During exercise, your body has an increased need for oxygen and an increased need to expel carbon dioxide. You may have noticed that you breathe faster with exercise but you also breathe deeper as well. This depth of breath is known as tidal volume. While you're exercising, tidal volume increases due to a natural need for more air.
In a very technical sense, tidal volume is the volume of air moved between one normal inhalation and one normal exhalation. This means that no “extra” effort is made to increase air intake or increase air output. Receptors in your blood vessels signal the brain to change your breathing depth to suit the demands of the activity you are performing. Exercise increases the demand for air, and your body responds naturally with a higher normal tidal volume.
One of the main contributors to increased tidal volume comes from a reduction in inspiratory reserve. Your inspiratory reserve is the difference between the amount of air you can maximally inhale and your tidal volume inspiration level. During exercise, your lungs will expand and fill with greater amounts of air. This greatly influences the depth of the inhalation and ensures that a natural pressure gradient from inhalation to exhalation is maintained.
Expiratory reserve also contributes to your tidal volume during exercise; however, the reduction in expiratory reserve is not nearly as great as that as inspiratory reserve. Expiratory reserve is the difference between a maximal effort exhalation, which blows out all your air, and your tidal volume expiration level. Deep exhalation requires significantly more musculature than inhalation.
Average Normal Values
During normal breathing, your average tidal volume is about 500 mL according to “Essentials of Exercise Physiology” by William McKardle. In people with normal lung functioning, this value can double to 1000 mL of air moved per full breath during exercise. Exercises of extremely high intensities can produce tidal volumes of up to 2000 mL in elite athletes.
- "Essentials of Exercise Physiology"; William D. McArdle, Frank I. Katch, Victor L. Katch; 2006.
- University of Deleware: Physiology of Activity
- Brain Mac - Sports Coach: Measurement of Ventilatory Function
- Jupiterimages/Polka Dot/Getty Images
This article reflects the views of the writer and does not necessarily reflect the views of Jillian Michaels or JillianMichaels.com.