WORK EFFICIENCY IN LACTATING WOMEN

这个子项目是许多研究子项目中的一个 由NIH/NCRR资助的中心赠款提供的资源。子项目和 研究者（PI）可能从另一个NIH来源获得了主要资金， 因此可以在其他CRISP条目中表示。列出的机构是 研究中心，而研究中心不一定是研究者所在的机构。 对于人类女性来说，哺乳期是生殖过程中最需要能量的阶段;它相当于比非妊娠非哺乳期水平增加约30%的能量需求。虽然假设妇女将通过增加食物摄入量和/或动员怀孕期间积累的体脂来满足这种能量需求的增加，但实证研究未能证明预期的食物摄入量和体脂储存利用率的增加。这促使研究人员研究第三种选择，即减少能源消耗。本研究的目的是通过检查哺乳对能量消耗的一个测量指标--运动能量效率的影响，来提高我们对哺乳期能量消耗的理解。 具体来说，我们假设，在运动的能量效率是在哺乳期高于哺乳后的状态。为了验证这一假设，我们将测量39名哺乳期妇女在哺乳高峰期（产后2 - 3个月）和母乳喂养完全停止后两个月进行纯母乳喂养的样本中的运动能量效率。 在泌乳高峰期和泌乳后，将在5 - 7天内的两个非连续日使用自行车测力计进行相同分级的运动试验测量能量效率。我们希望发现哺乳期妇女在运动中更有效地利用能量，他的发现将有助于解释她们如何满足哺乳期的能量需求。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. For human females lactation is the most energy-demanding phase of reproduction; it amounts to an increase in energy needs of approximately 30% above non-pregnant non-lactating levels. Although the assumption has been that women will meet this increase in energy need by increasing food intake and/or mobilizing body fat accrued in pregnancy, empirical studies have failed to demonstrate the increases in food intake and utilization of body fat stores expected. This has prompted researchers to examine a third option, i.e. reductions in energy expenditure. The purpose of this study is to improve our understanding of the energy expenditure in lactation by examining the effect of lactation on one measure of energy expenditure, energetic efficiency in exercise. Specifically, we hypothesize that energetic efficiency in exercise is higher in the lactating than the post- lactating state. To test this hypothesis we will measure energetic efficiency in exercise in a sample of 39 lactating women practicing exclusive breastfeeding at peak lactation (2-3 months postpartum) and two months after breastfeeding has ceased completely. At both peak lactation and post-lactation, energetic efficiency will be measured on two non-consecutive days within a 5-7 day period using an identical graded exercise test on a cycle ergometer. We expect to find that lactating women use energy more efficiently in exercise, and that his finding will help explain how they meet the energy demands of lactation.