Could sports nutrition get you a marathon Personal Best?

For even advanced runners, to complete a marathon in a personal best (PB) time requires fitness, training, and dedication. For the average recreational runner, this will certainly mean undertaking a programme of endurance exercise that demands a high energy expenditure and will require optimal fuelling. But that’s not all - endurance running places a heavy mechanical strain on digestion and this can hamper progress, not helped by the need to 'top up' energy stores before training or racing.

Both advanced and recreational runners need a sports nutrition plan that helps compensate for the energy and other physical demands on the body. The plan needs to give practical suggestions of what to eat, particularly before commencing an endurance exercise session (anything over 90 minutes).

This is the first in a series of articles that will reveal the optimal sports nutrition programme for runners wanting to achieve a PB marathon time. The overall strategy can be adjusted for body size, gender, and fitness levels, and the challenges of daily life.

Let’s start with energy needs

The body’s preferred source of energy for endurance exercise is carbohydrate, and runners will therefore have a substantial reliance on this food group. The daily diet needs to provide sufficient carbohydrate to fuel aerobic exercise and to optimise liver and muscle glycogen stores (glycogen is the body’s back-up form of carbohydrate for exercise).

Whilst there is a populist trend promoting 'low-carb' diets, a runner who fails to eat enough carbohydrate before a race will tire more quickly, feel an increased perception of effort, and run at a slower pace, making a PB very unlikely (Angus et al., 2002; Burke et al., 2006; Campbell et al., 2007). But how much carbohydrate is optimal?

Published recommendations for endurance athletes are typically in the range 6-10g/kg of body weight per day (Achten et al., 2003; American College of Sports Medicine, 2009). For a 70kg runner, for example, this means 420g-700g carbohydrate per day. To optimise the digestion of carbohydrate foods, it would be sensible to start at the lower end of the range at the beginning of the training programme, and gradually progress towards the upper end for later stages.

Which forms of carbohydrate are best?

Carbohydrates come in two main forms: fast-releasing for short, quick bursts of energy (e.g. energy drinks, honey or syrup, ripe fruit, or dried fruit), or slow-releasing for more sustained energy (e.g. oats and other whole-grains, brown rice, and root vegetables). For marathon runners, slow-releasing carbohydrates should make the largest contribution, to help avoid a 'sugar high' followed by an energy-sapping dip in performance shortly after (Donaldson et al., 2010).

Breakfast - the most important meal of the day?

At the lower end of the recommendations, each main meal will need to provide roughly 100g slow-release carbohydrates for lighter runners (Wong et al., 2008). As many races start mid-morning, then the athlete would typically need to focus on breakfast (consumed two-four hours before training/racing to complete digestion), for example;

• one plain omelette (two eggs)
• one average slice of rye toast with one heaped teaspoon fruit jam
• two wheat cereal biscuits with milk, one tablespoon raisins, one tablespoon sunflower seeds

Total: 96.2g carbohydrate, 29g protein, 24g fat

For heavier athletes, then breakfast would typically need 150g carbohydrate and could look like this;

• one small can (200g) baked beans in tomato sauce and two poached eggs
• one bowl fruit salad (6 strawberries, one small banana, half a small apple, five grapes)
• one large (220g) whole-meal scone with one heaped teaspoon of fruit jam
• two wheat cereal biscuits with milk, one tablespoon of raisins, one tablespoon sunflower seeds

Total: 155.6g carbohydrate, 40.7g protein, 24.7g fat

At higher level requirements of 200g of carbohydrate, then breakfast would be even more substantial;

• oat porridge (220g) made with milk
• one medium banana (120g), one tablespoon raisins, one tablespoon pumpkin seeds
• one whole-wheat bagel (80g) with one heaped teaspoon of fruit jam
• fruit smoothie (500ml) made with 120g soft fruit of choice, blended with water

Total: 191g carbohydrate, 27g protein, 15g fat

Conclusion

Both experienced and recreational runners need a sports nutrition plan to achieve a marathon PB. For optimal performance, slow-release carbohydrates need to form a substantial part of the diet (Burke et al, 2004).

Most races start mid-morning, so this means breakfast needs to be carefully considered to optimise glycogen stores, such that the right amount of carbohydrate is consumed (and eaten two-four hours before running to support digestion). Athletes should check the examples above to ensure they’re eating the right amount for their training and build.

Practicing, preparing and consuming the pre-training breakfast meal is an important part of a sports nutrition plan and will help the athlete experience a more comfortable marathon, plus achieve that all-important PB!

Coming next - how much protein and fat is needed in a marathon runner’s diet?

References

• Achten J, Halson S, Moseley L, Rayson M, Casey A, Jeukendrup A (2003). Higher dietary carbohydrate content during intensified running training results in better maintenance of performance and mood state. Journal of Applied Physiology, 96: 1331-1340.
• American College of Sports Medicine position statement (2009) Nutrition and Athletic Performance. Medicine and Science in Sports and Exercise, 41: 709-731.
• Angus D, Febbraio M, Hargreaves M (2002) Plasma glucose kinetics during prolonged exercise in trained humans when fed carbohydrate. American Journal of Physiology, 283: E573-E577.
• Burke L, Kiens B, Ivy J (2004) Carbohydrates and fat for training and recovery. Journal of Sports Sciences, 22: 15-30.
• Burke L, Loucks A, Broad N (2006) Energy and carbohydrate for training and recovery. Journal of Sports Sciences, 24: 675 – 685.
• Campbell B, Kreider R, Ziegenfuss T, La Bounty P, Roberts M, Burke D, Landis J, Lopez H, Antonio J (2007) Position stand: protein and exercise. Journal of the International Society of Sports Nutrition, 4: 8-15.
• Donaldson C, Perry T, Rose M (2010) Glycemic index and endurance performance. International Journal of Sport Nutrition and Exercise Metabolism, 20: 154-165.
• Wong S, Siu P, Lok A, Chen Y, Morris J, Lam C (2008) Effect of the glycaemic index of pre-exercise carbohydrate meals on running performance. European Journal of Sport Science, 8: 23-33.