Article · 3 min read

Stop swinging your bicep curls: how to curl with strict form

Published 30 September 2026 by TRACK AI Coach

The bicep curl looks like the simplest exercise there is, which is exactly why it’s so often done badly. The weight is a little too heavy, the hips start to rock, the elbows drift forward, and suddenly your back and shoulders are doing the lifting. Strict curls with a lighter weight train your biceps far better than heavy swings.

What a good curl looks like

You stand tall with your feet hip-width apart, knees soft and core braced.
Your upper arms stay by your sides, with your elbows close to your ribs.
Only your forearms move: you curl until your forearm is close to your upper arm, squeeze, and lower until your arms are straight.
The lowering takes a second or two. You control the weight all the way down.

Why curls turn into swings

The weight is too heavy. If you need to lean back to get it moving, the weight is choosing your technique for you.
Chasing reps. The last reps of a set are hard, so your body finds an easier way to finish them.
Nobody is watching. Small swings are hard to notice from the inside, especially when you’re tired.

Five ways to fix it

Drop the weight by about a third and do your reps slowly. If you can’t do 8 strict reps, it’s too heavy.
Pin your elbows. Imagine your elbows are stuck to your sides. Only your forearms move.
Brace as if you’re about to be pushed. Tighten your stomach and squeeze your glutes so your torso stays still.
Stand against a wall. With your back and head touching a wall, swinging becomes almost impossible. It’s a great way to learn how a strict curl feels.
Lower for two seconds. Controlling the lowering keeps tension on your biceps and takes away the bounce that starts the next swing.

Use the full range

Half reps are the other common curl fault. Stopping short at the top misses the squeeze at the end of the curl, and stopping short at the bottom skips the stretch. Straighten your arms at the bottom of every rep and curl all the way up at the top. If you can’t, the weight is too heavy.

How many sets and reps?

Curls work well with moderate weights and higher reps: 2 or 3 sets of 10 to 15, finishing each set with one or two good reps in the tank. Your biceps also work in pulling exercises such as rows, so a couple of sets of curls on top is usually plenty. See how many sets and reps for the bigger picture.

Together or alternating?

Both work. Curling both arms at once is quicker and makes a swing easier to spot. Alternating arms lets you focus on one side at a time, but it’s easier to twist your torso, so keep your shoulders square to the front.

No dumbbells?

Fill two water bottles or a backpack, or stand on a resistance band and hold the ends. Anything you can hold with your palms facing up works, as long as you can control it.

What the coach checks

Facing your phone at chest height, the TRACK AI coach watches both arms. It calls out “Swinging” when your torso starts to rock, “Elbows drifting” when your upper arms move, and “Half rep” or “Not extending fully” when you cut the range short. It also notices when you are “Dropping the weight” instead of lowering it.

Read the bicep curl guide for step-by-step technique and easier and harder versions.