Kinuthia Stanley K, Stratton Gareth, Wachira Lucy J, Okoth Victor O, Owino George Evans, Ochola Sophie, Kiplamai Festus, Onywera Vincent, Swindell Nils
Department of Physical Education, Exercise and Sports Science, Kenyatta University, Nairobi, Kenya.
Applied Sports, Technology, Exercise and Medicine (A-STEM) Research Centre, Swansea University, Swansea, United Kingdom.
PLoS One. 2025 Aug 4;20(8):e0329173. doi: 10.1371/journal.pone.0329173. eCollection 2025.
Physical activity (PA) is crucial for children's health, cardiorespiratory fitness (CRF) and weight status. However, research on the PA profiles of Kenyan children, especially between rural and urban areas, is limited.
This study examined the PA profiles of 537 school-aged children (51.6% girls, 9-11-year-olds) from Nairobi City County, Kenya (urban setting), and Kitui County, Kenya (rural setting), using stratified multistage random cluster sampling. Participants wore an accelerometer (Axivity AX3) on their non-dominant wrist for 24 hours a day over seven days. Raw accelerations were extracted and averaged over a 5-s epoch (AvgAcc) to estimate PA volume. Intensity gradient (IG) was calculated as a standardised metric of PA intensity. Participants' CRF was assessed by the 20-metre multistage fitness test. Anthropometric measurements (mass and stature) were taken to compute BMI z-scores.
PA metrics varied by sex, weight, and CRF. Boys had higher AvgAcc (p < .001) and IG (p < .001) than girls. Healthy weight participants differed significantly in AvgAcc from overweight (p = .001) and obese (p = .001) groups and in IG from overweight (p = .039) and obese (p = .003). Participants with sufficient CRF and insufficient CRF differed significantly in AvgAcc (p < .001) and IG (p < .001). AvgAcc was negatively associated with BMI z-scores (β = -0.02, p < .001) and positively associated with CRF (β = 0.21, p < .001), independent of IG and other covariates. IG showed a significant negative association with BMI z-scores (β = -1.27, p = 0.003) and a significant positive association with CRF (β = 18.93, p < .001), dependent on AvgAcc.
This study introduces AvgAcc and IG metrics among Kenyan children. Urban children accumulate less PA volume and exhibit an inferior intensity profile, which is reflected in important health indicators (BMI and CRF). These findings will inform policy as well as targeted interventions to enhance children's health in diverse contexts.
身体活动对儿童健康、心肺适能和体重状况至关重要。然而，关于肯尼亚儿童身体活动状况的研究，尤其是城乡之间的比较，较为有限。
本研究采用分层多阶段随机整群抽样法，对来自肯尼亚内罗毕市县（城市地区）和基图伊县（农村地区）的537名学龄儿童（女孩占51.6%，年龄9至11岁）的身体活动状况进行了调查。参与者在非优势手腕上佩戴加速度计（Axivity AX3），连续7天每天佩戴24小时。提取原始加速度，并在5秒时间段内求平均值（平均加速度）以估计身体活动量。计算强度梯度（IG）作为身体活动强度的标准化指标。通过20米多级适能测试评估参与者的心肺适能。测量人体测量学指标（体重和身高）以计算BMI z评分。
身体活动指标因性别、体重和心肺适能而异。男孩的平均加速度（p < 0.001）和强度梯度（p < 0.001）高于女孩。健康体重参与者的平均加速度与超重（p = 0.001）和肥胖（p = 0.001）组存在显著差异，强度梯度与超重（p = 0.039）和肥胖（p = 0.003）组存在显著差异。心肺适能充足和不足的参与者在平均加速度（p < 0.001）和强度梯度（p < 0.001）方面存在显著差异。平均加速度与BMI z评分呈负相关（β = -0.02，p < 0.001），与心肺适能呈正相关（β = 0.21，p < 0.001），不受强度梯度和其他协变量影响。强度梯度与BMI z评分呈显著负相关（β = -1.27，p = 0.003），与心肺适能呈显著正相关（β = 18.93，p < 0.001），依赖于平均加速度。
本研究在肯尼亚儿童中引入了平均加速度和强度梯度指标。城市儿童积累的身体活动量较少，且强度状况较差，这在重要健康指标（BMI和心肺适能）中有所体现。这些发现将为政策制定以及针对性干预措施提供参考，以在不同环境中促进儿童健康。
