The harder you're breathing, the more oxygen and food energy you're consuming, and the more Carbon Dioxide(CO2) is building up in your blood. That CO2 then has to be exhaled and Oxygen has to be inhaled. This is a continuous cycle and your heart rate is only a proxy for it.
The harder you're breathing, the more oxygen and food energy you're consuming, and the more Carbon Dioxide(CO2) is building up in your blood. That CO2 then has to be exhaled and Oxygen has to be inhaled. This is a continuous cycle and your heart rate is only a proxy for it.