Disclosures: One author reports he received honoraria from Today’s Dietician and grant funding from the NHLBI. The other authors report no relevant financial disclosures.
July 20, 2020
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AHA: Yearly cardiorespiratory testing may improve CV health in youth

Disclosures: One author reports he received honoraria from Today’s Dietician and grant funding from the NHLBI. The other authors report no relevant financial disclosures.
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More than half of children aged 12 to 15 years do not have healthy cardiorespiratory function, according to a scientific statement released by the American Heart Association.

Yearly testing for cardiorespiratory function performed in-office may not only be feasible for providers with little experience in exercise physiology, but may also result in improved CV health later in life for young patients, according to the statement.

Source: Adobe Stock.

“Cardiorespiratory fitness results in good physical and mental health and academic well-being,” Geetha Raghuveer, MD, MPH, pediatric cardiologist and professor of pediatrics at the University of Missouri-Kansas City School of Medicine in Missouri, told Healio. “In children who already have low fitness, any physical activity may be beneficial to begin with to improve conditioning, and then they can take on higher-intensity activities.

Cardiorespiratory function and CVD

According to a nationally representative sample of children in the U.S. in 2012, 42% of individuals aged 12 to 15 years had healthy cardiorespiratory function. Approximately 50% of boys and approximately 34% of girls exhibited healthy cardiorespiratory function.

Researchers reported there was an inverse relationship between cardiorespiratory function in youth and all-cause mortality and lifetime CVD:

  • all-cause mortality (HR for high vs. low cardiorespiratory function = 0.49; 95% CI, 0.47-0.51);
  • MI (HR per 1-SD higher VO2 = 0.82; 95% CI, 0.8-0.85);
  • stroke (HR per 1-SD higher VO2 = 0.84; 95% CI, 0.81-0.88);
  • HF (HR for low vs. high cardiorespiratory function = 1.6; 95% CI, 1.44-1.77); and
  • disability (HR for low vs. high cardiorespiratory function = 1.85; 95% CI, 1.71-2).

“Although the two are often conflated, physical activity and cardiorespiratory function are distinct but related concepts. Physical activity is voluntary movement produced by skeletal muscles that results in energy expenditure. Exercise and training refer to a subset of physical activity in which the goal is to improve performance, health or both,” the writing group wrote. “Cardiorespiratory function can reflect an individual’s past physical activity and reflect the ability to be physically active (an individual with greater cardiorespiratory function has more capacity for aerobic physical activity), forming a virtuous cycle of an active-fit lifestyle. Thus, physical activity is a behavior (will do), whereas cardiorespiratory function represents an individual’s capacity (can do) to perform certain types of aerobic physical activity.”

The authors also wrote that youth with good cardiorespiratory function demonstrated better academic achievement through attention allocation, cognition modulation and more efficient neural activation in the prefrontal and parietal cortices compared with those with poorer cardiorespiratory function.

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Moreover, the authors identified few studies that correlated genetic differences with cardiorespiratory function.

Cardiorespiratory testing

Geetha Raghuveer

“We hope that every office-based encounter will be an opportunity for providers to promote cardiac and overall health by discussing heart-healthy lifestyle habits,” Raghuveer said in an interview. “While BMI, BP and lipid profile measures are recorded often, more time is needed in counseling and interventions to support a healthy lifestyle.

“The ideal would be for cardiorespiratory fitness to be part of the school report card and part of the annual health visit for each child,” Raghuveer told Healio. “Heart-healthy lifestyle habits start in childhood, and children who are taught about the benefits of regular physical activity — for their body, mind and academic achievement — are more likely to have better lifetime cardiorespiratory function and overall health and well-being.”

Investigators identified six tests and protocols that may be used for the measurement of cardiorespiratory function and ranked them based on ability to provide accurate data.

The highest ranked test was gas-analyzed cardiopulmonary exercise testing. This method requires patients to exercise with increasing difficulty while a provider measures VO2 via respiratory gases. Although use of this method may be limited by the need for sophisticated equipment it, remains the gold standard for measuring VO2 levels, according to the authors.

According to the statement, a non-gas-analyzed, 20 m shuttle run test was considered the next best option, with patients walking or running between two points with incrementally increasing frequency, synchronized with audio signals from the provider. Although this method required 20 m of open space, variations exist for in-office populations.

Field exams such as 1.5-mile-run tests, where participants run a given distance as quickly as possible, are also effective but limited by dependency on the motivation and body size of the individual. Such tests are most effective in a school setting, according to the statement.

A step test, where participants step up and down on a block of a given height, is a portable and space-conscious method for cardiorespiratory function measurement, but its validity is not well-established, the authors wrote.

Methods such as the 6-minute walk test may be useful among participants with a low capacity for exercise but was determined to have poor validity in a healthy population.

Lastly, a questionnaire to assess levels of fitness was found to be the least effective options for cardiorespiratory function measurement among young participants due large error for estimation of VO2.

“Although accurate assessment of cardiorespiratory function in youth has traditionally relied on cardiopulmonary exercise testing, less resource-intensive tests … are useful,” the researchers wrote. “Office-based cardiorespiratory function testing that can be performed by providers with little or no formal training in exercise physiology and low-cost equipment is also superior to physical activity recall. With future research, a practical, widely applicable test to estimate cardiorespiratory function in office settings may become a reality and an essential part of health assessment in all youth during office visits.”