Everything you wanted to know about sports nutrition and never knew
By Dr. Nestor Lipovetzky – www.doctornestor.co.il
Healthy nutrition for many professional and amateur athletes focuses highly on the type, frequency and length of their workouts, and less on their daily diet.
The most significant ingredient for our physical and mental wellbeing, which we are responsible for, is our nutrition. As such, focusing solely on strength, velocity and flexibility, with no regard whatsoever to the food we consume, is a form of neglect, which first and foremost hampers our efforts and the advantages one can gain from physical exercise and body development.
There is no doubt that the goal of any athlete or trainee is to be "number 1". This means moving faster, jumping higher or farther, lifting heavier weights, and gaining the highest scores possible. An athlete's body is essentially a machine. This machine consumes fuel and needs information about the type and the quality of the fuel nourishing it. Combining this type information and quality can determine whether someone will come in first or second.
As far as we know, the Greeks were the first people to try and improve their athletes' performance with the help of a special diet, or at least they were the first to document their attempt. Around 450 BCE, according to historical testimony, Dromeus of Stymphalus was said to have eaten large quantities of meat in order to improve his muscular strength. Interestingly enough, this belief has prevailed to this day among many traineesaround the world.
However, the knowledge we have today about the impact of a trainee's nutrition on his athletic performance is far greater. Now we know that in order provide our body with optimal fuel, trainees must eat sufficient amounts of nutritional components, and not merely protein, even though athletes require a larger supply of this nutritional component than the rest of the population.
In order to understand how an athlete should eat, let's introduce the key players in the world of athletic nutrition.
Glycogen is the body's storage form of the carbohydrates we eat. Between 375-475 grams of the carbohydrates are stored in our body, of which 325 grams are stored in the muscle and approximately 90-110 in the liver. While we exercise the carbohydrates stored as glycogen in the active muscle serve as the muscle's energy source. When our body is emptied of glycogen, for example, due to nutritional restrictions or following vigorous exercise, out body increases the production of glucose from other basic food groups, particularly protein. The amount of glycogen our body is capable of storing is relatively small and one can also impact glycogen levels with nutritional manipulations. For example, avoiding carbohydrates for 24 hours will drastically lower the glycogen levels in the muscles and liver. However, insisting on a rich carbohydrate diet for several days may double the glycogen stored, compared to a standard diet.
The glycemic index describes the rate at which carbohydrates enter the blood. The glycemic index is affected by the amount of nutritional fibers and fats that accompany the carbohydrate, so that the greater the fibers and fat, the slower they enter the blood. An athlete, who needs available energy during a competition, will require food with a high glycemic index that enters the blood quickly for immediate consumption. However, when he is not participating in competitions, we will prefer to fill his body's carbohydrate reserves (glycogen) without causing a rapid surge in the bloodstream's glucose levels. We must remember that simple carbohydrates (sugar) are quickly absorbed into the bloodstream, "forcing" the pancreas to respond quickly by secreting insulin. The insulin indeed reduces the blood sugar level, but if the glucose is not used up immediately (consuming sugars during exercise) there will be a sharp rise in the blood sugar level, which can lead to harmful health issues.
The carbohydrate: Carbohydrates divide into simple carbohydrates or sugars, such as sweets and fruit, and complex carbohydrates, such as bread, legumes, noodles and rice. They provide our body with fuel. After each meal, our body uses the glucose component for energy purposes, and the rest is stored in our body as glycogen. Once our body cells exceed their glycogen storage space, the sugars turn into fat. But, if we don’t eat enough carbohydrates, our body will use the glycogen stored as energy.
Carbohydrates affect our body in other ways as well. They can reduce our body's consumption of protein. Protein's primary role is to build, maintain and repair body tissues. Its secondary role is to provide energy. When glycogen reserves are empty and our body lacks additional sources of sugar, the protein (which builds our muscles) turns into glucose. In such cases the protein becomes the primary source of energy. This comes at the expense of our body, because reducing our protein reserves harms the muscles. In extreme cases the kidneys experience overload, in which case they secrete the excess nitrogen (a key component of protein) resulting from the breakdown of protein. That is why it is important to note that a sufficient supply of carbohydrates in one's daily diet prevents the transformation of protein into glucose and helps protect our muscle mass.
