Mikalsen Hilde Kristin, Bentzen Marte, Säfvenbom Reidar, Lagestad Pål Aril
Department of Physical Education and Sport Science, Nord University, Levanger, Norway.
Department of Teacher Educations and Outdoor Studies, The Norwegian School of Sport Sciences, Oslo, Norway.
Front Sports Act Living. 2020 Aug 4;2:85. doi: 10.3389/fspor.2020.00085. eCollection 2020.
Research on physical activity (PA) behavior reveals an overall decrease worldwide from early childhood and throughout adulthood. The ability to illuminate which factors promote activity for whom and in which phase of life, therefore, becomes a key concept in extending our understanding of individuals' physical activity trajectories. Accordingly, this study investigates latent trajectories of objectively measured PA in adolescents ( = 306) over 3 years from ages 13 to 15. Further, it was tested whether eagerness for physical activity, perceived athletic competence, and parental support were associated with the different trajectories of PA. Latent class growth analysis revealed two PA trajectories (trajectory 1: "decrease from very high" and trajectory 2: "steeper decrease from high"). Trajectory 1 had a higher PA level at baseline and less PA decline than trajectory 2. Trajectory 1, "decrease from very high," was associated with higher levels of eagerness for physical activity and perception of competence at all three time points. Furthermore, the effect size of differences between trajectory 1, "decrease from very high," and trajectory 2, "steeper decrease from high," increased from baseline (age 13, seventh grade) to posttest (age 15, ninth grade). This finding indicates a stronger experience of PA as enjoyable, personally relevant, and self-confirming behavior (i.e., "I regard myself as a person who exercises") within the most active adolescents and even stronger as they get older. Consistent with previous research, the PA level declined from seventh to ninth grade. Being more eager for PA and perceiving oneself more as athletically competent is related to higher levels of PA. This highlights the importance of optimizing environmental factors that increase adolescents' experience of eagerness for physical activity and physical athletic competence.
对身体活动（PA）行为的研究表明，从幼儿期到成年期，全球范围内的身体活动总体呈下降趋势。因此，弄清楚哪些因素在人生的哪个阶段对谁的身体活动有促进作用，就成为扩展我们对个体身体活动轨迹理解的关键概念。据此，本研究调查了306名青少年从13岁到15岁3年间客观测量的身体活动潜在轨迹。此外，还测试了对身体活动的热情、感知到的运动能力和父母支持是否与身体活动的不同轨迹相关。潜在类别增长分析揭示了两种身体活动轨迹（轨迹1：“从非常高水平下降”和轨迹2：“从高水平急剧下降”）。轨迹1在基线时的身体活动水平较高，且身体活动下降幅度小于轨迹2。轨迹1，即“从非常高水平下降”，在所有三个时间点都与更高水平的身体活动热情和能力感知相关。此外，轨迹1（“从非常高水平下降”）和轨迹2（“从高水平急剧下降”）之间差异的效应大小从基线（13岁，七年级）到后测（15岁，九年级）有所增加。这一发现表明，在最活跃的青少年中，身体活动作为一种有趣、与个人相关且能自我确认的行为（即“我认为自己是一个锻炼的人”）的体验更强，并且随着年龄增长这种体验会更强。与之前的研究一致，身体活动水平从七年级到九年级有所下降。对身体活动更热情以及更认为自己有运动能力与更高水平的身体活动相关。这凸显了优化环境因素的重要性，这些因素能增加青少年对身体活动的热情体验和身体运动能力。
