Introduction:
Few data exist describing the temporal association between the time spent within various intensities of physical activity (PA) and cardiometabolic health outcomes in youth.
Study Hypotheses:
In contrast to light- or moderate-intensity physical activity (PA) Vigorous- intensity PA would be associated with a reduced risk incident overweight and high normal blood pressure and (2) time spent in vigorous-intensity but not moderate- or light-intensity PA would be associated with cardiometabolic risk factors two years following baseline measurements.
Design and Methods:
This was a 3-year prospective cohort study of objectively-measured PA (Actical) in 315 youth aged 9 to-17 yrs of age studied in 14 schools. The primary exposure variable was PA intensity. The main outcomes measures were incident overweght status and high normal blood pressure. Secondary outcomes included disproportionate weight gain (annual change in body mass index Z score), waist circumference, systolic blood pressure (SBP), and cardiorespiratory fitness (VO
2
max) at the three year time point.
Results:
After three year follow-up, increasing time spent in any of the three PA intensities was not associated with incident overweight or incident high normal blood pressure. Compared to the lowest quartile, waist circumference [β = -0.04 95% CI = -0.07 to -0.01; p trend <0.01) and SBP [β = -3.08 95% CI = -6.79 to 0.64; p trend = 0.05] were lower in boys while VO
2
max was significantly higher [43.3 (39.6-46.4) vs 50.2 (43.8-52.9) mL/kg/min; p trend <0.01] in both boys and girls in the highest quartile of vigorous PA. These trends were not observed or reversed across quartiles of moderate- and light-intensity PA.
Conclusions:
Increasing time spent in vigorous-intensity PA at 12 years of age was associated with a more favorable cardiometabolic profile two years later. Similar trends were not evident for lower intensity PA. Experimental trials are needed to determine if these associations are causal in nature.
Capsule Commentary on Cheung et al., Leisure-Time Physical Activity and Cardiovascular Mortality in an Elderly Population in Northern Manhattan: A Prospective Cohort Study
