Why Do My Fingers Swell When I Run?

Why Do My Fingers Swell When I Run?

Today we’re tackling a common but often misunderstood phenomenon that affects many of us during our runs: swollen fingers and hands.

I was lucky enough to be able to cheer on my Ironman athletes as they raced in the St George 70.3 Ironman earlier this month. I did a shift at a bike station and then I grabbed my water sprayer/mister and headed to a spot on the run course where I knew I would be able to see the athletes a few times. So much fun!!

I had a few athletes concerned I was spraying them with bug spray (it was water!) and many asked me to spray their swollen hands. That is were this post idea was born!

Have you ever noticed that your rings feel tighter or your hands just seem puffier after a run? (One the many reasons I have my plastic rings.)

It might seem alarming, but this is actually a normal, physiological response to running.

Let's dive into why this happens and what you can do about it.

The Science Behind the Swell - Why this might be happening?

1. Blood Flow Dynamics When you run, your heart rate increases to pump more blood to your muscles and lungs. While your body prioritizes sending blood to the muscles doing the heavy lifting—like your legs and arms—it’s the smaller blood vessels in your hands that might expand to accommodate more blood flow. This vasodilation can cause your hands to swell, they call this edema.

2. Gravity’s Pull Running involves a lot of arm swinging. If you think about it, your arms are mostly down by your sides, which means gravity is pulling blood down into your hands. This natural pull can contribute to the swelling.

3. Water and Salt Balance As you run, you lose water and salts/sodium. This loss can disrupt the balance of electrolytes in your body, leading to fluid retention as your body attempts to maintain a healthy balance. This retention often manifests in your extremities, including your hands.

We call this Exercise-Associated Hyponaterimia. Over-drinking fluids & under-replacing lost sodium - especially in warmer or more humid weather & multi-hour events.

4. Body Temperature Regulation When you exercise, your core body temperature rises, & you start sweating. Your body’s natural cooling mechanisms kick in, which include diverting blood, trigging capillary dilation, to the surface of your skin to release heat. This causes larger volumes of fluid to move through the dilated vessels & causes swelling.

Since your hands are exposed, they’re a prime location for this process, which can lead to swelling/edema as more blood flows to these areas.

What Can You Do About It?

1. Hydrate Properly Make sure you’re drinking enough water before, during, and after your runs. Proper hydration helps maintain your body’s salt balance and prevents excessive fluid retention. (When you do a sweat test with me - we discover how much water YOU need for your body to stay hydrated during your run.)

2. Loosen Your Grip Many runners subconsciously clench their fists while running, which can restrict blood flow. Try to keep your hands relaxed, as if you were holding an egg that you don’t want to break.

3. Raise Your Hands Every now and then during your run, lift your hands above your heart for a few seconds. This can help the fluids in your hands flow back towards your body, reducing swelling.

4. Check Your Sodium Intake If you're running long distances, you might need to replace the salt you lose through sweat. Consider consuming an electrolyte drink or a small amount of salty snacks, particularly during long or especially hot runs. (When you do a sweat test with me - we discover how much sodium and potassium YOU need for your body to stay hydrated during your run.)

Conclusion

While swollen hands and fingers during a run might look and feel odd, they’re generally not a cause for concern. However, if the swelling is accompanied by pain, lasts a significantly long time after running, or occurs with other worrying symptoms, it’s a good idea to consult a healthcare provider. For most runners, this swelling is just another part of our body’s fascinating ways of coping with the stresses of running.

Keep those legs moving and those hands relaxed!

Happy running, Dayna

Learn more:

The Crucial Role of Proper Hydration for Runners

What to know about Summer Running!

Importance of Electrolytes

What are electrolytes & what do they do for runners?

You have big PR goals this year? Time to dial in your hydration?

Sweat testing here.