Context: I've been boxing for a few years now and decided with my coaches (a bit before the pandemic hit) that I would move up a weight class. As I was confined and didn't have access to the gym, most of what I did for exercising was running, shadowboxing and some weightlifting (squats, push-ups and bicep curls).

As a result of the latter, my biceps developed a bit. I've been back to the gym for a bit over a week now and I feel like my punching power is greater, most noticeably in the right cross/overhand (I'm right-handed). That doesn't make much sense to me because I don't see how either head of the biceps brachii contributes to the kinetic chain involved with punching.

Question: does bicep development affect punching power? If so, what is the physiological explanation for that?

Thank you in advance!

  • Can you specify what you mean by "some weightlifting"? Most of your punching power will come from pecs/triceps, and just general increase in speed. All of which could have been affected by what you were doing, but specifics on the weightlifting would help.
    – JohnP
    Commented Aug 28, 2020 at 16:43
  • @JohnP I edited the question to answer your question, thanks!
    – Saucy Goat
    Commented Aug 29, 2020 at 15:41

4 Answers 4


Does bicep development affect punching power?

Yes, it does. I can't give you an explanation based on physics or biology; I will try to explain this in simple terms.

Here is how bicep development can affect punching power

Where do you punch from? Are your hands inside your jacket pockets before you take them out and punch? No. Your hands are up high! They are around your face/neck, guarding your chin. Which muscle groups help keep your hands glued to your face? Your biceps and front delts (i.e., the anterior deltoids) are the main set of muscles that help you keep your hands up. This is important because when you keep your hands up, you are essentially always using your biceps (i.e., through contraction). And don't forget that your biceps are constantly holding up some additional weight (e.g., ~ 17 ounce = wraps + 16 ounce bag gloves).

As we go through the rounds, our biceps get tired from the constant contraction; that is when our hands come down from our chins (and the coach yells "Oye, keep those hands up!"). This is also when we can't throw strong punches - the cross is strongest when it travels in a straight line. If you can't keep your right hand at chin-level, your cross won't travel in a straight line.

Here is an example: Let's say you could throw a maximum of 5 rear-straight punches before the Covid19-training. Your fifth punch was the weakest of the five because by this time, your hands were fully tired.

During your Covid19-training, you did some from of weight training that increased your strength. Both Bicep Curls and Push-ups strengthen your biceps. Now after the Covid19-training, you can throw a maximum of 8 rear-straight punches. The eight punch is your weakest now.

So it is quite possible that your post-Covid19-training fifth punch is stronger than your pre-Covid19-training fifth punch. This is because your biceps are now stronger than before, and they can keep your hands up high for much longer. So after the Covid19-training, at your fifth punch, your biceps are not fully tired.

Think about it this way. A beginner cannot bicep curl 40 lbs (i.e., a single dumbbell) on the first day. He is probably going to start with 25 lbs. But after 6 months, he will be able to curl dumbbells weighing 40 lbs. At this time, 25-pound dumbbells will feel much lighter and easier to curl. WHY? Because his biceps have grown stronger, they can easily handle 25 lbs. Similarly, your biceps have grown stronger. They can now easily keep your hands up high along with the weight of the gloves.

"Stronger muscles last longer. It takes longer before they get tired because every movement takes less effort than before." (Stronglifts - see Endurance)

Other factors that improved your punching power

... most of what I did for exercising was running, shadowboxing and some weightlifting (squats, push-ups and bicep curls)

First, let's look at the The Anatomy of a Punch:

The force used to deliver a powerful punch begins from the feet – when we push into the ground, the ground pushes back into us, followed by a sequence of muscular contractions that transfers force up our kinetic chain until our fist hits our target. The transfer of force happens quickly through a series of rotations and torques from the foot, up the legs and thighs, through the trunk and core, and finally out through the shoulders and arms.
The muscles of the shoulder are key players that deliver the punch, but also for taking the brunt of the impact. The anterior deltoid along with the pectoralis major, the muscles of your chest and shoulder, project your arm out towards your target.
The internal and external obliques are responsible for transferring rotational force without any energy leaks by having the rib cage and pelvis turn as a unit.
The quads and hamstrings help transfer force from the knee to the hips.

