Optimal Timing of Exercise Initiation Within a Lifestyle Weight Loss Program

描述（由申请人提供）：尽管生活方式干预对减肥有短期效果，但许多人在1年内体重会显著增加。有规律的身体活动（PA）是持续减肥的最佳预测因素之一，目前的活动指南建议高水平的PA以防止减肥后体重反弹。然而，大多数人在典型的减肥计划中没有达到或维持高水平的PA，其中饮食和运动干预同时开始。因此，必须评估新的策略，以促进坚持高水平的PA在生活方式减肥计划。在减肥计划中开始锻炼的最佳时机是一个以前没有研究过的领域。本提案的总体目标是评估在饮食诱导的体重减轻后（而不是同时开始）进行运动干预的程度，以提高运动坚持性并促进长期体重减轻。减肥后开始锻炼可能会改善锻炼的采用和坚持，并促进长期减肥，因为：1）在较低体重时锻炼可能更容易进行，2）减肥后受伤率（和锻炼损耗）可能会降低，3）一次专注于单一行为改变可能更有效（而不是尝试同时改变饮食和锻炼行为）。出于这些原因，我们认为在饮食引起的体重减轻的最初阶段之后开始锻炼可能更有效。我们的总体假设是 与同时开始相同的饮食和运动干预的传统计划相比，饮食和运动干预的顺序实施将导致18个月时体重减轻的改善。研究设计包括一项为期18个月的随机试验，其中肥胖受试者接受标准行为治疗（标准BT）或序贯行为治疗（序贯BT）。标准BT将接受传统的行为减肥计划，饮食和运动的变化同时开始。序贯BT将接受一个计划，在最初的6个月内只关注饮食变化，然后在随后的6个月内结合锻炼。两组都将接受18个月的随访，以评估长期体重减轻情况。在目标1中，我们将评估运动开始时间对体重减轻和身体成分的影响。在目标2中，我们将评估运动开始时间对自由生活PA和心肺适应性的影响。在目标3中，我们将评估运动开始时间对坚持饮食体重控制行为的影响。在目标4中，我们将探讨运动开始的时机可能影响长期减肥的机制（运动感知、运动相关损伤和与我们假设相关的行为结构）。该方法是创新的，因为它专注于确定开始锻炼的最佳时间，而不是评估特定的频率，强度或锻炼持续时间。的 这项拟议的研究意义重大，因为它可以确定一种策略，有助于制定更有效的肥胖治疗方案，帮助更多的人实现和维持减肥。

DESCRIPTION (provided by applicant): Despite the short-term effectiveness of lifestyle interventions for weight loss, many individuals regain a significant amount of weight within a 1 year period. Regular physical activity (PA) is one of the best predictors of sustained weight loss and current activity guidelines recommend high levels of PA to prevent weight regain after weight loss. However, most individuals do not achieve or sustain high levels of PA during typical weight loss programs in which diet and exercise interventions are initiated concurrently. Thus it is essential to evaluate novel strategies to promote adherence to high levels of PA within a lifestyle weight loss program. The optimal timing of exercise initiation within a weight loss program is an area that has not previously been studied. The overall objective of this proposal is to evaluate the extent to which an exercise intervention timed after diet-induced weight loss (rather than initiated concurrently) improves exercise adherence and facilitates long-term weight loss. Exercise initiation after weight loss may improve exercise adoption and adherence and promote long- term weight loss because: 1) exercise may be easier to perform at a lower body weight, 2) injury rates (and exercise attrition) may be reduced after weight loss and 3) it may be more effective to focus on a single behavior change at a time (rather than attempting concurrent changes in diet and exercise behaviors). For these reasons, we believe it may be more effective to initiate exercise after an initial period of diet-induced weight loss. Our overall hypothesis is that sequential delivery of diet and exercise interventions will result in improved weight loss at 18 months when compared to a traditional program in which identical diet and exercise interventions are initiated simultaneously. The study design involves an 18 month randomized trial within which obese subjects receive either standard behavioral therapy (Standard BT) or sequential behavioral therapy (Sequential BT). Standard BT will receive a traditional behavioral weight loss program where diet and exercise changes are initiated simultaneously. Sequential BT will receive a program that focuses solely on dietary changes in the initial 6 months, and then incorporates exercise in the ensuing 6 months. Both groups will be followed for 18 months to assess long-term weight loss. In Aim 1 we will assess the effect of timing of exercise initiatio on weight loss and body composition. In Aim 2 we will assess the effect of timing of exercise initiation on free living PA and cardio-respiratory fitness. In Aim 3 we will assess the effect of timing of exercise initiation on adherence to dietary weight control behaviors. In Aim 4 we will explore mechanisms (perception of exercise, exercise related injuries, and behavioral constructs related to our hypothesis) through which timing of exercise initiation may impact long-term weight loss. The approach is innovative as it focuses on determining the optimal time to begin exercise rather than evaluating a specific frequency, intensity, or duration of exercise. The proposed study is significant as it could identify a strategy that could aid in the development of more effective obesity treatment programs and help more people achieve and sustain a weight loss.