Brito Leandro C, Ely Matthew R, Sieck Dylan C, Mangum Joshua E, Larson Emily A, Minson Christopher T, Forjaz Cláudia L M, Halliwill John R
Exercise Hemodynamic Laboratory, School of Physical Education and Sport, University of São Paulo, São Paulo, Brazil.
Department of Human Physiology, University of Oregon, Eugene, OR, United States.
Front Physiol. 2019 Jun 25;10:762. doi: 10.3389/fphys.2019.00762. eCollection 2019.
Previous studies observed diurnal variation in hemodynamic responses during recovery from whole-body exercise, with vasodilation appearing greater after evening versus morning sessions. It is unclear what mechanism(s) underlie this response. Since small muscle-mass exercise can isolate peripheral effects related to postexercise vasodilation, it may provide insight into possible mechanisms behind this diurnal variation.
The study was conducted in ten healthy (5F, 5M) young individuals, following single-leg dynamic knee-extension exercise performed in the Morning (7:30-11:30 am) or the Evening (5-9 pm) on two different days, in random order. Arterial pressure (automated auscultation) and leg blood flow (femoral artery Doppler ultrasound) were measured pre-exercise and during 120 min postexercise. Net effect for each session was calculated as percent change in blood flow (or vascular conductance) between the Active Leg and the Inactive Leg.
Following Morning exercise, blood flow was 34.9 ± 8.9% higher in the Active Leg versus the Inactive Leg ( < 0.05) across recovery. Following Evening exercise, blood flow was 35.0 ± 8.8% higher in the Active Leg versus the Inactive Leg ( < 0.05). Likewise, vascular conductance was higher in the Active Leg versus the Inactive Leg (Morning: +35.1 ± 9.0%, < 0.05; Evening: +33.2 ± 8.2%, < 0.05). Morning and Evening blood flow ( = 0.66) and vascular conductance ( = 0.64) did not differ.
These data suggest previous studies which identified diurnal variations in postexercise vasodilation responses are likely reflecting central rather than peripheral modulation of cardiovascular responses.
先前的研究观察到全身运动恢复期间血流动力学反应存在昼夜变化，与早晨运动相比，晚上运动后血管舒张更为明显。目前尚不清楚这种反应背后的机制。由于小肌肉量运动可以分离与运动后血管舒张相关的外周效应，因此它可能有助于深入了解这种昼夜变化背后的潜在机制。
该研究纳入了10名健康的年轻个体（5名女性，5名男性），在两个不同的日子里，随机顺序进行单腿动态伸膝运动，分别在早晨（上午7:30 - 11:30）或晚上（下午5 - 9点）进行。在运动前和运动后120分钟内测量动脉压（自动听诊）和腿部血流（股动脉多普勒超声）。每次运动的净效应计算为活动腿和非活动腿之间血流（或血管传导率）的百分比变化。
早晨运动后，在整个恢复过程中，活动腿的血流比非活动腿高34.9±8.9%（<0.05）。晚上运动后，活动腿的血流比非活动腿高35.0±8.8%（<0.05）。同样，活动腿的血管传导率高于非活动腿（早晨：+35.1±9.0%，<0.05；晚上：+33.2±8.2%，<0.05）。早晨和晚上的血流（=0.66）和血管传导率（=0.64）没有差异。
这些数据表明，先前确定运动后血管舒张反应存在昼夜变化的研究可能反映了心血管反应的中枢调节而非外周调节。
