Osteoporosis Prevention in Sedentary Adolescent Females

描述（由申请人提供）：缺乏身体活动对健康有严重影响，并已达到流行病的程度。在我们最近完成的干预研究中，我们研究了在控制运动干预中青少年体育活动行为改变的机制。虽然在改善身体健康和体育活动方面取得了成功，但研究发现，任何提出的行为改变的心理社会调节因素都没有得到支持。目前提出的研究通过测试从最近的理论和实证工作中得出的一种新的身体活动行为生物行为模型，扩展了我们迄今为止的发现。本研究将检验以下假设：主要假设：1。在基线时，对运动有更积极情感反应的青少年将更有可能随着时间的推移维持或增加他们的身体活动水平。2. 在基线时具有更大的运动内在动机（即运动乐趣）的青少年将更有可能随着时间的推移维持或增加其身体活动水平。3. 急性运动相关情感与内在动机之间存在交互作用，即在那些内在动机较低的人群中，随着时间的推移，急性运动相关情感与体育活动参与之间的关联会更强。次要假设：4；通过脑电图确定，相对于右脑，左额叶大脑活跃度更高的青少年更有可能对运动产生积极的情感转变。5. 当青少年在锻炼时感到有能力，从锻炼中获得社会联系感和/或体验到与锻炼相关的自主性时，他们会更有内在动机去锻炼。120名女性和120名男性青少年将完成静息脑电图，以评估大脑活动的不对称性，并分别进行2项30分钟的中等和高强度运动任务。对运动的情感反应和运动的内在动机将使用标准化问卷进行评估。为期一年的随访将检查自基线测试以来体育活动参与情况的变化。

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.