Breathing rate increases during the vigorous exercising, Reason must be known to you
The living body requires constant supply energy This energy is in the form of ATP is released through oxidation of glucose in each cell
For this oxidation constant supply of oxygen is needed which is obtained through breathing
When vigorous exercise is done, there is a more need for ATP and thus more oxygen is required for the cellular respiration
To cater to this increased demand the breathing rate increases during the vigorous exercising.