首页 | 本学科首页   官方微博 | 高级检索  
   检索      


Carotid baroreflex responsiveness in high-fit and sedentary young men
Authors:Barney  J A; Ebert  T J; Groban  L; Farrell  P A; Hughes  C V; Smith  J J
Institution:Department of Physiology, Medical College of Wisconsin, Milwaukee.
Abstract:The influence of fitness on cardiac vagal activity and baroreflex-mediated control of heart rate has not been clearly established in humans. Therefore, we studied resting cardiac vagal activity by evaluating respiratory sinus arrhythmia (RSA) and examined carotid-cardiac baroreflex responsiveness with a neck collar in 11 high-fit and 9 sedentary based on maximal O2 consumption (VO2max) and history of physical activity] healthy young men (19-31 yr of age). Resting cardiac vagal activity was determined from the standard deviation of 100 consecutive resting R-R intervals. Baroreflex responsiveness was determined from the R-R interval responses to neck suction and pressure (repeated trials of 5-s stimuli of -20, -40, and 35 mmHg). Both RSA and the bradycardic (R-R interval) responses to neck suction of -40 mmHg were significantly greater (P less than 0.05) in the high-fit individuals (RSA, 116.5 +/- 11.5 ms; neck-suction response, 145.3 +/- 17.0 ms; mean +/- SE) compared with sedentary subjects (RSA, 65.2 +/- 6.6 ms; neck-suction response, 86.9 +/- 12.5 ms). Responses of the high-fit volunteers to the other intensities of neck stimuli (-20 and 35 mmHg) showed a similar trend but were not significantly different from those of the sedentary volunteers. The baroreflex slope derived from these data was significantly greater in the high-fit subjects (4.00 +/- 0.39 ms/mmHg) compared with the sedentary controls (2.53 +/- 0.28 ms/mmHg). These data suggest that resting cardiac vagal activity is greater, carotid-to-cardiac activity is well maintained, and baroreflex sensitivity, i.e., slope, is augmented in high-fit subjects.
Keywords:
点击此处可从《Journal of applied physiology (Bethesda, Md. : 1985)》浏览原始摘要信息
点击此处可从《Journal of applied physiology (Bethesda, Md. : 1985)》下载免费的PDF全文
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号