Nutrition

Should you change your diet leading up to a marathon or half marathon? The answer is a definite no – UNLESS you have bad eating habits now, which is a case for a diet change anyway. A sensible, balanced diet is essential as no one type of food contains all the nutrients essential for getting your body through the training necessary to complete 42.2 or 21.1 kilometres.

It is recommended that an active person’s diet should consist of around 60% carbohydrate (bread, cereals, vegetables, fruit, and pasta), 25% protein (meat, eggs, and fish) and 15% fat. Noted dietician Jeni Pearce advises carbohydrate intake should be 7 – 10g for each kg of bodyweight. So a 55kg athlete needs between 385 to 550g carbohydrates a day. Fat intake should be around 1g per kg bodyweight while protein should be 1.5 to 2g per kg bodyweight.

A study at Loughborough University (England) some years ago had 3 groups of 10 athletes run to exhaustion on a treadmill. Over the next 3 days the calorie intake was increased 70% for all runners. Group one’s increase was in fats and protein, group 2 simple carbohydrates (sweets and confectionary) and group 3 complex carbohydrates (pasta, grains). After three days the subjects repeated the test. Group one (fats/protein) increased distance covered by 3%, group two (sweets) by 23% and group 3 (pasta) by 26%. Moral: complex carbohydrates including cereals, bread, fruit and vegetables) are the best source of energy.

Glycogen (energy stored in muscles) is normally restored at around 5% an hour, but at 7% an hour in the first hour after exercise. So something high in carbohydrate (chocolate bar, fruit, glucose drink) as soon as possible after training improves recovery.

An analogy can be made on the role of diet in running performance. In a marathon natural ability will get you to 20km, training will take you the next 20 km and healthy eating the final 2.2km. But, and it is a big but, without a healthy diet you wont train well, so what you eat has a big influence on how far you get.