor magnus, with no balance or spinal-loading limit.
- Hack squat (machine) Moderate evidence
The machine hack squat lets you squat deep on a fixed track with your back supported, which makes it easy to push the quads close to failure.
- Romanian deadlift Moderate evidence
The Romanian deadlift is a hip hinge that loads the hamstrings and glutes at long muscle lengths, and trials of stiff-leg deadlifts and similar hip-extension exercises show real hamstring growth, mainly in the semimembranosus and biceps femoris long head.