Calorie Utilization in Football - Article Example

Fuel Utilization in Football: Physiology and Biochemistry in Sports INTRODUCTION: Sports make a person physically healthy. It is a known fact that any type of sport makes one physically fit by improving strength, skill, stamina, speed and suppleness. It has been proven to burn calories and to affect appetite. Football is one of the most favorite sports of all times. Unknown to many of us, there is more than what meets the eye in this game. Football is a scientific sport because it uses both physics and chemistry. Physics is involved in game strategy, while chemistry is involved in providing energy to football athletes. (Nagahama, 1988) Football players need effort determination and discipline, and they need to apply these principles in their nutrition habits. Nutrition makes an athlete perform to his optimum levels. Proper nutrition is fuel for all football players because this sport requires short bursts of energy. The role of nutrition in an athlete is multitude—it improves strength, stamina, speed and recovery. The nutrition of each athlete affects his performance and affects the performance of the team as well. (Manore, 2000) There is a certain balance between food consumed and energy used for carrying out work. This is measured in calories. A calorie is defined as a unit of work or energy equating to the amount of heat required to raise the temperature of one gram of water one degree centigrade. (Poortsman, 1988) When the body is in calorie balance the energy intake and output are equal and the body weight remains constant. Being active is not only good for the heart and circulation, it can use up many calories, which results in weight being controlled. This is the role of exercise in sports, such as football. There are two sources of fuel during football—external and internal. Extrenal fuel refers to nutrition. Nutrition in football involve taking in of nutrients dervived from carbohydrates, fat and proteins and how they contribute to the fuel supply needed by the body to perform exercise. These nutrients get converted to energy in the form of adenosine triphosphate or ATP. It is from the energy released by the breakdown of ATP that allows muscle cells to contract. However, each nutrient has unique properties that determine how it gets converted to ATP. (Maharam, 1999) Carbohydrate is the main nutrient that fuels exercise of a moderate to high intensity, while fat can fuel low intensity exercise for long periods of time. Proteins are generally used to maintain and repair body tissues, and are not normally used to power muscle activity. (Newshome, 1983) The ways these calories are being burned by the body are affected by our body’s energy pathways. This is what we refer to as the internal source of energy. It is said that energy production is both time and intensity related. When a football player runs at a very high intensity, he can operate effectively for only a very short period. However, when a player runs at a low intensity, he can sustain activity for a long period. There is a certain relationship between exercise intensity and the energy source. The energy sources being talked about are being regulated by energy pathways. D. Matthews and E. Fox, in their book, "The Physiological Basis of Physical Education and Athletics", divided the running requirements of various sports into the following "energy pathways": ATP-CP and LA, LA-02, and 02. ATP (Adenosine Triphosphate) is a complex chemical compound formed with the energy released from food and stored in all cells, particularly muscles. Only from the energy released by the breakdown of this compound can the cells perform work. The breakdown of ATP produces energy and ADP. (Macleod, 1992) CP (Creatine Phosphate) is a chemical compound stored in muscle, which when broken down aids in the manufacture of ATP. The combination of ADP and CP produces ATP (Macleod, 1992) LA (Lactic acid) is a fatiguing metabolite of the lactic acid system resulting from the incomplete breakdown of glucose. Although excessive lactate production is part of the extreme fatigue process, it is the protons produced at the same time that restrict further performance. (Macleod, 1992( O2 means aerobic running in which ATP is manufactured from food mainly sugar and fat. This system produces ATP copiously and is the prime energy source during endurance activities. (Macleod, 1992) These energy pathways are time duration restricted. In other words, once a certain time elapses that specific pathway is no longer used. The reaction is such that the result of muscle contraction produces ADP which when coupled with CP regenerates ATP. CP is stored in the muscles. Actively contracting muscles obtain ATP from glucose stored in the blood stream and the breakdown of glycogen stored in the muscles. Exercise for longer periods requires the complete oxidation of carbohydrates