Physical activity intensity and cardiometabolic risk in youth.

Objective To determine the association between physical activity (PA) intensities and cardiometabolic risk factors in youth. Design Cross-sectional study using data from the 2008 Healthy Hearts Prospective Cohort Study of Physical Activity and Cardiometabolic Health in Youth. Setting Rural and urban communities in Alberta, Canada. Participants A convenience sample of 605 youth aged 9 to 17 years. Youth were on average aged 12.1 years, 248 were boys (41%), and 157 were overweight or obese (26%). Main Exposure Actical accelerometer–measured PA intensity. Main Outcomes Measures The primary outcome was body mass index (calculated as weight in kilograms divided by height in meters squared) z score. Secondary outcome measures included waist circumference, systolic blood pressure, and cardiorespiratory fitness (maximal oxygen consumption [[Vdot]O 2max ]). Results Body mass index z score, waist circumference, and systolic blood pressure decreased and [Vdot]O 2max increased in a dose-response manner across tertiles of vigorous PA (adjusted P  Conclusions Only vigorous PA was consistently associated with lower levels of waist circumference, body mass index z score, systolic blood pressure, and increased cardiorespiratory fitness in youth. These findings underscore the importance of vigorous PA in guidelines for children and adolescents.