We know that distance, and endurance, running can benefit the body by strengthening bones, muscles and improving mood and sleep patterns. Running is also helpful for preventing cardiovascular disease and related risks such as high blood pressure.
But despite research showing that regular runners live three years longer than non-runners, and just a few minutes of running a day can decrease the risk of heart disease, distance running can also place a lot of stress on the body.
"Focusing on mileage is worthwhile only up to the point where you are primed to achieve your potential. After that, each excess kilometre you run increases your injury risk."
So, what are the health risks from long distance running? Read on to find out.
Bone stress injury
Long-distance runners are prone to developing bone stress injury (BSI) in long bones such as the tibia, fibula, and femur because of the rear foot strike pattern that they use. Additionally, runners may develop BSI in the pelvis and lumbar spine.
Research reveals that this condition makes the bone unable to withstand repetitive load, resulting in structural fatigue and localised bone pain and tenderness. In fact, one study found that between one to two thirds of competitive cross-country and long-distance runners have had this BSI condition.Treatment usually involves a temporary pause of running, a change in training workouts, and the gradual return to running.
"Around 40 per cent of running injuries happen in the knees," says Taylor. Patellofemoral pain syndrome (PFPS), or runner's knee, is the irritation of the cartilage on the underside of the patella (kneecap).
"These injuries usually occur because of weak quadriceps and glutes, tight hips, excessive inward foot rolling, a lack of stretching and over training," adds Taylor.
According to a Runners World poll of around 4500 people, 13 per cent of runners suffered knee pain in the past year. PFPS typically flares up during or after long runs, after extended periods of sitting, or while descending hills and stairs. The good news is that knee injuries can be avoided by strength training, having rest days, consistent stretching after exercise and wearing a supportive running shoe.
A report from the Mayo Clinic suggests that repeated, extreme exercise or long-distance racing can cause a buildup of scar tissue on the heart, which can lead to the development of patchy myocardial fibrosis in up to 12 per cent of marathon runners. The effects of "chronic exercise" can also include premature aging of the heart, stiffening of the heart muscles, and an increase in arrhythmias and atrial fibrillation.
Even crossing the finish line of one marathon can cause temporary damage to a runner's body. For example, multiple studies have shown that immediately after a marathon, 30 to 50 per cent of runners show increased levels of enzymes and biomarkers that are typically released during heart attacks and associated with heart failure.
If I've now got you worried that the marathon you're training for may give you a heart attack, take comfort in a study in the New England Journal that found that the rate of deaths in marathons continues to be very low, between one in every 100,000 and one in every 200,000.
Many long-distance runners develop colds and upper-respiratory infections, especially in the two weeks following a race. For example, 13 per cent of the runners who completed the Los Angeles Marathon became ill during the week after the race, compared to just two per cent of the control group of runners who didn't take part in the event.
Commonly called the marathon sniffles, evidence suggests that while 30 to 45 minutes of moderate daily exercise boosts the immune system, the stress of distance running temporarily weakens it. The theory is that during a long, hard run, the body produces the stress hormone cortisol, which suppresses the body's immunity.
Taylor says, "you can avoid getting knocked down by a respiratory infection by eating fresh fruit and vegetables, getting enough essential minerals, especially zinc, sleeping well and avoiding rapidly increasing your training load."
The goal of one day completing an ultra-marathon inspires running fanatic Laura Hill to clock up the kilometres each week. With a day job in the corporate world, Laura loves nothing more than lacing up her runners and hitting the pavement to clear her mind and challenge her body.
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Have you suffered injuries from long distance running? Share your experience, and how you overcame it, in the comments section below.