AEROBIC & ANAEROBIC EXERCISE Learning Objectives To be able to explain the difference between aerobic and anaerobic respiration. To be able to explain the different energy sources for aerobic and anaerobic activity. Content 1.3.1 Energy: the use of glucose and oxygen to release energy aerobically with the production of carbon dioxide and water; the impact of insufficient oxygen on energy release; the by-product of anaerobic respiration (lactic acid) 1.3.2 Energy sources: fats as a fuel source for aerobic activity; carbohydrates as a fuel source for aerobic and anaerobic activity

Aerobic & Anaerobic Put simply “aerobic is with oxygen” and “anaerobic is without oxygen”. These relate to how hard you are making the body work – the intensity of the activity. Activities that require maximal, or near maximal, effort are anaerobic (100m). When we work at this intensity we can’t supply the working muscles with oxygen to release energy, so they do it without oxygen (anaerobically). We then pay back an oxygen debt after the activity. The problem with this method is we can only do it for a limited period of time. Therefore activities that last longer (5000m) are mainly aerobic.

EVENT PREDICTED TIME IF WE COULD WORK ANAEROBICALLY THROUGHOUT CURRENT MEN’S WORLD RECORD CURRENT WOMENS WORLD RECORD 100m 10 seconds 200m 20 seconds 400m 40 seconds 800m 1500m 2 minutes 30 seconds 3000m 5000m Work out the predicted time for the 800m, 3000m and 5000m if we could continue to run at the same intensity as for the 100m.

Can you name 3 or more of the world record holders? EVENT PREDICTED TIME IF WE COULD WORK ANAEROBICALLY THROUGHOUT CURRENT MEN’S WORLD RECORD CURRENT WOMENS WORLD RECORD 100m 10 seconds 9.58 10.49 200m 20 seconds 19.19 21.34 400m 40 seconds 43.03 47.60 800m 1 minute 20 seconds 1:40.91 1:53.28 1500m 2 minutes 30 seconds 3:26.00 3:50.07 3000m 5 minutes 7:20.67 8:06.11 5000m 8 minutes 20 seconds 12:37.35 14:11.15 Can you name 3 or more of the world record holders? (If they hold more than 1 record they only count once)

10.49 (Florence Griffith Joyner) EVENT PREDICTED TIME IF WE COULD WORK ANAEROBICALLY THROUGHOUT CURRENT MEN’S WORLD RECORD CURRENT WOMENS WORLD RECORD 100m 10 seconds 9.58 (Usain Bolt) 10.49 (Florence Griffith Joyner) 200m 20 seconds 19.19 (Usain Bolt) 21.34 (Florence Griffith Joyner) 400m 40 seconds 43.03 (Wayde van Niekerk) 47.60 (Marita Koch) 800m 1 minute 20 seconds 1:40.91 (David Rudisha) 1:53.28 (Jarmila Kratochvilova) 1500m 2 minutes 30 seconds 3:26.00 (Hicham El Guerrouj) 3:50.07 (Genzebe Dibaba) 3000m 5 minutes 7:20.67 (Daniel Komen) 8:06.11 (Wang Junxia) 5000m 8 minutes 20 seconds 12:37.35 (Kenenisa Bekele) 14:11.15 (Tirunesh Dibaba)

Aerobic Respiration We need increased amounts of energy when we exercise. This energy comes from our food. This energy can be released using oxygen (aerobically) or without oxygen (anaerobically). Aerobic exercise involves working at a lower intensity, so you’re not putting in maximal effort throughout. Instead you tend to have to work for a longer period of time. We are able to release more energy using oxygen, therefore it allows us to maintain a good work rate for longer periods of time.

Aerobic Respiration C6H1206 + 6O2  6CO2 + 6H20 + Energy Glucose Oxygen Carbon Dioxide Water During aerobic respiration: Energy is released from respiration Glucose is needed Oxygen is needed Carbon dioxide is produced Water is produced From the equation it is clear to see why: Oxygen levels go down Carbon dioxide levels go up Levels of water vapour increase

Anaerobic Respiration If the level of exercise is too intense, for example 100m sprint, oxygen can’t be supplied quickly enough to release energy aerobically. Glucose  Energy + Lactic Acid When this happens we release energy anaerobically, which we can only do for a short period of time as it also produces lactic acid. If allowed to build up, lactic acid increases the acidity of blood and muscle cells causing the muscle to fatigue. This forces a performer to slow down or stop to recover before working at high intensity again. For example, a striker sprinting to chase a long pass walks/jogs back into position before sprinting again. When anaerobic exercise is stopped or the intensity is slowed and oxygen is present, lactic acid can be broken down into carbon dioxide and water which is breathed out.

Anaerobic Respiration During the recovery phase the performer continues to breathe heavily, even though they are not working hard at that moment. This allows them to take in additional oxygen to pay back the oxygen debt. The oxygen debt is the amount of oxygen consumed during recovery, above that which would normally be consumed at rest. The extra oxygen is used to: Restock oxygen in the muscles and tissues Break down any lactic acid that has formed.

Check your understanding… ACTIVITY AEROBIC OR ANAEROBIC? 100m sprint 1500m Sprint finish in 5000m Racing dive to start a swim race Throwing a discus Playing a tennis set 4 x 100m relay

Check your understanding… ACTIVITY AEROBIC OR ANAEROBIC? 100m sprint Anaerobic 1500m Aerobic Sprint finish in 5000m Racing dive to start a swim race Throwing a discus Playing a tennis set 4 x 100m relay

Energy Sources The food we eat contains different nutrients, some of which can be broken down to release energy. Carbohydrates and Fats are our main source of energy Fats can be broken down as an energy source for aerobic activity. Carbohydrates can be used for aerobic and anaerobic activity. The carbohydrates we consume in our diet can only be stored in limited quantities. Carbohydrates are broken down into glucose and enter the circulatory system. Some of this glucose is absorbed by muscle cells and is readily available, while excess glucose is converted to fat and stored.

Energy Sources Fats provide most of the energy required while we are at rest. The fat consumed in our diet is broken down into fatty acids and glycerol. The fatty acid can then be broken down to produce glucose. Fats are the most energy efficient source – they produce more energy than carbohydrates. However they take a lot longer to break down and require a lot more oxygen. This is because they are slow to digest and they have to be converted to a usable energy source. Due to the time it takes to use fats as an energy source, they are not used during anaerobic exercise. Fats are important in endurance events because: There is enough time for the fats to be broken down. Endurance events are aerobic so there is a lot of oxygen available. Fats provide a high amount of energy required to complete endurance events.

Questions Explain how the intensity of an activity determines how energy is released (2 marks) Explain the term “oxygen debt” and describe its importance in the recovery process (3 marks) Complete the following: Glucose + _____________  Carbon Dioxide + ______ + Energy Explain why fats are a well suited energy source for endurance events. (3 marks)