Hi can anyone tell me what kind of graph this is in mathematical terms?

I know it shows the relationship between heart rate, breathing and exercise (or at least I should know since I made it), but to be honest I would like also to say something interesting about the mathematical nature of the graph, since it's for a class assignment and I would like to possibly score a few extra credits for it if I can. The green area is the area when an individual is at rest. It has been included (although this may seem obvious) to show that heart rate and breathing maintain a normal stable state during rest. The maximum peak output (the flat area at the top of the curve) is the maximum work rate that can be sustained during exercise. The curve finally extends back down to the normal steady resting state after exercise has stopped.

It probably sucks (lol) but I couldn't think of any other way to represent this data. It looks a bit like some kind of thermodynamic output graph (I know only a very little about thermodynamics), where a stable state is maintained and where the maximum possible sustainable output is also represented. I'm also not sure if I can say that it is an exponential graph, since growth (and decay) to not continue indefinitely.

I admit I might be looking just to say something that seems quite clever (but is nonetheless true). However I would also like you guys opinions on whether this works OK, and maybe try to learn something about a good way to represent data like this in the future too?