From blisters to dehydration, injuries and illnesses can pop up from anywhere. But which health woes do event medical teams see the most, and how can you reduce your risk of race day ailments?
To find out, we spoke to some of the top medical team leaders on the running scene.
Heat Exhaustion/Heatstroke1 of 6
Heat-related illnesses don't just strike runners during summer races. According to Chris Troyanos, the longtime medical coordinator for the Boston Marathon (which takes place every April), temperatures at the 2012 race got so high, some 2,600 runners had to be treated for heat-related problems. That was nearly 10 percent of the field.
"Heat is always the great equalizer," he says. "I don't care how experienced a runner you are."
Since then, dozens of ice submersion tubs have been added to aid stations at the event. In heatstroke cases, the body needs to be cooled immediately, as extreme body temperatures can lead to organ damage.
Symptoms of heatstroke include a body temperature above 104 degrees, disorientation, rapid breathing, racing heart, flushed skin and headache, according to the Mayo Clinic. Some people may also lose consciousness.
Runners with heat exhaustion—a milder form of heat-related illness that can progress to heatstroke—may get dizzy, tired and suffer from muscle and abdominal cramps.
How to Avoid Heat-Related Illness: Experts recommend wearing loose, light-colored clothing, using sunscreen, drinking fluids and not overexerting yourself in hot weather. This means not aiming for a PR on a scorching day.
Hyponatremia2 of 6
In fear of becoming dehydrated, some runners actually drink too much water on race day. This can lead to a hyponatremia, a condition caused by dangerously low sodium levels in the blood.
While hydration is crucial for runners, forcing yourself to drink excessive amounts of water can dilute sodium in the body and cause cells to swell, experts say. Symptoms include nausea, vomiting, confusion, loss of energy, muscle weakness and body swelling.
Slower marathon runners can be especially vulnerable to hyponatremia, says David Watt, executive director of the American Running Association and the American Medical Athletic Association.
"The longer you are out there, the more you drink," he says. "(But) if you go out there and overdo it with a sports drink, you can still get in trouble."
According to Watts, such large numbers of competitors suffer hyponatremia that aid stations at many races are now equipped with intravenous saline bags.
How to Avoid Hyponatremia: To keep your sodium in check, you should consume fluids based on your thirst and urine color. Drink at a comfortable and natural rate when you are thirsty, instead of at a pre-defined schedule. If your urine is pale yellow (when you hit the Porta Potty), you are likely well hydrated.
Post-Race Fainting3 of 6
Medical teams frequently deal with runners who push themselves so hard, they collapse at the end of a race.
"I place station helpers at the finish line to grab woozy runners to keep them moving," says Dr. Cathy Fieseler, a sports medicine physician, experienced race medical director and president of the American Medical Athletic Association. "If they drop to the ground, they become patients."
Runners can collapse for a few reasons anywhere along the course, but it's common for it to occur when they abruptly stop running.
"While running, the calf muscles contract, assisting the return of blood to the heart," she explains.
When runners jam on the brakes, their heart rate is still elevated, but blood isn't pumping back into the heart as quickly.
How to Avoid Fainting: Runners can evade dizziness by not coming to a complete stop after crossing the finish line. Continue slowly walking around until your heart rate and circulation has returned to a normal rate (about five minutes).
Fieseler also emphasized that it's important to fill out the medical section on the back of your bib number before the race. If you get into trouble, the medical support team will need to know about any medical conditions or medications you're taking. If you're not able to respond to their questions, this critical information could save your life.
Leg Cramps4 of 6
It's common to see runners seized by muscle spasms in their legs at many road races.
Leg cramps—when a muscle involuntarily contracts—can have many causes, but runners tend to get them during long-distance races when they are fatigued or if they haven't stretched well.
According to the American Academy of Orthopaedic Surgeons, cramps can also be triggered by heat, dehydration and low levels of salt, potassium, magnesium and calcium.
How to Avoid Cramps: Some runners develop cramps because they haven't trained at race pace, Fiesler says. To help prevent cramps, she recommends runners practice the speed they plan to run on race day and experiment with their fluid/nutrition regimen ahead of time.
If you do get a cramp attack, stop running and gently massage and stretch the muscle that's twitching. Hold it in the stretched position until the cramp subsides.
Blisters5 of 6
These dreaded little monsters routinely wreak havoc on runners' feet on race day.
"Shoe fit and socks are the leading causes of blisters," Fieseler says. "Your feet swell while running, so shoes may become tight."
She adds that low sodium levels can also contribute to swelling. That increased pressure and friction against your running shoes can cause painful, fluid-filled welts.
How to Avoid Blisters: Runners should test their race day socks and shoes during training runs to make sure they fit properly and comfortably. Wearing moisture-wicking socks and/or dusting the inside of the shoes with talcum power can also help prevent rubbing.