Preparing for a Marathon

May 25, 2016

Running marathons is an increasingly popular activity, with plenty of marathons in many different areas from which people can choose. No matter the distance or the particular type of race you are focusing on, it’s important to evaluate your physical strength to prepare for running a marathon.

About Marathons

Marathon running is a kind of endurance sport that requires aerobic and cardiovascular endurance and strength, due to the continuously repeated movements and high energy requirements. A marathon is unlike any other type of running such as races or sprints, and therefore requires specific preparation and training.

There are plenty of running events such as a walk/run for a short distance of 2-3 kilometers, 5K Fun Runs (5 km), mini marathons (10.5 km), half marathons (21 km), or international full marathons (official distance of 42.195 km).

Physical Examination

Many people think that running a marathon is not a big deal purely because they assume they can stop running at any time or that they can just keep running until they reach the finish line. The truth is, if the body has not been properly trained for it, running a marathon can be very dangerous – and can even lead to a heart attack.

No matter the distance, it’s important to evaluate your physical strength before you begin running. If you do not have regular check-ups, start by seeing a doctor for a physical examination to ensure that you are healthy enough to run a marathon. It’s important to be sure that you have no underlying medical conditions such as bone and joint disease, high blood pressure, diabetes, asthma, or heart disease.

Experience Level and Required Preparation Time

After the physical examination, the next step is determining your running experience level – Beginner, Intermediate, Advanced, or Competitive – in order to help you prepare for the marathon at your level while avoiding physical harm.


Run regularly between 3-5 days a week

Weekly running distance (km/week)

Time required for marathon preparation




1 year




6 months




4 months



> 80

4 months

In theory, one should practice running the desired distance at least one week prior to the race. The training should be performed in similar conditions to the target event, including humidity, distance, and route so that the body is best prepared for the race.

How to Begin Training

A beginner should set a desired goal and gradually increase distance without overdoing it. If you don’t exercise regularly, you may begin with walking or alternate walking with running for 30 minutes a day between 3-5 times a week. As you become more comfortable with running, you can prepare for a Fun Run or 5K Race after 2-3 months. You can then gradually increase the amount of time spent running and the distance covered.

Tips For Running a Marathon

  • Choose a marathon race that is well-managed and well-planned with an accurate distance, route conditions, facilities, and safety arrangements such as first-aid stations with medical professionals and access to the required equipment.
  • Do not run in heat above 35ºC, especially in humid weather. Generally, there is no race when the WBGT (wet-bulb globe temperature) is above 32ºC.
  • Choose running shoes that properly fit the shape of your foot with proper weight support according to the route and surface of the ground. Do not wear new shoes on the day of the race.
  • Avoid drinking alcohol at least 24 hours before the race.
  • Warm up your body and stretch your muscles before the race.
  • Eat 1-2 hours before the race. If the long-distance race is longer than 2 hours, consume roughly 1 gram of carbohydrates per kilogram of body weight, per hour of exercise. The carbohydrates can be either liquid, gel, or a solid that is easily digestible to boost energy during the race.
  • Drink enough water to prevent dehydration, but do not drink too much water as it can cause the level of salt or sodium in your blood to drop too low, leading to hyponatremia. Drink only when you are thirsty. You may alternate sips of water and sports drinks approximately 120-180 ml every 15-20 minutes during the race. Observe the color and volume of your urine. Discharging a very small amount of dark yellow urine is the result of dehydration. Conversely, signs that you may be water-overloaded can include passing a large amount of clear urine frequently, headache, and dizziness.
  • Prior to running a marathon, please see a doctor and professional trainer for advice about exercise, diet, drinking to match sweat rate (amount of fluid lost through sweat during each hour of exercise), and techniques for the most efficient running and safety.
  • Have regular medical check-ups even if you are an experienced runner because the prolonged endurance increases the risk of heart disease.

By Dr. Montinee Sangtian, Emergency Medicine Specialist, Bumrungrad Hospital

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