What happens to your body when running a marathon

Commonwealth Games Marathon runner and Griffith graduate, Michael Shelley.

The Marathon is one of the most anticipated events at the Gold Coast 2018 Commonwealth Games (GC2018). Sixty-five finely-tuned and focussed athletes poised as they wait for the gun to signal the start.

Professional athletes commence their journey in pursuit of a Commonwealth Games gold medal years before the race even begins with a support team around them including a coach, sport psychologist, physiotherapist and dietitian to name a few.

For the everyday recreational runner who wants to run a marathon access to coaches, physiotherapists and dietitians may be limited and costly. But, even if you can’t afford a coach there are plenty of online resources which can help, join a running club and if necessary, check with a medical professional before embarking on any new strenuous training regime.

So, what exactly happens to the body when running a marathon? As Griffith University is an Official Partner of the Games and the Presenting Partner of the GC2018 Marathon GOLDOC, we asked Bachelor of Sport Development Program Director, Dr Brooke Harris-Reeves and Dr Ben Desbrow, Associate Professor in Sports Nutrition, for their insights.

“Physiologically, the body is pushed to its limits, it goes through significant changes to cope with the metabolic demands of the 42.2km race,’’ Harris-Reeves says.

“During the 40,000 steps a runner takes the body recruits every muscle fibre resulting in an increased rate of breathing and blood flow to cope with the oxygen demands of the muscles.”

Skeletal muscles: these muscles are attached to our bones and we use all of these in a physical activity. When running a marathon, the stress on our leg muscles creates tiny micro-tears in the tissues (the source of post-run soreness).

Heart and lungs: With each breath we take in a marathon, our lungs deliver oxygen-rich blood to our heart so it in turn can pump oxygen into our body’s cells and tissues so we can keep those legs moving.  The fitter we are, the more efficient the heart is in taking up oxygen.

“To reach elite status as a marathon runner an individual has to have a high VO2max, which is the amount of oxygen they can take in, transport to the muscles and utilise.” says Harris-Reeves.

“Running economy also plays a huge role in marathon running. This means how many calories your body needs to travel a certain distance, and how much oxygen your muscles need to run. Better runners use less oxygen, fewer calories and achieve a better overall performance than runners with poor running economy.”

Feet: Feet take a pounding when running a marathon so it is important athletes run in shoes they’ve been using for a while. Blisters and losing toenails are a common occurrence.

Nutrition: Selecting the best fuel for the marathon can turn all that training into a major life achievement, says Desbrow. “During a marathon your body will rely on liver glycogen (stored carbohydrate) to maintain your blood sugar and prevent hypoglycaemia (low blood sugar), while your muscle glycogen allows you to maintain your optimal pace. Breakfast provides a vital opportunity for a final top up of both glycogen stores and to optimise hydration levels. For an early morning race, where time is scarce, a light, low fibre carbohydrate-rich snack (100-200 grams) should be eaten 1-2 hours before. Some athletes find it difficult to eat during this time; they could benefit by getting their carbohydrates from drinks, bars and/or gels.”

Body temperature and hydration: Temperature rises due to the body’s increased activity, especially when running in warmer weather when the body can struggle to release heat as quickly. On cooler days, body temperature will go down. “The temperature in April is likely to be optimal for marathon running – not too hot and not cold.” Desbrow says. “Don’t forget that the best time to hydrate are the days leading to your race, then a drink of at least 500ml two hours before the start.”

Best places to watch GC2018 marathon.