At the 2008 Beijing Olympic Games David Davies

At the 2008 Beijing Olympic Games, David Davies won the silver medal in the swimming 10 kilometre marathon event, in a time of 1 hour 51 minutes and 53. 1 seconds. Explain how the majority of energy used during the race would be provided. (7 marks) A. Majority produced by the aerobic system/oxygen B. Glycolysis/Anaerobic glycolysis C. Carbohydrates/glycogen/glucose D. broken down into pyruvate/ pyruvic acid E. Some ATP produced/2 ATP F. Krebs cycle G. Fats/triglycerides/fatty acids/glycerol H. Beta oxidation I. Oxidation of acetyl-coenzyme-A/Citric acid/ production of CO 2 J. Electron transport chain K. Water/H 2 O formed/hydrogen ions formed (H+)/ hydrogen/protons L. Large quantities of ATP produced or resynthesised/34 - 36 ATP

Objective: To be able to explain how energy is produced during initial exercise and particularly at high intensity.

*When the body is unable to provide the oxygen required to resynthesise ATP it must start to work anaerobically. There are two anaerobic energy systems: 1. 2. Phosphocreatine (PC) energy system (or ATP-PC system) Lactate anaerobic energy system Anaerobic energy systems

PC → P + C + Energy AND Energy + P + ADP = ATP *For every molecule of PC broken down, one molecule of ATP can be resynthesised. *No oxygen is required. *Energy is released very rapidly and there are no waste products. *Stores only last for 5 -8 s of high intensity exercise. *It is therefore excellent for very high short intensity activities (e. g. 100 m sprint) but not for anything longer. *PC can be resynthesised quickly. 50% in 30 s, 100% in less than 4 mins (this requires O 2 so intensity must be reduced).

*This system involves the partial breakdown of glucose (oxygen is required for full breakdown). *2 molecules of ATP are produced for every molecule of glucose (19 times less than aerobic!). *Lactic acid is produced as a by-product. *This system can therefore only be sustained for between 10 seconds and 3 mins. *Few chemical reactions involved so energy can be produced quickly. summary of anaerobic energy systems

*Hydrogen is released during both glycolysis and the Kreb’s cycle. *These H ions combine with oxygen (in the electron transport chain). *At some point there becomes too many H ions for the amount of O 2 available. Excess H ions combine with pyruvate to form lactic acid. *The build up in lactate acid is a contributing factor fatigue. It produces an acidic environment which slows down enzyme activity and stops the breakdown of glucose. *It also effects nerve endings causing some pain.

Lactic acid is often seen as a ‘waste product’ but can be a useful energy source. During recovery from intense exercise (when O 2 is available) lactic acid can take the following routes: *1. conversion to water and carbon dioxide (after being converted back to pyruvate and entering the Kreb’s cycle) *2. conversion into glycogen and stored in liver / muscles *3. conversion into protein *4. conversion into glucose *5. conversion into sweat and urine

Objective: To be able to define lactate threshold and OBLA, and the effect on performance.

*Onset of blood lactic acid accumulation (OBLA) is the point at which lactic acid starts to accumulate in the blood (above 4 mmol per litre). *This occurs when there is insufficient O 2 available to break down lactic acid. *As exercise intensity increases, O 2 consumption increases until VO 2 max is reached. Any increase in intensity will then cross the lactate threshold. *Predominantly aerobic ATP resynthesis switches to anaerobic when there is insufficient oxygen in the mitochondria to combine with the H released when glucose is broken down. *OBLA shows fitness levels as the longer a performer can hold off lactate accumulation, the fitter they are.

* There are three energy systems that can regenerate ATP: *the ATP–PC system (anaerobic) *the lactic acid system (anaerobic) *the aerobic system The use of each of these systems depends on the intensity and duration of the activity: *If the activity is short duration (less than 10 seconds) and high intensity, we use the ATP–PC system. *If the activity is longer than 10 seconds and up to 3 minutes at high intensity, we use the lactic acid system *If the activity is long duration and submaximal pace, we use the aerobic system.

*During nearly all activities both systems will be involved at the same time, the one which is more predominant depends on: *The level of intensity *The duration *Your level of fitness *

* Muscle fatigue is the inability to maintain muscle contractions. There are numerous causes including: *An increasingly acidic environment caused by the build up of lactic acid and excess H ions results in a breakdown in chemical reactions. *Glucose stores being depleted. *A change in the balance of chemicals that instigate muscle contraction. *Dehydration causing increased blood viscosity (leading to increased HR, overheating etc. ).

