Nutrition can have a major impact on the adaptations to training (1). For example, in order to improve performance of the muscle, it is essential to exercise/train the muscle, but the effects of training influenced by nutrition. Nutrition can both improve and reduce the adaptations and is thus an important tool to optimize performance effects. It is not just the muscle that is affected (although this is the organ that is perhaps studied the most), other tissues such as the brain, the vasculature and the intestine, can also be affected.
There is more and more discussion, both in the scientific literature and also in the popular press, about the effects of nutrition on training adaptations. Sometimes this is referred to as “periodized nutrition”, sometimes “nutritional training” and others have referred to some aspects of this as “fueling for the work required” (2).
No one clearly defined, however, what methods are part of this periodized nutrition approach and people have interpreted the terms in different ways.
This is what I tried to address in a recently published review in Sports Medicine. I defined the concept of periodized nutrition as: the strategic combined use of exercise training and nutrition, or nutrition only, with the overall aim to obtain adaptations that support exercise performance. This is a mouthful, but it stresses that nutrition with or without exercise can affect the body in ways that will ultimately affect performance. It is not just the muscle, and performance is always the key outcome, even though the effects may not be acute and may only become visible after many weeks. The other important part of the definition is that is purposeful and planned! The term “nutritional training” is sometimes used to describe the same methods and these terms can be used interchangeably.
Some people think of periodized nutrition in terms of having different energy needs and intakes in different phases of the year. In some sports, carbohydrate intake may be much higher during the season and lower pre-season when changes in body composition may be the main goals. This is an example of periodized nutrition. Within a week there may be days with hard training and high carbohydrate intakes and days with low carbohydrate intake. Some will think of periodized nutrition as the strategic use of “training low” and “training high”: training with low and high carbohydrate availability respectively. But there is more. In addition to “train-low” and “train-high”, methods have been developed to “train the gut”, train hypohydrated (to reduce the negative effects of dehydration), and train with various supplements that may increase the training adaptations longer term.
There is not one diet that is the best diet for everyone, it will depend on goals and the individual.
The figure above shows a number of tools available to the nutritionist and trainer to optimize training adaptations. Which of these methods should be used depends on the specific goals of the individual and there is no method (or diet) that will address all needs of an individual in all situations. Therefore, appropriate practical application lies in the optimal combination of different nutritional training methods.
Some of these methods have already found their way into training practices of athletes, even though evidence for its efficacy is sometimes scares at best. Many pragmatic questions remain unanswered. One thing is clear however, in elite sport especially, the future of sports nutrition requires a close collaboration between trainer and sports dietitian/nutritionist. Working in silos will not work with the periodized nutrition approach and it is essential to incorporate nutrition planning into the long term (as well as short term) training planning.
References:
Free download of the paper in Sports Medicine:
2. Impey SG, Hammond KM, Shepherd SO, Sharples AP, Stewart C, Limb M, Smith K, Philp A, Jeromson S, Hamilton DL, Close GL & Morton JP (2016) Fuel for the work required: A practical approach to amalgamating train-low paradigms for endurance athletes, Physiological Reports, 4 (10), Art. No.: e12803.
