And Nutritional Examination Survey (NHANES), a cross-sectional study of a complex, multistage probability sample of the civilian, noninstitutionalized U.S. population in the United States. Data are described from 6329 participants who provided at least 1 d of accelerometer data and from 4867 participants who provided four or more days of accelerometer data. Results: Males are more physically active than females. Physical activity declines dramatically across age groups between childhood and adolescence and continues to decline with age. For example, 42% of children ages 6-11 yr obtain the recommended 60 min·d−1 of physical activity, whereas only 8% of adolescents achieve this goal. Among adults, adherence to the recommendation to obtain 30 min·d−1 of physical activity is less than 5%. Conclusions: Objective and subjective measures of physical activity give qualitatively similar results regarding gender and age patterns of activity. However, adherence to physical activity recommendations according to accelerometer-measured activity is substantially lower than according to self-report. Great care must be taken when interpreting self-reported physical activity in clinical practice, public health program design and evaluation, and epidemiological research....

Calorie restriction (CR) is the most effective and reproducible intervention for increasing lifespan in a variety of animal species, including mammals. CR is also the most potent, broadly acting cancer-prevention regimen in experimental carcinogenesis models. Translation of the knowledge gained from CR research to human chronic disease prevention and the promotion of healthy aging is critical, especially because obesity, which is an important risk factor for several chronic diseases, including many cancers, is alarmingly increasing in the Western world. This review synthesizes the key biological mechanisms underlying many of the beneficial effects of CR, with a particular focus on the insulin-like growth factor–1 pathway. We also describe some of the opportunities now available for investigations, including gene expression profiling studies, the development of pharmacological mimetics of CR, and the integration of CR regimens with targeted, mechanism-based interventions. These approaches will facilitate the translation of CR research into strategies for effective human chronic disease prevention.

OBJECTIVE: This study examined the association between objectively measured sedentary activity and metabolic syndrome among older adults. RESEARCH DESIGN AND METHODS: Data were from 1,367 men and women, aged ≥60 years who participated in the 2003–2006 National Health and Nutrition Examination Survey (NHANES). Sedentary time during waking hours was measured by an accelerometer (5 min. A sedentary break was defined as an interruption in sedentary time (≥100 counts per minute). Metabolic syndrome was defined according to the Adult Treatment Panel (ATP) III criteria. RESULTS: On average, people spent 9.5 h (65% of wear time) as sedentary. Compared with people without metabolic syndrome, people with metabolic syndrome spent a greater percentage of time as sedentary (67.3 vs. 62.2%), had longer average sedentary bouts (17.7 vs. 16.7 min), had lower intensity during sedentary time (14.8 vs. 15.8 average counts per minute), and had fewer sedentary breaks (82.3 vs. 86.7), adjusted for age and sex (all P < 0.01). A higher percentage of time sedentary and fewer sedentary breaks were associated with a significantly greater likelihood of metabolic syndrome after adjustment for age, sex, ethnicity, education, alcohol consumption, smoking, BMI, diabetes, heart disease, and physical activity. The association between intensity during sedentary time and metabolic syndrome was borderline significant. CONCLUSIONS: The proportion of sedentary time was strongly related to metabolic risk, independent of physical activity. Current results suggest older people may benefit from reducing total sedentary time and avoiding prolonged periods of sedentary time by increasing the number of breaks during sedentary time.

Directional selection is a major force driving adaptation and evolutionary change. However, the distribution, strength, and tempo of phenotypic selection acting on quantitative traits in natural populations remain unclear across different study systems. We reviewed the literature (1984–1997) that reported the strength of directional selection as indexed by standardized linear selection gradients (β). We asked how strong are viability and sexual selection, and whether strength of selection is correlated with the time scale over which it was measured. Estimates of the magnitude of directional selection (|β|) were exponentially distributed, with few estimates greater than 0.50 and most estimates less than 0.15. Sexual selection (measured by mating success) appeared stronger than viability selection (measured by survival). Viability selection that was measured over short periods (days) was typically stronger than selection measured over longer periods (months and years), but the strength of sexual selection did not vary with duration of selection episodes; as a result, sexual selection was stronger than viability selection over longer time scales (months and years), but not over short time scales (days).

A Youth Compendium of Physical Activities (Youth Compendium) was developed to estimate the energy costs of physical activities using data on youth only. Based on a literature search and pooled data of energy expenditure measurements in youth, the energy costs of 196 activities were compiled in 16 activity categories to form a Youth Compendium of Physical Activities. To estimate the intensity of each activity, measured oxygen consumption (V[Combining Dot Above]O2) was divided by basal metabolic rate (Schofield age-, sex- and mass-specific equations) to produce a youth MET (METy). A mixed linear model was developed for each activity category to impute missing values for age ranges with no observations for a specific activity. This Youth Compendium consists of METy values for 196 specific activities classified into 16 major categories for four age groups, 6-9, 10-12, 13-15, and 16-18 years. METy values in this Youth Compendium were measured (51%) or imputed (49%) from youth data. This Youth Compendium of Physical Activities uses pediatric data exclusively, addresses the age-dependency of METy and imputes missing METy values and thus represents advancement in the physical activity research and practice. This Youth Compendium will be a valuable resource for stakeholders interested in evaluating interventions, programs, and policies designed to assess and encourage physical activity in youth. This is an open-access article distributed under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives License 4.0 (CCBY-NC-ND), where it is permissible to download and share the work provided it is properly cited. The work cannot be changed in any way or used commercially without permission from the journal.