BackgroundThe appropriate limit to the amount of daily sedentary time (ST) required to minimize mortality is uncertain. This meta-analysis aimed to quantify the dose-response association between daily ST and all-cause mortality and to explore the cut-off point above which health is impaired in adults aged 18–64 years old. We also examined whether there are differences between studies using self-report ST and those with device-based ST.MethodsProspective cohort studies providing effect estimates of daily ST (exposure) on all-cause mortality (outcome) were identified via MEDLINE, PubMed, Scopus, Web of Science, and Google Scholar databases until January 2018. Dose-response relationships between daily ST and all-cause mortality were examined using random-effects meta-regression models.ResultsBased on the pooled data for more than 1 million participants from 19 studies, the results showed a log-linear dose-response association between daily ST and all-cause mortality. Overall, more time spent in sedentary behaviors is associated with increased mortality risks. However, the method of measuring ST moderated the association between daily ST and mortality risk (p < 0.05). The cut-off of daily ST in studies with self-report ST was 7 h/day in comparison with 9 h/day for those with device-based ST.ConclusionsHigher amounts of daily ST are log-linearly associated with increased risk of all-cause mortality in adults. On the basis of a limited number of studies using device-based measures, the findings suggest that it may be appropriate to encourage adults to engage in less sedentary behaviors, with fewer than 9 h a day being relevant for all-cause mortality.Electronic supplementary materialThe online version of this article (10.1186/s12916-018-1062-2) contains supplementary material, which is available to authorized users.

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This study examined associations between four health-related physical fitness measures and obesity in Taiwanese youth aged 10-18 years. Data from 13,500 school-aged youth were randomly selected from the "School Physical Fitness Database" of Taiwan by sex and age. Variables examined were height, body mass and performance on modified sit-and-reach (flexibility), bent-leg sit-up (abdominal muscular strength/endurance), standing long jump (lower body explosive strength) and distance run/walk (cardiorespiratory endurance). Adjusted logistic regression analyses were performed. Increased odds of being obese with decreased fitness levels were observed for lower body explosive strength and cardiorespiratory endurance in both sexes. The highest odds of being obese was found in the least fit quintile of cardiorespiratory endurance compared with the most fit quintile both in boys (Odds ratio, OR = 10.44; 95% confidence interval (CI), 7.94-13.73) and girls (OR = 5.40; 95% CI, 3.90-7.47). These findings suggest that in addition to cardiorespiratory fitness, lower body explosive strength is also associated with childhood and adolescent obesity.

The present study examined whether a culture-based virtual reality (VR) training program is feasible and tolerable for patients with amnestic mild cognitive impairment (aMCI), and whether it could improve cognitive function in these patients. Twenty-one outpatients with aMCI were randomized to either the VR-based training group or the control group in a 1:1 ratio. The VR-based training group participated in training for 30 min/day, two days/week, for three months (24 times). The VR-based program was designed based on Korean traditional culture and used attention, processing speed, executive function and memory conditions to stimulate cognitive function. The adherence to the culture-based VR training program was 91.55% ± 6.41% in the VR group. The only adverse events observed in the VR group were dizziness (4.2%) and fatigue (8.3%). Analysis revealed that the VR-based training group exhibited no significant differences following the three-month VR program in Korean Mini-Mental State Examination (K-MMSE) scores, working memory functions such as performance on the digit span test, or in Stroop test performance and word fluency. We conclude that although the 12-week culture-based VR training program did not improve cognitive function, our findings revealed that the culture-based VR training program was feasible and tolerable for participants with aMCI.