Fitness is important—but by how much?
During a health assessment at Executive Medicine, your exercise response and cardiorespiratory fitness may be assessed on a treadmill. Depending on the assessment selected, fitness may be estimated from exercise performance or VO₂ max may be measured directly using a CardioCoach metabolic mask.
VO₂ max is the maximum amount of oxygen your body can take in, transport and use during exercise. It provides an objective measure of cardiorespiratory fitness and helps us understand how effectively the heart, lungs, circulation and working muscles respond to increasing physical demand.
Fitness and long-term health
A large study published in 2018 examined the association between cardiorespiratory fitness and long-term mortality among 122,007 adults who underwent exercise treadmill testing.
Participants had a mean age of 53 and were followed for a median of 8.4 years. Their exercise performance was classified across five fitness categories, ranging from low to elite.
Higher fitness was consistently associated with a lower risk of death during the follow-up period. The greatest survival benefit was observed among those in the highest fitness category, including older people and those with hypertension.
The study found a graded relationship: as cardiorespiratory fitness increased, mortality risk generally decreased. Those with low fitness had substantially greater mortality risk than people with below-average, above-average, high or elite fitness.
Another 2018 study, the HUNT Fitness Study, directly measured peak oxygen uptake in 4,527 adults without known cardiovascular disease, lung disease, cancer or hypertension. Over approximately nine years, higher fitness was associated with a lower risk of developing coronary heart disease. Each increase of 3.5 mL/kg/min in measured fitness was associated with an approximately 15 per cent lower risk of coronary heart disease.
More recent research has strengthened the overall conclusion. A 2024 overview representing more than 20 million observations found cardiorespiratory fitness to be a strong and consistent predictor of illness and mortality across adult populations.
These studies show association rather than guaranteeing an outcome for an individual. Fitness is one important part of health and should be interpreted alongside blood pressure, cholesterol, blood glucose, smoking, family history, body composition and other medical factors.
Why measuring fitness can be useful
Cardiorespiratory fitness provides information that cannot be obtained simply by asking how frequently someone exercises.
Two people may complete a similar amount of physical activity but have very different fitness levels because of differences in exercise intensity, training history, health, genetics and the way their bodies respond to exercise.
An objective fitness measure can help to:
- Establish a baseline
- Identify whether current activity is producing an adequate training effect
- Guide an appropriate exercise program
- Track change over time
- Provide motivation through a measurable health marker
The result should always be interpreted in context. A high VO₂ max does not eliminate other health risks, and a lower result is not a diagnosis. It provides another useful piece of information from which an individual plan can be developed.
Improving cardiorespiratory fitness
Aerobic activities such as brisk walking, running, cycling, swimming and rowing can improve cardiorespiratory fitness when performed regularly and at an appropriate intensity.
The best starting point depends on current fitness, medical history, symptoms, injuries and previous exercise experience. Someone who is currently inactive should not attempt to reproduce the program of a highly trained person. Exercise should be progressed gradually and safely.
An Accredited Exercise Physiologist can help interpret fitness results and develop an exercise program suited to the individual.
The takeaway
Cardiorespiratory fitness is one of the strongest measurable indicators of long-term health. It is also modifiable.
Measuring fitness provides a useful baseline, but the most important step is using that information to guide realistic and sustainable improvement over time.
References
- Mandsager K, Harb S, Cremer P, et al. Association of cardiorespiratory fitness with long-term mortality among adults undergoing exercise treadmill testing. JAMA Network Open. 2018;1(6):e183605.
- Letnes JM, Dalen H, Vesterbekkmo EK, Wisløff U, Nes BM. Peak oxygen uptake and incident coronary heart disease in a healthy population: the HUNT Fitness Study. European Heart Journal. 2019;40(20):1633–1639.
- Lang JJ, Prince SA, Merucci K, et al. Cardiorespiratory fitness is a strong and consistent predictor of morbidity and mortality among adults: an overview of meta-analyses representing over 20.9 million observations from 199 unique cohort studies. British Journal of Sports Medicine. 2024.