Evaluation of rate-pressure product in obese children.

The purpose of this study was to evaluate the relationship between rate-pressure product (RPP) and degree of obesity in 511 obese 7 and 12 year old Chinese children. Obesity was assessed by anthropometry and skinfold thickness. The children were defined obese by relative weight (RW) > 120%. Bodyweight (W) and height (H) were used to derive body mass index (W/H2). Brachial systolic and diastolic pressures in these children were measured by cuff sphygmomanometry. RPP was calculated by the formula: heart rate x mean arterial pressure. More obese children (RW > or = 150%) had greater mean RPP (7 year old: 6389 vs 5976 beats/min x mmHg, P < 0.05; 12 year old: 7024 vs 6686 beats/min x mmHg) than those with RW < 150%. Children in the upper 25 percentiles of RPP had significantly larger BMI (7 and 12 year olds) and RW (12 year olds), thicker biceps, triceps and subscapular skinfolds (12 year olds) (P < 0.01-< 0.05). The results indicate that RPP is, to some extent, related to the degree of obesity in obese children. The differences in RPP may imply varying degrees of hemodynamic stress to the heart. Whether such differences may contribute to the long-term development of cardiovascular morbidity in more obese individuals is uncertain.