or free fatty acids in the mitochondria. The carbohydrate store will last approximately 90 minutes and the free fatty store will last several days. (Jones, 1986) All these three energy systems contribute at the start of exercise but the contribution depends upon the individual, the effort applied or on the rate at which energy is used. Adenosine Triphosphate (ATP) in the muscle lasts for about 2 seconds. It is said that the resynthesis of ATP from Creatine Phosphate (CP) continues until CP stores are depleted, which is approximately 4 to 6 seconds. This will give us around 5 to 8 seconds of ATP production. (Frayn, 1996) The ATP-CP energy pathway (sometimes called the phosphate system) supplies about 10 seconds worth of energy and is used for short bursts of exercise such as a 100 meter sprint. This pathway doesn't require any oxygen to create ATP. It first uses up any ATP stored in the muscle and then uses creatine phosphate (CP) to resynthesize ATP until the CP runs out (another 6-8 seconds). After the ATP and CP are used the body will move on to either aerobic or anaerobic metabolism (glycolysis) to continue to create ATP to fuel exercise. (Frayn, 1996) There is another system in our body which we term as the anerobic lactate or Glycolytic system. Once the CP stores are depleted, the body then resorts to stored glucose for ATP. The breakdown of glucose or glycogen in anaerobic conditions results to the production of lactate and hydrogen ions. The accumulation of hydrogen ions is the limiting factor causing fatigue in runs of 300 metres to 800 metres. (Prayn, 1996) The anaerobic energy pathway, or glycolysis, creates ATP exclusively from carbohydrates, with lactic acid being a by-product. Anaerobic glycolysis provides energy by the (partial) breakdown of glucose without the need for oxygen. Anaerobic metabolism produces energy for short, high-intensity bursts of activity lasting no more than several minutes before the lactic acid build-up reaches a threshold known as the lactate threshold and muscle pain, burning and fatigue make it difficult to maintain such intensity. (Frayn, 1996) It is said that there are three different working units within this energy system: Speed Endurance, Special Endurance 1 and Special Endurance 2. (Hargreaves, 2006) There is another system in our body which we term as the aerobic energy system. The aerobic energy system utilises proteins, fats and carbohydrate (glycogen) for resynthesising ATP. This energy system can be developed with various intensity or tempo runs. The types of Tempo runs are continuous tempo, extensive tempo and intensive tempo.(Hargreaves, 2006) Continuous Tempo are long slow runs occurring at 50 to 70% of maximum heart rate. This places further demands on muscle and liver glycogen. The normal response by the system is to enhance muscle and liver glycogen storage capacities and glycolytic activity associated with these processes.(Hargreaves, 2006) Extensive Tempo are continuous runs at 60 to 80% of maximum heart rate. This places demands on the system to cope with lactate production. Running at this level assists the removal and turnover of lactate and body's ability to tolerate greater levels of lactate.(Hargreaves, 2006) Intensive Tempo are continuous runs at 80 to 90% of maximum heart rate. Lactate levels become high as these runs boarder on speed endurance and special endurance. Intensive tempo training lays the base for the development of anaerobic energy systems. (Hargreaves, 2006) Aerobic metabolism fuels most of the energy needed for long duration activity. It uses oxygen to convert nutrients (carbohydrates, fats, and protein) to ATP. This system is a bit slower than the anaerobic systems because it relies on the circulatory system to transport oxygen to the working muscles before it creates ATP. Aerobic metabolism is used primarily during endurance exercise, which is generally less intense and can continue for long periods of time. (Houston, 2006) Although all energy systems turn on at the same time the recruitment of an alternative system occurs when the current energy system is almost depleted. During exercise an athlete will move through these metabolic pathways. As exercise begins, ATP is produced via anaerobic metabolism. With an increase in breathing and heart rate, there is more oxygen available and aerobic metabolism begins and continues until the lactate threshold is reached. If this level is surpassed, the body can not deliver oxygen quickly enough to generate ATP and anaerobic metabolism kicks in again. Since this system is short-lived and lactic acid levels rise, the intensity can not be sustained and the athlete will need to decrease intensity to remove lactic acid build-up. (Houston, 2006) Football is a sport which combines strategy with physical play. The objective of the game is to score points by advancing the ball into the opposing team's end zone. The