The benefits of CRF plateaued after about 20 minutes of vigorous exercise, with most adolescents reaching median CRF following about 14 minutes of vigorous exercise daily, reported Oxford's Alexander Jones, British Heart Foundation Intermediate Clinical Research Fellow in Paediatric Cardiovascular Medicine (Department of Paediatrics), and colleagues.
Moderate and light exercise were not correlated with CRF. Teens in the upper quartile of vigorous physical activity scored higher than those in the lowest quartile, they noted in Pediatrics.
The World Health Organization (WHO) recommends that young adults get moderate to vigorous exercise for about one hour per day, but this goal wasn't met by 81% of adolescents in a previous study. Jones and team noted that their results suggested that less intense exercise endorsed by the WHO is not linked to CRF in the same way as vigorous exercise.