There are many factors that make a punch stronger. When you throw the right cross, you engage several things - your core, your hips (the turn), your lats, your biceps and triceps, your shoulders, and your chest.

Push-ups strengthen your triceps, your shoulders, and your chest muscles (i.e., the pectorals). Together, they all made your punches stronger.

Running may have helped with over all endurance. And squats do work your core in addition to your legs, both of which are massive contributors to effective punching. Even bicep curls, when done standing up, engage the core. Your squats made your legs stronger, which means you can go for more powerful bursts of flurries now (power transfers through the kinetic chain), and more often than before.

Add your shadowboxing to these, and you have a good explanation for why your punches are stronger now. Your core, shoulders & chest (which are mainly responsible for shooting/projecting out your hands), biceps (partly responsible for keeping your hands up and cocking your hands back), and your triceps (mainly responsible for extension or straightening of the arms) have all become stronger. Your push-ups clearly worked your triceps. This means more faster and snappy punches.

  • What biceps do is contract to bring the forearm closer to the upper arm. When the forearms are almost vertical anyway, when protecting the head, not much weight is being expended to keep it there; it'd be the shoulders keeping the whole arm slightly raised. I could see biceps' fast-twitch muscles being useful to pull back fast after a jab or cross. Commented Mar 31, 2021 at 16:58

Muscles operate by contractings, so... it's hard to imagine. I can't visualize a punch that changes the lower-to-upper arm angle from a larger to a smaller angle unless it's an awkward sucker-punch haymaker from down at your side to head height. For me, at least, a twisty hook/uppercut to the abdomen leaves the angle about the same. There are lots of other factors that go into a good punch (speed, practice for good technique, mental breakthroughs as to how to do it "right", twisting the upper body, foot position), but the only one I can think of that could result from lifting would be some upper-chest / shoulder muscles.

  • Since the long head of the biceps is connected to the shoulder, could it be that stronger biceps help "carry" momentum from the shoulder to the fist?
    – Saucy Goat
    Commented Aug 29, 2020 at 15:59
  • I'm not a doctor (or much of a martial artiste), but I just can't see how, unless there's some contraction of the bicep, which I can't imagine how that would happen either. Commented Aug 31, 2020 at 12:13

I was experimenting on that for some time, and, from my opinion - NO, biceps generally does not affect punching power.

What biceps decreases - your punching speed (if you do not do stretching exercises for your arms! As Philip mentioned in comments, that can give you both strength and speed) - just because with increased biceps it's harder(and so, consuming some more time) to straighten your arm at full length.

What biceps increases - your speed while returning hand back after the punch - just because arm flexing is fully biceps work.

In fact, your question contains part of the answer - you noticed, that your crosses/overhands become more powerful.

That may be a result of your arm angle decreased - biceps eats arm straightening (if I'm right, you may also notice some distance decreasing on such strikes), but also make your flexed(while throwing cross) hand more solid - and delivering more power as a result.

  • Strength only affects flexibility if you are not stretching. You can stretch the biceps, so I think your point is flawed. Commented Sep 14, 2020 at 11:57
  • @PhilipKlöcking, some time ago I wondered if it is true, but never checked. REALLY? Commented Sep 14, 2020 at 12:13
  • There are stretching exercises for the biceps, yes. And you can get stronger without loss in flexibility, yes. But the flexibility and maximum strength of a given muscle are reducing each other. Since you don't go for maximum strength since what you need is speed, you never reach the point where opportunity costs are a problem, though. Especially since you would want to and do strengthen your triceps muscles as well. Commented Sep 14, 2020 at 16:33
  • This is somewhat revelation for me.. I heard about it but never trusted. Thank you! I'll correct my answer Commented Sep 15, 2020 at 4:36

I people don't mind an answer from a college A&P professor.

First thing to know is that there are two parts to answer.

If you are asking if the biceps Brachi is used by the punching hand when the punch is going out then the answer is no. Think of the exercises that make your biceps sore, they are pulling in.

But the size in general does aid in power because of the idea of Kinetic energy. If you keep the same velocity in your punch, and a stronger biceps is bigger (not always the case) then, as the punch carries more weight, it will have more energy behind it.

I hope this helps

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