Chopra Swati, Morrow Melissa M, Ngufor Che, Fortune Emma
Leeds Institute of Rheumatic and Musculoskeletal Medicine, University of Leeds, Leeds, United Kingdom.
Robert D. and Patricia E. Kern Center for the Science of Health Care Delivery, Department of Health Sciences Research, Mayo Clinic, Rochester, MN, United States.
Front Sports Act Living. 2020 Jul 9;2:83. doi: 10.3389/fspor.2020.00083. eCollection 2020.
Recent evidence suggests that sedentary behavior (SB) may be associated with bone health. This study compares free-living physical activity (PA) and SB distribution patterns of postmenopausal women with normal vs. low total hip bone mineral density (BMD). Sixty nine post-menopausal women [mean (min-max) age: 61 (46-79) years] wore ActiGraph GT3X+ activity monitors on the bilateral ankles for 7 days in free-living. Participants were split into two groups: those with normal hip BMD (T-scores ≥-1.0; = 34) and those with low hip BMD (T-scores <-1.0; = 35) as defined by the World Health Organization. Daily active time, step counts, sedentary time, sedentary break number, and median sedentary bout length were estimated from ankle acceleration data. The distribution and accumulation patterns of time spent in sedentary bouts, sedentary breaks, and stepping bouts, and sedentary break and stepping bout lengths' variability were also investigated. Group differences were assessed using two-sampled -tests and Mann-Whitney -tests with significance levels of 0.5. Significant between group differences ( < 0.05) were in total daily active time [median (IQR): 257 (209-326) vs. 249 (199-299) min], step count [14,188 (10,938-18,646) vs. 13,204 (10,337-16,630) steps], sedentary time [669 (584-731) vs. 687 (615-753) min], and sedentary break number [93 (68-129) breaks vs. 88 (64-113) breaks], as well as median sedentary bout length [15.1 (11.9-22.1) vs. 15.8 (12.1-24.9) min]. Participants' sedentary bouts were found to be power law distributed with 52% of sedentary time occurring in bouts ≥20 min for the normal BMD group, and 58% for the low BMD group. Significant differences were observed between groups in sedentary bouts' and sedentary breaks' power distribution exponents ( < 0.0001) and patterns of sedentary and stepping time accumulation using the Gini index ( ≤ 0.0014). Variability was significantly lower for sedentary break and stepping bout lengths for the low BMD group ( ≤ 0.0001). Participants with lower hip BMD have longer sedentary bouts with shorter and less complex activity bouts compared to participants with normal hip BMD. The results suggest healthier hip BMD may be associated with PA distributed more evenly throughout the day with shorter sedentary bouts. PA distribution should be considered in exercise-based bone health management programs.
近期证据表明，久坐行为（SB）可能与骨骼健康相关。本研究比较了全髋骨矿物质密度（BMD）正常与偏低的绝经后女性的日常体力活动（PA）和久坐行为分布模式。69名绝经后女性[平均（最小 - 最大）年龄：61（46 - 79）岁]在日常活动中双侧脚踝佩戴ActiGraph GT3X +活动监测器7天。参与者被分为两组：根据世界卫生组织的定义，全髋BMD正常组（T值≥ - 1.0；n = 34）和全髋BMD偏低组（T值< - 1.0；n = 35）。根据脚踝加速度数据估算每日活动时间、步数、久坐时间、久坐中断次数以及久坐时段的中位数时长。还研究了久坐时段、久坐中断和步行时段所花费时间的分布和累积模式，以及久坐中断和步行时段时长的变异性。使用双样本t检验和曼 - 惠特尼U检验评估组间差异，显著性水平为0.05。组间显著差异（P < 0.05）存在于每日总活动时间[中位数（四分位间距）：257（209 - 326）分钟 vs. 249（199 - 299）分钟]、步数[14,188（10,938 - 18,646）步 vs. 13,204（10,337 - 16,630）步]、久坐时间[669（584 - 731）分钟 vs. 687（615 - 753）分钟]、久坐中断次数[93（68 - 129）次 vs. 88（64 - 113）次]以及久坐时段的中位数时长[15.1（11.9 - 22.1）分钟 vs. 15.8（12.1 - 24.9）分钟]。发现参与者的久坐时段呈幂律分布，正常BMD组中52%的久坐时间出现在时长≥20分钟的时段，低BMD组为58%。在久坐时段和久坐中断次数的幂分布指数（P < 0.0001）以及使用基尼指数的久坐和步行时间累积模式（P ≤ 0.0014）方面，组间观察到显著差异。低BMD组的久坐中断和步行时段时长的变异性显著更低（P ≤ 0.0001）。与全髋BMD正常的参与者相比，全髋BMD较低的参与者久坐时段更长，而活动时段更短且更简单。结果表明，更健康的全髋BMD可能与全天更均匀分布的体力活动以及更短的久坐时段相关。在基于运动的骨骼健康管理计划中应考虑体力活动的分布情况。
