Question

During heavy exercise, the breathing rate can increase up to _____ per minute.
(a) 35 times
(b) 40 times
(c) 20 times
(d) 25 times

Answer 1

Hint: An adult human being at rest breathes in and out 15 to 18 times a minute on average. The breathing rate will increase faster during heavy exercise and it is similar to a perfect square number.

Complete answer:
Your lungs and the respiratory system must provide more oxygen to the blood during exercise. Since the respiratory muscles are activated by sympathetic nerves in order to increase the rate of breathing, you can breathe harder and faster. Breathing rates may increase from a normal resting rate of 15 breaths per minute if the exercise is intense. Hence, during vigorous exercise, the breathing rate will increase up to 25 times.
Muscle cells require more oxygen during exercise to support their function. Both the lungs and the heart work extra to keep up with the ever-increasing need for oxygen resulting in a rise in breathing and heart rate.
During exercise, fermentation takes place in the muscle cells, resulting in an increase in the volume of lactic acid, the hydrogen ion. This activates the cardiovascular system further and allows the heart rate to rise so that more blood is pumped by the heart. The increase in blood pressure contributes to more blood flow to the alveoli.
More oxygen is absorbed by the lungs and more blood is obtained by the muscle cells and the oxygen requirement is thus met. When the lungs operate twice to put in oxygen and take out carbon dioxide to avoid lactic acid production, the breathing rate increases.
So, the correct answer is, ‘(d) 25 times’.

Note: The number of breaths taken per minute is the respiratory rate, one of the main vital signs of the human body. Not only do we breathe quickly as we exercise, but we also take deep breaths and thus inhale more oxygen.