There are many different factors involved in sports nutrition. In addition to how much you eat, the amounts of the different nutrients, protein, carbohydrate and fats are crucial. Ideally, 50-60% of the daily energy requirement should be carbohydrates, 20% protein and 20–30% fat.
Finally, the timing of foods and nutrients are increasingly being seen as a very important factor in performance nutrition. A specific element of this is the carbohydrate and protein requirements around training where fuelling and recovery requirements are at their highest. A significant quantity of your carbohydrate intake should fall in the hours before and after training to ensure you fuel both training and recovery. Protein can also aid the body's utilisation of carbohydrate and will speed recovery. Slower digesting whole food proteins are more easily tolerated after training with the more easily digested protein supplements used in the times just before and after training.
The calorie requirements for a sedentary person are normally somewhere between 1900 and 2100 calories per day, but with an hour or more training this can go up to approximately 3000 calories. As an endurance athlete, about 1650 calories should come from carbohydrates (which corresponds to a quantity of about 400g carbohydrates). Potatoes, pasta, muesli, fruit and vegetables, for example, are carbohydrates foods that can be consumed on a daily basis.
You should also pay special attention to your intake when on training camps and travelling to competitions. Here portable sources of carbohydrate that are going to remain safe to eat when you don't have access to a fridge are important. This is also one place where the convenience and palatability of sports supplements come into their own.
When you train hard and deplete the muscle, processes are initiated by the body to recover and repair the tissues, and also to make the body more able to cope with that stress in the future. This 'supercompensation' process is usually viewed in terms of repairing muscle tissue, but it also applies to the ability of the body to store carbohydrate.
Although quite limited, as opposed to body fat, the amount of carbohydrate the body is able to store can be increased by the cycle of depleting it with training and then restoring it with carbohydrate from the diet.
Pay attention to getting a decent supply of whole food starch sources with meals and emphasise carbohydrate intake around training from a mixture of food sources and, where useful, sports supplements like sports drinks and recovery bars.
Dehydration is the quickest killer of performance and adequate hydration is crucial. Two or more litres a day is a good baseline, with the majority of the intake coming from plain water. Over longer training sessions you should drink an additional 250-300 ml or so every 15 minutes, and pay attention to the conditions such as temperature and wind speed as these can effect sweating rates. Isotonic drinks are a particularly good option, as they contain exactly the right concentrations of energy-giving carbohydrates and important minerals like sodium and potassium that aid hydration, speeding the movement of liquid out of the gut and into the body.
Nutrition for competition
One to two days before the competition, you should ensure your glycogen stores are topped up by increasing your carbohydrate uptake to approximately 70% of your daily intake of calories (this amounts to about 6–10 g carbohydrates per kilogram of body weight per day). This, coupled with the reduction in training volume just before competition, will provide a 'carb loading' effect without overloading your body and leaving you feeling bloated.
On the day of the competition, you should ideally have the last big meal two to three hours before the race. The meal should be easily digestible and should not contain too much roughage. During the race, even with energy stores totally depleted, the body cannot absorb much more than 60-100 g of carbohydrate per hour. It is then particularly important to drink enough and ensure carbohydrate replenishment.
Recovery and training are flip sides of the same coin and if you don't pay attention to both then you'll not be getting the most from your training. The less experienced athletes undertaking harder, longer training or competition will need longer to recover but usually a recovery period of 24 to 48 hours is sufficient, provided you've supplied the body with sufficient nutrients.
To speed up the recovery process nutrients should be taken in straight after training, and ideally a little before and during as well. Carbohydrate and protein are the emphasis here and after longer sessions, approximately 1.5 g of carbohydrates per kilogram of body weight and 0.3–0.5 g protein per kilogram of body weight should be consumed in the first hour.
As time is an important factor this is an ideal place to look at the use of specific sports supplements like carbohydrate and protein drinks and recovery formulas. These are deigned to be easy to use and quickly absorbed by the body.