The Fitness Blind Spot: Why Toronto's Serious Athletes Are Getting Lung Function Tests

Spirometry is a pulmonary function test that measures the volume and speed of air movement during a forced breathing manoeuvre. It is the most widely used respiratory assessment tool in clinical medicine worldwide and has been validated in sports science settings as a meaningful indicator of aerobic performance capacity.

The test itself is straightforward. After a full inhalation, you exhale as forcefully and completely as possible into the spirometer, a handheld device that measures airflow. The manoeuvre is typically repeated three times to ensure consistent results. The whole process takes a few minutes.

The two values the test produces are the ones that matter most for active adults: FVC and FEV1.

FVC, forced vital capacity, is the total volume of air you exhale during the full forced exhalation. This is your lung capacity in functional terms: how much air your lungs can hold and expel when pushed to their maximum. FVC is measured in litres and compared against a predicted value calculated from your height, age, sex, and ethnic background. An FVC that is meaningfully below predicted may reflect reduced lung volume, which can limit the total oxygen delivery capacity of the respiratory system.

FEV1, forced expiratory volume in one second, is the volume of air you exhale in the first second of the forced exhalation. This measures airflow rate: how quickly your airways can move air. FEV1 is also compared against a predicted value. A low FEV1 may reflect airway narrowing or obstruction that limits the rate at which air can move in and out during exercise, which has direct consequences for aerobic performance at moderate to high intensities.

The FEV1/FVC ratio is the percentage of your FVC that you can exhale in the first second. In healthy adults this ratio is typically above 70 percent. A ratio below this threshold suggests airflow obstruction, which may indicate asthma, exercise-induced bronchoconstriction, or other obstructive airway conditions worth investigating with a physician.

The connection between spirometry values and aerobic performance is more direct than most athletes appreciate. Your aerobic capacity, broadly measured by VO2 max, depends on a chain of physiological steps: lung ventilation, gas exchange in the alveoli, oxygen transport in the blood, cardiac output, and muscle oxygen utilization. Spirometry measures the first link in that chain.

For the majority of healthy, fit adults, the lungs are not the primary limiting factor in aerobic performance. The cardiovascular system and muscle oxygen utilization typically determine performance ceiling in well-trained individuals. But this is a population-level generalization. For individuals with reduced FVC or FEV1 relative to predicted values, the respiratory system does become a meaningful bottleneck.

A runner whose FVC is 15 percent below predicted for their age, height, and sex is working their respiratory system harder to deliver the same volume of oxygen at a given pace compared to a runner whose FVC is at or above predicted. Their aerobic ceiling is lower, their perceived exertion at any given intensity is higher, and their recovery between intervals is slower, not because of their fitness level, but because of their pulmonary mechanics.

More importantly for active adults in Toronto, exercise-induced bronchoconstriction is a common condition that causes temporary airway narrowing during or after sustained aerobic exercise. Estimates suggest it affects 10 to 15 percent of athletes, many of whom have no idea it is happening because the symptoms, including breathlessness disproportionate to exertion and prolonged recovery of breathing after exercise, are easily attributed to fitness level rather than airway physiology.

For a runner who feels like they hit a wall at a specific pace and cannot improve despite consistent training, for a cyclist who is strong on climbs but struggles disproportionately with sustained aerobic efforts, or for a gym-goer who notices their breathing recovery after conditioning work is slower than their general fitness would predict, spirometry data provides a physiological explanation that training data alone cannot.

The clinical interpretation of spirometry results is not simply about whether your FVC and FEV1 are high or low in absolute terms. It is about how your values compare to the predicted normal range for a person of your height, age, sex, and ethnic background.

Predicted spirometry values are derived from large population studies and reflect the expected lung function of a healthy non-smoking adult of your specific characteristics. A person who is 180 cm tall will have a higher predicted FVC than a person who is 165 cm tall, because lung volume scales with body size. A 25-year-old will have higher predicted values than a 50-year-old, because lung function declines gradually with age even in healthy individuals.

Results are typically expressed as a percentage of predicted. An FVC of 95 percent of predicted is normal. An FVC of 75 percent of predicted is a mild reduction that warrants attention and potentially follow-up with a physician. An FVC of 60 percent of predicted is a moderate reduction that should be investigated.

Ethnic background also affects predicted values in ways that are clinically significant. Research has established that predicted spirometry values differ between populations of European, Asian, African, and other descents. Population-specific equations produce more accurate reference ranges than generic equations applied across all backgrounds. For the large Chinese, South Asian, Korean, and Southeast Asian communities in Markham, Richmond Hill, Scarborough, and North York, applying the correct population-specific reference equations produces more meaningful results than using generic reference ranges.

WOXY Health registered nurses apply appropriate population-specific predicted value equations when interpreting spirometry results, ensuring that the comparison your results are made against reflects your actual biological context rather than a generic population average.

The relevance of spirometry data varies by sport, but for every aerobic discipline, it provides a dimension of performance context that training metrics alone cannot.

