Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, UNITED KINGDOM.
School of Biomedical Sciences, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UNITED KINGDOM.
Med Sci Sports Exerc. 2019 Jun;51(6):1169-1177. doi: 10.1249/MSS.0000000000001901.
INTRODUCTION/PURPOSE: To investigate whether (a) lower levels of daily physical activity (PA) and greater sedentary time accounted for contrasting metabolic phenotypes (higher liver fat/presence of metabolic syndrome [METS+] vs lower liver fat/absence of metabolic syndrome [METS-]) in individuals of similar body mass index and (b) the association of sedentary time on metabolic health and liver fat.
Ninety-eight habitually active participants (53 female, 45 male; age, 39 ± 13 yr; body mass index 26.9 ± 5.1 kg·m), underwent assessments of PA (SenseWear armband; wear time ~98%), cardiorespiratory fitness (V˙O2 peak), body composition (magnetic resonance imaging and magnetic resonance spectroscopy) and multiorgan insulin sensitivity (oral glucose tolerance test). We undertook a) cross-sectional analysis comparing four groups: nonobese or obese, with and without metabolic syndrome (METS+ vs METS-) and b) univariate and multivariate regression for sedentary time and other levels of PA in relation to liver fat.
Light, moderate, and vigorous PA did not account for differences in metabolic health between individuals, whether nonobese or obese, although METS+ individuals were more sedentary, with a higher number, and prolonged bouts (~1-2 h). Overall, sedentary time, average daily METS and V˙O2 peak were each independently associated with liver fat percentage. Each additional hour of daily sedentary time was associated with a 1.15% (95% confidence interval, 1.14%-1.50%) higher liver fat content.
Greater sedentary time, independent of other levels of PA, is associated with being metabolically unhealthy; even in habitually active people, lesser sedentary time, and higher cardiorespiratory fitness and average daily METS is associated with lower liver fat.
研究个体的身体活动水平（PA）和久坐时间是否存在差异，导致其具有不同的代谢表型（更高的肝脂肪/存在代谢综合征 [METS+] 与更低的肝脂肪/不存在代谢综合征 [METS-]），这些个体的身体质量指数相似，以及久坐时间与代谢健康和肝脂肪之间的关系。
98 名习惯性活跃的参与者（53 名女性，45 名男性；年龄 39 ± 13 岁；身体质量指数 26.9 ± 5.1 kg·m）接受了 PA（SenseWear 臂带；佩戴时间约为 98%）、心肺功能（V˙O2 峰值）、身体成分（磁共振成像和磁共振波谱）和多器官胰岛素敏感性（口服葡萄糖耐量试验）的评估。我们进行了 a）横断面分析，比较了四个组：非肥胖或肥胖，有或没有代谢综合征（METS+ 与 METS-），b）单变量和多变量回归，分析了久坐时间和其他 PA 水平与肝脂肪之间的关系。
无论是否肥胖，低水平、中水平和高水平的 PA 都不能解释个体代谢健康的差异，尽管 METS+个体更久坐，有更多的久坐时间和更长的久坐时间（约 1-2 小时）。总的来说，久坐时间、平均日常代谢当量和 V˙O2 峰值都与肝脂肪百分比独立相关。每天多坐一个小时，肝脂肪含量就会增加 1.15%（95%置信区间，1.14%-1.50%）。
久坐时间的增加，与其他 PA 水平无关，与代谢不健康有关；即使是在习惯性活跃的人群中，久坐时间较少、心肺功能较好和平均日常代谢当量较高，与较低的肝脂肪有关。
