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Unlock This CourseBreathing is something we do automatically, but have you ever wondered how much air you actually breathe in and out? Or how your breathing changes when you exercise? Through practical investigations, we can measure and understand exactly how our respiratory system works. These experiments help us see the amazing efficiency of our lungs and how they adapt to different situations.
Key Definitions:
The simplest breathing investigation involves counting breaths. Place one hand on your chest and count how many times it rises and falls in one minute. Normal resting breathing rate is 12-20 breaths per minute for teenagers. This increases dramatically during exercise as your body demands more oxygen.
There are several ways to investigate breathing practically, from simple observations to sophisticated equipment. Each method gives us different insights into how our respiratory system functions.
This investigation shows how breathing rate changes with activity level. You'll need a stopwatch and someone to help count breaths.
Sit quietly for 2 minutes, then count breaths for 1 minute. Record the number. This is your resting breathing rate - typically 12-16 breaths per minute.
Do 2 minutes of step-ups or jumping jacks, then immediately count breaths for 1 minute. You'll find this number is much higher - often 25-40 breaths per minute.
Continue measuring every minute until breathing returns to resting rate. This usually takes 3-5 minutes, showing how efficiently your body recovers.
During exercise, your muscles work harder and need more oxygen to release energy from glucose. Your breathing rate increases to take in more oxygen and remove the extra carbon dioxide produced. Your heart rate also increases to pump this oxygen-rich blood around your body faster.
A spirometer is the gold standard for measuring lung volumes. Modern digital spirometers are safe and easy to use in schools, giving accurate measurements of different lung capacities.
What a spirometer measures:
One of the most interesting investigations is seeing how exercise affects not just breathing rate, but also the depth of breathing and recovery time.
Measure breathing rate before, during and after different intensities of exercise. Light exercise might increase breathing to 20 breaths/min, while intense exercise can push it to 40+ breaths/min. The fitter you are, the quicker your breathing returns to normal.
You can estimate lung capacity using a large plastic bottle, tubing and water - though this is less accurate than a spirometer.
Equipment needed:
Method:
A study comparing a trained swimmer with a non-athletic student showed fascinating differences. The swimmer had a vital capacity of 5200ml compared to 4100ml for the non-athlete. More importantly, the swimmer's breathing rate only increased to 28 breaths/min during intense exercise, while the non-athlete reached 42 breaths/min. The swimmer also recovered to resting rate in just 2 minutes compared to 6 minutes for the non-athlete.
When investigating breathing, safety must come first. Never push anyone beyond their comfort zone and always have someone supervising exercise activities.
Take multiple measurements and calculate averages. Breathing can vary due to nervousness, time of day, or recent activity. The more data you collect, the more reliable your results will be. Always record conditions like temperature and humidity as these can affect measurements.
The real learning comes from analysing what your measurements mean. Look for patterns in your data and try to explain the biological reasons behind what you observe.
When analysing breathing data, consider these factors:
These investigations mirror tests used in medicine and sports science. Doctors use spirometry to diagnose conditions like asthma and COPD. Sports scientists use similar tests to assess athlete performance and design training programmes. Understanding how to measure and interpret breathing data is a valuable skill beyond the classroom.
Even simple breathing investigations can go wrong if you're not careful. Here are the most common mistakes and how to avoid them.
Always use a stopwatch and count for a full minute. Counting for 15 seconds and multiplying by 4 introduces errors because breathing isn't perfectly regular.
People breathe differently when they know they're being watched. Try to be discreet when counting, or use equipment that measures automatically.
Write down measurements immediately. It's easy to forget numbers, especially when taking multiple readings from different people.