Running has tons of health benefits that make it a truly great workout: It's beginner-friendly, it helps improve heart health — the list goes on. But it's not always easy on your feet. With issues like blisters and black toenails, running can do a doozy on your dogs.
Swelling is a potential less-than-stellar side effect of running. And while most cases of running-related swollen feet are fleeting, others may be a sign of something more serious.
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Here, we spoke with podiatrists to get the 411 on why your feet may puff up post-run, plus ways to reduce the swelling.
1. You Have an Overuse Injury
"For the most part, an overuse injury is the number-one reason for swelling of the foot," says Alex Kor, DPM, a podiatrist at Witham Health Services and clinical assistant professor for the Marian University College of Osteopathic Medicine.
An overuse injury (such as tendinitis, bursitis or a stress fracture) is caused by repetitive trauma to a muscle, joint or bone. Typically, these types of injuries occur when you increase the intensity of exercise too quickly, fail to get adequate amounts of rest or use improper technique (more on this later).
Running regularly can place excessive tension, pressure or load on a tendon, bone or a ligament, Dr. Kor says. And over time, this can lead to abnormal wear-and-tear of the tissues — and eventually injury.
"Think of the bones of the foot as a coat hanger," Dr. Kor says. "If you bend a coat hanger multiple times without a rest, the coat hanger breaks."
Localized inflammation and swelling are telltale signs of an overuse injury. That's because when you're hurt, your body will respond by moving fluid and white blood cells into the injured area to help the healing process, Dr. Kor says.
Overuse injuries are very concerning because they can cause potentially permanent degenerative changes to the tendons and joints, says Elena K. Wellens, DPM, FACFAS, a podiatric surgeon at Rothman Orthopedic Institute and clinical assistant professor at Temple University School of Podiatric Medicine.
That's why it's essential to heed your body's signals and focus on recovery. To properly manage an overuse injury, it's best to refrain from running. Additionally, to promote proper healing, you should protect the extremity, rest, ice, use some form of compression and elevate (P.R.I.C.E.), Dr. Kor says.
Acute injuries, like ankle sprains, can also cause swollen feet and pain.
2. You Have Venous Insufficiency
Venous insufficiency happens when the veins of the lower extremity don't function properly. With this condition, the venous valves fail to push deoxygenated blood back up to the heart, causing blood to pool in your legs and feet, Dr. Wellens says.
Usually swelling due to a venous insufficiency will be present in both legs or feet, Dr. Kor says. This distinguishes it from the typical single-foot swelling that accompanies an overuse or acute injury.
In addition to swelling, other possible signs of venous insufficiency include the following, according to Keck Medicine of USC:
- Varicose veins
- Leg pain or cramping
- Red, weepy or crusty skin
- Hard or thick skin
- A wound or ulcer that is slow to heal
"Running or exercise (that utilizes the lower extremity) is rarely, if ever, the primary cause of venous insufficiency," Dr. Kor says. Often, systemic conditions like congestive heart failure are the root of the problem, he adds.
For runners with venous insufficiency, Dr. Kor recommends taking the following precautions to prevent (or reduce) foot swelling:
- Wear compression socks or hose, even when running. "Just make sure to consult with a vascular specialist to determine if more aggressive treatment is needed to prevent complications such as an ulceration," Dr. Wellens adds.
- Elevate both feet two to three times per day for 20 to 30 minutes
- Incorporate pool-based cross-training (including walking in a pool, swimming or water aerobics)
If the above strategies don't help hinder your foot swelling, see your primary care provider who may prescribe a diuretic (i.e., water pill), Dr. Kor says.
3. Your Electrolyte Levels Are Off
An electrolyte imbalance may be the source of your swollen feet after a run.
Electrolytes are minerals, such as sodium, potassium, calcium, chloride, magnesium and phosphate, that are essential to many important functions in your body. One of their main roles is maintaining the proper balance of water in your body, according to the National Library of Medicine.
"Usually, an electrolyte imbalance occurs when a runner loses a large amount of body fluids through sweating," Dr. Kor says. This is more likely if you overexert yourself during a run or if's super humid or hot outside.
On top of swelling, other symptoms of an electrolyte imbalance may include, per Dr. Kor:
- Numbness of toes
Typically, these imbalances can be resolved by drinking water and other beverages that contain electrolytes (think: Gatorade), Dr. Kor says.
But you may want to sip slowly rather than guzzle. "In rare instances, excessive water intake after being dehydrated can also cause swelling of the feet," he says.
That's because an influx of too much H2O in your system can flush the blood of the sodium it needs. "As a result, your cells will retain more fluid than normal, which can lead to swelling of the extremities," Dr. Kor says.
Still, this is a very uncommon occurrence. And water is by far the best fluid for rehydration, he adds.
