Aging and the conservation of energy.
详细信息
- 作者：Schrack ; Jennifer Ann.
- 学历：Ph.D.
- 年：2011
- 导师：Chaves, Paulo H.M.,eadvisor
- 毕业院校：The Johns Hopkins University
- ISBN：9781124761381
- CBH：3463561
- Country：USA
- 语种：English
- FileSize：4916842
- Pages：155
文摘
Energy is the essence of life； in the absence of energy, life expires. As individuals age, a greater proportion of daily energy is needed purely for survival and the availability of energy for instrumental daily activities and recreational pursuits progressively shrinks. Decreased energy availability may be an important determinant of why older individuals experience increased fatigability and demonstrate progressive sedentary behavior over time. If higher levels of energy are required to perform everyday functional tasks, less energy is held in reserve and available for discretionary activity. Accordingly, assessing the amount of energy an individual uses at rest and during performance of daily tasks such as walking may provide insight into the mechanisms that lead to high fatigability and disability in older adults. Walking is the most common component of discretionary activity and is fundamental for independent living. Since gait speed declines with age and predicts negative health outcomes, including disability and mortality, we propose to examine the mechanisms contributing to reduced gait speed with age and, in particular, to test the hypothesis that this reduction derives from insufficient energy production. Four manuscripts are included in this dissertation using cross-sectional data from the Baltimore Longitudinal Study of Aging. The first examines the relationship between energy consumption, energy availability, and age. The second assesses the relationship between the energy expended during customary overground walking and usual gait speed in older adults. The third examines the concept of walking efficiency in older adults and its relationship to peak energy availability and usual gait speed. Finally, the fourth is a validation study Appendix A) comparing a portable metabolic analyzer with a standard metabolic cart. The work presented in this dissertation will examine the predominant energetic contributors to usual gait speed and will help elucidate the imbalance between energy availability and energy consumption that occurs with age as a potential new target for the prevention of mobility disability.