How does a marathon affect your body?

Dr DJ Kalonji considers the effects of long-distance running in the wake of the Comrades Marathon.

THE quest for physical fitness is viewed as a great accomplishment in the 21st century.

In prehistoric times, fitness was driven by survival. However, today people’s desire for fitness is to maintain their health and physical well-being.

Global health organisations advise that regular moderate exercise of up to 150 minutes a week (or 75 minutes of vigorous exercise) significantly improves your health.

Long-distance running races in athletics start from 3 000m. A marathon is a race which is a minimum of 41 195m.

Anything longer than that is referred to as an ultra-marathon. South Africa’s Comrades Marathon, which is 89km long, is one such example.The marathon is run annually in KwaZuluNatal between Durban and Pietermaritzburg.

The positive effects of the marathon are both physical and psychological. Participants can set tough goals for themselves, while improving their health and fitness.

Marathon running is indeed a wonderful platform to exhibit your fitness. In addition, the increased popularity of marathon events has led to a focus on fundraising for charities.

In the early 1970s, it was believed long-distance running provided protection from cardiovascular diseases.

However, the effects of longdistance running on the human body have been of concern recently following media reports of cases of sudden deaths among marathon runners.

The question arises: What really happens to your body as you make your way to the finish line?

Mental

Extreme fatigue, especially among ultra-marathon runners, can result in temporary hallucinations.

Eyes and skin

Corneal swelling may result in temporarily blurred vision.

Runners are likely to sustain cuts and bruises, sunburn, insect bites and stings.

Blisters are also common as a result of stones, water, dust and rocks that can get into your shoes while running.

Temperature

Your body temperature is more likely to drop (hypothermia) during marathons as your energy stores become depleted due to the intense effort.

Respiratory system

A 2014 study reported an increased rate of respiratory conditions among long-distance runners as a result of dust and flora along the terrain.

Metabolism

Marathon runners should be aware of the potentially life- threatening risk of exerciseassociated hyponatremia.

This is a condition in which an intake of excessive amounts of water or energy drinks actually dilutes your body’s natural sodium (salt) and causes your cells to swell and burst. But runners who are not adequately hydrated will add strain to their kidneys.

Heart

Running for 30-60 minutes a day is known to benefit the heart and circulatory system. However, recent research has shown that marathon runners may be at a slightly higher risk of cardiac dysfunction such as atrial fibrillation (irregular heartbeat).

It is important to note that these findings were among the worst trained participants.

Exercising for more than 60 minutes a day can lead to diminished cardiac returns.

Experts have found that marathon runners are at greater risk of a heart attack within two years of their race.

Muscle

Quadriceps, hamstrings and calves are muscles likely to cramp during long-distance races. Evidence has attributed muscle cramps to fatigue. Muscle soreness can last for up to a week after a marathon.

Stress fractures commonly occur on the feet of runners; however, marathon runners may be at risk of pelvic, femur, tibial and fibula fractures.

Those most at risk of the negative effects of long-distance running include novice runners, individuals with pre-existing conditions, use of orthotics/ inserts, runners with previous injuries and those who have had infrequent or inadequate training sessions.

Mortality

The incidence rates of cardiac arrest and sudden death during long-distance running races are 1:184 000 and 1:259 000 participants respectively, according to the Race Associated Cardiac Arrest Event Registry.

The four main death risk factors for marathon runners are: heart disease (those over 35); genetic heart defects (under 35); hyponatremia; and heat-related illnesses, such as heat stroke.

Heart disease accounts for more than 90 percent of the deaths.

Exercise has many benefits, such as improving oxygenation and circulation, strengthening the muscles and increasing flexibility and stamina.

The problem is that it also depletes nutrients and causes some degree of organ damage. Always remember the adage that too much of a good thing can be bad.