What is Lung Function Testing?

Lung function testing is sometimes performed as part of a general health check-up or for people with ongoing lung function problems. For athletes, understanding respiratory capacity is essential for optimizing performance and identifying conditions such as exercise-induced asthma that may limit training potential.

Spirometry is the most common lung function test, measuring how much air you can breathe in and out and how quickly you can exhale. The two primary measurements are forced vital capacity (FVC) and forced expiratory volume in one second (FEV1), which together provide a comprehensive picture of respiratory health and capacity.

Test Procedure

The usual measures of lung function are of forced vital capacity (FVC) and forced expired volume in 1 second (FEV1). These can be measured with a full maximal expiration. Explain to the subject that they must fill their lungs completely, seal their lips around the mouthpiece, and empty their lungs as hard and fast as possible. The best of two trials is usually recorded.

Equipment Required

Equipment required: Spirometer (e.g., Vitalograph). Professional-grade spirometers provide the most accurate measurements and are used in clinical and sports medicine settings.

Understanding Your Results

Interpretation: Lung function and lung volumes vary with age, sex and body size (especially height). The calculator above uses reference equations that account for these factors to generate predicted values specific to your demographics.

When interpreting results, values are typically expressed as a percentage of predicted. For healthy individuals, measured values should be at least 80% of predicted. Athletes often exceed predicted values due to enhanced respiratory muscle strength and conditioning.

Key Lung Function Parameters

  • FVC (Forced Vital Capacity): Total volume of air that can be forcibly exhaled after maximum inhalation. Normal range is typically 80-120% of predicted.
  • FEV1 (Forced Expiratory Volume in 1 second): Volume of air exhaled in the first second of forced expiration. A key indicator of airway obstruction.
  • FEV1/FVC Ratio: The proportion of lung capacity exhaled in one second. Values below 70% may indicate obstructive airway disease.
  • PEF (Peak Expiratory Flow): Maximum speed of expiration, useful for monitoring conditions like asthma.

Lung Function for Athletes

Endurance athletes, swimmers, and those participating in high-intensity sports often demonstrate superior lung function compared to the general population. Regular aerobic training can improve respiratory muscle strength and efficiency, though actual lung size is primarily determined by genetics and body size.

Sports that particularly benefit from optimal lung function include swimming, cycling, running, rowing, cross-country skiing, and team sports requiring sustained high-intensity effort. Athletes in these disciplines should consider regular lung function monitoring as part of their comprehensive fitness assessment.

Disadvantages: This test requires expensive equipment that is not generally available. A simple and inexpensive measure of lung function is the peak flow test, which measures the maximum speed of exhalation and can be performed with portable devices.

spirometry test

Spirometry testing measures lung capacity and airflow rates

The Science Behind the Calculations

This calculator uses the NHANES III (National Health and Nutrition Examination Survey) reference equations developed by Hankinson et al. (1999). These equations are widely used in clinical practice and research to generate predicted spirometry values based on age, sex, and standing height.

The prediction equations incorporate polynomial terms for age and linear terms for height, with separate coefficients for males and females. The formulas were derived from a large, representative sample of the United States population and have been validated across diverse populations.

For athletes, it's important to recognize that these reference values represent the general population. Trained endurance athletes may exceed predicted values by 10-20% due to adaptations in respiratory muscle strength, chest wall compliance, and overall pulmonary efficiency.

How to Improve Lung Function

While lung size is largely fixed after development, athletes can improve respiratory efficiency and functional capacity through targeted training approaches:

  • Aerobic Training: Regular endurance exercise improves respiratory muscle efficiency and oxygen utilization
  • Respiratory Muscle Training: Using inspiratory muscle trainers can strengthen the diaphragm and intercostal muscles
  • Swimming: The horizontal position and breath control demands provide excellent respiratory conditioning
  • High-Altitude Training: Exposure to reduced oxygen stimulates adaptations in oxygen-carrying capacity
  • Proper Breathing Techniques: Diaphragmatic breathing and controlled breathing patterns optimize ventilation during exercise

Frequently Asked Questions

What is FVC in lung function testing?

FVC (Forced Vital Capacity) is the total amount of air you can forcibly exhale from your lungs after taking the deepest breath possible. It's measured in liters and indicates overall lung capacity. For most adults, normal FVC ranges from 3 to 5 liters, depending on body size and sex.

What is a normal FEV1/FVC ratio for athletes?

A normal FEV1/FVC ratio is typically above 70-80% for healthy adults. Athletes often have ratios at the higher end of normal or even elevated due to superior respiratory muscle conditioning. A ratio below 70% may indicate obstructive lung disease and warrants further evaluation.

How do athletes benefit from lung function testing?

Lung function testing helps athletes identify potential respiratory limitations, detect exercise-induced asthma or bronchoconstriction, optimize training programs, establish baseline values for monitoring, and ensure respiratory health doesn't limit performance potential.

What factors affect predicted lung function values?

Predicted lung function values are influenced by age (lung function naturally declines after age 25-30), sex (males typically have larger values), height (taller individuals have greater lung capacity), and ethnicity. Body composition and training status can also affect actual measured values.

How often should athletes have their lung function tested?

Healthy athletes should consider annual lung function testing as part of routine health screening. Those with respiratory conditions, symptoms like unexplained breathlessness, or exercise-induced symptoms should test more frequently as recommended by their sports medicine physician.

Can training improve lung function test results?

While lung size is largely determined by genetics and reaches maximum capacity in early adulthood, respiratory muscle training and aerobic conditioning can improve breathing efficiency, vital capacity, and overall pulmonary performance. Endurance training can increase the efficiency of oxygen extraction and utilization.

What does percent predicted mean in spirometry results?

Percent predicted compares your actual lung function values to the expected values for someone of your age, sex, and height. Values above 80% of predicted are generally considered normal. Values between 60-79% indicate mild impairment, 40-59% moderate impairment, and below 40% severe impairment.

References

  1. Hankinson, J.L., Odencrantz, J.R., & Fedan, K.B. (1999). "Spirometric reference values from a sample of the general U.S. population." American Journal of Respiratory and Critical Care Medicine, 159(1), 179-187.
  2. Quanjer, P.H., Stanojevic, S., Cole, T.J., et al. (2012). "Multi-ethnic reference values for spirometry for the 3-95-yr age range: the global lung function 2012 equations." European Respiratory Journal, 40(6), 1324-1343.
  3. Miller, M.R., Hankinson, J., Brusasco, V., et al. (2005). "Standardisation of spirometry." European Respiratory Journal, 26(2), 319-338.
  4. Pellegrino, R., Viegi, G., Brusasco, V., et al. (2005). "Interpretative strategies for lung function tests." European Respiratory Journal, 26(5), 948-968.
  5. Rundell, K.W., & Jenkinson, D.M. (2002). "Exercise-induced bronchospasm in the elite athlete." Sports Medicine, 32(9), 583-600.
  6. Sheel, A.W., & Romer, L.M. (2012). "Ventilation and respiratory mechanics." Comprehensive Physiology, 2(2), 1093-1142.
  7. American Thoracic Society. (2017). "Pulmonary function testing guidelines." American Journal of Respiratory and Critical Care Medicine, 195(10), 1339-1352.