WORK EFFICIENCY IN LACTATING WOMEN

本子项目是利用由NIH/NCRR资助的中心赠款提供的资源的众多研究子项目之一。子项目和研究者（PI）可能已经从另一个NIH来源获得了主要资金，因此可以在其他CRISP条目中表示。列出的机构是中心的，不一定是研究者的机构。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；这相当于比未怀孕、未哺乳的人的能量需求增加约30%。尽管假设女性会通过增加食物摄入和/或动员怀孕期间积累的体脂来满足能量需求的增加，但实证研究未能证明预期的食物摄入和体脂储存利用的增加。这促使研究人员研究第三种选择，即减少能量消耗。本研究的目的是通过研究哺乳对能量消耗的一项指标——运动中的能量效率的影响，来提高我们对哺乳能量消耗的理解。具体来说，我们假设运动中的能量效率在泌乳状态比泌乳后状态更高。为了验证这一假设，我们将以39名哺乳期妇女为样本，在哺乳期高峰期（产后2-3个月）和完全停止母乳喂养后两个月进行纯母乳喂养，测量运动中的能量效率。在泌乳高峰和泌乳后，将在5-7天内的两个非连续的天使用相同的分级运动测试来测量能量效率。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.