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American Society for Testing and Materials

Reported values in the literature on the number of cells in the body differ by orders of magnitude and are very seldom supported by any measurements or calculations. Here, we integrate the most up-to-date information on the number of human and bacterial cells in the body. We estimate the total number of bacteria in the 70 kg "reference man" to be 3.8·1013. For human cells, we identify the dominant role of the hematopoietic lineage to the total count (≈90%) and revise past estimates to 3.0·1013 human cells. Our analysis also updates the widely-cited 10:1 ratio, showing that the number of bacteria in the body is actually of the same order as the number of human cells, and their total mass is about 0.2 kg.

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Revised Estimates for the Number of Human and Bacteria Cells in the Body.

Asian Working Group for Sarcopenia: 2019 Consensus Update on Sarcopenia Diagnosis and Treatment

Sedentary behaviour is associated with deleterious health outcomes, which differ from those that can be attrib- uted to a lack of moderate to vigorous physical activity. This has led to the field of ''sedentary physiology'', which may be considered as separate and distinct from exercise physiology. This paper gives an overview of this emerging area of re- search and highlights the ways that it differs from traditional exercise physiology. Definitions of key terms associated with the field of sedentary physiology and a review of the self-report and objective methods for assessing sedentary behaviour are provided. Proposed mechanisms of sedentary physiology are examined, and how they differ from those linking physi- cal activity and health are highlighted. Evidence relating to associations of sedentary behaviours with major health out- comes and the population prevalence and correlates of sedentary behaviours are reviewed. Recommendations for future research are proposed.

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Physiological and health implications of a sedentary lifestyle

Moderate-to-vigorous physical activity (MVPA) is essential for disease prevention and health promotion. Emerging evidence suggests other intensities of physical activity (PA), including light-intensity activity (LPA), may also be important, but there has been no rigorous evaluation of the evidence. The purpose of this systematic review was to examine the relationships between objectively measured PA (total and all intensities) and health indicators in school-aged children and youth. Online databases were searched for peer-reviewed studies that met the a priori inclusion criteria: population (apparently healthy, aged 5–17 years), intervention/exposure/comparator (volumes, durations, frequencies, intensities, and patterns of objectively measured PA), and outcome (body composition, cardiometabolic biomarkers, physical fitness, behavioural conduct/pro-social behaviour, cognition/academic achievement, quality of life/well-being, harms, bone health, motor skill development, psychological distress, self-esteem)....

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Systematic review of the relationships between objectively measured physical activity and health indicators in school-aged children and youth.

Background Cigarette smoking is associated with adverse health effects, including cancer, respiratory illness, heart disease and stroke. National data on smoking prevalence often rely on self-reports. This study assesses the validity of self-reported cigarette smoking status among Canadians. Data and methods Data are from the 2007 to 2009 Canadian Health Measures Survey, a nationally representative cross-sectional survey of 4,530 Canadians aged 12 to 79. The survey included self-reported smoking status and a measure of urinary cotinine, a biomarker of exposure to tobacco smoke. The prevalence of cigarette smoking was calculated based on self-reports and also on urinary cotinine concentrations. Results Compared with estimates based on urinary cotinine concentration, smoking prevalence based on self-report was 0.3 percentage points lower. Sensitivity estimates (the percentage of respondents who reported being smokers among those classified as smokers based on cotinine concentrations) were similar for males and females (more than 90%). Although sensitivity tended to be lower for respondents aged 12 to 19 than for those aged 20 to 79, the difference did not attain statistical significance. Interpretation Accurate estimates of the prevalence of cigarette smoking among Canadians can be derived from self-reported smoking status data.

Assessment of validity of self-reported smoking status.

Background: Actical accelerometer thresholds have been derived to enable objective measurement of time spent performing sedentary activity in children and adolescents, but not adults. Thus, the purpose of this study was to determine Actical accelerometer sedentary activity thresholds for adults. Methods: Data were available from 3187 participants aged 6 to 79 years from a preliminary partial dataset of the Canadian Health Measures Survey, who wore an Actical for 7 days. Step count data were used to evaluate the use of 50, 100, and 800 counts per min (cpm) as sedentary activity thresholds. Minutes when no steps were recorded were considered minutes of sedentary activity. Results: The use of higher cpm thresholds resulted in a greater percentage of sedentary minutes being correctly classified as sedentary. The percentage of minutes that were incorrectly classified as sedentary was substantially higher when using a threshold of 800 cpm compared with 50 or 100 cpm. Results were similar for children, adolescen...

