In a statement published in the Journal of the American Heart Association, several clinicians identify low-cost alternatives to traditional cardiopulmonary exercise tests (CPETs) for healthy children.1

As the percentage of children in the United States with healthy cardiorespiratory fitness (CRF) has decreased from 1999 to 2012,2 the study authors aimed to identify simple, replicable, and cost-effective ways to assess CRF in children to identify risk and make early intervention possible.

For the purpose of the recommendation statement, researchers focused on raising awareness on the importance of youth CRF and advocated that CRF measurements are the best way to capture a child’s overall health when compared with physical activity recall, which is currently the most common assessment method.

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The study authors highlighted that half of boys and two-thirds of girls aged 12 to 15 years do not have a healthy CRF and only 20% of obese children have a healthy CRF. Poor CRF is linked to multiple conditions that compound cardiovascular risk as well as all-cause mortality; in children, CRF is positively associated with cognitive function, self-worth and life satisfaction.  

The study authors described assessing a healthy child’s oxygen uptake (VO2) as the most accurate CPET but acknowledged that having pediatric patients exercise to exhaustion in an office or hospital setting can be expensive and requires the presence of trained staff. Researchers also noted that CPETs may not reflect the type of physical activity in which children typically engaged, providing little insight into how their CRF impacts their daily life.

The 20-meter shuttle run test (20mSRT) was found to have moderate to high validity against CPETs to estimate CRF; researchers concluded that the 20mSRT is an efficient way to test large groups of children simultaneously due to its feasibility to administer in school settings. The 6-minute walk test is also easily administered in schools, but was found to have a poor correlation with VO2 max, suggesting that tests that require less effort are not appropriate measures for CRF in otherwise healthy children.

In situations where space or resources are limited, researchers stated that step tests may be an acceptable alternative if steps per minute are monitored appropriately and heart rates are collected immediately following exercise. Researchers discouraged use of questionnaires for assessing CRF due to the likelihood of inaccuracy.

Though hereditary factors are known to influence youth CRF, the study authors noted that the most dominant determinants of CRF are age, sex, and physical activity which can be modified by duration, frequency, and intensity. Researchers stated that there is little evidence to support a link between sedentary behavior and CRF in children once data is adjusted for objectively measured physical activity.

“Accurately and reliably measured CRF may identify youth who would benefit from lifestyle interventions but may be missed by subjective physical activity recall, anthropometric measures, or CVD risk factor testing, which are current standards of care,” concluded the study authors.


  1. Raghuveer G, Hartz J, Lubans D, et al. Cardiorespiratory fitness in youth: an important marker of health. [published online July 20, 2020]. J Am Heart Assoc. doi:10.1161/CIR.0000000000000866
  2. Gahche J, Fakhouri T, Carroll DD, Burt VL, Wang CY, Fulton JE. Cardiorespiratory fitness levels among U.S. youth aged 12-15 years: United States, 1999-2004 and 2012. NCHS Data Brief. 2014;(153):1-8.