Endo Masako, Tauchi Shinko, Hayashi Naoyuki, Koga Shunsaku, Rossiter Harry B, Fukuba Yoshiyuki
Dept. of Exercise Science and Physiology, School of Health Sciences, Hiroshima Prefectural Women's Univ., 1-1-71, Ujina-higashi, Minamiku, Hiroshima 734-8558, Japan.
J Appl Physiol (1985). 2003 Oct;95(4):1623-31. doi: 10.1152/japplphysiol.00415.2003. Epub 2003 Jul 3.
The mechanism(s) underlying the attenuation of the slow component of pulmonary O2 uptake (Vo2) by prior heavy-intensity exercise is (are) poorly understood but may be ascribed to either an intramuscular-metabolic or a circulatory modification resulting from "priming" exercise. We investigated the effects of altering the circulatory dynamics by delayed vagal withdrawal to the circulation induced by the cold face stimulation (CFS) on the Vo2 kinetics during repeated bouts of heavy-intensity cycling exercise. Five healthy subjects (aged 21-43 yr) volunteered to participate in this study and initially performed two consecutive 6-min leg cycling exercise bouts (work rate: 50% of the difference between lactate threshold and maximal Vo2) separated by 6-min baseline rest without CFS as a control (N1 and N2). CFS was then applied separately, by gel-filled cold compresses to the face for 2-min spanning the rest-exercise transition, to each of the first bout (CFS1) or second bout (CFS2) of repeated heavy-intensity exercise. In the control protocol, Vo2 responses in N2 showed a facilitated adaptation compared with those in N1, mainly attributable to the reduction of slow component. CFS application successfully slowed and delayed the heart rate (HR) kinetics (P < 0.05) on transition to exercise [HR time constant; N1: 55.6 +/- 16.0 (SD) vs. CFS1: 69.0 +/- 12.8 s and N2: 55.5 +/- 11.8 vs. CFS2: 64.0 +/- 17.5 s]; however, it did not affect the "primary" Vo2 kinetics [Vo2 time constant; N1: 23.7 +/- 7.9 (SD) vs. CFS1: 20.9 +/- 3.8 s, and N2: 23.3 +/- 10.3 vs. CFS2: 17.4 +/- 6.3 s]. In conclusion, increased vagal withdrawal delayed and slowed the circulatory response but did not alter the Vo2 kinetics at the onset of supra-lactate threshold cycling exercise. As the facilitation of Vo2 subsequent to prior heavy leg cycling exercise is not attenuated by slowing the central circulation, it seems unlikely that this facilitation is exclusively determined by a blood flow-related mechanism.
先前的高强度运动使肺摄氧量（Vo2）慢成分减弱的潜在机制尚不清楚，但可能归因于“预运动”引起的肌肉代谢或循环系统改变。我们研究了通过冷脸刺激（CFS）诱导的迷走神经对循环系统的延迟撤离来改变循环动力学，对重复进行高强度自行车运动期间Vo2动力学的影响。五名健康受试者（年龄21 - 43岁）自愿参与本研究，最初进行了两次连续的6分钟腿部自行车运动（工作强度：乳酸阈值与最大Vo2差值的50%），两次运动之间有6分钟的基线休息，且无CFS作为对照（N1和N2）。然后在重复高强度运动的第一次运动（CFS1）或第二次运动（CFS2）期间，分别在休息 - 运动转换期通过用凝胶填充的冷敷袋对脸部进行2分钟的冷脸刺激。在对照方案中，与N1相比，N2中的Vo2反应显示出促进性适应，这主要归因于慢成分的减少。冷脸刺激应用成功减慢并延迟了运动转换时的心率（HR）动力学（P < 0.05）[HR时间常数；N1：55.6±16.0（标准差）对CFS1：69.0±12.8秒，N2：55.5±11.8对CFS2：64.0±17.5秒]；然而，它并未影响“主要”Vo2动力学[Vo2时间常数；N1：23.7±7.9（标准差）对CFS1：20.9±3.8秒，N2：23.3±10.3对CFS2：17.4±6.3秒]。总之，迷走神经撤离增加延迟并减慢了循环反应，但并未改变高于乳酸阈值的自行车运动开始时的Vo2动力学。由于先前高强度腿部自行车运动后Vo2的促进作用不会因减缓中心循环而减弱，因此这种促进作用似乎不太可能完全由与血流相关的机制决定。
