Side effects of marathon running include a number of foot ailments.
Running is good for your muscles and cardiovascular system. The workout strengthens and tones your muscles, including your heart, and can increase lung capacity, according to Boston.com. Marathon running -- a 26.2-mile race -- is one of the most vigorous forms of exercise a person can do. Even trained and healthy runners experience some side effects of marathon running. Marathoners can encounter minor injuries as well as changes to their fluid balance, body temperature and immune system.
Most marathon runners experience minor discomforts ranging from muscle soresness to painful feet. Blisters and black toenails are common among marathoners, and are caused by the rubbing and banging of the feet against the shoes. Keep your toenails trimmed to avoid discoloration. Wear shoes and dry socks that are comfortable to prevent blisters. Muscle soreness and stress fractures, shin splints and knee pain are also side effects of marathon running. Classified as overuse injuries -- your body sometimes can't handle the repetitive motion of running -- these conditions range in severity and may require medical treatment from your doctor.
Dehydration can be a side effect in marathon runners who don't drink enough. "Running Times" recommends drinking a liter of water per hour during a race. People who run slower than seven and a half minutes per mile may not need as much fluid replenishment. Slower runners could end up over-hydrated if they drink more than they need without expelling excess through urination. This rare condition is called water intoxication. Boston.com recommends drinking as much water as you want after you urinate post-race. You'll know your kidneys are functioning to eliminate the unneeded fluids.
Marathoners can end up with hyperthermia, a higher-than-normal body temperature that increases your risk of dehydration. Marathon and Beyond contributor Jake Emmett explains that some marathon runners' body temperatures reach a high of 105 degrees Fahrenheit directly after a race. Drinking water at each aid station can help reduce your risk of hyperthermia. A less-common side effect seen in cool or wet weather marathons is hypothermia, or a low body temperature. Wear several layers of waterproof clothing to protect from the elements. Shed layers as you warm up to avoid hyperthermia.
Your immunity to respiratory illness and the common cold may be reduced as a side effect of marathon running. Jake Emmett explains that after running, your immune system is concerned with your recovery and diverts white blood cells to repair muscle damage. As a result, you are left with weak spots in your immunity, leaving you more susceptible to infection.