Authors : Anca Iliescu , R.D.C. S Beth Gulyasy and Angel L?pez-Candales
Abstract: Recent data suggests that measures of autonomic dysfunction while differ with heart rate, gender and functional capacity are unaffected by body mass index (BMI); however none of these same parameters have been assessed during routine stress testing despite the well-known modulation of heart rate (HR) by the autonomic nervous system during dynamic exercise. In this study, data from 88 consecutive individuals who had a normal treadmill stress echo study was analyzed and differences in HR during and after exercise were recorded and examined with regards to gender, BMI and total exercise duration. An exercise capacity of less than 9 min identified individuals with significantly faster increments in HR during early stages of exercise (p<0.02 for 1 min, p<0.0003 at 2 min, p<0.0001 at 3 min) when compared to individuals who exercised longer. Although, no statistical difference was noted between HR response with either age or BMI, females had significantly higher increments in HR early during exercise than males (115?15 versus 103?15 beats per minute; p< 0.0004; respectively) at 1 min, (125?17 versus 109?16 beats per minute, p<0.0001) at 2 min, (129?17 versus 112?18 beats per minute, p<0.00002) at 3 min and (144?18 versus 130?18 beats per minute p<0.001) at 6 min even though both females and males attained similar peak HR. Rapid increments in HR early into exercise occur more commonly in females; that although independent of age and BMI, are associated with a shorter exercise time duration. Further studies are now required to assess the importance of these fast increments in HR early into exercise seen more commonly in females, in the absence of exercise-induced myocardial ischemia and with a preserved left ventricular systolic function with relation to long term cardiovascular events.
Anca Iliescu , R.D.C. S Beth Gulyasy and Angel L?pez-Candales , 2005. Faster Heart Rates During Early Graded Exercise May Account for Shorter Exercise Time Duration in Women . The Cardiology, 1: 108-113.