3a: Pulmonary Function and VO₂ Max Testing

What is the Respiratory Rate and Minute Volume?

• Respiratory Rate (RR): Number of breaths per minute

  • Rest: ~ 12-16 breaths

• Minute Ventilation (MV or VE ): Volume of air breathed each minute

  • Rest: 6-8 L/min

  • VE = Respiratory Rate x Tidal Volume

What are the different raspatory volumes?

What is tidal volume?

• Volume of air moved during inspiration or expiration

  • Rest: ~ 500 ml

What is Inspiratory Reserve Volume, Expiratory Reserve Volume, & Residual Volume?

• Inspiratory Reserve Volume (IRV): Maximum volume of air that can be inspired above TV

  • About 3 Liters

• Expiratory Reserve Volume (ERV): Maximum volume of air that can be expired below TV

  • About 1.3 Liters

• Residual Volume (RV): Volume of air still in lungs after maximum exhalation

  • Prevents lungs from collapsing

  • Cannot be directly measured

What is Forced Vital Capacity and Total Lung Capacity?

• Forced Vital Capacity (FVC): Total Volume of air in one breath from total inspiration to total expiration

  • FVC = TV + IRV + ERV

  • Different between sex

• Total Lung Capacity: IRV + TV + ERV + RV FVC + R

  • About 6 Liters

what is Forced Expiratory Volume

• Forced Expiratory Volume/1 second (FEV1.0 )

• Amount that can be forcibly expired in 1 second-

• Can be measured in other time intervals (0.5, 2 , 3 seconds)

• FEV1.0 /FVC Ratio: Indication of expiratory power and overall resistance to airflow

  • Healthy ≥85%

  • Airway obstruction ≤ 70%

what factors does volumes depend on?

1. Genetic influences

2. Body size

3. Sex differences

4. Exercise training cannot change static lung volume

What is a pulmonary function test?

• Test Uses a spirometer to measure

  • Handheld or larger apparatus

• Useful in assessing lung function & diagnosing lung disease

  • Obstructive (asthma) vs. restrictive (fibrosis) lung disease

  • Pre & Post Exercise

What two factors need to increase to meet increased O2 demands?

• VE = Respiratory Rate (RR) x Tidal Volume (TV)

• Need to increase both RR and TV to meet increased O2 demand and to expel increased CO2 created from metabolism

What is VE response in the beginning and end of exercise?

• Initially, VE increases mildly

  • To take in more O2

• Later, VE increases sharply

  • To get rid of excess co2

How do you work a handheld Spirometer?

What is VO₂ max?

• VO2 = Q x a-vO2diff

  • Q = SV x HR

  • a-vO2diff = difference in oxygen content between the arterial and venous blood

  • VO2 increases with increasing intensity

• At MAX, our body cannot utilize any more O₂ for ATP production

• Measure of:

  • Capacity of Aerobic Energy System

  • Cardiorespiratory Fitness

Purpose of VO₂ Max Test

• General Population:

  • CR fitness is inversely related to CVD

  • ↑VO₂max/CR fitness → ↓risk of mortality and morbidity

• Athletes

  • Good predictor of exercise performance

  • ↑VO₂ max → ↑aerobic performance

    • Not perfect predictor

    • Dependent on sport

Limiting Factors of VO2 Maximal consumption of oxygen depends on

1. Alveolar ventilation

2. Diffusing capacity of the lungs

3. O2 transport to the capillaries of the working muscles

4. Ability of the working muscles to receive and utilize oxygen

what is Respiratory Exchange Ratio (RER)?

• Reflects intensity of exercise and fuel being used for ATP production

  • RER = 0.70, main source of energy is fat

  • RER = 1.0, main source of energy is carbohydrate

• RER >1.0, CO2 produced > O2 consumed

  • VCO2 /VO2

  • ↑CO₂ production beyond an RER of 1 is a result of buffering of H+ ions (acids) produced solely with anaerobic metabolism

What factors that Influence VO₂ Max?

• Mode of exercise: How much muscle mass is involved (contrast bike vs treadmill)

• Genetics: 25-50% variation

• State of training (fitness level and specificity)

• Gender:

  • Females typically lower (15-20%) ***

  • Body mass difference***

  • Lower hematocrit/hemoglobin to carry O2

• Body size and composition

  • How much muscle mass does a person have?

  • Type I vs Type II muscle fibers

• Age Decline can begin after age 30

what re the different modes of VO₂ Max Testing?

• Graded Exercise Test (GXT): Various protocols can be used

• Various modes:

  • Treadmill

  • Cycle

  • Arm

  • Stepping

• Predicted vs. Measured: Maximal effort required

Criteria for Max vs. Peak test ?

Must achieve at least ¾ to be considered a true VO2 Max

1. Plateau in O₂ consumption with increasing workload - <0.150 L/min increase in VO2 with last increase in workload

2. RER > 1.10\

3. RPE > 17 (GREATER than 17, an RPE of 17 does NOT count)

4. HR within 10 beats of Age Predicted MHR