Physical Activity by Far Provides the Greatest Demand for Energy Essay Example for Free

Physical Activity by Far Provides the Greatest Demand for Energy Essay Physical activity by far provides the greatest demand for energy. Discuss how the intensity and duration of the exercise period and the relative contributions of the body’s means for energy transfer affect performance. In your answer mention availability of O2, food fuels used, energy threshold points, enzyme control and how the fitness of the participant affect performance. 20 marks Intensity is how hard you work for and duration is the length of time you exercise for. The energy continuum is used to show how the energy systems interact, to provide energy for the resynthesis of ATP and highlights the predominance of each of the 3 energy systems related to duration and intensity of exercise. When we look at high intensity and short duration such as 100m sprinting or 1500m we say the exercise intensity is anaerobic. This is because it takes place without the presence of oxygen. This type of exercise will use ATP/PC and LA systems will be predominant systems. A threshold represents the point at which one energy system is over by another as predominant energy systems to provide the energy to resynthesis ATP. The ATP/PC also known as the alactic system has a duration of 3-10 seconds during high intensity activities. It takes place in the sarcoplasm of the muscle cell and produces 1ATP molecule with aid of the enzyme Creatine Kinase. This is why in activities such as the 100m sprint it is predominant as it is a short duration with high intensity. The Lactic acid system uses glucose as the energy source to produce ATP from ADT and Pi, through various processes (phosphorlation dehydration and cleavage). The whole system provides 2ATP molecules with the aid of the enzyme PFK, this system also takes place in the sacroplasm of the muscle cell. This system has a maximum duration of 3 minutes, as during this process pyruvate is produced eventually leading to a build up of lactic acid. Therefore this system is most predominant during activities such as the 1500m running. During the higher intensisty exercise, lactate production will start to accumulate above resting levels and this is termed the ‘lactate threshold’. When blood lactate levels reach 4mmol/l the exercise intensity is referred to as ‘ the onset of blood lactate accumulation’ (OBLA). At this point the production of lactate has exceeded the removal rate. OBLA will continue to increase if exercise intensity remains the same/ increases eventually causing muscle fatigue. During these 2 systems it is important to allow recovery time. This is because if OBLA is exceeded. The acidity of the blood rises. This will cause efficiency of enzymes to decrease and may even cause them to denature. If this were to occur there would be a decrease in break down of energy stores and rate at which the enzymes used of the resysnthes of ATP would also slow down. This would lead to a lack of energy and in turn lead to muscle fatigue. Enzyme control is therefore important as a decrease in blood pH leads to a decrease in performance due to the inhibition of enzymes. To uses these energy systems require the uses of carbohydrates as their food fuel. As a result lack of carbohydrate stores will lead to earlier on set of fatigue therefore decreasing the duration of time that you can continue to work at a high intensity. Training is used to delay the onset of OBLA; therefore the fitter you are the later the onset of fatigue. This will therefore enable you to train harder for longer. When considering medium to low intensity activities with long duration such as marathon running, we say the exercise intensity is aerobic as it is done in the presence of oxygen. The predominant energy system will be aerobic system. This system has three sub systems; Aerobic glycolisis, kerb cycle and electron transport chain. Glycolisis involves the phosphoration of glucose (which comes from carbohydrate stores) which makes the its more reactive. The phosphate molecules come from the conversion of ATP to ADP. During the 7 steps with in glycolisis a total of 2 ATP molecules we used and 4 produced with pyruvate as the by-product. During the kerb cycle Co enzyme A is used to stimulate the reaction between the reaction pyruvate to produce 2ATP molecules and the by-products carbon dioxide and hydrogen. This reaction takes place in the matrix of the cell. Finally the electron transport chain which uses the enzyme ATPsynthase. In the respiratory chain the hydrogen atoms from NADH gradually release all their energy to form ATP. In total the aerobic system produces 34molecules of ATP and has a duration of grater than 3 mins. This is the type of system that would be used for marathon running. When exercise intensity reaches a point that anaerobic energy systems cannot supply energy quick enough, it has to use the lactic acid system to continue to provide energy for the resysnthesis of ATP. During the aerobic system availability of oxygen need to be high otherwise the performer will not bale to maintain the same intensity for a long duration. Many athletes train at altitude for endurance events. This is because altitude training allows the body to naturally increase the number of red blood cells available in the blood. It must do this in order to supply working muscles with enough oxygen as the percentage of oxygen in the air at altitude is lower. This adaption will remain when returning to sea level. For this system to work efficiently it requires the both carbohydrate stores and fat stores. Carbohydrates are used first as they are easier to use. However with training your, you can make your body use fat stores earlier. This will have an advantage for long distance and endurance athletes as it allows them to train for a longer duration of time. Enzyme control should remain constant as there is little production of lactic acid as the Aerobic energy system is predomaniant. In conclusion there is never a point at which one energy system is being used, only points where on is more prominent than another. The energy continuum shows how the ratio of energy systems in use can vary between activates. It is also important to remember that energy system can only work efficiently if the have the correct availability to oxygen, the correct food stores, energy control is maintained and good fitness levels are maintained.