Exercise

• When you exercise, your body responds in different ways to get enough energy to your cells
• When you exercise you respire more
• Muscles need energy from respirationn to contract. When you exercise, some of your muscles contract more frequently than normal so you need more energy. This energy comes from increased respiration
• The increase in respiration in your cells means you need to get more oxygen into them
• When doing exercise, your breathing rate and breath volume increase to get more oxygen into the blood, and your heart rate increases to get this oxygenated blood around the body faster. This removes CO2 more quickly at the same time
• When you do really vigorous exercise, your body can't supply oxygen to your muscles quickly enough, so they start respiring anaerobically
• Respiring anaerobically is not the best way to transfer energy from glucose because lactic acid builds up in the muscles, which gets painful
• Long periods of exercise also cause muscle fatigue - the muscles get tired and then stop contracting efficiently
• Lactic acid is formed from the incomplete oxidation of glucose
• Anaerobic respiration leads to an oxygen debt
• After resorting to anaerobic respiration, when you stop exercising you'll have an 'oxygen debt'
• An oxygen debt is the amount of extra oxygen your body needs to react with the build up of lactic acid and remove it from the cells
• Oxygen reacts with the lactic acid to form harmless CO2 and water
• In anaerobic respiration you have to ''repay'' the oxygen that you didn't get to your muscles in time, because your lungs, heart and blood couldn't keep up with the demand earlier on. This means you have to keep breathing heard for a while after you stop, to get more oxygen into your blood, which is transported to the muscle cells
• The pulse and breathing rate stay high whilst there are high levels of lactic acid and CO2
• Your body also has another way of coping with the high level of lactic acid - the blood that enters your muscles transports the lactic acid to the liver. In the liver, the lactic acid is converted back to glucose
• You can measure breathing rate by counting breaths, and heart rate by taking the pulse
• To take your pulse, put 2 fingers on the inside of your wrist of neck and count the number of pulses in 1 minute
• You could take your pulse after:

  Sitting down for 5 minutes

  Then after 5 minutes of gentle walkingThen again after 5 minutes of slow jogging

  • Then again after running for 5 minutes
• You could take your pulse after:

  • Sitting down for 5 minutes
  • Then after 5 minutes of gentle walking
  • Then again after 5 minutes of slow jogging
  • Then again after running for 5 minutes

  and plot your results in a bar chart

  
• Your pulse will increase the more intense the execise is, as your body needs to get more oxygen to the muscles and take more carbon dioxide away from the muscles
• To reduce the effect of any random errors on the results, do it as a group and plot the average pulse rate for each exercise