Importance of Cardiorespiratory Fitness

In recent years, the scientific importance of measuring, estimating and monitoring cardiorespiratory fitness has been increasing.

In 2016, the American Heart Association (AHA) made a scientific statement on the subject, in the article “Importance of Assessing Cardiorespiratory Fitness in Clinical Practice: A Case for Fitness as a Clinical Vital Sign. A Scientific Statement From the American Heart Association” by Ross et al. The article is available free of charge here.

According to the article:

“Mounting evidence has firmly established that low levels of cardiorespiratory fitness (CRF) are associated with a high risk of cardiovascular disease, all-cause mortality, and mortality rates attributable to various cancers. A growing body of epidemiological and clinical evidence demonstrates not only that CRF is a potentially stronger predictor of mortality than established risk factors such as smoking, hypertension, high cholesterol, and type 2 diabetes mellitus, but that the addition of CRF to traditional risk factors significantly improves the reclassification of risk for adverse outcomes.” 1

And it further recommends:

“At a minimum, all adults should have CRF estimated each year using a non-exercise algorithm during their annual healthcare examination. Clinicians may consider the use of submaximal exercise tests or field tests as alternatives because these involve individual-specific exercise responses.” 1

The two graphs show VO2-max as a function of age. The red curves represent quantile reference values at 5, 25, 50, 75 and 95%. The reference values are derived from a sample of 10,090 subjects from the “Prevention First Registry”2, 3.

Even small changes to a person’s VO2-max level are associated with an overall improvement in survival rate. According to the AHA statement paper, an improvement in VO2-max of approximately 3.5 mL * min-1 * kg-1 is associated with a 10-25% improvement in survival 1.

There is much evidence of Cardiorespiratory Fitness as a health indicator and that it can be improved by the individual. We have curated a list of some of the other relevant publications that are related to the importance of measuring VO2-max.

"Exercise performed frequently over weeks or months may improve CRF with 15-20% in VO2max in adults."
Skinner et al
Med Sci Sports Exerc. 2000; 32: 157-161 (HERITAGE)​
"Small increases in CRF (eg 3-6 VO2max-units) are associated with 10-30% reduction in adverse cardiovascular events."
Kodama et al
JAMA. 2009; 301:2024-2035
"High Intensity Training (HIT) regime leads to higher improvement than Moderate-Intensity Continuous Training (MICT)."
Weston et al
Br J Med. 2014,48.1227-1234 – A meta-analysis​
"Seismocardiography could be used in the clinic for a more accurate estimation of VO2max compared to current non-exercise methods."
Sørensen et al
Int J Sports Med 2020; 41(10): 661-668
"122.000 patients were monitored over a 10 years period and a five-time higher mortality rate was observed in low fitness patients compared to high fitness. Cardiorespiratory Fitness is a modifiable indicator of long-term mortality and health care professionals should encourage patients to achieve and maintain high levels of fitness."
Kyle Mandsager et al
JAMA Network Open 2018; 1(6): e183606

1 Ross et al, Circulation. 2016;134:00–00.
2 Rapp D et al, BMJ Open. 2018 Mar 5;8(3):e018697.
3 Franklin BA et al 2000, American College of Sports Medicine. ACSM’s guidelines for exercise testing and prescription.