School of Physical Education and Sports, Macao Polytechnic Institute, Macao, China.
Med Sci Sports Exerc. 2011 Nov;43(11):2081-8. doi: 10.1249/MSS.0b013e31821d4a82.
This study examined the effect of two bouts of prolonged exercise performed on the same day on cardiac biomarkers and left ventricular (LV) function in trained adolescent runners.
Twelve male adolescent runners (age = 14.5 ± 1.5 yr) performed two 45-min constant-load treadmill runs (RUN1 and RUN2), separated by 255 min of recovery, with intensity set at the running speeds that corresponded to ventilatory threshold. Serum cardiac troponin T (cTnT) and N-terminal pro-brain natriuretic peptide (NT-pro-BNP) were assessed before (PRE1, PRE2), immediately after (POST1, POST2), and 255 min after each run (POST1+4, POST2+4) where PRE2 and POST1+4 were the same sample. LV function was examined echocardiographically before and after each run.
cTnT was undetectable at PRE1 and POST1 but was elevated in eight-twelfths (67%) of runners at POST1+4/PRE2 (median (range) = 0.018 (<0.01-0.375 ng·mL(-1))). cTnT decreased progressively thereafter up to POST2+4 (four-twelfths, 33%). Data for NT-pro-BNP were significantly increased at POST1 and POST2 but returned to baseline at POST1+4 and POST2+4. Ejection fraction (EF) was significantly reduced after RUN1 (74% ± 5% to 70% ± 5%, P < 0.05), although still within normal range. There was no evidence of a cumulative drop in EF after RUN2 because the change was similar in magnitude (73% ± 4% to 68% ± 5%, P < 0.05). The decrease in the early-atrial (E:A) diastolic flow velocity ratio was greater after RUN1 (1.91 ± 0.13 to 1.83 ± 0.08, P < 0.05) than after RUN2 (1.86 ± 0.15 to 1.85 ± 0.12, P > 0.05), and thus, changes were not cumulative.
Neither cardiac biomarkers (cTnT or NT-pro-BNP) nor LV function (EF or E:A) demonstrate cumulative changes after two 45-min runs at ventilatory threshold separated by ∼ 4 h of recovery. Adolescent hearts seem to cope well with two prolonged runs performed on the same day.
本研究旨在探讨在同一天进行两次长时间运动对训练有素的青少年跑步者的心脏生物标志物和左心室（LV）功能的影响。
12 名男性青少年跑步者（年龄=14.5±1.5 岁）进行了两次 45 分钟的恒定负荷跑步机跑步（RUN1 和 RUN2），两次跑步之间恢复 255 分钟，强度设定为与通气阈相对应的跑步速度。在 RUN1 和 RUN2 之前（PRE1、PRE2）、之后（POST1、POST2）以及每次跑步后 255 分钟（POST1+4、POST2+4）测量血清心肌肌钙蛋白 T（cTnT）和 N-末端脑钠肽前体（NT-pro-BNP）。在每次跑步前后进行超声心动图检查 LV 功能。
cTnT 在 PRE1 和 POST1 时无法检测到，但在 POST1+4/PRE2 时，有八分之六（67%）的跑步者升高（中位数（范围）=0.018（<0.01-0.375ng·mL-1））。此后，cTnT 逐渐下降，直至 POST2+4（八分之四，33%）。NT-pro-BNP 的数据在 POST1 和 POST2 时显著增加，但在 POST1+4 和 POST2+4 时恢复到基线。在 RUN1 后，射血分数（EF）显著降低（74%±5%至 70%±5%，P<0.05），尽管仍在正常范围内。在 RUN2 后没有证据表明 EF 持续下降，因为变化幅度相似（73%±4%至 68%±5%，P<0.05）。在 RUN1 后，早期心房（E:A）舒张流速比的下降更大（1.91±0.13 至 1.83±0.08，P<0.05），而在 RUN2 后下降更小（1.86±0.15 至 1.85±0.12，P>0.05），因此，变化不是累积的。
在通气阈下进行两次 45 分钟的跑步，两次跑步之间恢复约 4 小时后，两种心脏生物标志物（cTnT 或 NT-pro-BNP）或左心室（EF 或 E:A）功能均未显示出累积变化。青少年的心脏似乎能够很好地应对同一天进行的两次长时间跑步。
