Physical activity (PA) counseling can be a challenging aspect of pediatric care. Although a 2020 clinical report by the American Academy of Pediatrics emphasizes the value of clinical PA counseling, it acknowledges the difficulty of the task, and the lack of data regarding effective strategies.1 For many families and patients, meeting current recommendations for 60 minutes of moderate-to-vigorous physical activity (MVPA) per day feels unattainable. However, in this issue of Pediatrics, findings reported in “The intensity and duration of physical activity associated with maximal cardiorespiratory fitness” by Burden et al brings into question our current paradigm regarding activity guidance and may make PA counseling easier, and a bit more effective, for pediatric providers.2
The 2019 Youth Risk Behavior Survey found that only 23.2% of United States adolescents reported levels of activity that meet current recommendations, and this rate has been on a decreasing trend for over a decade.3 For many families, finding 60 extra minutes per day is a major barrier to meeting fitness goals, but results from Burden et al2 suggest an alternative approach that may ease the time burden on busy schedules. Based on adult data that equivalent risk reduction for cardiovascular disease requires 14 hours/week of moderate activity, but only 40 minutes/week of vigorous activity,4 the authors studied whether similar differences exist in adolescents while controlling for other factors and patterns of activity. Their findings suggest that in this population of 13- to 14-year-old adolescents, maximal cardiorespiratory fitness (CRF) increased as vigorous PA increased up to 20 minutes daily, then plateaued with longer durations.2 No CRF benefit was seen with moderate levels of activity.
These findings have 2 important implications for pediatric providers:
Optimal CRF can be achieved with much shorter periods of activity than previously recommended.
Current “moderate-to-vigorous” PA recommendations may not be sufficient to improve CRF in adolescents, if achieved through moderate activity only.
Shorter periods of higher intensity activity reduce the time burden for families but require education regarding the additional effort needed to achieve vigorous levels of activity. Patients can be counseled that activity is vigorous when they start to sweat, their face gets red, and they feel short of breath and unable to talk during activity.1 For children who are sedentary, or accustomed to lower intensity activity, these sensations can be uncomfortable and difficult to obtain initially. Patients can work up to this intensity by starting with several daily “exercise snacks” consisting of several minutes of activity, which gradually become more difficult over time. Exercise snacks can include anything that elevates the heart rate for a minute or more, such as running up and down the stairs a few times; chasing the dog around the backyard; or just putting on some music and dancing hard. These brief periods of higher intensity activity are effective at reducing cardiovascular risk in adults, and a 2019 feasibility study showed promise looking at their effects on weight loss in diabetic adolescents.5
Although Burden et al2 make a strong case for emphasizing the value of shorter periods of high intensity activity, this study evaluated activity duration and intensity specifically in relation to CRF. Although CRF is a widely accepted determinant of health and has been correlated with improved metabolic and mental health in pediatric patients, it is important to consider that other benefits associated with physical activity may accrue at different rates, and that accumulating 60 minutes of daily MVPA may have benefits beyond that of improving CRF. This is an area of active research, and activity recommendations in the pediatric population are likely to continue to evolve. However, it should be emphasized that PA counseling is not an “all or nothing” effort. Some exercise is better than none, and extrapolating from adult data, the biggest benefit likely occurs when we can help our most sedentary and least fit patients become a bit more active, even if it falls short of currently recommended levels.4,6
COMPANION PAPER: A companion to this article can be found online at www.pediatrics.org/cgi/doi/10.1542/peds.2021-056003.
FUNDING: No external funding.
CONFLICT OF INTEREST DISCLOSURES: The authors have indicated they have no conflicts of interest relevant to this article to disclose.