On your marks… get set… breathe
Lesson 2
Lesson 2 uses a carousel approach to further investigate breathing and lung function: blood O2 concentration level, pulse rate, peak flow, and lung volumes. The carousel comprises Experiments B, C and D (Teacher Guide pages 22–24, 26–27, and
30–31). Experiment D forms part of an exciting national data-collecting exercise that your students can take part in. Students will need to carefully carry out the investigation to ensure standardisation with data collected from other classes and schools so that when they analyse the national data their results are more reliable. Students should do warm-up exercises and stretches before they begin the carousel activities. Suggested warm-up exercises are walking on the spot and then raising it up to a gentle jog on the spot, followed by stretches for the quadriceps, hamstrings, and calves (see page 57).
Do my blood oxygen level and pulse rate
change after exercise?
The student notes for this experiment are on page 25.
Aim
Students will investigate how the blood oxygen concentration level and pulse rate areaffected by different activities.
Equipment
From the kit box / From your school●pulse oximeter / ●stopclocks
optional:
●running track/field
●skipping rope
●metronome or music
Safety
●Identify any students with asthma so they can have their inhaler close at hand anduse it if required.
●Ensure students are dressed appropriately for the activities – for classroom-based activities, normal school uniform with sensible shoes will be fine. Trainers arerequired for some of the aerobic activities.
●Identify any student (such as those with heart/lung problems) not able to take part in school PE/games lessons. They may need to be excused from taking part in the physical part of this activity but can take on a time-keeper or data recording role.
●Be aware of any student with any blood oxygen abnormality who may be distressedby having to take part in the pulse oximeter activity.
●Ensure students carry out the activities in a suitable place, clear of any obstruction.
Running the experiment
1Students decide in their groups who will take part in the activities and who will time the activities and record the data.
2Students who are going to take part in the activities each measure the resting level of O2 in their blood and their pulse rate using the pulse oximeter. See the Student sheet for the protocol for obtaining evidence.
3The pulse oximeter is opened by pushing down on one end (please refer to the 'How to use the equipment in the box' section on page 7 of this guide). Students insert one finger into the oximeter. They must wait at least 10 seconds before taking the blood oxygen concentration levels and pulse rate readings.
4Students will need to perform their selected activity for 1 minute. Make sure that everyone performs the activity at the same intensity.
Suggestions for classroom-based activities
The table below gives some suggestions for activities that the students can do. The second table of suggestions can also be used if you have the equipment available. The key idea is that students carry out a few different types of activity. Students may also have suggestions for activities themselves.
These activities should all be carried out continuously for a period of 1 minute.
Activity / EquipmentJumping on the spot / Metronome or music to help keep time
Jumping jacks / Metronome or music to help keep time
Jogging on the spot / Metronome or music to help keep time
Lunges / None
Ski squat / Wall to lean against
Press-ups / None
Suggestions for activities using sport facilities
These activities should be carried out continuously for a period of 1 minute.
Activity / EquipmentExercise to music, e.g. aerobics, step aerobics, Zumba® / Music, DVD
Skipping / Skipping rope
5Students must not wear the pulse oximeter whilst exercising. They must ensure that they have access to a pulse oximeter immediately after finishing their exercise. Immediately after the timed exercise, students take their blood oxygen concentration levels and pulse rates again.
Expected results
Blood oxygen concentration is a measure of the amount of oxygen carried in the blood. More specifically it measures the percentage of haemoglobin binding sites in the bloodstream that are occupied by oxygen. The pulse oximeter measures the arterial blood oxygen concentration using red and infrared light that is emitted by the pulse oximeter when a finger is inserted into it. The pulse oximeter is able to give an oxygen concentration reading using the absorption of this red and infrared light by the finger. Oxyhaemoglobin and deoxyhaemoglobin in the arteries absorb red and infrared waves very differently and so a ratio can be calculated from the absorption rates.
The normal expected range is between 95 and 100%. Blood oxygen concentration does not often change even when the body is taking part in strenuous exercising. This is because the body responds to exercise by taking more oxygen into the lungs by increasing the breathing rate. Oxygen is transported around the body more quickly with an increased heart rate which means that the volume of blood reaching the target (muscles) increases and hence more oxygen is delivered. Consequently blood oxygen concentrations are unaltered.
In athletes during exercise, and in individuals with some respiratory illnesses, oxygen saturation levels can fall to around 90%. In athletes this decrease is because their muscles are more efficient at taking oxygen from the blood and using it to help produce energy.
The average resting pulse rate for a child aged 11–14 is 70–100 beats per minute (bpm). Pulse rate will usually decrease as the child gets older because their heart will get bigger and therefore be able to pump out more blood each time it beats. Children who take part in aerobic types of exercise will also usually have a lower resting heart rate compared to their counterparts. This is because the exercise that they take part in trains their heart to make it stronger so that it can pump out more blood during each beat.