The stagnation paradox: the ever-improving but (more or less) stationary population fitness.
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ABSTRACT:
SUBMITTER: Kokko H
PROVIDER: S-EPMC8596016 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Background: Very few studies have evaluated the independent and combined associations of sedentary behavior (SB), moderate-to-vigorous physical activity (MVPA) and cardiorespiratory fitness (CRF) on obesity. Our recent work has evaluated this paradigm in the adult population,but no study has evaluated this paradigm in the child population, which was the purpose of this study. Methods: A national sample of children (N=680, 6-11 years) were evaluated via the National Youth Fitness Survey; this study was conducted in 2012, employing a nationally representative sample, occurring across 15 different geographic regions in the United States. SB and MVPA were assessed via parental recall, with CRF objectively measured via a treadmill-based aerobic test. Obesity was determined for measured body mass index. A PACS (Physical Activity Cardiorespiratory Sedentary) score was created ranging from 0-3, indicating each child's number of positive characteristics (PA, CRF, SB). Results: Meeting MVPA guidelines (OR adjusted=0.47; 95% CI: 0.29-0.77) and above-median CRF (OR adjusted=0.12; 95% CI: 0.07-0.21), but not SB (OR adjusted=0.62; 95% CI: 0.35-1.10),were associated with reduced odds of obesity. Compared to those with a PACS score of 0, the odds of obesity for PACS scores of 1-3, respectively, were: 0.31 (0.18-0.53), 0.12 (0.04-0.34), and 0.05 (0.02-0.10). Conclusion: These findings highlight the need for public health strategies to promote child MVPA and CRF, and to reduce SB.
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Project description:The adoptive transfer of labelled cell populations has been an essential tool to determine and quantify cellular dynamics. The experimental methods to label and track cells over time range from fluorescent dyes over congenic markers towards single-cell labelling techniques, such as genetic barcodes. While these methods have been widely used to quantify cell differentiation and division dynamics, the extent to which the applied labelling strategy actually affects the quantification of the dynamics has not been determined so far. This is especially important in situations where measurements can only be obtained at a single time point, as e.g. due to organ harvest. To this end, we studied the appropriateness of various labelling strategies as characterised by the number of different labels and the initial number of cells per label to quantify cellular dynamics. We simulated adoptive transfer experiments in systems of various complexity that assumed either homoeostatic cellular turnover or cell expansion dynamics involving various steps of cell differentiation and proliferation. Re-sampling cells at a single time point, we determined the ability of different labelling strategies to recover the underlying kinetics. Our results indicate that cell transition and expansion rates are differently affected by experimental shortcomings, such as loss of cells during transfer or sampling, dependent on the labelling strategy used. Furthermore, uniformly distributed labels in the transferred population generally lead to more robust and less biased results than non-equal label sizes. In addition, our analysis indicates that certain labelling approaches incorporate a systematic bias for the identification of complex cell expansion dynamics.
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Project description:ObjectiveTo investigate associations of cardiorespiratory fitness (CRF) and different measures of adiposity with cardiovascular disease (CVD) and all-cause mortality in men with known or suspected coronary heart disease (CHD).Patients and methodsWe analyzed data from 9563 men (mean age, 47.4 years) with documented or suspected CHD in the Aerobics Center Longitudinal Study (August 13, 1977, to December 30, 2002) using baseline body mass index (BMI) and CRF (quantified as the duration of a symptom-limited maximal treadmill exercise test). Waist circumference (WC) and percent body fat (BF) were measured using standard procedures.ResultsThere were 733 deaths (348 of CVD) during a mean follow-up of 13.4 years. After adjustment for age, examination year, and multiple baseline risk factors, men with low fitness had a higher risk of all-cause mortality in the BMI categories of normal weight (hazard ratio [HR], 1.60; 95% confidence interval [CI], 1.24-2.05), obese class I (HR, 1.38; 95% CI, 1.04-1.82), and obese class II/III (HR, 2.43; 95% CI, 1.55-3.80) but not overweight (HR, 1.09; 95% CI, 0.88-1.36) compared with the normal-weight and high-fitness reference group. We observed a similar pattern for WC and percent BF tertiles and for CVD mortality. Among men with high fitness, there were no significant differences in CVD and all-cause mortality risk across BMI, WC, and percent BF categories.ConclusionIn men with documented or suspected CHD, CRF greatly modifies the relation of adiposity to mortality. Using adiposity to assess mortality risk in patients with CHD may be misleading unless fitness is considered.
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