Shorter Periods of Daily Vigorous Activity May Be Better for Busy Teens

By Jonathan Springston, Editor, Relias Media

Young people might achieve maximal cardiorespiratory fitness (CRF) with just 20 minutes of vigorous physical activity (PA) daily, a much shorter period than indicated in current guidelines.

Researchers recruited 339 participants age 13 and 14 years to wear accelerometers and engage in 20 meter shuttle runs. Investigators were measuring levels of PA and CRF. The authors noted 20 minutes of vigorous PA (i.e., red in the face, sweating, panting) every day accounted for optimal CRF. Associations plateaued after 20 minutes.

“As moderate-to-vigorous PA guidelines can be satisfied by only undertaking moderate PA, with no apparent independent benefit, we suggest that future guidelines focus on vigorous PA alone, simplifying public health messaging,” the authors concluded.

In an editorial accompanying this study, the authors noted trying to meet the current recommendation of 60 minutes of moderate-to-vigorous PA (MVPA) per day is challenging. Thus, shorter periods of vigorous PA that pay dividends might be appealing. However, that is not the whole story.

“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,” the editorialists wrote. “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.”

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