Osteoporosis Prevention in Sedentary Adolescent Females

描述(由申请人提供)：缺乏运动对健康造成严重后果，并正在达到流行的程度。在我们最近完成的干预研究中，我们研究了受控运动干预下青少年体育活动行为变化的机制。尽管在改善身体健康和体育活动方面取得了成功，但这项研究发现，任何被提议的行为改变的心理社会中介都没有得到支持。目前提出的这项研究通过测试一个新的身体活动行为的生物行为模型来扩展我们迄今的发现，该模型来自最近的理论和实证工作。这项研究将检验以下假设：主要假设：1.青少年对基线运动的积极情感反应将更有可能随着时间的推移维持或增加他们的体育活动水平。2.具有更大内在锻炼动机(即，锻炼享受)的青少年将更有可能随着时间的推移维持或增加他们的体力活动水平。3.急性运动相关情绪与内在动机之间存在交互作用，在内在动机较低的人群中，随着时间的推移，急性运动相关情绪与体育活动参与度之间存在较强的关联性。第二个假设：4.通过EEG确定，左侧额叶大脑比右侧激活更多的青少年，更有可能对一轮运动做出积极的情感转变。5.那些在锻炼时感到有能力、从锻炼中获得社会连通感和/或体验到与锻炼相关的自主性的青少年，将更有内在的锻炼动机。120名女性和120名男性青少年将完成一次静息脑电波，以评估大脑活动的不对称性，并将分别以中等强度和高强度进行两项30分钟的运动任务。对锻炼的情感反应和内在动机将使用标准化问卷进行评估。为期一年的跟踪调查将检查自基线测试以来体力活动参与度的变化。

DESCRIPTION (provided by applicant): Physical inactivity has dramatic health consequences and is reaching epidemic proportions. In our recently completed intervention study, we examined the mechanisms of adolescent physical activity behavior change in a controlled exercise intervention. Though successful in terms of improving physical fitness and physical activity, the study found no support for any of the proposed psychosocial mediators of behavior change. The currently proposed study extends our findings to date by testing a novel biobehavioral model of physical activity behavior drawn from recent theoretical and empirical work. The study will test the following hypotheses: Primary Hypotheses: 1. Adolescents with a more positive affective response to a bout of exercise at baseline will be more likely to sustain or increase their level of physical activity over time. 2. Adolescents with greater intrinsic motivation to exercise (i.e., exercise enjoyment) at baseline will be more likely to sustain or increase their level of physical activity over time. 3. There will be an interaction between acute exercise-associated affect and intrinsic motivation, such that among those with low intrinsic motivation there will be a stronger association between acute exercise induced affect and physical activity participation over time. Secondary Hypotheses: 4. Adolescents with greater left frontal brain activation relative to right, as determined via EEG, will be more likely to respond to a bout of exercise with a positive affective shift. 5. Adolescents who feel competent when exercising, derive a sense of social connectedness from exercising and/or experience autonomy related to exercise will be more intrinsically motivated to exercise. 120 female and 120 male adolescents will complete a resting EEG to assess brain activity asymmetry, and will perform 2 30-minute exercise tasks at moderate and hard levels of intensity, respectively. Affective response to exercise and intrinsic motivation to exercise will be assessed using standardized questionnaires. A one-year follow-up will examine changes in physical activity participation since the baseline testing.