Scott Jessica M, Esch Ben T A, Haykowsky Mark J, Isserow Saul, Koehle Michael S, Hughes Bevan G, Zbogar Dominik, Bredin Shannon S D, McKenzie Don C, Warburton Darren E R
Cardiovascular Physiology and Rehabilitation Laboratory, University of British Columbia, Vancouver, British Columbia, Canada.
J Appl Physiol (1985). 2007 Feb;102(2):681-7. doi: 10.1152/japplphysiol.00641.2006. Epub 2006 Nov 2.
Sex differences in neuroendocrine and metabolic responses to prolonged strenuous exercise (PSE) have been well documented. The aim of this investigation was to examine sex differences in left ventricular function and cardiac beta-receptor responsiveness following a single bout of PSE. Nine male and eight female triathletes were examined during three separate sessions: before, immediately after, and 24 h following a half-ironman triathlon using dobutamine stress echocardiography. Steady-state graded infusions of dobutamine were used to assess beta-receptor responsiveness. Slopes calculated from linear regressions between dobutamine doses and changes in heart rate and contractility for each participant were used as an index of beta-receptor responsiveness. Despite no change in preload, fractional area change decreased from baseline after the race in both men and women, with a greater decrease in men [men: 54.1% (SD 2.1) to 50.7% (SD 3.4) vs. women: 55.4% (SD 2.7) to 53.3% (SD 2.5); P < 0.05]. The amount of dobutamine necessary to increase heart rate by 25 beats/min [men: 29.6 microg x kg(-1) x min(-1) (SD 6.6) to 42.7 microg x kg(-1) x min(-1) (SD 12.9) vs. women: 23.5 microg x kg(-1) x min(-1) (SD 4.0) to 30.0 microg x kg(-1) x min(-1) (SD 7.8); P < 0.05] and contractility by 10 mmHg/cm2 [men: 20.9 microg x kg(-1) x min(-1) (SD 5.1) to 37.0 microg x kg(-1) x min(-1) (SD 11.5) vs. women: 22.6 microg x kg(-1) x min(-1) (SD 6.4) to 30.7 microg x kg(-1) x min(-1) (SD 7.2); P < 0.05] was greater in both men and women postrace. However, the amount of dobutamine required to induce these changes was greater in men, reflecting larger beta-receptor alterations in male triathletes following PSE relative to women. These data suggest that following an acute bout of PSE, male triathletes demonstrate an attenuated chronotropic and inotropic response to beta-adrenergic stimulation compared with female triathletes.
神经内分泌和代谢对长时间剧烈运动（PSE）的反应中的性别差异已有充分记录。本研究的目的是检查单次PSE后左心室功能和心脏β受体反应性的性别差异。在三个不同阶段对9名男性和8名女性铁人三项运动员进行了检查：在半程铁人三项赛前、赛后即刻以及赛后24小时，采用多巴酚丁胺负荷超声心动图检查。使用多巴酚丁胺的稳态分级输注来评估β受体反应性。根据每位参与者多巴酚丁胺剂量与心率和收缩性变化之间的线性回归计算的斜率用作β受体反应性的指标。尽管前负荷没有变化，但比赛后男性和女性的分数面积变化均从基线下降，男性下降幅度更大[男性：54.1%（标准差2.1）降至50.7%（标准差3.4），女性：55.4%（标准差2.7）降至53.3%（标准差2.5）；P<0.05]。使心率增加25次/分钟所需的多巴酚丁胺量[男性：29.6微克·千克-1·分钟-1（标准差6.6）至42.7微克·千克-1·分钟-1（标准差12.9），女性：23.5微克·千克-1·分钟-1（标准差4.0）至30.0微克·千克-1·分钟-1（标准差7.8）；P<0.05]以及使收缩性增加10 mmHg/cm2所需的多巴酚丁胺量[男性：20.9微克·千克-1·分钟-1（标准差5.1）至37.0微克·千克-1·分钟-1（标准差11.5），女性：22.6微克·千克-1·分钟-1（标准差6.4）至30.7微克·千克-1·分钟-1（标准差7.2）；P<0.05]在赛后男性和女性中均更大。然而，诱导这些变化所需的多巴酚丁胺量在男性中更大，这反映了与女性相比，男性铁人三项运动员在PSE后β受体的变化更大。这些数据表明，在急性PSE后，与女性铁人三项运动员相比，男性铁人三项运动员对β-肾上腺素能刺激的变时性和变力性反应减弱。
