Why Are My Biceps Sore After Running? (5 Factors to Consider)

I see this question asked over-and-over again, “Why Are My Biceps Sore After Running?”

It sounds really weird, as running is basically a cardiovascular exercise.

Furthermore, if you’re going to feel sore after a run you would expect it to be in the lower half of the body.

In fact, I’m sure you’ve experienced sore quads, hamstrings, calves, and even glutes, depending on the type of run you do.

But, as it turns out it is perfectly reasonable to experience sore biceps.

However, this is usually because of something you’re doing with your hands or arms, and even the terrain or type of run.

I shall explain these in more detail now.

Why Are My Biceps Sore After Running?

There are various reasons why your biceps are sore after running, although the most obvious is that your fists are clenched. It is also extremely common to be tense in your shoulders and arms when running, so you should focus on keeping them relaxed before and during your run. If you’re running downhill this has a surprising gravitational effect on the elbow flexors. You should also be wary of excessively pumping your arms, allowing your arms to cross in front of your body when they swing, or if you’re holding anything in your hands while you run.

1. Are You Running With Clenched Fists?

An Athletic Man Running Outside

You should never run with your fists clenched.

In fact, this is viewed as a cardinal sin among runners.

There are those who will say that good form when it comes to running starts with your hands.

There is a tendency for runners to clench their fists when faced with a particularly difficult section of their run.

This may involve running uphill, along difficult terrain, or simply that your lungs are burning and you feel you can’t continue.

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I guess most of us feel as though we’re exerting more effort with a closed fist.

However, in terms of running you’re actually making things more difficult.

Firstly, clenched fists will restrict the movement of both the arms and shoulders.

This will actually make running less efficient and is likely to reduce the speed at which you run.

You’ll also find that clenched fists create tension in your forearms and upper arms.

If you continue in this manner for a prolonged period you’re bound to have sore biceps after your run.

2. Ensure Your Shoulders & Arms Are Relaxed Before You Run

It’s extremely common to be tense in your shoulders and arms when you run.

Yet again, this may automatically happen when you increase perceived effort.

So, you’re finding a particular section of your run quite difficult and this transfers to your arms and shoulders.

I would also say that many of you actually start your run all tensed up.

Prior to starting, stand as tall as you can, lift your arms overhead, and then allow them to naturally drop to your sides.

Your aim is to maintain this posture throughout your run with your arms and shoulders remaining just as relaxed throughout.

Any form of tension will typically mean that you’ll end up contracting the muscles in this area of the body.

In fact, you may even feel as though you’ve just been through a shoulder and arm workout in the gym.

Once more, tension in this area of the body will make your run less effective, and it will probably affect your speed.

3. Are You Running Downhill?

We always consider uphill running as a great way to increase intensity.

However, running downhill also has various benefits.

One of the major benefits is that you will engage and activate the stabilizer muscles of the knee, especially the knee extensors.

This is a fantastic way to increase strength and power in the knee joint, which will also place more force on your quads.

The result being that this will help to improve your overall running strength.

However, as it turns out downhill running also has an impact on the elbow flexors.

And the three primary elbow flexor muscles happen to be the bicep brachii, the brachioradialis, and the brachialis.

So, in effect, running downhill is giving the entire biceps muscle group a great workout.

Your arms and shoulders can remain as relaxed as possible, but the gravitational forces at play during downhill running will automatically engage the elbow flexors.

How to Run Downhill – Downhill Running Technique Explained

4. Are You Holding Anything While You Run?

This is something that I see all the time, people running while holding something in their hand.

It could be your smartphone, a water bottle, or even your house/car keys.

A Woman Jogging While Holding a Water Bottle

Now, of course these are all fairly lightweight objects.

However, even carrying something as light as your phone in your hand for 30-45 minutes will have some impact on the muscles of your arm.

You may find that you’re gripping exceptionally tight, as the last thing you want is to drop and smash your phone.

If so, this is pretty much the equivalent of clenching your fist.

You’ll also find that carrying an object in your hand will lead to tension in your arms and shoulders.

And you’re probably not allowing your item-holding arm to fully relax.

You may even have a slight bend in your elbow throughout your run, which will constantly activate the elbow flexors of that arm.

In effect, you are contracting your biceps and maintaining an isometric hold for the full duration of your run.

If that doesn’t leave you will sore biceps, nothing will.

5. What Are You Doing With Your Arms While Running?

I’ve spoken of your posture, as well as relaxing your arms and shoulders during your run.

However, what you actually do with your arms while running can alter your posture and create tension in the shoulders.

You’ll want your arms to be swinging completely naturally at around hip level.

Your arms should go forward and back at around a 90 degree angle.

But, there are all sorts of things that can happen to your arms during your run.

Something you should be wary of is allowing your arms to cross in front of your body.

This will immediately create tension in the arms and shoulders.

Furthermore, you don’t want your fingers to be completely straight, as this can lead to the chopping action of the hands, more akin to sprinting.

You will literally be pumping with your arms to propel yourself forwards.

You basically want your hands to be slightly cupped with your thumbs on top.

But, obviously make sure that this never becomes a closed fist.

It’s a good idea to periodically check what your arms and shoulders are doing during your run.

You want to maintain an ideal shoulder position throughout.

If you find that you are tensing either your arms or shoulders at any point, simply shrug your shoulders, and focus on keeping as relaxed as possible.

What Should You Do With Your Arms While Running?

Final Thoughts

So, I hope you have a better understanding of why your biceps are sore after running.

As you can see, there are quite a number of reasons why this can occur.

The most obvious of these is that you are running with clenched fists.

You should avoid this at all costs, as it will impact on the effectiveness of your run and also your speed.

Ensure that your arms and shoulders are relaxed throughout and check yourself regularly during your run.

Be wary of excessive pumping of the arms, or swinging them out in front of the body.

You should also be aware that running downhill or holding something in your hands will activate the elbow flexors.

You may even end your run feeling as though you’ve just completed an arm workout in the gym.

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