Background: Rate pressure product is a measure of the stress put on the cardiac muscle based on the heart rate and the systolic blood pressure that it is pumping against. It allows us to calculate the internal workload or hemodynamic response and is a direct indication of the energy demand of the heart. Increased incidence of sedentary lifestyle and obesity in developed and developing countries is one of the major risk factors for the development of cardiovascular diseases. This study was undertaken to analyze the differences in certain anthropometric and cardiovascular parameters in sedentary and non-sedentary male subjects of different body mass index.
Material and method: This cross sectional study consisted 60 male employees of 30-40 years who worked in the office was taken as cases and control group consisted of 60 male age matched physical laborers. Institutional Medical Ethical committee approval was obtained and written consent was obtained from all participants. Their anthropometric measurements were taken and were divided into low, normal and high Body Mass Index (BMI) groups based on the WHO recommendations. Their heart rate and systolic blood pressure were recorded and rate pressure product was calculated. Statistical analysis was done by using Student’s unpaired ‘t’ test. P value was taken as significant at 5 percent confidence level (p < 0.05).
Result: The heart rate of high BMI sedentary (85.85±8.74) subjects was increased and had statistical significance (P< 0.05) compared to non-sedentary high BMI [79.72±8.59 (P=0.0312)] subjects. The heart rate of low and normal BMI of sedentary subjects is more compared to that of non-sedentary subjects but without any statistical significance. The systolic blood pressure and the rate pressure product of sedentary subjects of different BMI group is higher compared to that of non-sedentary subjects, but without any statistical significance.
Conclusion: Increased heart rate in sedentary high BMI people is due to minimal vagal tone and sympathetic over activity. Accumulated adipose tissue in high BMI group will cause damage to the myocardium by pressure induced atrophy or by causing lipotoxicity of the myocardium induced by free fatty acids, causing apoptosis of lipid-laden cardiomyocytes. This will reduce the efficiency of the heart making it more prone to ischemia during exercise and stress. This study shows that the easily measurable heart rate is one of the important hemodynamic predictor to assess the functioning of the heart.
heart rate, systolic pressure, rate pressure product, body mass index.