Adolescents just require 20 minutes of vigorous exercise daily to stay fit, suggests a new study published in the journal Pediatrics.¹

The effect of physical activity on cardiorespiratory fitness was examined in 339 adolescents, aged 13-14 years with wrist-worn accelerometers and 20 m shuttle run test.

Results showed a correlation between greater vigorous physical activity and better cardiorespiratory fitness, though this association plateaued after 20 minutes of vigorous activity. Engaging in vigorous activity for longer duration offered no additional advantage.

No association with cardiorespiratory fitness was observed for moderate and light physical activity, including sedentary time. Compared to adolescents in the lowest quartile of vigorous physical activity, those in the upper quartile of vigorous physical activity had 1.03 z-scores higher cardiorespiratory fitness. Boys indulged in vigorous exercise more than girls and had better fitness levels.

The World Health Organization (WHO) recommends moderately intense or vigorous exercise every day for an hour. The findings of this study suggest that 20 minutes of vigorous physical activity was enough for adolescents for cardiorespiratory fitness, which seems to be a more attainable target and is likely to encourage better compliance. However, the activity level must be vigorous to gain maximum benefit since the study failed to identify any beneficial association of moderate exercise with cardiorespiratory fitness.

Reference

1. Burden SJ, et al. Intensity and duration of physical activity and cardiorespiratory fitness. Pediatrics. 2022 Jul 1;150(1):e2021056003. doi: 10.1542/peds.2021-056003.