Cawley John, Meyerhoefer Chad, Newhouse David
Department of Policy Analysis and Management, Cornell University, Ithaca, New York 14853, USA.
Health Econ. 2007 Dec;16(12):1287-301. doi: 10.1002/hec.1218.
To combat childhood overweight in the US, which has risen dramatically in the past three decades, many medical and public health organizations have called for students to spend more time in physical education (PE) classes. This paper is the first to examine the impact of state PE requirements on student PE exercise time. It also exploits variation in state laws as quasi-natural experiments in order to estimate the causal impact of PE on overall student physical activity and weight. We study nationwide data from the Youth Risk Behavior Surveillance System for 1999, 2001, and 2003 merged with data on state minimum PE requirements from the 2001 Shape of the Nation Report. We find that high school students with a binding PE requirement report an average of 31 additional minutes per week spent physically active in PE class. Our results also indicate that additional PE time raises the number of days per week that girls report having exercised vigorously or having engaged in strength-building activity. We find no evidence that PE lowers BMI or the probability that a student is overweight. We conclude that raising PE credit requirements may make girls more physically active overall but there is not yet the scientific base to declare raising PE requirements an anti-obesity initiative for either boys or girls.
为应对美国儿童超重问题（该问题在过去三十年中急剧上升），许多医学和公共卫生组织呼吁学生增加体育课时间。本文首次研究了各州体育课程要求对学生体育锻炼时间的影响。它还利用各州法律的差异作为准自然实验，以估计体育课对学生总体身体活动和体重的因果影响。我们研究了来自青少年风险行为监测系统1999年、2001年和2003年的全国性数据，并与2001年《国家状况报告》中有关各州体育课程最低要求的数据相结合。我们发现，有强制性体育课程要求的高中生报告称，他们每周在体育课上进行体育活动的时间平均增加了31分钟。我们的结果还表明，增加体育课时间会增加女孩报告每周进行剧烈运动或参加力量训练活动的天数。我们没有发现证据表明体育课能降低身体质量指数（BMI）或学生超重的概率。我们得出结论，提高体育课程学分要求可能会使女孩总体上更加积极地进行体育活动，但目前还没有科学依据宣称提高体育课程要求是一项针对男孩或女孩的抗肥胖举措。
