Exercise laboratory, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand Medical School, 7 York Road, Parktown, 2193 Johannesburg, South Africa.
Eur J Appl Physiol. 2012 Jun;112(6):2243-55. doi: 10.1007/s00421-011-2201-z. Epub 2011 Oct 14.
This study investigated the effect of multi-stage cycling on left ventricular function with optimal carbohydrate and fluid replacement. Eleven well-trained cyclists completed 4 days of 3 h race-simulated cycling at an average intensity of 51.8 ± 2.8 %W (max) with carbohydrate supplements (50 g h(-1)). Left ventricular function was assessed by conventional echocardiography and tissue-Doppler imaging before and immediately after exercise on each day and a final recovery measurement on day 5. The rate of passive ventricular filling was persistently suppressed during repeated days of strenuous cycling (change in Septal E' wave pre to post-exercise: -3.9 ± 3.2; -1.0 ± 1.7; -1.9 ± 2.1; -2.2 ± 2.4 cm s(-1) for day 1-4, respectively) and was not completely restored before the subsequent exercise bout. Ejection fraction was significantly reduced post-exercise on day 1 and 2 (by -6.3 ± 7.1 and -6.8 ± 7.6%, respectively), whereas the change was not significant on day 3 and 4 (-3.8 ± 8.5 and -5.5 ± 10.6%, respectively), and may be partly due to the augmented rate of late diastolic filling (Septal A' wave) noted only on day 3 and 4. Finally, resting end-diastolic volume on day 5 (recovery day) was increased compared to day 1 before exercise (127 ± 23 and 108 ± 25 ml, respectively) and may indicate secondary hypervolemia; induced to further compensate for the cardiovascular strain of multi-day exercise. Strenuous prolonged cycling even with carbohydrate replacement is sufficiently stressful to impair cardiac function. As a multi-day cycling event progresses, cardiovascular strain is mitigated by adaptations that assist in restoring systolic function, while diastolic function remains impaired.
本研究旨在探讨多阶段循环运动对左心室功能的影响，并优化碳水化合物和液体的补充。11 名训练有素的自行车运动员以 51.8 ± 2.8%W（最大）的平均强度完成了 4 天 3 小时的模拟比赛，同时补充碳水化合物（50 g h(-1)）。在每天运动前后和第 5 天的最后一次恢复测量时，使用传统超声心动图和组织多普勒成像评估左心室功能。在反复剧烈运动的多天中，被动心室充盈率持续受到抑制（室间隔 E'波运动前后的变化：第 1-4 天分别为-3.9 ± 3.2；-1.0 ± 1.7；-1.9 ± 2.1；-2.2 ± 2.4 cm s(-1)），在下一次运动前尚未完全恢复。第 1 天和第 2 天运动后射血分数显著降低（分别降低了-6.3 ± 7.1%和-6.8 ± 7.6%），而第 3 天和第 4 天的变化不显著（分别降低了-3.8 ± 8.5%和-5.5 ± 10.6%），这可能部分归因于仅在第 3 天和第 4 天观察到的晚期舒张充盈率（室间隔 A'波）增加。最后，与运动前的第 1 天相比，第 5 天（恢复期）的静息舒张末期容积增加（127 ± 23 和 108 ± 25 ml），可能表明继发的血容量过多；进一步代偿多日运动对心血管的压力。即使有碳水化合物补充，剧烈的长时间骑行也足以对心脏功能造成压力。随着多日骑行比赛的进行，心血管压力通过适应性变化得到缓解，有助于恢复收缩功能，而舒张功能仍然受损。
