Trexler Eric T, McCallister Drew, Smith-Ryan Abbie E, Branca Rosa T
Human Movement Science Curriculum, University of North Carolina, Chapel Hill, NC, USA.
Department of Exercise and Sport Science, University of North Carolina, Chapel Hill, NC, USA.
J Nat Sci. 2017 Mar;3(3).
Brown adipose tissue (BAT) in adults has been shown to have a meaningful impact on energy expenditure and cold-induced thermogenesis. Data from rodent research have suggested that exercise may be a promising method of increasing BAT activity, with potential applications to the treatment and prevention of obesity and diabetes. However, emerging human research using positron emission tomography (PET) with [18F] Fluorodeoxyglucose (FDG) has identified lower BAT activity in endurance-trained athletes compared to sedentary controls, despite similar metabolic rate responses to cold exposure. Here we report a similar incidental finding in a pilot study that included a sample of 2 endurance athletes and 10 untrained individuals. This incidental finding motivated a retrospective analysis of the data aimed at assessing the potential confounding influence of muscle FDG uptake on BAT estimation. Results indicated that athletes skewed the relationship between body mass index (BMI) and supraclavicular fat (sFAT) FDG uptake, while a non-significant inverse relationship between muscle FDG uptake and sFAT FDG uptake was also observed. The current retrospective analysis provides preliminary evidence suggesting that BAT estimation may be biased in endurance-trained individuals, which may relate to skeletal muscle FDG uptake. These results point to important methodological considerations for estimating BAT activity via FDG uptake, for which we propose potential solutions that facilitate unbiased estimation of BAT activity in groups that differ in terms of lean body mass and physical activity level.
成人棕色脂肪组织（BAT）已被证明对能量消耗和冷诱导产热有显著影响。啮齿动物研究数据表明，运动可能是增加BAT活性的一种有前景的方法，在肥胖和糖尿病的治疗与预防方面具有潜在应用价值。然而，新兴的使用正电子发射断层扫描（PET）和[18F]氟脱氧葡萄糖（FDG）的人体研究发现，与久坐不动的对照组相比，耐力训练运动员的BAT活性较低，尽管他们对冷暴露的代谢率反应相似。在此，我们在一项试点研究中报告了类似的偶然发现，该研究包括2名耐力运动员和10名未经训练的个体样本。这一偶然发现促使我们对数据进行回顾性分析，旨在评估肌肉FDG摄取对BAT估计的潜在混杂影响。结果表明，运动员使体重指数（BMI）与锁骨上脂肪（sFAT）FDG摄取之间的关系发生了偏差，同时还观察到肌肉FDG摄取与sFAT FDG摄取之间存在不显著的负相关关系。当前的回顾性分析提供了初步证据，表明在耐力训练个体中，BAT估计可能存在偏差，这可能与骨骼肌FDG摄取有关。这些结果指出了通过FDG摄取估计BAT活性时的重要方法学考虑因素，为此我们提出了一些潜在的解决方案，以促进在瘦体重和身体活动水平不同的群体中无偏差地估计BAT活性。