ball can be advanced by carrying it or by throwing it to a teammate. Points can be scored in a variety of ways, including carrying the ball over the opponent's goal line, catching a pass thrown over that goal line, kicking the ball through the goal posts at the opponent's end zone, or tackling an opposing ball carrier within his end zone. The winner is the team with the most points when the time expires. (Ekblom, 1986) With sporting events such as cycling, swimming and running, where the intensity is constant for the duration of the event, it is possible to estimate the relative contribution of each energy system. For example, the energy for the 100 metre sprint is split 50% from the ATP-PC system and 50% from the anaerobic glycolysis system, whereas the marathon relies entirely on the aerobic system (Newsholme et al, 1992). By contrast, games such as football are characterized by variations in intensity. Short sprints are interspersed with periods of jogging, walking, moderate-paced running and standing still. This kind of activity has been termed "maximal intermittent exercise". (Jones, 1986) It would seem reasonable to assume that during a football game all three energy systems would be required, as intensity varies from low to very high. However, because it is not obvious just how fast, how many and how long the sprints are, and just how easy and how long the intervening periods are, it is difficult to determine which of the energy systems are most important. ENERGY SYSTEMS IN FOOTBALL Reilly and Thomas (1976) have investigated the patterns of football play in the old first division. They soon found out that a player would change activity every 5 to 6 seconds, and on average he would sprint for 15 meters every 90 seconds. They found the total distance covered varied from 8 to 11km for an outfield player - 25% of the distance was covered walking, 37% jogging, 20% running below top speed, 11% sprinting and 7% running backwards. Ohashi and colleagues, who have been researching football in Japan, confirmed these findings, showing 70% of the distance was covered at low to moderate pace below 4m/s, with the remaining 30% covered by running or sprinting at above 4m/s. Thus, for example, if a football player covers 10km in total, around 3km will be done at fast pace, of which probably around 1km will be done at top speed. The pattern of football play has also been expressed in terms of time. Peter Apor have described football as comprising sprints of 3 to 5 seconds interspersed with rest periods of jogging and walking of 30 to 90 seconds. Therefore, the high to low intensity activity ratio is between 1:10 to 1:20 with respect to time. The aerobic system will be contributing most when the players' activity is low to moderate, especially when they are walking, jogging and running below maximum. Conversely, the ATP-PC and anaerobic glycolysis systems will contribute during high-intensity periods. These two systems can create energy at a high rate and so are used when intensity is high. The above research has described the average patterns of play during football and from this we can reasonably deduce when each of the energy systems is contributing most. There is also evidence that the aerobic system is extremely important for football. Reilly had found heart rate to average 157 bpm in athletes. This is the equivalent of operating at 75% of your VO2max for 90 minutes, showing that aerobic contributions are significant. This is confirmed by the fact that various studies have shown footballers to have VO2max scores of 55 to 65 ml/kg/min. These VO2max scores represent moderately high aerobic power. Reilly and Thomas (1976) have shown that there was a high correlation between a player's VO2max and the distance covered in a game. This was later on confirmed by Smaros (1980) who also showed that VO2max correlated highly with the number of sprints attempted in a game. The aerobic system is crucial for fuelling the low to moderate activities during the game, and as a means of recovery between high-intensity bursts. As the sprints a player makes are mostly 10 to 25 meters in length, or 3 to 5 seconds in duration, some researchers have assumed that the ATP-PC system will be the most important. However, since football has an intermittent intensity pattern, just because the sprints are brief does not mean that anaerobic glycolysis does not occur. Instead research has shown that anaerobic glycolysis will begin within 3 seconds. To determine whether anaerobic glycolysis is significant during football, researchers have analysed blood lactates during match play. Tumilty and colleagues from Australia cite research varying from 2 mmol/l, which is a low lactate score indicating little anaerobic glycolysis, to 12 mmol/I, which is quite a high score. Most studies seem to find values in the 4-8 mmol/I range, which suggests that anaerobic glycolysis has a