4. You Ate Something Salty
That salty pre-run meal may be messing with the fluid in your feet. Excessive salt intake is another well-known reason for swelling of the lower extremity and feet, according to Dr. Kor.
"In the human body, the amount of sodium you have controls fluid balance," he says. It also monitors blood volumes and blood pressure. So, when you consume too much salt (which contains sodium), your blood pressure may increase and cause fluid retention.
To avoid swelling, stick to low-sodium foods. Read nutrition info on food labels and opt for the ones that have less than 20 percent your daily value (DV) of sodium per serving.
Even if your feet don't swell, keeping your salt intake to a minimum is a good practice for overall health. Consuming too much salt raises your risk of high blood pressure, which can contribute to chronic health conditions like heart disease, per the Harvard T.H. Chan School of Public Health.
5. You're Taking Certain Medications
"There is a long list of medications that (independent of running) cause swelling of the feet and lower legs," Dr. Kor says.
Some of the most common culprits include:
- Hormones (like estrogen and testosterone)
- Blood pressure medications
- Anti-inflammatory meds (such as NSAIDS)
"Some of these medications cause the swelling by exacerbating fluid retention," Dr. Kor says.
Other drugs, such as diuretics, may disrupt your electrolyte levels, Dr. Wellens adds. And as we know, an electrolyte imbalance can bring on a domino effect that results in foot swelling.
If you suspect your medication is the source of your swollen feet, talk with your doctor who may choose to adjust your dose or prescribe a different drug.
And if your meds are affecting your electrolyte balance, "proper hydration is also important," Dr. Wellens says. Your doctor may also choose to monitor your electrolyte levels to determine if you need supplementation such as potassium, she adds.
6. You're Wearing Ill-Fitting Shoes
Ill-fitting footwear is often to blame for swollen feet during or after a run, Dr. Kor says.
Think about it: If your running shoes are cramping your toes, bothering your bunion or causing your heel to fishtail, you're likely to experience irritation and inflammation post-run.
In fact, many overuse injuries occur after prolonged use of incorrect shoe gear for your foot type, Dr. Wellens says. For example, if you have flat feet, but your shoe doesn't provide the necessary stability and arch support, you can exacerbate your arch issues and further weaken your foot.
A runner who experiences swelling and pain should discontinue wearing bad-fitting shoes ASAP.
"Sometimes, if the shoe is only too tight in a localized area, the runner can purchase a shoe-stretcher and remedy the situation without any other intervention," Dr. Kor says.
To avoid these shoe problems in the first place, it's best to buy running shoes in the latter portion of the day, Dr. Kor says. Your feet tend to swell slightly and are a bit bigger as the day goes on. Buying shoes later in the day will ensure you choose shoes with a little wiggle room.
Similarly, to ensure a good fit that's not too snug, wear the same socks to the shoe store that you wear when you go running, Dr. Kor says.
It's also helpful to have your feet properly fitted at a reputable running shoe store, Dr. Wellens adds.
7. You Have Improper Running Technique
As mentioned previously, overuse injury is the top reason for foot swelling in runners. And one fundamental factor that can increase your risk of injury is incorrect running form.
One common running mistake is landing on your heel instead of the middle of your foot (known as heel striking). This unhealthy habit puts more load on your bones, joints and muscles, according to Boston Children's Hospital.
Likewise, letting your hip sag when your foot comes off the ground will throw your body out of proper alignment and place excessive strain on the knees, per Boston Children's Hospital.
To learn correct form and prevent swelling and overuse injuries, Dr. Wellens recommends working with a running coach. In addition, you may also consider seeing a physical therapist who can offer a computerized running assessment and design a program to allow you to run more safely and efficiently, she adds.
When to See a Doctor
"Exercise in general, especially high-impact activities such as running, can naturally cause mild swelling in the feet and legs," Dr. Wellens says. "However, this should subside quickly after rest."
If you've followed the P.R.I.C.E. (protection, rest, ice, compression, elevation) protocol, and your foot swelling has not improved after seven to 10 days, Dr. Kor suggests you consult with a podiatrist who can properly examine you and assess your situation.
Dr. Wellens agrees: "If swelling persists, causes pain and/or is accompanied by cramping, dizziness or fatigue, see a physician to help determine the cause and treatment options."
Managing Swollen Feet
Even with the best of efforts, some runners are still prone to develop swollen feet. If this is you, management of the condition — versus prevention — is your best option.
Elevating swollen feet after a run can be one of the most effective ways to eliminate the signs and symptoms of this condition. Applying an ice pack for 10 to 15 minutes may also aid in vasoconstriction (the constriction of blood vessels), thus preventing blood pooling and managing moderate to severe foot swelling.