I wear at least three rings every day—wedding and engagement bands, and an Oura ring as a fitness/recovery tracker. But in the summer, I often find myself taking them off before I go for a run. If I don’t, sometimes they’ll be stuck. This is a common problem, especially in hot weather. Here's what's going on, and what you can do about it.

Why your hands swell after you exercise

There are several reasons why your hands might swell during or after a run (or walk). Scientists haven’t figured out this phenomenon with as much precision as we might hope, but there seem to be a few factors that affect swelling in otherwise healthy people who exercise. They include the following:

Your fingers change size throughout the day

It’s normal for your fingers to change size throughout the day. Scientists have noted that our hands swell slightly overnight, and that this swelling resolves over the course of the day. By afternoon, our hands are back to what you might call their normal size. Because of this, you may be more likely to notice swollen fingers after morning runs than afternoon or evening runs.

Hot weather can result in swelling

Part of the way our body responds to heat is by dilating the blood vessels close to the surface of our skin. This helps cool us down, but it can also result in swelling since there is more fluid closer to the skin. Fluid can leave the blood vessels and pool in body tissues, which is fine—normal motion of our body tends to massage the lymph away. But when we’re running or walking, there may be more fluid entering our hands than leaving, with the result that we end up with sausage fingers.

Exercise increases blood flow

Just as our heat response increases blood flow, so does exercise. Even in weather that’s not too hot, the increase in blood flow can result in more fluid entering the hands and fingers. The swinging of our arms that happens when running or walking may also be a factor; this and gravity both contribute to moving fluid toward our hands while also impeding its path back up.

Electrolytes may be a factor

Electrolytes like sodium and potassium can affect the way our bodies hold fluid. If you drink plenty of water but don’t get enough sodium—a condition called hyponatremia that can become life-threatening if severe—you may experience swelling of the hands. This has led some runners and doctors to conclude that electrolytes may help with ordinary finger swelling.

Other medical issues

There are other issues that can cause swollen hands or fingers. An allergic reaction, for example, can cause swelling. Swelling is also a symptom of some types of liver disease and heart disease, among other medical conditions. If the swelling is severe or if you notice it often, you may want to see a doctor to find out whether you have a condition that needs treatment.

What to do about swollen fingers after a run or hike

“The treatment of [swollen hands] is observation and reassurance,” writes a dermatologist who himself gets swollen hands after running. “Once the inciting event—be it hiking, running, or walking—is discontinued, the hand swelling spontaneously resolves.” In other words, it goes away on its own after the workout.

Swelling that is triggered by exercise tends to go down significantly within one to two hours, and it will usually be long gone by the next day. So in that sense, you don’t need to do anything—but the swelling can be uncomfortable, so we have a few tips. You can do these during or after exercise:

• Hold your hands above your head, and massage the fingers from fingertip to palm.

• Move your arms and hands—for example, repeatedly making a fist or wiggling the fingers.

• Make sure nothing is restricting the flow of blood to and from your hands. Consider loosening your watch or adjusting your backpack straps if you are running or hiking with a pack.

How to prevent your fingers from swelling when you run or walk

To prevent the swelling going forward, or at least try to make it less unpleasant:

• Remove your rings (and anything else you wear on your hands) before running. If you’re the kind of person to never leave the house without your wedding band, consider a silicone ring for when you’re exercising.

• Adjust the fit of your watch as needed: a snug fit helps with accuracy, but you don't want it too tight. If you can't find a good fit, consider using a chest strap monitor for heart rate, and wearing the watch loosely or just keeping it in your pocket.

• Consider the time of day you run. Evenings may be best, since the weather is cooler and you don’t already have that morning swelling we talked about.

• Stay hydrated, and remember your electrolytes. This can mean carrying an electrolyte drink or tablets, or simply have salty snacks throughout the day in addition to water.

That said, if your finger swelling is just the normal kind triggered by exercise—and not a result of a more serious medical condition—then it may simply help to know it’s common and it will go down after your workout. If you wear a pack or running belt, consider keeping a carabiner on it to carry your rings in case you forget to leave them at home.