role. Ekblom from Sweden has shown that the level of play was crucial to the lactate levels found. Division One players showed lactate levels of 8-10 mmol/1 progressively down to Division Four players showing only 4 mmol/1. Tumilty and colleagues have concluded that the contribution of anaerobic glycolysis remains unclear, but is probably significant. They suggest that the tempo of the game may be crucial to whether anaerobic glycolysis is significant or not. Thus based on the researches mentioned above, we can say that for the high-intensity bursts during play both the anaerobic glycolysis and the ATP-PC systems contribute, but that the ATP-PC system is more important. This is because the ratio of high-intensity to low-intensity activity is between 1:10 and 1:20 by time. The high-intensity periods are very short and the rest periods relatively long. Therefore, the ATP-PC system will probably be more useful and also has sufficient time to recover. Research has also shown that lactate values become moderately high but not so high as to indicate that the anaerobic glycolysis system is working extremely hard. This was confirmed by Smaros who showed that glycogen depletion was mostly in the slow-twitch muscle fibres, which suggests that glycogen is being used for the aerobic system but not the anaerobic system. Physiological responses. So what are the consequences of the use of these cycles? The most important muscle that adapts to training is the heart. During exercise, it pumps blood containing oxygen, fluids and nutrients to the active muscles. Blood flow then drains the metabolic waste products away. The more blood pumped, the more oxygen is available to the exercising muscles. The heart adapts to aerobic exercise over time so it can pump more blood per stroke. In football athletes, the cardiac output can increase up to eight times the resting output. This is brought about not only by an increase in heart rate, but also by a training-induced increase in the stroke volume - the amount of blood ejected with each heartbeat. Also, the stroke volume can increase up to 50 to 60 percent during exercise. This is due to an increased force of contraction and a greater emptying of the heart chamber. (Frayn, 1996) The circulatory system also adapts in football. During play, blood flow is redistributed-less blood goes to all major organs except the heart and brain, and more blood flows to the working muscles and skin. At rest, 20 percent of blood flows to the muscles, compared to 88 percent at maximum exertion. (Ekblom, 1986) Arteries and veins have the capability to either constrict or dilate, rapidly redistributing blood flow to meet the demands of exercise. During exercise, the arteries dilate in the working muscles and blood flow increases through the smallest vessels (capillaries), which were previously closed. The increased flow of blood to the muscles increases the exchanges of oxygen, the release of heat and the removal of metabolic wastes: lactic acid and carbon dioxide. (Budgett, 2000) The nervous system prepares the body for exercise by secreting hormones signaling dilation of the blood vessels in the heart and working muscles, and secretion of hormones in inactive tissue for constriction of blood vessels. With training, these systems act more efficiently and rapidly to redistribute blood. (Budgett, 2000) The total number of red blood cells stays the same or slightly increases, but with adaptation to aerobic training, more water and dissolved proteins are added to the plasma volume to effectively thin the blood. The result is an increase in the total plasma volume and a decrease in the relative concentration of the red blood cells. (Budgett, 2000) Football, just like any other sport, also causes major changes in the muscles. During exercise, muscle oxygen consumption increases up to 70 times above resting values. More than 4,000 capillaries may be delivering blood to each square millimeter of muscle cross-section. In exercise, the body develops more mitochondria, the subcellular powerhouses that use oxygen to convert glycogen to usable energy known as ATP (adenosine triphosphate). Training does not significantly increase or change the fiber type, but it does maximize the abilities of the particular fiber type. Training for speed and power develops the fast-twitch fibers, while training for endurance develops the slow-twitch fibers. (Brooks, 1996) Nutritional Intervention Nutrients get converted to ATP based upon the intensity and duration of activity, with carbohydrate as the main nutrient fueling exercise of a moderate to high intensity, and fat providing energy during exercise that occurs at a lower intensity. Fat is a great fuel for endurance events, but it is simply not adequate for high intensity exercise such as sprints or intervals. (Astrand, 1986) As exercise intensity increases, carbohydrate metabolism takes over. It is more