The Influence of 24-Hour Activity Behavior on College Students’ Fatigue<sup>—Based on the </sup><sup>Compositional Isotemporal Substitution Model</sup>

目的：基于成分等时替代模型探讨大学生24 h活动行为与疲劳的关系及替代效应，为缓解大学生疲劳提供建议。方法：于2023年11~12月采取随机抽样方法，对浙江省某高校630名大学生进行24 h活动行为调查与疲劳状况调查，调查内容为久坐(SB)时间、睡眠(SLP)时间、低强度身体活动(LPA)时间、中高强度身体活动(MVPA)时间；采用成分等时替代方法，探究24 h活动行为与疲劳的量效关系。结果：(1) SB与疲劳各维度及总分均呈正相关关系(β = 0.25~1.77)；SLP与躯体疲劳、活动减少、动机降低维度及总分呈正相关关系(β = 0.25~1.38)；LPA仅与动机降低维度呈负相关关系(β = −0.10)；MVPA与一般疲劳、躯体疲劳、活动减少、动机降低维度及总分呈负相关关系(β = −1.04~−0.13)。(2) 15 min等时替代模型预测变化显示，MVPA替代SB、SLP后大学生疲劳总分显著降低，且MVPA代替SB对降低大学生疲劳总分的积极效应最佳。(3) 在从−20 min到20 min的剂量–效应关系中，MVPA代替SB、SLP产生的积极影响小于SB、SLP代替MVPA产生的消极影响。结果：MVPA对大学生疲劳具有积极正向的影响效应。在改善大学生疲劳状况时，尽可能提高MVPA时间减少SB时间可能是有效方法之一。Objective: Based on the compositional isotemporal substitution model, this study aimed to explore the relationship and substitution effects between 24-hour activity behaviors and fatigue among college students, and to provide suggestions for alleviating college students’ fatigue problems. Methods: From November to December 2023, a random sampling method was adopted to conduct a 24-hour activity behavior survey and a fatigue status survey on 630 college students from a university in Zhejiang Province. The survey covered the time spent on sedentary behavior (SB), sleep (SLP), low-intensity physical activity (LPA), and moderate-to-vigorous physical activity (MVPA). The isotemporal substitution method of components was used to explore the dose-response relationship between 24-hour activity behaviors and fatigue. Results: (1) SB was positively correlated with all dimensions and the total score of fatigue (β = 0.25~1.77). SLP was positively correlated with the dimensions of physical fatigue, reduced activity, reduced motivation, and the total score (β = 0.25~1.38). LPA was only negatively correlated with the dimension of reduced motivation (β = −0.10). MVPA was negatively correlated with the dimensions of general fatigue, physical fatigue, reduced activity, reduced motivation, and the total score (β = −1.04~−0.13). (2) The predicted changes in the 15-minute isotemporal substitution model showed that after MVPA replaced SB or SLP, the total fatigue score of college students decreased significantly, and replacing SB with MVPA had the best positive effect on reducing the total fatigue score of college students. (3) In the dose-response relationship from −20 minutes to 20 minutes, the positive impact of replacing SB or SLP with MVPA was less than the negative impact of replacing MVPA with SB or SLP. Conclusion: MVPA has a positive and beneficial effect on college students’ fatigue. To improve the fatigue status of college students, increasing the time of MVPA and reducing the time of SB as much as possible may be one of the effective methods.