Rowland Thomas, Heffernan Kevin, Jae Sae Young, Echols George, Krull Gary, Fernhall Bo
Department of Pediatrics, Baystate Medical Center, Springfield, MA 01106, USA.
Eur J Appl Physiol. 2006 Jul;97(5):637-42. doi: 10.1007/s00421-006-0234-5. Epub 2006 Jun 13.
Ventricular functional changes and mechanisms of the cardiovascular responses during static exercise have not been well delineated in children. In this study, Doppler echocardiographic techniques were utilized to assess cardiovascular adaptations to bilateral isometric leg extension at 30% maximal voluntary contraction for three minutes in a group of 14 healthy boys (mean age 10.2 +/- 1.5 years). Mean heart rate rose from 77 +/- 9 to 106 +/- 11 bpm, stroke volume fell from 59 +/- 9 to 52 +/- 7 ml, and cardiac output increased from 4.58 +/- 0.58 to 5.62 +/- 0.81 l min(-1) (P < 0.05). Mean arterial pressure rose from 86 +/- 7 to 109 +/- 9 mm Hg, with no significant change in peripheral vascular resistance. By tissue Doppler imaging markers, inotropic function improved by 59%, while lusitropic function increased 38%. These findings suggest that (1) cardiovascular responses to static leg extension in boys are similar to those in adult men, and (2) isometric leg extension triggers modest increases in both systolic and diastolic function.
儿童在静态运动期间的心室功能变化及心血管反应机制尚未得到充分阐明。在本研究中，利用多普勒超声心动图技术评估了一组14名健康男孩（平均年龄10.2±1.5岁）在30%最大自主收缩状态下进行双侧等长腿部伸展三分钟时的心血管适应性。平均心率从77±9次/分钟升至106±11次/分钟，每搏输出量从59±9毫升降至52±7毫升，心输出量从4.58±0.58升/分钟增加至5.62±0.81升/分钟（P<0.05）。平均动脉压从86±7毫米汞柱升至109±9毫米汞柱，外周血管阻力无显著变化。通过组织多普勒成像标记物，心肌收缩功能提高了59%，而心肌舒张功能增加了38%。这些发现表明：（1）男孩对静态腿部伸展的心血管反应与成年男性相似；（2）等长腿部伸展引发收缩和舒张功能适度增加。
