B4 H) Effects of Exercising
When you start more vigorous exercise (such as power walking), your muscles will be contracting more and will therefore require more energy. The muscle cells get the additional energy that they require from respiration reactions. As the muscle cells are undertaking more respiration reactions, they need a greater supply of oxygen. The body increases the supply of oxygen to the muscle cells in a few ways. Here are some of those ways:
- We increase both the breathing rate and the volume of air breathed in for each breath; we breathe more frequently and take in a greater quantity of air each time. This is to get more oxygen into the blood stream.
- Our heart rate and blood pressure increases to move blood around the body faster, thus meaning that more oxygen is delivered to the muscle cells (and more carbon dioxide gets taken from the muscle cells; carbon dioxide is a waste product of respiration).
When we then exercise really vigorously (such as sprinting), our muscle cells undertake even more respiration reactions. However, our body will be unable to supply enough oxygen to the muscle cells, which results in the muscle cells respiring anaerobically (without oxygen) rather than aerobically. Anaerobic respiration is not the most efficient way of converting glucose into energy. Also, lots of anaerobic respiration reactions leads to the build-up of lactic acid, which can become painful and cause muscle fatigue (which is where the muscles get tired and stop contracting efficiently; it can cause cramp). However, anaerobic respiration allows muscle cells to produce energy for a while when there is no oxygen available.
Anaerobic respiration leads to oxygen debt, which is where your body must repay the oxygen that it did not get during the anaerobic respiration reactions. It is the amount of oxygen that is required to convert the lactic acid produced during anaerobic respiration into carbon dioxide (CO2) and water (H2O). Oxygen debt is why our breathing rate and heart rate stays quite high for a while after vigorous exercise; we need to keep supplying the muscle cells with oxygen so that they can repay the oxygen debt/ react lactic acid with oxygen to produce carbon dioxide and water.
Another way that your body deals with the lactic acid produced during anaerobic respiration is to take the lactic acid to the liver via the bloodstream. The liver then converts the lactic acid back into glucose, which can then be used for respiration at another point in the future.
We can measure breathing rate by counting the number of breaths in a certain period of time (e.g. 30 seconds or 1 minute). And, we can measure heart rate by using a heart rate strap, smartwatch or by placing 2 fingers on your neck and counting the number of beats in a certain period of time (like 10 seconds).
We then undertake a few different activities with different levels of intensity and monitor how breathing rate and heart rate change after each of the different activities. I am going to have my activities as sitting, walking, jogging and sprinting. I will do 5 minutes of each of the different activities and monitor my breathing rate and heart rate after each of the activities. I can then plot my results on a bar chart.
The bar chart for the effect that exercise has on breathing rate (count rate) is shown below.
The bar chart for the effect that exercise has on heart rate is shown below.
So, an increase in the intensity of exercise will increase both the heart rate and the breathing rate (count rate) of individuals.