Biology Internal Assessment. How does exercise affect breathing rate?

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How does exercise effect breathing rate?


Different activities have different effects on the breathing rate because of the difference in the amount of oxygen needed. This investigation will assess how breathing rate changes in three different state of humans’ body: at rest, after light exercise and after heavy exercise. Base on the result we can find out the way in which our body adapts to particular activities that need different amount of oxygen or in another word, how exercises affect breathing rate.

Research question

What effect does exercises’ intensity have on breathing rate?


The increasing in the intensity of exercise results in the higher breathing rate.

+ At rest, breathing rate will maintain at normal speed to provide enough oxygen for cells to carry out aerobic respiration because at this state, body as well as muscle don’t need much energy.

+ After light exercise, breathing rate will increase slightly because during light exercises, small amount of lactic acid is generated and it needs to be broken down into energy.

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+ After heavy exercise, breathing rate will increase sharply because during vigorous exercises, lung and heart are unable to get enough oxygen to muscle quickly enough, a large amount of lactic acid is generated and as a result the breathing rate must increase to get more oxygen in order to break down lactic acid into energy and stop causing cramp due to lactic acid.


Independent variable:

+ Intensity of exercises (rest, light and heavy)

Dependent variable:

+ Breathing rate is measured (unit bmp (breaths per minute))


+ Stop watch (unit s (second))

+ Poles to chin up



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