Does anyone have any suggestions for a lab that would test the effects of exercise on human physiology?

I thought of a lab involving running and heart rate, but my other classmates came up with a similar idea and i would prefer to do something different. is there any way of measuring respiratory rates without medical equipment. i.e. with a stopwatch?

i'm open to any and all suggestions,even just theoretical ones. thanks.

You might check blood pressure after different times and exertion.