What muscles do knuckle push-ups work?

The same muscles as any push-up, in the same order: chest leading, triceps helping, shoulders steadying. The addition is your forearms, which have to hold the fist closed and the wrist straight under load for the whole set.

Are knuckle push-ups better for your wrists?

The direction of the evidence says yes and the size of it is small. Two hand surgery studies found that a straight wrist carries the load more evenly than a bent-back one, using 14 volunteers in one and 6 cadaver wrists in the other. Neither followed a person over time, so nothing has been shown about pain.

Which knuckles should I put my weight on?

The index and middle knuckles, with the flat of the fist facing forward. That is the strongest column through the hand, and a study modeling a knuckle push-up applied its load along exactly those two lines into the base of the hand.

Do knuckle push-ups toughen your knuckles?

Nobody has measured it. The nearest thing is a pilot that measured 1 person and reported a small bone density increase in the arms, and no study has looked at what this exercise does to the knuckles, and none has linked it to fewer injuries. Treat the claim as folklore rather than a finding.

Do knuckle push-ups hurt?

On a hard surface the skin over your knuckles usually runs out before your chest does. Something soft to rest the fists on removes that without touching the wrist position, which is the part with evidence behind it.

Are knuckle push-ups harder than normal push-ups?

Usually, for two reasons that have nothing to do with your chest. Your fists lift your hands off the floor so your chest travels further on each rep, and holding a fist and a straight wrist is work your forearms do not have to do on your palms.

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Bodyweight · intermediate · chest

Knuckle push ups

Also called Fist push-ups, Knuckle pushups, Push-ups on fists, Closed-fist push-up.

The short answer

Knuckle push-ups are push-ups done on closed fists instead of flat palms, with your weight on the front two knuckles and your wrist in line with your forearm. The pressing half is the same movement as on your palms: chest leading, triceps helping. What the fists change is the hand and the wrist: instead of resting at the end of its range, the wrist stays straight, and your forearm muscles have to hold both the fist closed and that wrist position for every rep.

How to do it

Step oneBegin in a push-up position but make fists with both hands and place your knuckles on the floor, aligned under your shoulders.
Step twoKeep your wrists neutral and straight throughout the movement.
Step threeLower your chest toward the floor in a controlled manner, keeping your elbows at roughly a 45-degree angle to your body.
Step fourPause briefly at the bottom, then press back up to the starting position.

What usually goes wrong

Each starts with what you would notice.

Your weight has rolled outward onto your ring and little finger knuckles.

WhyThe fist is a narrow, uneven base and it tips easily. The knuckles meant to carry you are the first two, the ones the loading model puts the force down, and once you roll off them the load is going through the outside of the hand instead.

FixSet your fists so the index and middle knuckles are the ones touching the floor, with the flat of your fist facing forward, then start the rep. If the roll comes back every set, drop to your knees and rebuild the position with less weight on it.

Your wrist is bending anyway, so the forearm is not stacked over the fist.

WhyThe wrist is the entire reason for making a fist, and it will quietly give a little under load unless it is being held. That is forearm work, and it is the first thing to tire.

FixCheck from the side that your forearm runs straight into the back of your hand with no angle at the wrist. When you cannot hold that any more, the set has ended, regardless of what your chest still had left.

The set finishes because of your skin, not your chest.

WhyBare knuckles on a hard floor is a small contact area under a large share of your bodyweight, and most floors are unpleasant long before your chest is finished.

FixPut a folded towel or a mat under your fists. It changes nothing about the wrist position, which is the part with evidence behind it, and it lets the set end for a training reason.

You go deeper than you can on your palms and the line through your body breaks.

WhyYour fists raise your hands off the floor by their own depth, so your chest can travel further before it runs out of room. That extra range is range your trunk now has to hold you through.

FixTake the depth you can reach with your hips still in line with your shoulders and heels. Extra depth bought with a sagging middle is not extra range, it is a different position.

Knuckle push-ups or regular push-ups

This is the whole question, and unusually for a bodyweight variation there are two hand surgery studies on it rather than opinions.

In the first, 14 people did push-ups on a hyperextended wrist and on a neutral wrist while force plates and motion capture recorded what happened. On the neutral wrist, the force through the arm stayed more even through the rep. On the hyperextended wrist, it traveled further toward the back of the wrist, over a wider area, and further toward the little finger side. The authors concluded that the neutral position is the one to recommend, both for people rebuilding after an injury and to limit wear over time.

