Background/Objectives: Long-term effects of post-COVID-19 on several health outcomes remain unclear. We assessed PA and sedentary behaviour changes and explored behaviour-change factors twelve months post-COVID-19 in people with and without Long COVID. Methods: A prospective cohort study followed people treated for COVID-19 in different settings (home, hospital ward, intensive care unit) from twelve months to eighteen months post-COVID-19. Participants with and without Long COVID were identified. PA (Light PA-LPA, Moderate-to-Vigorous PA-MVPA, Steps·day^-1), sedentary time, functional capacity (six-minute walk test-6MWT), muscle strength (quadriceps maximal voluntary contraction-QMVC), dyspnoea (modified Medical Research Council scale-mMRC), fatigue, symptoms of anxiety and depression, and health-related quality of life-HRQoL were assessed. Results: Among 148 participants (58 ± 15 years, 54% male), 101 had Long COVID. All remained physically inactive. People with Long COVID significantly increased LPA (LPA_LongCOVID +28 [1; 55] min·day^-1; LPA_Controls +6 [-32; 45] min·day^-1), and decreased MVPA (MVPA_LongCOVID -4 [-7; -2] min·day^-1; MVPA_Controls -4 [-8; 1] min·day^-1) and sedentarism (Sedentarism_LongCOVID -47 [-89; -4] min·day^-1; Sedentarism_Controls -30 [-88; 28] min·day^-1). At eighteen months, higher proportions of individuals with Long COVID had impaired 6MWT (17% vs. 0%), reduced QMVC (25% vs. 6%), dyspnoea (24% vs. 0%), fatigue (67% vs. 13%), symptoms of anxiety (47% vs. 9%) and depression (26% vs. 0%) as well as poor HRQoL (50% vs. 6%). PA and sedentary behaviour changes at eighteen months were associated with dyspnoea and impaired QMVC at twelve months (LPA: mMRC ≥ 2: -41.56 [-129.30; 46.00] min·day^-1, Steps·day^-1: mMRC: -416.13 [-1223.83; 391.57]; QMVC ≤ 70% predicted: -1251.39 [-2661.69; 158.91], Sedentarism: mMRC ≥ 2: +47.21 [-90.57; 184.99] min·day^-1; 0.24 ≤ R² ≤ 0.32). Conclusions: PA and sedentary behaviour remain altered long after COVID-19, with people with Long COVID adjusting to fit lower PA levels, possibly driven by physical limitations and symptoms. Dyspnoea and muscle weakness may influence PA and sedentary behaviour.

Keywords: Long COVID; dyspnoea; muscle weakness; physical activity; quality of life; sedentary behaviour.

背景/目的：COVID-19后的长期健康影响尚不清楚。我们评估了有和没有长新冠的人在感染后一年中身体活动（PA）和久坐行为的变化，并探讨了行为变化的因素。方法：一项前瞻性队列研究追踪了不同治疗环境（居家、普通病房、重症监护室）中的COVID-19患者，从感染后十二个月到十八个月。确定了有长新冠和没有长新冠的参与者。评估的身体活动包括轻度身体活动（LPA）、中高强度身体活动（MVPA）、每日步数；久坐时间、功能能力（六分钟步行测试-6MWT）；肌力（股四头肌最大自主收缩-QMVC）；呼吸困难（改良医学研究委员会量表-mMRC）；疲劳感；焦虑和抑郁症状，以及与健康相关的生活质量-HRQoL。结果：在148名参与者中（平均年龄58 ± 15岁，男性占54%），有101人患有长新冠。所有人均保持身体不活跃状态。患有长新冠的人显著增加了轻度身体活动时间（LPA_LongCOVID+28[1;55]分钟/天；对照组LPA+6[-32;45]分钟/天），减少了中高强度身体活动时间和久坐时间（MVPA_LongCOVID-4[-7;-2]分钟/天；对照组MVPA-4[-8;1]分钟/天；久坐行为_LongCOVID-47[-89;-4]分钟/天；对照组久坐行为-30[-88;28]分钟/天）。在感染后十八个月，长新冠患者的六分钟步行测试受损的比例更高（17% vs. 0%），股四头肌最大自主收缩力降低的比例也较高（25% vs. 6%），呼吸困难比例较高（24% vs. 0%），疲劳感更严重（67% vs. 13%），焦虑症状和抑郁症状更多见（47% vs. 9%，26% vs. 0%）以及生活质量较差（50% vs. 6%）。感染后十八个月的身体活动和久坐行为变化与十二个月时的呼吸困难及肌力受损相关（轻度身体活动：mMRC ≥ 2: -41.56[-129.30; 46.00]分钟/天；步数：mMRC: -416.13 [-1223.83; 391.57]；肌力 ≤ 预测值的70%: -1251.39[-2661.69; 158.91]; 久坐行为：mMRC ≥ 2: +47.21 [-90.57; 184.99]分钟/天；相关系数R²: 0.24 ≤ R² ≤ 0.32）。结论：在COVID-19后的很长时间内，身体活动和久坐行为仍然受到影响。长新冠患者可能由于生理限制和症状的原因而适应了较低的身体活动水平。呼吸困难和肌肉无力可能影响身体活动和久坐行为。

关键词： 长新冠；呼吸困难；肌力下降；身体活动；生活质量；久坐行为。