School of Human Sciences (Exercise and Sport Science), The University of Western Australia , Perth, Western Australia , Australia.
Baker Heart and Diabetes Institute , Melbourne, Victoria , Australia.
J Appl Physiol (1985). 2019 Apr 1;126(4):1049-1055. doi: 10.1152/japplphysiol.00001.2019. Epub 2019 Feb 7.
Preventing declines in cerebral blood flow is important for maintaining optimal brain health with aging. We compared the effects of a morning bout of moderate-intensity exercise, with and without subsequent light-intensity walking breaks from sitting, on cerebral blood velocity over 8 h in older adults. In a randomized crossover trial, overweight/obese older adults ( n = 12, 70 ± 7 yr; 30.4 ± 4.3 kg/m), completed three acute conditions (6-day washout); SIT: prolonged sitting (8 h, control); EX+SIT: sitting (1 h), moderate-intensity walking (30 min), followed by uninterrupted sitting (6.5 h); and EX + BR: sitting (1 h), moderate-intensity walking (30 min), followed by sitting (6.5 h) interrupted with 3 min of light-intensity walking every 30 min. Bilateral middle cerebral artery velocities (MCAv) were determined using transcranial Doppler at 13 time points across the day. The temporal pattern and average MCAv over 8 h was determined. The pattern of MCAv over 8 h was a negative linear trend in SIT ( P < 0.001), but a positive quadratic trend in EX + SIT ( P < 0.001) and EX + BR ( P < 0.01). Afternoon time points in SIT were lower than baseline within condition ( P ≤ 0.001 for all). A morning dip in MCAv was observed in EX + SIT and EX + BR ( P < 0.05 relative to baseline), but afternoon time points were not significantly lower than baseline. The average MCAv over 8 h was higher in EX + SIT than SIT ( P = 0.007) or EX + BR ( P = 0.024). Uninterrupted sitting should be avoided, and moderate-intensity exercise should be encouraged for the daily maintenance of cerebral blood flow in older adults. The clinical implications of maintaining adequate cerebral blood flow include the delivery of vital oxygen and nutrients to the brain. NEW & NOTEWORTHY This is the first study to measure the combined effects of an exercise bout with breaks in sitting on cerebral blood velocity in older adults. Using frequent recordings over an 8-h period, we have performed a novel analysis of the pattern of cerebral blood velocity, adjusting for concurrent measures of mean arterial pressure and other potential confounders in a linear mixed effects regression.
预防大脑血流下降对于维持老年人的大脑健康至关重要。我们比较了晨练中等强度运动，以及随后从坐姿中进行的低强度步行休息，对老年人 8 小时内大脑血流速度的影响。在一项随机交叉试验中，超重/肥胖老年人（n=12，70±7 岁；30.4±4.3kg/m）完成了三种急性条件（6 天洗脱期）；SIT：长时间坐姿（8 小时，对照）；EX+SIT：坐姿（1 小时），中等强度步行（30 分钟），然后不间断坐姿（6.5 小时）；EX+BR：坐姿（1 小时），中等强度步行（30 分钟），然后坐姿（6.5 小时），每隔 30 分钟中断 3 分钟低强度步行。使用经颅多普勒在一天中的 13 个时间点确定双侧大脑中动脉速度（MCAv）。确定 8 小时内 MCAv 的时间模式和平均 MCAv。在 SIT 中，8 小时内 MCAv 的模式呈负线性趋势（P<0.001），但在 EX+SIT（P<0.001）和 EX+BR（P<0.01）中呈正二次趋势。SIT 中的下午时间点在条件内低于基线（所有 P≤0.001）。在 EX+SIT 和 EX+BR 中观察到 MCAv 晨发性下降（与基线相比，P<0.05），但下午时间点与基线相比没有显著降低。EX+SIT 中 8 小时内的平均 MCAv 高于 SIT（P=0.007）或 EX+BR（P=0.024）。应避免不间断坐姿，应鼓励进行中等强度运动，以维持老年人的大脑血流。维持足够的大脑血流的临床意义包括向大脑输送重要的氧气和营养。新的和值得注意的是，这是第一项研究测量锻炼与坐姿中断相结合对老年人脑血流速度的综合影响。使用 8 小时内的频繁记录，我们对脑血流速度的模式进行了新颖的分析，在线性混合效应回归中，同时调整了平均动脉压和其他潜在混杂因素的并发测量。
