How do different types of exercise affect heart rate

Investigation: How heart rate changes with exercise?

Aim:

The aim of this investigation is to find out how different types of exercise (jumping rope, jogging, weights, walking & stretching) affect the heart rate, and compare the heart rate after the exercise to the resting heart rate.

Hypothesis:

The heart rate after the exercise will be significantly higher than the resting heart rate. The more intense the exercise, the higher the heart rate as well.

Background information:

When the body is exercising the muscles respire to produce energy, so the muscles can contract. Oxygen is needed for this process; the oxygen is carried in the hemoglobin of the red blood cell. The heart and lungs need to work harder in order to get a greater amount of oxygen to the muscles for respiration. In muscle cellsdigested food substances are oxidized to release energy. These oxidation reactions are called cellular respiration. When muscles use oxygen in order to respire the process is called aerobic respiration:

Glucose + Oxygen Carbon Dioxide + Water

Important terms to consider:

Pulse: A rhythmical throbbing of the arteries as blood is propelled through    them.

Maximum heart rate: maximum heart rate (MHR) is the fastest rate at which your heart will be in one minute.

Target heart rate zone: The number of heartbeats per minute reflecting the exercise intensity that gains the maximum training benefits from an aerobic workout.

Exercise: Activity requiring physical effort, carried out especially to sustain or improve health and fitness

Variables:

Dependent Variable: Pulse (bpm)

Independent Variable: Different types of exercise (jumping rope, jogging, weights, walking & stretching)

Control (See table after Method)

Uncertainty of equipment:

Using a stopwatch: ±0.5s

Method:

1.      Measure your resting heart rate (heart rate before the exercise). Use the first two fingers of one hand to feel your radial pulse on the opposite wrist (see Figure 1). Do this for 15 seconds (using a stopwatch) and then times the number of beats by 4.

2.      Perform the first activity (jumping rope) for 1 minute. Ask a friend the measure the time.

3.      Feel your radial pulse for 15 seconds straight after the exercise. See Figure 1 to see how to feel your radial pulse.

4.      Rest for 3 minutes to allow the heart rate to decrease to resting heart rate again.

5.      Take your pulse again (to obtain a second reading for the resting heart rate)

6.      Perform the procedure two more times and take your pulse. This will give you three readings and will allow you to calculate the average. Remember to wait for 3 minutes and measure the resting heart rate before starting the exercise again.

7.      Perform the experiment for the other types of exercise.

8.      Record your results in a Table of Results. See Figure 1.1 for methods of data presentation.

See Control Variables Table below to see what needs to be constant throughout the investigation.

Control Variables:

 Control Variable How it can impact results? How will it be controlled? Room temperature If at one trial the temperature is 25oC, but at another it is 30oC, the heart rate will automatically be higher at the higher temperature – this would make the results less reliable The experiment is going to be carried out in the school’s sports hall, at a temperature of 18oC – which is going to be maintained throughout the investigation. All doors and windows will be shut. Wind Walking or running with the wind at your back is easy, therefore HR decreases. Walking or running into the wind is more difficult: HR increases. Same as above – experiment will be carried out in a closed sports hall ensuring there is no wind. Age of person Heart rate decreases with age. Therefore, if one person is 16 years old and the other is 30 years old and both carry out the experiment, the heart rate of the 30year old would automatically, without any exercise be lower. People carrying out the experiment (doing the exercise) will be between 16 and 17 years of age.

Independent variable range/type justification:

For this investigation, the independent variable is the type of activity or exercise. The types of exercise have been chosen as they allow for a clear comparison to see which type of exercise affects or increases heart rate the most and which causes the biggest change in heart rate (See figure 1.3 and 1.4).

For example, jogging involves different muscles than stretching. One would expect jogging to be more tiring and therefore a bigger change in heart rate than for instance stretching or weights (3kg). Such different types of exercise increase the validity of the investigation as the hypothesis can easily be either proved or disproved.

Due to the fact that we have multiple trials and 50 participants (although of the same or similar age and body mass), the reliability of the experiment is increased. We can easily spot anomalies and work out averages, which later helps us to construct graphs.

Health & Safety:

·         Only participants that have no heart diseases or past history of such diseases/problems or conditions are tested in the experiment

·         Participants take 3 minute breaks in order to cool down and for the heart to come back down to resting heart again

·         Water is always available for the participant – however this might reduce reliability of results (see conclusion & evaluation)

Conclusion & Evaluation & Improvements:

As can be seen from Figure 1.3 in Methods of Data Collection, the largest increase in heart rate was after jogging. The average Heart rate before exercise was 67 beats per minute and it increased by 89 beats per minute after 1 minute of exercise to 156 beats per minute.

The lowest increase in heart rate (only by 21 beats) was after lifting weights (3kg). The heart rate increased from 60 beats per minute to 81 beats per minute after exercise. However as can be seen from the results table, the heart rate before the exercise can be considered as an anomaly as it is significantly lower than the starting heart rate before all the other activities (66, 67, 68 and 69 beats per minute).

Generally the results are quite close together (See figure 1.2) and therefore rather precise & accurate. Few anomalies were spotted and this proves the reliability of the investigation. The anomalies that were indeed spotted (see results table 1.2), however, could have been caused by the fact that the people doing the experiment were of different body mass – even though this was tried to be kept as constant and similar as possible. Also, the person might have miss- counted their heart rate – this again had an impact on results.

In conclusion, the experiment was carried out well. However certain improvement can be made. The body mass of the person doing the exercise could have been measured more accurately – perhaps by using a more accurate (more decimal places) weighing machine – height of the person also could have been measured and together with age the BMI could have been worked out.

Also, the individuals had access to water in between the trials. Some drank a lot of cold water, some a lot of hot water and some might have not drank at all. This again has a negative impact on results as water could potentially affect heart rate straight after exercise. We should not forbid participants to drink water as this would impose a health risk or hazard but we should control the amount each individual drinks – by setting set amounts (e.g. one cup of cold water).