PAG 11.1

Question 1

Equipment

Answer 1

• Stopwatch/ timer
• Calculator
• Exercise equipment if required and available

Question 2

method

Answer 2

Method

Note: You will investigate the effect of low and moderate intensity exercise on heart rate. You will use statistical tests to evaluate two null hypotheses using data gathered from a group of test subjects.

Null hypothesis A: Low intensity exercise produces no change in heart rate in young adult healthy humans.

Null hypothesis B: Moderate intensity exercise produces no change in heart rate in young adult healthy humans.

A formula sheet is available to support this practical activity.

1. Working individually, design two exercise regimes according to the following criteria:

Low intensity:

• 3 minutes duration
• Feasible given the equipment and venue available to you
• Low intensity (should not produce any sensation of exertion in healthy subjects)
• Standardised (such that two subjects can carry out identical exercise)

Moderate intensity:

• 3 minutes duration
• Feasible given the equipment and venue available to you
• Moderate intensity (healthy subjects will notice mild exertion but should feel they could maintain this level of exercise over a long period of time)
• Standardised (such that two subjects can carry out identical exercise)
  2. Discuss your ideas with the rest of the class and reach an agreement on which two regimes (one low intensity, one moderate) will be adopted by the whole group. These need not be two regimes from the same individual and it might be that the final agreed regimes are modified in the light of class discussion.
  3. Agree on the details of the standardised way in which each subject will carry out each regime and measure the resulting pulse rate.
  4. Once all subjects have completed both regimes and recorded their pulse rates, collect all the data, record it in an appropriate format and complete your write up. Include your conclusions concerning the two hypotheses above.

Question 3

1. Why does exercise affect pulse rate in humans?

Answer 3

Answers to extension questions

1. When animals exercise they have an increased requirement for oxygen and respiratory substrate delivery to the muscles and carbon dioxide delivery to the lungs, due to rising rates of respiration in the muscle cells to provide the ATP needed for muscular contraction. Increasing the heart rate, and hence the pulse rate, is one way of increasing the rate of flow of the medium (blood) in which oxygen, respiratory substrates and carbon dioxide are transported.

Question 4

2. What further human responses could you go on to investigate?

Answer 4

2. Pulse rate could be measured before, during and after exercise. Breathing rate could also be investigated and compared with pulse rate. Blood pressure could be measured. Reaction times or even performance in some cognitive task could be assessed before, during and after exercise.

Question 5

3. Ethical and health and safety issues are important when deciding whether an individual can be a test subject. How will you determine who can participate as a test subject?

Answer 5

3. The individual should give informed consent – they know what they are letting themselves in for, they agree to it freely and they make known any health issues which should be considered.

Question 6

4. Evaluate the validity of the chosen method (the regimes used, the method provided and the group of test subjects) in this investigation.

Answer 6

4. The age of the individuals, time of day, type and duration of exercise may have all been controlled. However, factors such as sex, weight, height, physical fitness, BMI, sustenance etc. may not have been considered by the students. When measuring animal responses it is difficult to account for all the factors that would cause variation. If one or both of the null hypotheses were accepted, students might suggest that a larger number of test subjects might allow a significant difference to be identified.