Nutritional Requirements of Water Polo Players
This is the first of a series of articles about nutrition requirements for water polo players. Before we can look at what kinds of foods that are required for maximum performance, we have to look at the energy requirements for water polo. The first part of this article will analyze where a person involved in strenuous sport activities gets the energy from to contract their muscles.
This probably is a little more science than most you want to hear about; but it is necessary to understand what goes on in the athlete’s body before we can advise the athlete about the right kinds of foods to fuel the muscles. We will also look at the specific energy requirements for the sport of water polo. Finally we will find out which foods, in general, can help fill the energy requirements for water polo players. A more specific diet will be discussed in future articles.
WHERE DO WE GET THE ENERGY TO FUEL OUR MUSCLES?
Your body is perfectly designed to move by a series of coordinated muscle contractions. When your brain tells your body to move, nerve signals trigger a powerful release of muscular energy through a special molecule called adenosine triphosphate (ATP). ATP is a high-energy molecule, that when the chemical bond that holds it together snaps apart, energy is released and used by the muscles to contract and away you go. The process that causes this to happen is simply converting chemical energy from food to mechanical energy for muscle contraction. Three systems in the body create the ATP energy required for physical activity, and all three are used for water polo in varying degrees.
The ATP-CP system provides enough energy for a five to eight-second swim sprint, or other rapid muscle contractions, such as lifting weights. Creatine phosphate (CP) is a high- energy molecule that can deliver its energy to manufacture ATP very quickly. CP is readily available and stored in large quantities in the muscle fibers. Immediately upon the start of exercise, CP is the preferred method of supplying energy before other methods can “kick-in”.
Since the CP is depleted very quickly, the short period of exercise must be followed by a rest period, so that the CP that was depleted may be regenerated in the muscles used. No oxygen is required for this system to work; so you don’t need to inhale air during a short sprint. Because no oxygen is required, it is called anaerobic (without oxygen) exercise.
To better understand how the ATP-CP system works, go to the weight room and do 3-sets of the bench press. While you are performing the first set, creatine phosphate stored in the muscles is creating the ATP that allows the muscles to contract, and allows you to perform the bench press maneuver. At the end of the first set, most of the CP in the muscles involved is depleted. In order to perform another set you must have a rest period after the first set that will restore the CP in the muscles. After a rest period of 30-60 seconds, the CP is restored, and you can start performing the second set. The same goes for the third set; a rest period followed by an exercise period.
If a water polo player continues swimming at a fast pace after the ﬁrst 8-10 seconds, there will be a lag in time when ATP produced from Creatine Phosphate runs out. The ATP needed to continue muscular contraction after this time is supplied by another energy producing system called anaerobic glycolysis, the breakdown of glycogen, again with little requirement for oxygen. The glycogen used for this process is found in the muscles and in the liver; and is actually the storage form of the simple carbohydrates (sugars) that you eat in your diet.
Anaerobic glycolysis produces enough ATP for a longer period of time, for 40-50 seconds and up to 2 minutes, depending on the level of training of the athlete. This process quickly delivers enough ATP to allow the water polo player to maintain a fast pace, even after the CP levels are low. The drawback to anaerobic-gylcolysis is the production of lactic acid. Even though the athlete can swim at near maximum speed for this time period, the accumulation of lactic acid will eventually cause the muscles to fatigue, and muscular contraction to slow down. The heavy arms and exhaustion that you feel when the 1000 lb gorilla jumps on your back, is a result of lactic acid in your muscles.
The body avoids acid fatigue by switching to a third system that requires oxygen, the aerobic system. In order to utilize the oxygen system, however, the pace of the exercise has to be reduced. The intensity of the exercise, and the bodies ability to deliver oxygen to the muscles, are important factors in which system is being utilized. As long as the intensity and pace is high, the body relies more on the glycolytic system fueled by glucose. The cardiovascular system simply cannot deliver oxygen fast enough to supply the demands of the exercise. When the intensity is lower (e.g. during slow swimming or jogging), the body prefers the aerobic system that uses both fat and glucose for muscle fuel.
WHICH SYSTEMS ARE UTILIZED?
During exercise, all three systems come into play. The contribution of the three systems depends on the speed and intensity of the performance, and the conditioning of the athlete. Generally, fast pace swims utilize more of the anaerobic systems while slower paced swims utilize more of the aerobic system. There is a small amount of oxygen stored in the muscle fibers and in the blood in the vicinity of the muscle. This can be utilized right away and does contribute to the production of ATP, even for short and fast paced swims. Oxygen contributes about 20% of the ATP for short sprints of 20-25 meters, and about 30% to swims of 30-75 meters. Slower paced swims are almost entirely aerobic.
