PURPOSE: The rate pressure product (RPP), calculated by multiplying systolic blood pressure (SBP) and heart rate (HR), has been recognized as an index of cardiac oxygen consumption and allows the estimation of the total heart work. Only little data is available for adolescents. The study determined the association between RPP and lifestyle factors, including physical activity, fitness, obesity and screen time in youth. METHODS: The school-based study comprised 492 adolescents, aged 12 to 17 years (240 girls, 48.8%; 14.6 ± 1.5 years), who had their SBP and HR measured at rest and during cycle ergometry (1.5 W / kg body weight). BMI, waist circumference (WC), waist-to-height-ratio (WtHR), physical activity (PA) and screen time (h/d), as well as physical fitness (PWC 170) were assessed during a routine school day. Myocardial workload was calculated using the double product (HR x SBP). Analyses were performed by linear regression models adjusted for age, sex and height. RESULTS: There was a significant association between resting SBP percentile (according to German reference data) and RPP during exercise (ß=0.452, p<0.001) with a 33.1% (95% CI 27.3-38.8, p<0.001) higher exercise RPP in subjects with elevated resting SBP values. Higher BMI (ß=0.283), WC (ß=0.255) and WtHR (ß=0.219) were related to higher exercise RPP (p<0.001). PA was inversely associated with RPP (p<0.001, additionally adjusted for BMI), with regard to organized sports (ß=-0.113), amount of MVPA (ß=-0.216) and active commuting to school (ß=-0.185). Moreover, screen time was linked to higher RPP even after further adjustment for PA (ß=0.117, p=0.009), whereas the strongest association was observed between RPP and physical fitness (ß=-0.743, p<0.001). When all components were included in the model, adolescent’s physical fitness was the only variable that predicted exercise RPP. CONCLUSIONS: In younger age, cardiac stress during exercise testing is associated with elevated SBP at rest and negative lifestyle factors. However, only physical fitness was independently linked to exercise RPP among adolescents. As burden of functional capacity is more important under stress conditions, we conclude that measuring the hemodynamic response to physical stress provides additional parameters to evaluate cardiovascular risk in youth, just as in adulthood.
