General principles

An appropriate diet is one of the most important factors facilitating sports and health training. It is assumed that the diet of people who are physically active should not deviate in its composition from the typical one, yet meet the increased energy and nutritional demands of the body. This applies to both athletes and those practicing amateur or recreational sports.
Any strenuous exercise causes the organism to leave the state of equilibrium (homeostasis). Effective dietary regeneration not only ensures a rapid return to the normal state, but is also a prerequisite for increasing the fitness level. Adequate nutritional strategy is also an ally in building an attractive and athletic body shape, delivering loss of fat mass and increase in the share of muscle tissue in the general body build.
The demand for energy and nutrients in the diet of physically active people varies and depends on many factors, such as the type and duration of exercise, its nature and intensity. Not without significance is also the person's age, health and fitness level. But before a specialised nutritional plan is implemented, tailored to the individual body requirements, first it is important to note the basic principles of nutrition ensuring the maintenance of proper physical fitness and health:
 

Calorie needs

Energy is essential for all the processes occurring in the body. Each muscle contraction, the functions of internal organs, secretion of enzymes or hormones – they all depend on the supply of energy. For the human body, its only source is food. The energy-supplying nutrients (not alcohol) are: carbohydrates, fats and proteins. As a result of conversions of these compounds, there are formed high-energy molecules, utilised by the body in the maintenance of basic life functions, thermogenesis and physical activity.
Exercise is an important element of metabolism and significantly affects the amount of daily energy expenditure. The demand for energy in persons practicing sports varies and depends on many factors, such as the type of exercise, muscle work intensity and its duration. Not without significance is also the age, weight and body composition.
A proper food ration should provide approximately 12-13% of energy from protein, 25-30% from fat and 50-60% from carbohydrates.

Energy balance

To ensure health and proper physical development, a human being must derive energy from food, and its amount should correspond to that expended by the body. If both sides of the equation are the same, the so-called equilibrated energy balance is kept. However, if the amount of energy taken with food exceeds the energy expenditure of the body, a positive balance is created, leading to the intensification of anabolic processes and increase in body weight. In adults, long-term acquisition of excess energy in relation to the actual needs of the body inevitably leads to excess weight and obesity. Positive energy balance is physiologically justified only in the case of body growth (children and pregnant women), in some sports (such as bodybuilding) or in underweight persons.
When energy intake from food is lower than the daily energy expenditure, catabolic processes start to prevail, which ultimately leads to weight loss, since the body is forced to use the stored energy reserves. From a physiological point of view, maintaining a negative energy balance is justified only in the case of weight loss diets and in athletes required to meet weight limits. Thus, control over the energy needs is not only important from the point of view of improving physical fitness and health but also for ensuring the proper body composition.

Training efficacy

Currently, thousands of people practice sports in Poland: aerobics, bodybuilding, mountain climbing, cycling, skiing, marathon running, etc. For many of them, the intensity of exercise does not differ much from the training of competitive athletes. No wonder that in such situations the demand for basic nutrients, such as proteins, carbohydrates, fats, vitamins, minerals, exceeds (sometimes several times) the standards recommended for people not practicing sports. An adequate specialist dietary approach is not only to enhance the training effect but also to prevent overstraining and excessive usage of the body. One of the most important elements of properly applied nutritional strategy is to ensure an appropriate amount of energy needed for intensive muscle work.

Carbohydrates are fundamental

Energy requirements posed by physical training are covered mainly by the oxidation of fats and carbohydrates (sugars). Most experts are of the opinion that the percentage of these compounds in the diet of physically active persons should correspond to the values set for the general population, i.e. ca. 55-65% carbohydrates and 25-30% fat. Undoubtedly, the most important role in energy processes is played by carbohydrates, which constitute the main source of energy both in exercises of moderate intensity and in more intensive sports.
The human body has the ability to store sugar as glycogen. This compound is synthesised in many tissues, but significant amounts of this polysaccharide are accumulated in the liver and in muscles only.
The content of muscle glycogen (the main source of energy for muscle work) is within the range of 1 1.5% of wet tissue, which in the case of the body of an average person is about 200-300 g. The content of this compound in the muscle tissue is variable. In the body of physically active people, with appropriate training and diet, it can visibly go well above the initial state. This is called the supercompensation phenomenon. Since muscle glycogen is the only source of energy for myocytes, the size of its stores is particularly important in prolonged or intensive physical training. During exercise, carbohydrate reserves stored in the muscles are reduced, and if they are not replenished before the next training session, the intensity of exercise can become reduced, leading to lowered effectiveness. Thus, the fundamental principle of a well-balanced diet after a completed workout is the consumption of carbohydrates in a quantity sufficient to ensure the replenishment of glycogen stores.
The maintenance of adequate muscle glycogen reserves is of particular importance for persons performing prolonged endurance exercises (long-distance running, road cycling, cross-country skiing), since carbohydrates are necessary for the proper burning of fatty acids which are the primary source of energy in these sports disciplines.
Well-balanced diet for physically active people should be distinguished by a sufficient amount and quality of carbohydrates determining the effective restoration of energy reserves in muscles. This applies particularly to persons whose physical exercises last more than 60 minutes. The best source of this nutrient in the diet are coarse cereal products, vegetables and fruit. Carbohydrate, high-fibre, products not only deliver adequate amounts of sugars in the diet but also plenty of valuable vitamins and minerals, determining their correct metabolism in the body. However, carbohydrate products with high sucrose and monosaccharide content (refined sugar, sweets, fruit preserves, sweet drinks, etc.) are not recommended. An excess of their share in the diet leads to reduced consumption of dietary fibre and valuable nutrients of regulatory importance, which may lead not only to the deterioration of athletic performance, but also health. The role of carbohydrates in sports training does not come down to energy conversions only, since they are also essential in many metabolic processes, are components of many tissues and biologically active substances, as well as affect the efficiency of thermoregulatory processes.

In the next section: how, in practice, quickly and effectively regenerate the body after a workout?

MSc Pharm. Dariusz Szukała
Specialist in diet and supplementation
Laboratory of Sports and Metabolic Nutrition
www.apz.pl