While completing a marathon may give you a sense of accomplishment, you also risk damaging your body, at least in the short run.

Running a marathon puts tremendous physiological demands on you. Your body temperature rises. You lose water and electrolytes through sweat. Your heart pumps faster and harder. Your legs need more blood to fuel their movement. Your muscles produce more waste products from prolonged exertion.

These bodily changes affect you in several ways:

You Risk Injury to Your Joints, Bones, and Ligaments

Although marathons won’t necessarily contribute to joint and feet injuries, prolonged running on hard surfaces will. And in a concrete jungle like Singapore, your race route will inevitably include such surfaces.

“Your knees and joints bear the brunt of shock from your feet pounding repeatedly on hard surfaces,” said Dr Ganesan Naidu, Specialist in Orthopaedic Surgery & Consultant, Raffles Orthopaedics Centre. “Wearing the wrong running shoes worsens this, since there’s nothing cushioning your joints from these shocks.”

The result? Your joints and tendons risk getting inflamed. You may experience pain in your hips, knees and / or feet after your run. The repetitive strain from marathons can even cause stress fractures in your shins and feet, and occasionally in your pelvis.

You Strain Your Heart

Running too hard, too fast, and for too long stresses your heart. Studies have shown that most marathoners display signs of heart damage immediately after their race. Fortunately, their hearts returned to normal, without any lingering effects.

But for regular marathoners, the damage may be longer lasting.

“A study by Mayo Clinic suggests that heart damage caused by frequent marathons can add up over time,” said Dr Derek Li, Family Physician, Raffles Medical. “Long-term effects include premature heart ageing, arterial plaque build-up, and an irregular heart rhythm.”

These findings did not surprise Dr Li.

“Our hearts just aren’t designed for such sustained and intense activities,” he emphasised.

Your Immune System Gets Compromised

Despite the health benefits of exercising, many marathoners still fall sick after their race.

“Long endurance activities such as marathons trigger your body to produce a large amount of the stress hormone cortisol,” explained Dr Li. “This hormone suppresses your immune system, leaving you vulnerable to infections and sickness.”

When you consider the number of germs potentially passed around by spectators and fellow runners at a marathon, it’s not difficult to imagine yourself catching them in your exhausted, weakened state.

Your Kidneys Work Harder

Your kidneys work harder to filter out the additional waste produced after a marathon. At the same time, they lack water and oxygen-rich blood to function efficiently. The combination of more work with less resources may leave your kidneys damaged, albeit temporarily.

The good thing is, your kidneys can reverse the damage within a few days, just like your heart.

Enhance Your Marathon Training Plan to Reduce Injuries

These risks shouldn’t put you off from attempting a marathon. Proper preparation will help you cross the finish line safely.

Apart from having a marathon training plan, incorporate these five strategies to improve your performance and keep yourself safe.

Go for a Medical Check-Up Before Your Marathon

You should get checked by a doctor regardless of your state of health. It helps identify your risk of medical conditions that may occur during your marathon, so you can plan your training to reduce them.

You can also glean insights from your screening results to improve your training programme. If you’re found to be anaemic, for example, you can eat more iron-rich foods to promote red blood cell production.


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Invest in a Pair of Well-Fitting Shoes

Replace your running shoes if they are old and worn out. All shoes have a shelf life. Their midsole foam can break down or become stiffer and less cushioned over time. This means your feet gets less cushioning from the impact of running, which increases your risk of injuries.

A good pair of shoes should provide adequate support for your feet and help make your running motion more natural. Your running efficiency will improve, and your risk of injuries will reduce.

Go to a speciality shoe store if you are not sure which type of running shoes suits you. These stores have experienced staff who will give you recommendations based on your running gait and goals.

Supplement Your Joints

Glucosamine supplements may be helpful for those suffering from joint and knee pains after intense exercises. They may offer relief from the pain, while supporting joint flexibility and mobility.

There’s a caveat to this, though: They don’t work on everyone. Evidence on the supplement’s efficacy in relieving joint pain remains inconclusive.

Nonetheless, there’s no harm going on a trial of glucosamine if you experience joint pain after running.

Watch Your Nutrition Intake

Don’t forget about your diet in the midst of training for your marathon. “What you eat affects how well you train,” said Ms Kesslyn How, Nutritionist, Raffles Diabetes & Endocrine Centre. “Good nutrition also reduces your risk of injuries and optimises your performance on race day.”

Besides ensuring you get adequate carbohydrates, protein, and fluids, having enough of these nutrients are important as well:

Iron: Promotes red blood cell production to carry oxygen to your muscles and reduce fatigue. It is found mostly in red meat, spinach, and iron-fortified cereals.

Magnesium, selenium, and zinc: Decrease your risk of muscle cramps and fatigue; improve your immunity and promote cellular repair. They are found in nuts and seeds, oysters, green leafy vegetables, and grains.

Potassium and sodium: Improve water retention to keep your body well hydrated. You can get them from bananas, beans, and isotonic water.

Vitamin D and calcium: Help your body regain bone minerals lost from running, and reduce your risk of brittle bones and fractures. Vitamin D is found in eggs and oily fish, while calcium is found in spinach and milk.

Vitamins C and E: Promote a strong immune system, and help your body combat against free radical damage from the oxidative damage done to it during exercise. Eat nuts and sunflower oil, as well as a range of fruits and vegetables to meet your daily requirements. If you find yourself falling sick frequently, consider taking a supplement to support your immunity.

Get Enough Rest

Your tissues get damaged and inflamed during exercise. Remember to fit some rest days into your marathon training schedule to allow your body to recover.

“Resting helps your body heal and adapt itself to the training it has been put through,” said Dr Li. “You’ll not only approach your next training session feeling fresh, you may also experience a boost in your fitness and performance as well.”

Make sure you get enough sleep too. When you sleep, your body releases hormones to help you recover from training. Conversely, not enough sleep causes the cortisol levels in your body to rise, hampering your body’s ability to recover.

If you're having trouble sleeping, check out these 5 tips on getting better rest.

Reviewed by Dr Derek Li, General Physician, Raffles Medical