Rajalakshmi R, Vageesh Vijaya Y, Nataraj S M
Department of Physiology, JSS Medical College, Constituent College of JSS University, Mysore 570015, India.
Niger J Physiol Sci. 2013 Jun 30;28(1):35-9.
Overweight and obesity are major risk factors for cardiovascular diseases. The objective of this study was to determine the effect of increased adiposity on myocardial oxygen consumption at rest and during submaximal exercise in young adults. The study consisted of 85 young adults (18-22 years) grouped into 3 based on their body mass index as normal (NW, n=30), overweight (OW, n=25) and obese (OB, n=30). Steady dynamic exercise test equivalent to Grade 2 Bruce protocol was carried out on treadmill for 5min. Blood pressure and heart rate were recorded before, during 3rd min of exercise, immediately after cessation of exercise and during 5th min of recovery. MVO2 was measured by the Rate Pressure Product (RPP) calculated as product of heart rate and systolic blood pressure. Statistical analysis was done using ANOVA and regression analysis. The mean resting RPP was significantly higher in overweight and obese groups when compared with the normal weight group (p<0.05). There was significant increase in RPP changes to exercise [mean difference in NW-8270.93 bpm.mmHg (99.61%), OW-10593.12 bpm.mmHg (118.39%) and OB-10897.33 bpm.mmHg (118.10%), p< 0.05] and the value did not return to baseline after 5 mins of recovery in study groups (p< 0.05). BMI and Waist stature ratio were the most important independent parameters in prediction of RPP. The study shows that overweight and obese young adults have elevated resting RPP and much higher RPP response to exercise indicating increased (MVO2) at rest and during exercise suggesting higher hemodynamic stress to the heart.
超重和肥胖是心血管疾病的主要危险因素。本研究的目的是确定肥胖增加对年轻成年人静息和次最大运动时心肌耗氧量的影响。该研究包括85名年轻成年人（18 - 22岁），根据体重指数分为3组，即正常体重组（NW，n = 30）、超重组（OW，n = 25）和肥胖组（OB，n = 30）。在跑步机上按照二级布鲁斯方案进行5分钟的稳定动态运动测试。在运动前、运动第3分钟、运动停止后立即以及恢复第5分钟记录血压和心率。通过心率与收缩压的乘积计算速率压力乘积（RPP）来测量心肌耗氧量（MVO2）。使用方差分析和回归分析进行统计分析。与正常体重组相比，超重和肥胖组的平均静息RPP显著更高（p < 0.05）。运动时RPP变化有显著增加[正常体重组平均差异为8270.93次/分·毫米汞柱（99.61%），超重组为10593.12次/分·毫米汞柱（118.39%），肥胖组为10897.33次/分·毫米汞柱（118.10%），p < 0.05]，且研究组在恢复5分钟后该值未恢复到基线水平（p < 0.05）。体重指数（BMI）和腰围身高比是预测RPP的最重要独立参数。该研究表明，超重和肥胖的年轻成年人静息RPP升高，运动时RPP反应更高，表明静息和运动时心肌耗氧量增加，提示心脏承受更高的血流动力学压力。
