Division of Training and Movement Science, Research Focus Cognitive Sciences, University of Potsdam, Am Neuen Palais 10, Building 12, 14469, Potsdam, Germany.
Sci Rep. 2024 May 20;14(1):11500. doi: 10.1038/s41598-024-61038-x.
The dissociation of effects of age, time of assessment and cohort is a well-known challenge in developmental science. We examined effects of time of assessment in the school year on children's physical fitness using data from 75,362 German third-graders from seven cohorts. Children were tested once either in the first or second school term of third grade. Tests examined cardiorespiratory endurance (6-min run), coordination (star-run), speed (20-m sprint), lower (standing long jump) and upper (ball-push test) limbs muscle power, and flexibility (stand-and-reach test). We estimated the effect of time of assessment using a regression discontinuity design specified in a linear mixed model with random factors child and school and adjusted for age, sex, and cohort effects. Coordination, speed, and upper limbs muscle power were better in second compared to first school term, with boys exhibiting a larger increase of upper limbs muscle power than girls. There was no evidence for changes in cardiorespiratory endurance, lower limbs muscle power, and flexibility between assessments. Previously reported age and sex effects as well as secular fitness trends were replicated. There is thus evidence for improvement of some physical fitness components beyond age and cohort effects that presumably reflects the benefit of physical activity in physical education and other settings. Effects of assessment time should be taken into consideration in performance-based grading or norm-based selection of children.
年龄、评估时间和队列效应的分离是发展科学中众所周知的挑战。我们使用来自七个队列的 75362 名德国三年级学生的数据，研究了学年中评估时间对儿童身体素质的影响。儿童在三年级的第一个或第二个学期进行一次测试。测试检查了心肺耐力（6 分钟跑）、协调性（星形跑）、速度（20 米冲刺）、下肢（站立跳远）和上肢（球推测试）肌肉力量以及柔韧性（站立摸高测试）。我们使用线性混合模型中指定的回归不连续性设计来估计评估时间的影响，该模型具有随机因素儿童和学校，并调整了年龄、性别和队列效应。与第一个学期相比，第二个学期的协调性、速度和上肢肌肉力量更好，男孩的上肢肌肉力量增长幅度大于女孩。在评估之间，心肺耐力、下肢肌肉力量和柔韧性没有变化。先前报告的年龄和性别效应以及季节性健身趋势得到了复制。因此，有证据表明，一些身体素质成分在年龄和队列效应之外得到了提高，这可能反映了体育教育和其他环境中体育活动的益处。在基于表现的评分或基于标准的儿童选拔中，应考虑评估时间的影响。