efficient than fat metabolism, but has limited energy stores. This stored carbohydrate (glycogen) can fuel about 2 hours of moderate to high level exercise. After that, glycogen depletion occurs. An athlete can continue moderate to high intensity exercise for longer simply replenishing carbohydrate stores during exercise. This is why it is critical for football athletes to eat easily digestible carbohydrates during moderate exercise that lasts more than a few hours. (Ekblom, 1986) As exercise intensity increases, carbohydrate metabolism efficiency drops off dramatically and anaerobic metabolism takes over. This is because the body can not take in and distribute oxygen quickly enough to use either fat or carbohydrate metabolism easily. In fact, carbohydrates can produce nearly 20 times more energy per gram when metabolized in the presence of adequate oxygen than when generated in the oxygen-starved, anaerobic environment that occurs during intense efforts (sprinting). With appropriate training these energy systems adapt and become more efficient and allow greater exercise duration at higher intensity.(Ekblom, 1986) Football is a physically demanding sport and needs a high rate of energy production. This can only be done by the breakdown of carbohydrates. The importance of high muscle glycogen stores for performance in events lasting longer than 60 minutes has been demonstrated by numerous researchers. The diets of players involved in an exhibition match have been manipulated, with those players having higher muscle glycogen stores before the match also covering a greater distance at a faster pace during the match. This effect was particularly noticeable towards the end of the match when glycogen always becomes lowered - and many goals are often scored as the game tends to open up. Therefore, a high-carbohydrate diet leads to increased muscle glycogen stores, which in turn leads to a greater distance covered during the final stages of the match, which increases team optimal performance. (Ekblom, 1986) Energy levels pre and post performance There are a number of data which exposes the fact that most football athletes experience greater stress during pre-season practice than in the actual game. This makes them vulnerable to a lot of injuries during pre-season practice. From 1995 to 2001, 21 young football players reportedly died from heat stroke in the United States during the said period. This may be related to the intensity and duration of practice, scheduling of fluid breaks, uniform configurations, and number of sessions per day. (Hargreaves, 2006) It was also observed that mandatory preseason football practices generally begin in the late summer for the fall youth and high school football seasons. With these physically demanding sessions being held during the hottest and most humid part of the year for many teams, it is no surprise that the high incidence of on-field heat-related problems is expected. Thus it is said that greater energy expenditure is expected during practices than during the actual game itself. CONCLUSION AND RECOMMENDATIONS Considering the energy needs of football players, it is a must that we give them proper nutrition and protect them from forms of stresses in order to avoid injuries and strains in their health. These can be achieved by some recommendations, which we are gong to discuss now. A knowledge of the energy system involved in football will make us reduce injury rates among these athletes by placing more deliberate attention to progressive training and acclimatization, utilizing appropriate practice modification that reflects the environmental and physiological challenges facing football players. Acclimatization plans and practice modification are created to improve the football players’ safety profile while practicing. Appropriate fluid replacement during and after practice also contributes to heat illness reduction. Water is an appropriate and adequate fluid replacement during preseason practice, although sports drinks can be advantageous in encouraging greater fluid intake and providing energy (carbohydrates) and electrolytes, which help to avert fatigue and maintain fluid balance. (Fell, 1997) A preparticipation exam should be integrated into the athlete’s routine periodic health screening and specifically address medication and supplement use, cardiac disease, and other health problems. Any one of these factors may increase the risk of illness during football practices and games. Proper nutrition should be observed among athletes. An ideal diet for football players requires 55 to 60 percent of their daily caloric intake to come from carbohydrates, 15 percent from protein and 30 percent from fat. Diet should be 2/3 carbohydrates and 1/3 protein, with an emphasis on moderate fat. Carbohydrates-containing foods with lower fat should be emphasized. (Houston, 2006) During Two-a-days/Pre-season, carbohydrates