Actical accelerometer sedentary activity thresholds for adults.

https://espace.library.uq.edu.au/view/UQ:331183/UQ331183_OA.pdf

Patterns of sedentary time and cardiometabolic risk among Canadian adults

Self-reported screen time is associated with elevated health risk in children and youth; however, research examining the relationship between accelerometer-measured sedentary time and health risk has reported mixed findings. The purpose of this study was to examine the association between accelerometer-measured patterns of sedentary time and health risk in children and youth. The results are based on 1,608 children and youth aged 6 to 19 years from the Canadian Health Measures Survey (2007–2009). Sedentary time was measured using the Actical accelerometer. Breaks in sedentary time and prolonged bouts of sedentary time lasting 20 to 120 minutes were derived for all days, weekend days and during the after-school period (i.e., after 3 pm on weekdays). Regression analyses were used to examine the association between patterns of sedentary time and body mass index (BMI), waist circumference, blood pressure and non-HDL cholesterol. Boys accumulated more sedentary time on weekdays after 3 pm and had a higher number of breaks in sedentary time compared to girls. Overweight/obese boys (aged 6–19 years) accumulated more sedentary time after 3 pm on weekdays (282 vs. 259 min, p < .05) and as prolonged bouts lasting at least 80 minutes (171 vs. 133 min, p < .05) compared to boys who were neither overweight nor obese. Prolonged bouts of sedentary time lasting at least 80 minutes accumulated after 3 pm on weekdays were positively associated with BMI and waist circumference in boys aged 11–14 years (p < .006). Each additional 60 min of sedentary time after 3 pm on weekdays was associated with a 1.4 kg·m-2 higher BMI and a 3.4 cm higher waist circumference in 11–14 year old boys. No sedentary pattern variables differed between girls who were not overweight or obese and those who were overweight/obese and none of the sedentary pattern variables were associated with any health markers in girls. The findings confirm results of other studies that reported accelerometer-measured sedentary time was not associated with health risk in children and youth. Even when the pattern and timing of sedentary time was examined relative to health markers, few associations emerged and were limited to boys aged 11–14 years.

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The association between accelerometer-measured patterns of sedentary time and health risk in children and youth: results from the Canadian Health Measures Survey

BACKGROUND: In a collaboration between the Canadian Laboratory Initiative on Pediatric Reference Intervals (CALIPER) and the Canadian Health Measures Survey (CHMS), we determined reference value distributions using an a priori approach and created a comprehensive database of age- and sex-stratified reference intervals for clinically relevant hematologic parameters in a large household population of children and adults.

METHODS: The CHMS collected data and blood samples from 11 999 respondents aged 3–79 years. Hematology markers were measured with either the Beckman Coulter HmX or Siemens Sysmex CA-500 Series analyzers. After applying exclusion criteria and removing outliers, we determined statistically relevant age and sex partitions and calculated reference intervals, including 90% CIs, according to CSLI C28-A3 guidelines.

RESULTS: Hematology marker values showed dynamic changes from childhood into adulthood as well as between sexes, necessitating distinct partitions throughout life. Most age partitions were necessary during childhood, reflecting the hematologic changes that occur during growth and development. Hemoglobin, red blood cell count, hematocrit, and indices (mean corpuscular volume, mean corpuscular hemoglobin, and mean corpuscular hemoglobin concentration) increased with age, but females had lower hemoglobin and hematocrit starting at puberty. Platelet count gradually decreased with age and required multiple sex partitions during adolescence and adulthood. White blood cell count remained relatively constant over life, whereas fibrinogen increased slightly, requiring distinct age and sex partitions.

CONCLUSIONS: The robust dataset generated in this study has allowed observation of dynamic biological profiles of several hematology markers and the establishment of comprehensive age- and sex-specific reference intervals that may contribute to accurate monitoring of pediatric, adult, and geriatric patients.

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Complex Biological Profile of Hematologic Markers Across Pediatric, Adult, and Geriatric Ages: Establishment of Robust Pediatric and Adult Reference Intervals on the Basis of the Canadian Health Measures Survey

Suzy L Wong

Papers

Assessment of validity of self-reported smoking status.

Actical accelerometer sedentary activity thresholds for adults.

Patterns of sedentary time and cardiometabolic risk among Canadian adults

The association between accelerometer-measured patterns of sedentary time and health risk in children and youth: results from the Canadian Health Measures Survey

Complex Biological Profile of Hematologic Markers Across Pediatric, Adult, and Geriatric Ages: Establishment of Robust Pediatric and Adult Reference Intervals on the Basis of the Canadian Health Measures Survey