SOURCES OF ENERGY FOR EXERCISE
The foods that you eat provide the potential energy, or fuel, that your body needs in three forms: carbohydrate, fat and protein. Your body can store some of these fuels in a form that offers your muscles an immediate source of energy. Carbohydrates, such as sugar and starch, are readily broken down into glucose, the principal energy source of the body. Glucose can be used immediately, or it can be stored in the muscles and liver as glycogen. During exercise, glycogen is converted back into glucose and can be used a fuel by the muscle fibers. Not only is glycogen the most significant source of energy for muscle contraction in high intensity exercise; but it is also a source of energy for brain function both during rest and exercise.
If an athlete wants to train and compete efficiently, he needs a full tank of glycogen every time he exercises. This can only come from food sources. Frequent long and hard training sessions and games can reduce the amount of glycogen available. The likely cause of poor performance and fatigue in practice, or in games, is because of low levels of glycogen in the muscles. Studies have shown that the glycogen stored in the body will start depleting after only one hour of continuous exercise. It can be depleted completely if not restored through diet and rest. This is called “tapering” and will be discussed in a future article.
As mentioned above, fat can also be utilized by the body to provide energy for muscle contraction; but only at lower intensity levels of exercise. Because of the tremendous amounts of fat stored in the body, exercise that requires fat can go on for very long periods of time. The intensity and pace of the exercise, however, has to be low. Once the intensity picks up, the system that utilizes fat is too slow to provide energy for rapid muscle contraction.
Converting fat to ATP requires the availability of oxygen, which is often the limiting factor in fat utilization. The heart and the cardiovascular system cannot pump enough oxygen rich blood to the muscles fast enough to convert fat into ATP. Glycogen thus becomes the most reliable source of fuel for muscular contraction in high intensity exercise.
The only way that your body can utilize fats is to slow down the pace of the exercise. Marathon runners utilize both fat and oxygen during their long run. That is why it is considered an aerobic (with oxygen) athletic event. The pace that a marathon is run, however, is much slower than say the pace for a 400-meter race. The marathon runner can go for three hours, but at a much slower pace. The 400-meter runner can go much faster; but for only a short period of time.
The faster pace of the 400 requires glycogen and creatine phosphate for energy; but the price the runner pays for the faster pace is the build-up of lactic acid in the muscles. Because of the Lactic acid build-up, the sprinter can only go for a short distance before he has to slow down or stop. The goal of conditioning and training an athlete is to allow him to go at faster and faster speeds without the build-up of lactic acid. This also holds true for the water polo player.
Protein can also be utilized by the body to produce energy (ATP) for muscular contraction; but only in extreme conditions where the body has utilized all of its carbohydrate and fat reserves. Proteins are an important part of foods that are utilized by the body to build, maintain, and repair body tissues like muscle, and to synthesize important enzymes and hormones.
WATER POLO ENERGY REQUIREMENTS
Short and long bursts of speed followed by rest periods of different lengths are required to play the game of water polo. In ﬁlm-analysis studies done in various countries, it was found that 70% of the time in a water polo game is spent in short bursts of speed of 5-25meters. These swims require use of both anaerobic systems, the breakdown of creatine phosphate, and the breakdown of glycogen by anaerobic glycolysis. Aerobic glycolysis also contributes to the production of ATP for all activities, regardless of speed. It also contributes to water polo; but because of the high intensity required to play the game. water polo remains a predominantly anaerobic sport, and thus requires a diet that is rich in carbohydrates.
MYTH- CARBOHYDRATES ARE BAD!
TRUTH- Because of fad diets, carbohydrates have attained a reputation as a food that is bad for you. However, just the opposite is true. Any person, especially an athlete, cannot survive without carbohydrates in their diet. High-protein, low-carbohydrate diets cannot support optimal health very long, especially for the young, active athletic person. An active person, especially a water polo player that is involved in very strenuous physical activity for several hours a day, cannot perform in practice or in a game on this kind of diet.
There is one reason why some people lose weight on a no-carb/high-protein diet. Because of the very limited foods that they can eat that don’t contain carbohydrates, people will eat less. By eating less they take in less calories, and thus lose weight. This weight loss cannot be sustained however; because people lose interest in the few boring foods that they are allowed to eat. They usually gain all of the weight back that they lost.
The quality of the diet also suffers when carbohydrates are restricted. Without fruits, vegetables, and whole grains there is a lack of fiber, vitamins, minerals and anti-oxidants; all dietary factors that protect against disease. Low carbohydrate diets include extreme amounts of saturated fats that usually accompany high-protein foods, the leading cause of heart disease caused by clogging of the arteries. Excluding carbohydrates can lead to nausea, fatigue, light-headedness, constipation and low blood pressure; and that is for the average sedentary person. An active and fit person, such as a competitive water polo player, cannot live without carbohydrates. Both your health and your performance will suffer.
Limiting different foods is not good for anybody, especially for athletes. Athletes need carbohydrates, as well as fats and proteins, in their diet. The next article will go into specifics about the kinds of foods, and when the water polo player should eat them, for optimum performance.
[Click Dante's photo to learn more about his water polo experiences
and Click the water polo ball to learn more about Dante's books.]