Which changes occur when a person exercises?A. Depth of breathing decreases and breathing rate also decreasesB Depth Of breathing decreases and breathing rate increases C. Depth of breathing increases and breathing rate decreases D Both decrease 

Expert Answers

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The best answer, given your choices, is choice "B."  

I would like to make it clear that choice "B" is not absolutely guaranteed when a person exercises.  A lot will depend on the person that is exercising and their own physical fitness level.  I would also like to point out that breathing depth and rate will change depending on the intensity and duration of the exercise.  

Choice "B" is the best choice, because it is the only choice that lists a breathing rate increase.  When a person exercises, their cells are using more oxygen and producing more carbon dioxide through the process of cellular respiration.  The body then needs to supply more oxygen to meet the increased demand and expel the toxic carbon dioxide quicker.  That means the blood the needs to move those gas loads more quickly to and from the lungs. The heart rate will increase to do that.  In order to exchange gas the gas loads within the alveoli more quickly, the body will increase the breathing rate.  

The reason I can't wholeheartedly endorse choice "B" is because very fit, well trained athletes will increase their breathing depth during certain aerobic exercises.  But in general, choice "B" is what happens when most people exercise.  

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