Department of Physical education and Sports Sciences. University of Dar es Salaam, Dar es Salaam, Tanzania.
School of Sport Exercise and Rehabilitation Sciences, University of Essex, Colchester, United Kingdom.
PLoS One. 2019 Feb 15;14(2):e0211414. doi: 10.1371/journal.pone.0211414. eCollection 2019.
Comparisons of physical fitness measures between children or within group measures over time are potentially confounded by differences in body size. We compared measures of strength (handgrip) and aerobic fitness (running-speed [20m shuttle-run]) of 10.0-15.9 year-olds from Dar es Salaam, Tanzania (n = 977) with schoolchildren from England (n = 1014) matched for age and sex. Differences in fitness were analyzed using general linear models, with allometric scaling for body size (mass and stature) and further adjustments for physical activity. Mean handgrip of Tanzanians was lower than English youth (F = 165.0, P<0.001, ηp2 = .079). The difference became trivial when run-speed was scaled for body size (ηp2 = .008). Running-speed of the English children was higher than in Tanzanians (F = 16.0, P<0.001, ηp2 = .014). Allometric scaling for accentuated this between-county difference in running-speed (ηp2 = .019) but when adjusted for physical activity between-country differences in running-speed were trivial (ηp2 = .008). These data contradict those studies showing poor muscular fitness in African youth and highlight the need for appropriate scaling techniques to avoid confounding by differences in body size. In contrast to those from rural areas, our sample of contemporary urban Tanzanians were less aerobically fit than European youth. Differences were independent of body size. Lower aerobic fitness of urban Tanzanian youth may be due to reported physical activity levels lower than those of English youth and lower still than previously reported in rural Tanzania.
比较儿童之间或群体随时间推移的体能指标可能会因身体大小的差异而受到影响。我们比较了来自坦桑尼亚达累斯萨拉姆的 10.0-15.9 岁儿童（n=977）与英国同龄同性别学童（n=1014）的力量（握力）和有氧健身（20 米穿梭跑速度）指标。使用一般线性模型分析了身体素质的差异，对身体大小（体重和身高）进行了异速标度调整，并进一步进行了身体活动调整。坦桑尼亚人的平均握力低于英国青少年（F=165.0，P<0.001，ηp2=0.079）。当按身体大小对跑步速度进行标度时，差异变得微不足道（ηp2=0.008）。英国儿童的跑步速度高于坦桑尼亚人（F=16.0，P<0.001，ηp2=0.014）。身体大小的异速标度强调了这种国家间跑步速度差异（ηp2=0.019），但当调整身体活动时，国家间跑步速度的差异微不足道（ηp2=0.008）。这些数据与那些表明非洲青年肌肉健康状况不佳的研究结果相矛盾，强调需要使用适当的标度技术来避免因身体大小差异而产生混淆。与来自农村地区的人相比，我们当代城市坦桑尼亚人的有氧健身能力较差。差异与身体大小无关。城市坦桑尼亚青年的有氧健身能力较低可能是由于报告的身体活动水平低于英国青少年，甚至低于以前在坦桑尼亚农村地区报告的水平。