must be the main fuel source. Players will not recover in time for the next practice unless carbohydrate intakes are adequate. While protein is needed in an athlete’s diet to build and maintain muscle mass, excess protein consumption will be stored as fat and may dehydrate the body. (Houston, 2006) For optimal recovery after competition, protein-carbohydrate mix should be consumed. The snack should contain 6 grams of protein and 35 grams of carbohydrates. The primary goal for providing athletes with a pre-game meal is to fuel the body for competition. The best strategy is to choose lower-fat foods. Fats take longer to digest, so high-fat meals can leave the athlete with a full, heavy stomach and not enough energy to perform at his best. (Houston, 2006) After the game, players should still watch out for their diet. They should replenish fluids and carbohydrates immediately following the game by sports drinks, sports bars or fruit. During two-a-day practices, football players need to eat about 5,000 calories per day. Some players need as much as 9,000 calories per day. A sports dietitian can create a nutrition plan to help players build muscle mass, increase speed, or lose body fat. (Jones, 1990) Football players need more than 2.7 grams of carbohydrate per pound of body weight per day (6 g/kg/day). During hard training, they may need 3.6 to 4.5 grams per pound of body weight per day (8 to 10 g/kg/day). Good carbohydrate choices include whole grain breads and cereals, fruits, and vegetables. (Jones, 1990) Football players need 0.6 to 0.8 grams of protein per pound of body weight per day (1.4–1.7 g/kg/day). Good sources of protein are fish, chicken, turkey, beef, low-fat milk, cheese, yogurt, eggs, nuts, and soy. (Jones, 1990) Football players need at least 0.45 grams of fat per pound of body weight per day (1 g/kg/day). Healthy fats, such as canola oil, olive oil, and nuts are good choices. (Jones, 1986) Football players may sweat at a rate of 10 liters per day, and they can lose 12 pounds of sweat in practice. It can be hard to get enough fluids, especially during two-a-day practices in the summertime. The uniform and pads add weight, which makes the body work harder when players exercise in the heat. This can contribute to dehydration. References: 1. Apor, P. (1988). "Successful formulae for fitness training." in Science and Football (eds. Reilly at al). E, and F. N. Spoon, London 2. Astrand, P. O. & Rodahl, K., (3rd Edition 1986) Textbook Of Work Physiology, New York, Mcgraw Hill. 3. Brooks, G. A., Fahey, T. D., & White, T. P., (2nd Edition 1996) Exercise Physiology: Human Bioenergetics And Its Application, London Mayfield. 4. Budgett R. (2000) The Overtraining Syndrome. In Harries, M., Mclatchie, G, Williams,C And King, J. Abc Of Sports Medicine. Bmj Books 5. Ekblom, B. (1986). "Applied physiology of football." Sports Medicine, 3, 50-60 6. Fell D. Understanding the Control of Metabolism. Portland Press. 1997. 7. Frayn KN. Metabolic Regulation. Portland Press. 1996. 8. Hargreaves, M., Spreight, L, (2006) Exercise Metabolism 2nd Ed, Champaign, Il., Human Kinetics. 9. Houston (2006) Biochemistry Primer For Exercise Science. 3rd Ed Human Kinetics. 10. Jones, D. & Round, E. M., (1990) Skeletal Muscle In Health And Disease, Manchester, Mup. 11. Jones, N. L., Mccartney, N. & Mccomas, A. J. (Eds), (1986) Human Muscle Power, Champaign, Il., Human Kinetics. 12. Kreider, R. B. Et Al. (Eds) (1998) Overtraining In Sport. Champaign, Human Kinetics 13. Macleod, D. (1992) Intermittent High Intensity Exercise, London, E & Fn Spon. 14. Maharam, L. G., Bauman, P. A., Kalman, D., Skolnik, H. & Perle, S. M. (1999) Masters Athletes: Factors Affecting Performance. Sports Med, 28, 273-85. 15. Manore Mm Et Al. (2000). Nutrition And Athletic Performance. Joint Position Stand Of Acsm/Ada/Dc. Msse 32:2130-2145. 16. Maughan R .The athletes diet: nutritional goals and dietary strategies. Proc of the Nutrition Society (2002),61,87-96 17. Nagahama, K., Isokawa, M., Suzuki, S., & Ohashi, J. (1988). in Science and Football, as above (1) 18. Newsholme, E. A. & Leech, T., (1983) Biochemistry For The Medical Sciences, New York, John Wiley. 19. Ohashi, J., Isokawa, M., Nagahama, K. & Ogushi, T. (1988). in Science and Football, as above (1) 20. Poortmans, J. R. (1988) Principles Of Exercise Biochemistry, Basle, Karger. 21. Reilly, T. (1990). "Football". in Physiology of Sports (eds Reilly et al.) E. and F. N. Spoon, London 22. Smaros, G. (1980). "Energy usage during a football match." In Proceeding 1st International Congress on Sports Medicine Applied to Football, Vol. II (ed L. Vecchiet), D. Guanello, Rome 23. Stryer, L., (1995) Biochemistry (4th Ed), New York, W H Freeman. 24. Tumilty, D., Hahn, A., Telford, R. & Smith, R. (1988). In Science and Football, as above (1) 25. Viru, A.,Viru, M., (2001) Biochemical Monitoring Of Sport Training, Human Kinetics Read More