Graduate School of Human-Environment Studies, Kyushu University, Kasuga, Fukuoka, 816-8580, Japan.
Eur J Appl Physiol. 2012 Sep;112(9):3313-8. doi: 10.1007/s00421-012-2313-0. Epub 2012 Jan 20.
It is unclear whether exhaustive dynamic exercise increases ocular blood flow, although we have reported that submaximal exercise increases ocular blood flow. We hypothesized that ocular blood flow decreases at exhaustion, since exhaustion causes hyperventilation, which induces a reduction in PaCO(2). To test this hypothesis, ocular blood flow, blood pressure, and respiratory measurements were made in 12 healthy male subjects during cycle ergometer exercise at 75% of maximal heart rate, until exhaustion. Blood flows in the retinal and choroidal vasculature (RCV), the superior temporal retinal arteriole (STRA), and the superior nasal retinal arteriole (SNRA) were measured with the aid of laser-speckle flowgraphy every 3 min during the exercise. The conductance index (CI) in the ocular vasculature was calculated by dividing the blood flow by the mean arterial pressure (MAP). The mean arterial partial pressure of CO(2) (PaCO(2)) was estimated from tidal volume and end-tidal CO(2) partial pressure. MAP significantly increased from the resting baseline throughout the exercise, while PaCO(2) was significantly decreased at exhaustion and during the recovery period. By 6 min after the onset of exercise, blood flow velocity in the RCV significantly increased by 32 ± 6% (mean ± SD) from the resting baseline value. At exhaustion, blood flow velocity in the RCV did not differ significantly from the resting baseline value, and the STRA blood flow was significantly decreased by 13 ± 4%. The CIs in the RCV, STRA, and SNRA were significantly decreased compared to baseline at exhaustion. These findings suggest that ocular blood flow is increased by submaximal exercise, whereas it is suppressed by the hypocapnia associated with exhaustion.
目前尚不清楚剧烈运动是否会增加眼血流，但我们已经报告过，次最大运动可以增加眼血流。我们假设，由于运动性通气过度导致 PaCO2降低，因此眼血流会在运动性疲劳时下降。为了验证这一假设，我们对 12 名健康男性受试者在踏车运动时进行了眼血流、血压和呼吸测量，运动强度为最大心率的 75%，直至疲劳。通过激光散斑血流图，每 3 分钟测量一次视网膜和脉络膜血管（RCV）、颞上视网膜小动脉（STRA）和鼻上视网膜小动脉（SNRA）的血流。通过将血流除以平均动脉压（MAP）计算出眼血管的传导指数（CI）。从潮气量和呼气末 CO2分压估算平均动脉 CO2分压（PaCO2）。MAP 在整个运动过程中从休息基线显著增加，而 PaCO2在运动性疲劳和恢复期显著降低。在运动开始后的 6 分钟，RCV 的血流速度比休息基线值显著增加了 32±6%（平均值±标准差）。在运动性疲劳时，RCV 的血流速度与休息基线值无显著差异，而 STRA 的血流显著减少了 13±4%。与基线相比，RCV、STRA 和 SNRA 的 CI 在运动性疲劳时均显著降低。这些发现表明，次最大运动可增加眼血流，而与运动性疲劳相关的低碳酸血症会抑制眼血流。
