Blood Pressure, Abdominal Obesity, Physical Activity and Cardiorespiratory Fitness in Youths

Aim The purpose of the present study was to analyse differences in blood pressure between different levels of cardiorespiratory fitness (CRF) controlling for the influences of age, sex, waist circumference (WC) and objectively measured physical activity levels (PA).

Methods Participants were 405 students aged 10-19 years (239 girls and 166 boys) from North of Portugal. Systolic (SBP) and diastolic blood pressure (DBP) were measured in a resting seating position, according to a standardized protocol. Mean arterial pressure was calculated as: MAP = [(SBP-DBP)/3]+DBP. WC was measured to the nearest mm at the superior border of the iliac crest. PA was objectively measured with accelerometers (Actilife GT3x), during 7 consecutive days. Total PA was expressed as the average counts per minute. To determine the time spent in different PA intensities, the following counts intervals were considered: 0-499 for sedentary PA, 500-1999 for light PA, 2000-3999 for moderate PA and ≥4000 for vigorous PA. The 20-meter Shuttle Run Test was used to assess CRF, which was expressed as the number of completed laps. CRF was classified into low fit and fit groups, according to Portuguese reference standards suggested by Silva et al [1]. General Linear Model was used to analyse differences in blood pressure between CRF levels with adjustments for covariables.

Results Differences (p <0.05) were found between low and fit groups for WC, SBP, DBP and MAP, controlling for age and sex. No differences were found for PA variables. After adjustments for MVPA and total PA, differences remained significant (p<0.05) with favourable values for the fit group. When WC was also included as a covariable, differences remained significant (p<0.05) for SBP and MAP, but not for DBP in the comparisons between low fit and fit groups.

Conclusions In youths, CRF might favourably affect blood pressure independently of abdominal obesity and PA levels.