Using the definition of fitness, we have a lot of different processes which go on the body which we are trying to improve. The stress of training is the stimulus for this improvement but the changes themselves need to be supported by proper recovery. As we have discussed, recovery is aided by proper programming, such as not putting three similar sessions all next to each other in the training week, but there are other factors to look at as well, namely nutrition. Whole diet, the big picture of food intake is of paramount importance. After this we look at the performance nutrition picture.
Sports or performance nutrition are the special measures you take in the time period around competition and/or training that aid the body's recovery. Here we address the time critical needs of the body in order that we are able to recover faster in time for the next bout of physical exertion.
When thinking about what the body needs at this time, it is important to look at what is happening in training and competition. The body's energy reserves are being depleted, most notably carbohydrate, the muscle tissue is being stressed or broken down, and, of course, the body is loosing water, primarily through sweat.
For every hour spent training, a good baseline nutrition protocol is 30g of carbohydrate and 15g of protein in 500ml to 800ml of water. Some sessions like strength session may demand a little less carbohydrate and a little more protein. Similarly, if you wish to gain weight, increasing both carbohydrate and protein intake may well be beneficial.
Fueling and recovering from your training is time sensitive, there is a window where these calories are going to be better used by the body as it actively shuttles amino acids (from the protein you consume) and carbohydrate to where they are most needed.