What muscles do chin-ups work?

The lats pull your upper arms down and in. The biceps take a substantially larger share than in an overhand pull-up, which has been measured directly, and your mid-back and chest assist. Your midsection holds the folded leg position.

Are chin-ups easier than pull-ups?

Most people can do more of them, because the underhand grip brings the biceps and chest in more strongly and more muscle shares the work. That is a redistribution, not the back doing less.

Why should my legs be folded?

Straight legs are a pendulum, and a swing can finish a rep your back could not. Bending the knees and crossing the ankles shortens that pendulum and takes the option away.

Why do my elbows hurt on chin-ups?

A straight bar holds your forearms turned fully palm-up with no room to adjust for the whole set. Rings, a rotating handle or a neutral grip let the forearm find its own angle. If something hurts and keeps hurting, that is a question for a physiotherapist.

Can chin-ups replace bicep curls?

They are a genuine biceps stimulus and they do not cover the same range. A chin-up bends the elbow to roughly a right angle. A curl takes it further into the shortened end. Which you need depends on whether the arms are the point.

How far down should I go?

To arms fully straight, every rep. The bottom is the hardest place to restart the pull, which is exactly why it disappears first and exactly why it is worth keeping.

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Bodyweight · intermediate · back

Chin up leg folded

Also called Chin-up, Chinup, Underhand pull-up, Supinated pull-up.

The short answer

A chin-up hangs you from a bar with your palms facing you and pulls your chin above it, here with the knees bent and the ankles crossed behind. Your lats do the work of drawing your upper arms down and in toward your ribs. Your biceps take a much larger share than they do with an overhand grip, which has been measured, and your mid-back helps finish the pull. Folding the legs takes away the long straight legs a swing needs, so the rep has to come from pulling.

How to do it

Step oneHang from a pull-up bar with an underhand grip, hands shoulder-width apart.
Step twoCross your ankles and bend your knees to bring your legs up behind you in a folded position.
Step threeEngage your core and pull your body upward until your chin clears the bar.
Step fourPause at the top, squeezing your lats and biceps.
Step fiveSlowly lower yourself back to the hanging position.

What usually goes wrong

Each starts with what you would notice.

The inside of your elbow or your forearm aches during or after sets.

WhyA straight bar holds your forearms turned fully palm-up for the entire set with nowhere to go. Some people are comfortable there and some are not, and the bar does not care which you are.

FixUse rings or a rotating handle if you have access to them, since they let your forearms find their own angle as you pull. A neutral grip on parallel handles is the next best option.

Your body angles back and your chest comes to the bar sideways.

WhyYou are leaning away from the bar, which turns a vertical pull into something closer to a row. It is easier, and it is a different exercise with a different set of muscles finishing the rep.

FixKeep your torso close to upright and pull your chest up to the bar rather than back from it. The folded legs help here, since there is less of you hanging out in front to lean with.

You never quite straighten your arms at the bottom.

WhyThe very bottom is where the pull is hardest to restart, so the hang gets shorter over a set and the reps live in the easy middle of the range.

FixLet your elbows come to full extension every rep and pause there for a moment before pulling. It will cost you reps. Those reps were not doing much.

Your knees drive forward each time you pull.

WhyThe knees have become the kip. Even with the legs folded, a forward jerk of the thighs generates a little momentum, and once it works it happens automatically.

FixKeep the ankles crossed and the knees still, pointing at the floor. If the rep only happens with the knee drive, you have found the end of the set.

Should you learn the chin-up or the pull-up first

The chin-up, if you cannot yet do either, and the reason is not that it is the soft option.

Turning the palms toward you brings the biceps into a stronger position and recruits significantly more of them, along with more chest. More muscle sharing the load means most people complete a chin-up before they complete a pull-up, sometimes by months.

That matters because reps you can actually finish are what teach the pattern. Failed pull-up attempts train very little except the habit of failing at pull-ups.

The overhand version is worth having later for the mid-back work it brings, and it will be easier to reach from a position of being able to pull yourself up at all.

Are chin-ups enough for biceps

Chin-ups are often offered as a reason to skip curls entirely, and the truth sits somewhere in between.

The biceps really are strongly involved. When grips were compared, the underhand version recruited significantly more biceps than the overhand one, so anyone calling chin-ups pure back work is under-counting what they just did.

What they do not cover is the whole range at the elbow. A chin-up starts with the arms straight and finishes with them bent to somewhere around a right angle or slightly past. A curl carries the elbow further into the shortened end of its range, and it does so with your body out of the way.

So chin-ups are a real biceps stimulus, and they are not the same stimulus as a curl. If your only goal is a strong back with arms that come along for the ride, chin-ups are plenty. If you specifically want the arms trained through their full range, add the curl.

What the folded legs are for

Most chin-up instructions say nothing about your legs, and the version here is specific: knees bent, ankles crossed, legs tucked up behind you. It is worth knowing why.

Straight legs hanging below you are a pendulum. A small push at the bottom of a rep sets them swinging, and a swing that arrives at the right moment can lift you several inches with no help from your back. Nobody decides to do this. It appears on its own once a set gets hard, and it is why rep counts sometimes rise without anything getting stronger.

Fold the legs and there is much less to swing. The pendulum shortens, the kip stops being available, and the only thing left that can raise you is pulling.

It is not a magic position and it does not make the exercise harder in itself. It removes an escape route, which over a few months is worth more than most technique adjustments.

One aside for anyone who arrived here believing chin-ups are the cheating version. More muscle is sharing the load, not less back doing the work. The lats are working hard in both.

What it is for

The chin-up with legs folded is a bodyweight exercise targeting the latissimus dorsi. The underhand grip emphasizes bicep involvement, while folding the legs shifts the body's center of gravity and reduces the use of momentum.

Questions people ask

What muscles do chin-ups work?: The lats pull your upper arms down and in. The biceps take a substantially larger share than in an overhand pull-up, which has been measured directly, and your mid-back and chest assist. Your midsection holds the folded leg position.
Are chin-ups easier than pull-ups?: Most people can do more of them, because the underhand grip brings the biceps and chest in more strongly and more muscle shares the work. That is a redistribution, not the back doing less.
Why should my legs be folded?: Straight legs are a pendulum, and a swing can finish a rep your back could not. Bending the knees and crossing the ankles shortens that pendulum and takes the option away.
Why do my elbows hurt on chin-ups?: A straight bar holds your forearms turned fully palm-up with no room to adjust for the whole set. Rings, a rotating handle or a neutral grip let the forearm find its own angle. If something hurts and keeps hurting, that is a question for a physiotherapist.
Can chin-ups replace bicep curls?: They are a genuine biceps stimulus and they do not cover the same range. A chin-up bends the elbow to roughly a right angle. A curl takes it further into the shortened end. Which you need depends on whether the arms are the point.
How far down should I go?: To arms fully straight, every rep. The bottom is the hardest place to restart the pull, which is exactly why it disappears first and exactly why it is worth keeping.