Question

With more demanding exercises (eg, running) more energy is needed and
therefore also more oxygen is needed in the citric acid cycle) and more
carbon dioxide is produced. Therefore the heart and breathing rate is
becoming higher to enable the transportation of carbon dioxide and oxygen.
Normal resting heart rate for an untrained man is 70 - 75 bpm. And it's ower
for people that are well trained, it can be low as 25 bpm. And for old people it
is higher. Normal breathing rate/min is 13 - 16
​

Answer 1

Answer:

12 to 16min in normal breathing rate.