In the second, 6 cadaveric wrists were loaded at half a bodyweight in what the paper calls the neutral knuckle push-up position and in an extended one. The pull across the joint between two of the small wrist bones measured 45 newtons in extension against 25 in neutral.

Read that second one carefully, because it is the figure that will get quoted at you. Those wrists were tested with the ligament between those two bones cut. The paper says so, and its own clinical relevance statement is about the forces across that joint when the ligament is already disrupted. It is a model of an injured wrist, not a measurement of a healthy one.

What the two studies establish between them is the direction: a straight wrist and a bent-back wrist carry the load differently, and fists give you the straight one. What neither establishes is that anybody feels better, because neither followed a person for a single day. That is the whole evidence base: 14 volunteers and 6 cadaver wrists.

Fists or push-up handles

Handles, parallettes and a pair of dumbbells all do the same thing to your wrist that a fist does, by letting you grip something vertical instead of pressing into the floor.

They do it with two advantages. Your knuckles are not carrying anything, so the floor stops being a factor and the set ends for a training reason. And they usually sit higher than a fist, so the extra depth is larger.

The advantage of the fist is that you already have one. Nothing to buy, nothing to pack, and it works on any surface you are willing to put your hands on.

If your reason for being here is the wrist, either answer is the same answer. Pick whichever you will actually use.

The conditioning story, and what is actually behind it

Knuckle push-ups arrive attached to a set of beliefs from striking training: that doing them toughens the knuckles, builds up the bone at the front of the hand, and makes punching safer later. It is repeated so consistently that it reads as established. It is not.

What exists is small and general. A 100 day pilot of hand strengthening measured 1 person and reported bone density increases of about 2 percent in the arms, and observational work reports higher grip strength in people who box or practice karate than in people who do not, with the bone density differences small and not consistently significant. Both are about loading hands broadly. Neither is about this exercise, and neither measured the knuckles themselves.

What does not exist is any study measuring bone at the knuckles before and after doing knuckle push-ups, and any study linking the exercise to fewer hand injuries in anyone. There is a real injury literature about the joints at the front of the hand, covering damage to the sheath over the knuckle and fractures further back, but it is about repeated impact, which is a different thing from holding a still fist on the floor. It neither supports the conditioning claim nor argues against the exercise.

So the honest position is narrow. The wrist argument has two studies behind it and a clear direction. The knuckle argument has folklore, some general hand loading research that was not about this, and nothing measuring what it claims. A page that presents the second with the same confidence as the first is telling you more than anyone knows.

None of that is a reason not to do them. It is a reason to do them for the wrist rather than for the knuckles.

What it is for

Knuckle push ups are a bodyweight exercise targeting the chest, with secondary engagement of the upper arms, shoulders, and lower arms. Performing push ups on the knuckles maintains neutral wrist alignment, reduces wrist strain, and increases the range of motion during the descent.

Questions people ask

What muscles do knuckle push-ups work?: The same muscles as any push-up, in the same order: chest leading, triceps helping, shoulders steadying. The addition is your forearms, which have to hold the fist closed and the wrist straight under load for the whole set.
Are knuckle push-ups better for your wrists?: The direction of the evidence says yes and the size of it is small. Two hand surgery studies found that a straight wrist carries the load more evenly than a bent-back one, using 14 volunteers in one and 6 cadaver wrists in the other. Neither followed a person over time, so nothing has been shown about pain.
Which knuckles should I put my weight on?: The index and middle knuckles, with the flat of the fist facing forward. That is the strongest column through the hand, and a study modeling a knuckle push-up applied its load along exactly those two lines into the base of the hand.
Do knuckle push-ups toughen your knuckles?: Nobody has measured it. The nearest thing is a pilot that measured 1 person and reported a small bone density increase in the arms, and no study has looked at what this exercise does to the knuckles, and none has linked it to fewer injuries. Treat the claim as folklore rather than a finding.
Do knuckle push-ups hurt?: On a hard surface the skin over your knuckles usually runs out before your chest does. Something soft to rest the fists on removes that without touching the wrist position, which is the part with evidence behind it.
Are knuckle push-ups harder than normal push-ups?: Usually, for two reasons that have nothing to do with your chest. Your fists lift your hands off the floor so your chest travels further on each rep, and holding a fist and a straight wrist is work your forearms do not have to do on your palms.