Respiration in muscles can happen in two different ways, aerobic respiration and anaerobic respiration. Aerobic respiration is where oxygen and glucose are combined to release energy, but it has two by-products, carbon dioxide and water.
Glucose + Oxygen → Carbon Dioxide + Water + Energy
C6H12O6 + 6O2 → 6CO2 + 6H2O + Energy
Anaerobic respiration is when glucose is used by itself to produce energy without oxygen. But it isnt as efficient and not as much energy is released, a by-product of it is lactic acid. The carbon dioxide that is produced is taken away by red blood cells and what ever is left over is taken by the plasma back to the lungs where goes through the alveoli into the lungs and is breathed out. The energy is used to carry out basic functions like make your muscles contract
1
and carry out chemical reactions.
Glucose → Lactic acid + Energy
These two ways of respiring occur in muscles, respiring aerobically in the muscles is carried out by the mitochondria. Anaerobic respiration occurs when there is not enough oxygen getting to the muscles for aerobic respiration to take place.
Input variables:
Intensity of exercise:
If the exercise is more intense then the heart rate will increase because the muscles are working harder, because they need more oxygen and glucose. Once oxygen is in the blood the heart needs to beat faster, so that oxygen and glucose get to the muscles that are working faster. However it is quite hard to measure and change intensity so I will not use this.
Type of exercise:
Some types of exercise involve using more muscles than others. So if more muscles are used more oxygen and glucose are needed, which means the heart rate will increase to pump it quicker. I will not change this variable, as it is not a continuous scale and is difficult to measure.
Fitness of person doing the exercise:
A more fit person has blood with higher oxygen carrying capacity. This is where the number of red blood cells increases. This makes the blood more efficient at carrying oxygen, so the heart of a fit person does not have to beat as hard or as fast to supply oxygen to the muscles to combine glucose and oxygen. Also a fit persons heart will pump more blood in 1 beat than an unfit person.
Frequency of Exercise (no. of reps)
If the exercise were repeated more times then the muscles would need to respire quicker. This means that they would need oxygen and glucose as fast as possible, in turn meaning that the heart would need to beat faster to supply the muscles. I have chosen this as my input variable.
For my exercise I have decided to do step-ups.
Prediction:
I think that as the duration of my exercise increases my heart rate will also increase. This is because the muscles I use for step-ups will be using more energy to contract, by the fibers in them sliding backwards and forwards.
If I work for longer it means I will respire quicker so more oxygen enters the blood. To get this glucose and oxygen to the more quickly my heart will have
2
to beat faster and this is why my heart rate will increase.
On a graph of duration of exercise against heart rate I would expect the line on it to rise steadily upwards in proportion and then slowly level off. This is because I will have to start doing exercise anaerobically and lactic acid will build up. I will have to start doing exercise anaerobically because the heart will not be able to supply oxygen any faster because there is a maximum BPM that
the heart can achieve.
Method:
1) Firstly I will measure my resting heart rate (pulse), and record it. (The easiest place to measure your pulse is on the left hand side of your upturned wrist with your index and middle finger)
2) Next I will find a step and do 10 step-ups at a rate that will be maintainable.
3) Straight after I will measure my pulse and record it.
4) I will have a rest period until my heart rate has dropped to its original resting rate. This is because if I did not and started doing step-ups again my heart rate would already be quite high.
5) Once my heart rate has dropped to its normal level I will do 20 step-ups at the same rate and record my heart rate straight after and record it.
6) I will have another rest period until my heart rate drops again.
7) I will repeat doing step-ups at the rate of; 30, 40, 50, 60, 70, 80, 90, 100, step-ups with a rest period between each and I will measure my heart rate in BPM each time. I have chosen this range as I am fairly confident that my heart will achieve its maximum B.P.M in the time given so I will have a complete set of readings, and it should also level off on a graph.
8) After a large rest period of a couple of hours, I will repeat exactly as before, twice more, and record all the results. These are check readings and I will take an average for each set of results, to make my readings more reliable.
Safety precautions:
The safety precautions I will take are to stop if I feel ill and to have someone with me just in case I pass out or get injured. I will also wear appropriate clothing and shoes.
3
Apparatus:
The only apparatus that I will need for this experiment is a stopwatch, and a
suitable set of stairs.
Results Table:
4
