During the electron transport, chan energy stored in electrons is used to pump hydrogen protons from the mitochondrial matrix to the intermembrane space. The numbers of protons increase this creates a chemical gradient(because there is a higher concentration of ions) and an electrical gradient(because the intermembrane space becomes more positive than the matrix because of the protons-H⁺). Those protons need to flow towards the matrix for equilibrium to occur. As we know the inside membrane of the mitochondria has a reduced permeability. The main place where protons can diffuse is the ATP-synthase(a protein that turns ADP and inorganic phosphate into ATP). When protons pass through they release the energy necessary for this reaction to occur(ADP+H₃PO₄-->ATP+H₂O)
they have experience in there breath rate they've probably been doing it for a minute. while on the other hand someone who is not used to working out has a hard time getting there breath back and are breathing heavily