Carbohydrates play another significant role, which is to help our body in the metabolic process of stored fat. In order for fat to undergo oxidation and become a substance that can be used for energy consumption, our body requires a steady supply of glucose. You might say that the fat in our body is burned in the flame of carbohydrates. Furthermore, carbohydrates are vital for the proper function of our central nervous system. If for any reason there is an insufficient supply of carbohydrates via nutrition or glycogen reserves, the brain, which usually feeds off glucose, can use fat as a source of energy. In such cases the body will recruit large quantities of fat. The excess fat in our body will turn into ketone bodies, substances that raise the body's liquid acids and may lead to a state of ketosis. This process might ultimately lead to acidosis, which risks one's health, and might even cause death.
Proteins: Proteins are the most common substance in the human body after water. In fact, they are the body's building blocks. They not only grow, preserve and rehabilitate cells, including muscle cells, but they also create enzymes, hormones and genetic substance.
Proteins are built from a repertoire of 20 amino acids, 8 of which the body is incapable of producing, which is why these amino acids are so essential. When we eat protein we should aim, at the very least, to consume these 8 essential amino acids, since our body we'll know how to produce the others on its own. Seeing as not all foods contain all amino acids, the proteins found in food are ranked according to the quality of their protein component. The perfect protein is whey, after which come eggs, meat, milk products and foods that, when combined, provide a reasonable protein (such as mixing rice with lentils).
Either way, muscles are capable of transforming proteins into energy. Amino acids are released from the active muscle into the liver. From there, some of them turn into glucose that is secreted into the blood so that it returns to nourish the active muscle for energy production. Needless to say, carbohydrate reserves that reach their full capacity harm the potential contribution of protein to the production of energy from muscles. In other words, they reduce the breakdown of the muscle during exercise.
The amount of protein a healthy person should consume is 0.8 grams per kilogram. An athlete requires no more than 1.5 grams of protein per kilogram. This amount of protein enables the body to reach the maximum level of muscle-building. Beyond this protein level the protein is no longer stored in the body as a protein but turns into fat, and once protein turns into fat it will remain so.
Fat: We will not focus on the healthy aspects of different fats in this article. What is most important is the ratio between the overall fat percentage and the overall weight of the body. The body fat percentage (BFP) among men who exercise varies between 8-15 percent, whereas among women who exercise it varies between 12-20 percent. Women who have tried to reduce their body fat (for example, body builders) to 7 percent, compared to their total weight, have been known to lose breast tissue, their menstrual periods ceased, and their lives were at greater risk.
During ongoing physical activity, the fat is released from the fat tissue as free fat acids, which reach the bloodstream through the muscle tissue. At medium physical exertion the energy the body requires can be produces from similar levels of carbohydrates and fats. When exercise lasts for over an hour, the carbohydrates' reserves begin to drop and the fat's contribution to energy consumption reaches up to 80% of the energy the body requires.
Water: 66% of an athlete's body weight is made up of water. The muscle of an athlete, who drinks sufficient amounts of water, contains 75% liquid, while his blood contains 93% liquid. Consequently, water is the elixir of life. Our body can cool itself by releasing heat through the liquids it secretes, because it operates a heat-regulating mechanism. Therefore, a trainee who does not consume a sufficient amount of liquids will not cool himself off properly and his athletic performance will suffer as a result. It is important for athletes to saturate their body with water before, during and after practice.
Speaking of saturation, we should mention isotonic drinks. Isotonic drinks contain the same particulate concentration as blood. Isotonic drinks are meant to improve the carbohydrates' reserve (when sodium and carbohydrates are combines it accelerates the intake of the drink even more). An ideal drink for workouts will generally not be too sweet (so as not to cause drastic changes in the blood sugar level), will not be fizzy (carbonated beverages inflate the stomach and mislead the body regarding the amount of water it has absorbed), provides instant saturation (does not contain substances that might remain in the stomach for very time), helps the muscle recuperate quickly while and after exerting effort, and is neither too hot nor too cold, so as to allow athletes' to drink a suitable amount.
There are athletes who dilute freshly squeezed orange juice with water, at a ratio of 1:2. In this way they saturate themselves within a short period of time. The recommended amount of water to consume in normal circumstances ranges between 1.5-2 liters of liquid per day.
In the following articles we will discuss the muscle's specific energy requirements during resistance and aerobic exercises.