Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, TX 75231, United States.
Respir Physiol Neurobiol. 2011 Dec 15;179(2-3):235-47. doi: 10.1016/j.resp.2011.08.011. Epub 2011 Aug 27.
The exercise ventilatory response (EVR; defined as the slope of the relationship between ventilation and CO(2) production) is reversibly augmented within a single exercise trial with increased respiratory dead space (DS) in both younger (Wood, H.E., Mitchell, G.S., Babb, T.G., 2008. Short-term modulation of the exercise ventilatory response in young men. J. Appl. Physiol. 104, 244-252) and older (Wood, H.E., Mitchell, G.S., Babb, T.G., 2010. Short-term modulation of the exercise ventilatory response in older men. Respir. Physiol. Neurobiol. 173, 37-46) men. The neural mechanism accounting for this augmentation is known as short-term modulation (STM) of the EVR. Since the effects of female sex hormones on STM are unknown, we examined the capacity for STM in healthy adult women of two age groups; nine younger (29±3 yrs, eumenorrheic) and seven older (69±3 yrs, postmenopausal) women were studied at rest and during cycle exercise (10 W, 30 W; not randomized) in control conditions and with added external DS (200 mL, 400 mL; randomized). Within groups, the main effects of DS and work rate on EVR were analyzed with a two-way repeated measures ANOVA; EVR comparisons between groups were made with unpaired t-tests. In both groups, EVR increased progressively with increasing DS volume (e.g. at 10 W 31±4 and 35±6 in control, 40±11 and 40±6 with 200 mL, 48±12 and 49±11 with 400 mL DS in younger and older women, respectively). In younger women, the effects of DS on EVR differed between work rates (significant interaction, p<0.05), although this was not the case for older women. In both groups, [Formula: see text] regulation was similar between DS and control; hence, increased EVR was not due to altered chemoreceptor feedback from rest to exercise. EVR with and without added DS did not differ between age groups. We conclude that the capacity for STM of the EVR with added DS is similar in healthy younger and older women.
运动通气反应（EVR；定义为通气和二氧化碳产量之间关系的斜率）在单次运动试验中可随增加的呼吸死腔（DS）而可逆性增加，这种情况在年轻（Wood, H.E., Mitchell, G.S., Babb, T.G., 2008. 年轻男性运动通气反应的短期调节。应用生理学杂志 104, 244-252）和老年男性（Wood, H.E., Mitchell, G.S., Babb, T.G., 2010. 老年男性运动通气反应的短期调节。呼吸生理学与神经生物学 173, 37-46）中均有出现。引起这种增加的神经机制被称为 EVR 的短期调节（STM）。由于女性性激素对 STM 的影响尚不清楚，我们研究了两个年龄组健康成年女性的 STM 能力；9 名年轻（29±3 岁，月经正常）和 7 名年长（69±3 岁，绝经后）女性在休息和循环运动（10 W，30 W；未随机）时在对照条件和外加外部 DS（200 mL，400 mL；随机）下进行研究。在组内，用双因素重复测量方差分析分析 DS 和工作率对 EVR 的主要影响；通过独立样本 t 检验比较组间 EVR。在两组中，EVR 随 DS 容积的增加而逐渐增加（例如，在 10 W 时，年轻女性的控制、200 mL 和 400 mL DS 分别为 31±4 和 35±6、40±11 和 40±6、48±12 和 49±11）。在年轻女性中，DS 对 EVR 的影响因工作率而异（显著的交互作用，p<0.05），而年长女性则不然。在两组中，DS 和对照之间的[Formula: see text]调节相似；因此，EVR 的增加不是由于从休息到运动时化学感受器反馈的改变。有和没有外加 DS 的 EVR 在年龄组之间没有差异。我们的结论是，健康的年轻和年长女性对 EVR 的 STM 能力相似。
