Lung Volumes and Capacities

Learning Objectives  Be familiar with the concepts of, and be able to measure lung volumes and capacities.  Understand the concepts of minute ventilation, tidal volume and ventilation rates during quiet breathing and during exercise.  Account for the differences in lung volumes and capacities between untrained and trained sportspersons.

Lung Volumes  During normal quiet breathing, we inspire approximately 500ml of air. The same amount is exhaled during the process of expiration.  The volume of air inspired and expired is known as TIDAL VOLUME.  Of this 500ml, only about 350ml makes its way into the alveoli. The other 150ml remains in the passageways of the nose, throat and trachea and is known as dead space.  The volume of air which is inspired or expired in one minute is called MINUTE VENTILATION and is calculated by multiplying tidal volume by the number of breaths taken per minute.

 On average we breathe 12 to 15 times per minute, so our resting minute ventilation can be calculated as follows:  VE = T.V x f = 500ml x 15 = 7,500ml/min (7.51/min)

Lung volume Capacity Definition Approximate normal values (ml) Changes during exercise Tidal volume (TV) Volume inspired or expired per breath 500 Increases up to 3-4 litres Inspiratory reserve volume (IRV) Maximal volume inspired from end inspiration 3,300Decreases Expiratory reserve volume (ERV) Maximal volume expired from end expiration 1,000-1,200 Slight decrease Residual volume (RV) Volume remaining at end of maximal expiration 1,200 Slight increase Total Lung Capacity (TLC) Volume in lung at end of maximal inspiration Up to 8,000 Slight decrease Vital Capacity (VC) Maximal volume forcefully expired after maximal inspiration 5,500 Slight decrease Inspiratory capacity (IC) Maximal volume inspired from resting expiratory level 3,800Increase Functional residual capacity (FRC) Volume in lungs at resting expiratory level 2,400 Slight increase Dead space Volume of air in the trachea etc that does not take part in gaseous exchange 150None Minute ventilation Volume of air inspired/ expired per minute TE= TV x F 7,500 Large increase (200L/min) in trained athletes

Ventilation during exercise  When we exercise depth and rate of breathing increases  Tidal volume increases by using Inspiratory reserve volume and expiratory reserve volume.  These volumes decrease, while tidal volume increases- up to 6 x  Minute ventilation increases Tidal Volume (TV) x frequency (breaths/min) = minute ventilation Rest 500ml (0.5L) x 15 =7.5L/min Maximal work 4,000 (4.0L) x 50 = 200L/min

Ventilation during exercise  Changes in ventilation occur before exercise begins Anticipatory rise  Result of hormones, stimulating the respiratory centre- adrenaline  Once we start to exercise there is a rapid rise in ventilation due to nervous stimulation  Sub max exercise- this slows down and steady state is reached  Maximal exercise- ventilation increases until exercise is finished.

Ventilation during exercise  If intensity continues to rise to a point near the athletes VO2 max (maximum amount of oxygen that can be taken in, transported and utilised in one minute) is reached, they cant get enough oxygen to working muscles so will have to slow down or stop.

Recovery…  During recovery- ventilation drop rapidly at first followed by a slower decrease  More intense the preceding exercise- longer the recovery  Removal of lactic acid

Guess Who??  Choose from one of the key words from today's lesson.  Write it on the post it note and stick to your partners head.  They have to guess which key word they are by asking questions  You are only allowed to answer ‘Yes’ or ‘No’  Tidal volume (TV)  Inspiratory reserve volume (IRV)  Expiratory reserve volume (ERV)  Residual volume (RV)  Total Lung Capacity (TLC)  Vital Capacity (VC)  Inspiratory capacity (IC)  Functional residual capacity (FRC)  Dead space  Minute ventilation  Steady state  VO2 max  Anticipatory rise  Adrenaline  Spirometer