* *When an athlete crosses their lactate threshold fatigue will quickly set in. *Pacing themselves to work near, but not over, their lactate threshold is key to success in endurance events. *As an individual becomes fitter they will be able to work at a higher percentage of their VO 2 max (higher intensity) before crossing the lactate threshold (and moving to anaerobic energy systems). The Brownlee Brothers

*“he sprinted away for victory” *“you have to race the conditions” *“It was hot. I just made sure I took on plenty of water” *“I wish the flipping idiot had just paced it, he could have jogged and won” *“I was happy with 2 nd or 3 rd so I took it easy” *An increasingly acidic environment caused by the build up of lactic acid and excess H ions results in a breakdown in chemical reactions. *Glucose stores being depleted. *A change in the balance of chemicals that instigate muscle contraction. *Dehydration causing increased blood viscosity (leading to increased HR, overheating etc. ).

* *The ability to withstand the effects of lactic acid accumulation. *This may be related to the amounts of bicarbonate in the blood (which can combine with lactic acid to reduce its acidity). *May just be down to motivation/determination levels.

* To recover from intense exercise the body needs to: *Restore ATP levels *Restore phosphocreatine levels *Deal with excess lactic acid (either by oxidating lactic acid into pyruvate, or by converting lactic acid into glycogen in the liver – both are eventually used to create ATP) *Resaturating myoglobin with oxygen *Restoring muscle glycogen levels (high carb diet)

Energy System Fuel Used ATP-PC ATP PC Lactic Acid (Anaerobic Glycolysis) Glycogen / Glucose Aerobic (Glycolysis) Carbohydrates Fats Proteins (extreme circumstances) Intensity / Duration Contribution Sporting Examples High / Short Up to 10 s (approx) Diving Gym vault 100 m sprint High Intensity 10 s – 3 mins Short – Moderate Duration Depending on intensity Submaximal Extended Peak efficiency achieved in 1 -2 mins. Dominant system when HR <85% 200 m sprint 400 m sprint 50 m swim 1500 m Marathon Triathlon

* Many elite swimmers use blood lactate sampling during training as a means of establishing their training load. (i) What do you understand by the term lactate threshold ? (2 marks) (ii) How is lactate threshold related to VO 2 max? (2 marks) (iii) Explain how knowing blood lactate levels during a swim might assist an elite performer. (2 marks) i) 1 Exercise has become anaerobic; 2 Lactic acid accumulates in blood; 3 4 mmol/L of blood. (ii) 1 Lactate threshold is some proportion/percentage of VO 2 max; 2 Proportion/percentage increases as fitness increases. (iii) 1 Accurately measures intensity of training; 2 Elite performers need to train close to their Lactate threshold/VO 2 max;

EXAM QUESTION Successful track and field performance is dependent upon an effective energy supply. Figure 3 shows how the supply of each energy system varies according to the duration of a task. 1. Identify each of the energy systems A, B and C. (2 marks) 2. Explain how the differing energy sources of these systems are used during: * (i) a series of javelin throws; (2 marks) * (ii) a long-distance run of increasing intensity. (4 marks)

* Elite games players require high levels of fitness and psychological preparation, therefore regular fitness testing and after-match performance analysis are common. Figure 1 illustrates the relationship between the concentration of blood lactate and the workload. a) Use Figure 1 to identify the workload level at which lactate threshold occurs, and explain why lactate (lactic acid) tends to be produced when a player is exercising. (3 marks) (b) Explain how lactate is removed from the blood by the body. (4 marks)

a) 1. Lactate threshold correctly identified as between 500 and 800 Watts; 2. Lactate from anaerobic (glycolosis)/lack of oxygen (O 2)/high demand/lack of supply; 3. High intensity/workload exercise/equiv. b) 1 Used as respiratory substrate/for respiration / energy / using oxygen (O 2)/ lactate to replenish ATP; 2 Converted to pyruvate/pyruvic acid; 3 then to Carbon Dioxide (CO 2) and water; 4 In inactive muscle and various tissues/organs; 5 Converted to glycogen/glucose; 6 In liver; 7 Some excreted in sweat/urine/conversion to protein