Runners who train consistently often reach a point where progress plateaus despite continued effort. When this happens after years of training, the plateau is sometimes attributed to genetics or age. But for runners who have never had their pulmonary function measured, there is a meaningful possibility that airway mechanics are contributing to the ceiling. Knowing your FEV1 baseline and whether it is within predicted range or below it tells you whether your respiratory system is a performance constraint or whether you should look elsewhere for the explanation.

Cyclists, particularly those who train and race at sustained moderate to high intensities, rely heavily on efficient ventilation during prolonged efforts. Spirometry provides baseline data that frames the respiratory side of their aerobic capacity in a way that heart rate and power data alone cannot. A cyclist with an FEV1 at 85 percent of predicted has a respiratory system that is limiting their aerobic ceiling in ways that core strength, cadence, and nutrition strategy cannot fully compensate.

Swimmers experience the highest respiratory demands of any common aerobic sport. Breath control, respiratory muscle strength, and lung capacity are all central to swimming performance at any level. Spirometry gives swimmers a measured baseline of the lung mechanics that underlie their breathing pattern in the water, and identifies any patterns that warrant adjustment in training or medical investigation.

Gym-goers engaged in conditioning work, HIIT, and metabolic circuits may not think of themselves as aerobic athletes, but sustained conditioning work places substantial demands on the respiratory system. Knowing your pulmonary baseline adds context to how you respond to high-intensity conditioning and why some workout formats feel disproportionately harder than their programmed intensity suggests.

The Performance Lab includes spirometry as part of a three-test panel alongside the InBody 570 body composition scan and the vital signs assessment covering blood pressure, resting heart rate, and blood oxygen saturation. The value of spirometry within this panel is amplified by the context that the other measurements provide.

A spirometry result interpreted alongside resting heart rate and blood oxygen saturation tells a richer story than the same result in isolation. An athlete with an FVC at 85 percent of predicted, a resting heart rate in the low 50s, and a blood oxygen saturation of 98 percent presents a different physiological profile than an athlete with the same FVC result and a resting heart rate in the high 60s with a blood oxygen saturation of 96 percent. The former suggests a respiratory system that may have a mild capacity limitation but is otherwise functioning efficiently. The latter may warrant more comprehensive investigation.

Similarly, spirometry data interpreted alongside body composition data from the InBody 570 can reveal whether body weight relative to lean mass is contributing to the respiratory load during exercise. A higher body fat percentage relative to skeletal muscle mass increases the metabolic demand on the respiratory system during exercise, effectively reducing the relative efficiency of a given FVC.

Your WOXY Health registered nurse interprets all three results together during the 20-minute clinical review, identifying patterns and providing specific guidance that the individual numbers cannot generate on their own. This integration of multiple physiological measurements into a coherent performance picture is what distinguishes the Performance Lab from a collection of individual tests.

The Performance Lab is a health monitoring and performance assessment service, not a clinical diagnostic service. The registered nurse who conducts and interprets your assessment is not in a position to diagnose respiratory conditions. What the nurse can do is identify results that fall outside normal reference ranges, explain what those findings may suggest, and provide specific guidance on what type of follow-up with your family physician or a specialist would be appropriate.

Most active adults who undertake a Performance Lab assessment will have spirometry results within normal predicted ranges. For these individuals, the spirometry data provides a valuable baseline, confirms that pulmonary function is not a limiting factor in their aerobic performance, and establishes a reference point for future assessments.

For a smaller number of active adults, spirometry results will fall below predicted reference ranges or produce an FEV1/FVC ratio that warrants further evaluation. For these individuals, the Performance Lab nurse provides a clear explanation of what the finding means, what conditions it may be associated with, and what the appropriate next step is, whether that is a conversation with their family physician, a referral to a respirologist, or a pre- and post-bronchodilator spirometry test to assess airway reversibility.

The Performance Lab digital report, which is provided after each assessment, presents all findings in clinical language that is shareable with the client's healthcare team. A family physician or respirologist who receives a client's Performance Lab report has a clear picture of the spirometry findings and can make an informed decision about what further assessment is indicated.

Active adults across Toronto, North York, Scarborough, Markham, Richmond Hill, Vaughan, Etobicoke, and Mississauga can access spirometry testing as part of the WOXY Health Performance Lab without a clinic visit, without a physician referral, and without a wait list.

The Performance Lab visit includes the InBody 570 body composition scan, spirometry, and vital signs assessment, followed by a 20-minute clinical interpretation and a digital results report. The entire visit takes 45 minutes. Appointments are available seven days a week including evenings, and booking is straightforward at www.woxy.ca.

If you have been training seriously for months or years and have never had your lung function measured, the Performance Lab gives you the data to finally understand the physiological foundation of your aerobic capacity. Your lungs have been doing the work. It is time to find out how well.

Train hard. Measure smarter. Book your Performance Lab at www.woxy.ca.

Book your Performance Lab athletic health assessment at www.woxy.ca, serving active adults across Toronto, North York, Scarborough, Markham, Richmond Hill, Vaughan, Etobicoke, Mississauga, and the Greater Toronto Area.