Physical activity: the present in the context of the past

Variation and covariation of external shape and cross-sectional geometry in the human metacarpus

OBJECTIVES

Analyses of external bone shape using geometric morphometrics (GM) and cross-sectional geometry (CSG) are frequently employed to investigate bone structural variation and reconstruct activity in the past. However, the association between these methods has not been thoroughly investigated. Here, we analyze whole bone shape and CSG variation of metacarpals 1-5 and test covariation between them.

MATERIALS AND METHODS

We analyzed external metacarpal shape using GM and CSG of the diaphysis at three locations in metacarpals 1-5. The study sample includes three modern human groups: crew from the shipwrecked Mary Rose (n = 35 metacarpals), a Pre-industrial group (n = 50), and a Post-industrial group (n = 31). We tested group differences in metacarpal shape and CSG, as well as correlations between these two aspects of metacarpal bone structure.

RESULTS

GM analysis demonstrated metacarpus external shape variation is predominately related to changes in diaphyseal width and articular surface size. Differences in external shape were found between the non-pollical metacarpals of the Mary Rose and Pre-industrial groups and between the third metacarpals of the Pre- and Post-industrial groups. CSG results suggest the Mary Rose and Post-industrial groups have stronger metacarpals than the Pre-industrial group. Correlating CSG and external shape showed significant relationships between increasing external robusticity and biomechanical strength across non-pollical metacarpals (r: 0.815-0.535; p ≤ 0.05).

DISCUSSION

Differences in metacarpal cortical structure and external shape between human groups suggest differences in the type and frequency of manual activities. Combining these results with studies of entheses and kinematics of the hand will improve reconstructions of manual behavior in the past.

Body and Fat mass are not Regulated, Controlled, or Defended: An introduction to the Invisible Hand' and 'Competition' Models of Metabolism

This paper presents two inter-dependent frameworks for understanding the etiology of obesity and the regain of body and fat mass after weight loss. The 'Invisible Hand of Metabolism' illustrates how physiologic states such as body and fat mass and blood glucose levels arise from the unregulated, uncontrolled, yet competitive behavior of trillions of semi-autonomous cells. The 'Competition Model of Metabolism' is an explanatory (mechanistic) framework that details how organismal and cell-specific behaviors generate the apparent stability of physiologic states despite metabolic perturbations (e.g., weight-loss and exercise). Together, these frameworks show that body and fat mass and blood glucose levels are not regulated, controlled, or defended but emerge from the complexity and functional plasticity of competitive cellular relations. Therefore, we argue that the use of abstract constructs such as 'regulation', 'control', 'glucostats', 'adipostats', and 'set-/settling-points' hinders the understanding of obesity and cardiometabolic diseases in human and nonhuman mammals.

Recent Secular Trends in Child and Adolescent Physical Activity and Sedentary Behavior Internationally: Analyses of Active Healthy Kids Global Alliance Global Matrices 1.0 to 4.0

Background: We examined recent global secular trends in 5 indicators of child and adolescent physical activity and sedentary behavior (Overall Physical Activity, Organized Sport and Physical Activity, Active Play, Active Transportation, and Sedentary Behavior) and 4 influences on these (Family and Peers, School, Community and Environment, and Government). Methods: Active Healthy Kids Global Alliance letter grades (A+ to F) were assigned numbers from 15 to 2, with 0 assigned for missing/incomplete grades. Trends from Active Healthy Kids Global Alliance Global Matrices 1.0 (2014) to 4.0 (2022) were analyzed using linear mixed-effects models with level of economic development and gender inequity considered as potential moderators. Results: Report card grades were generally relatively stable. Trends generally did not differ significantly by level of economic development (except for Active Transportation and Active Play), but gender inequality did significantly moderate trends for most of the indicators, with higher gender inequality associated with more adverse changes in grades. The number of “incomplete” grades decreased over time, but this did not reach statistical significance. Conclusions: While trends varied within and between countries, physical activity and sedentary behaviors, and the influences on these behaviors globally, were relatively stable over the past decade or so, albeit at undesirable levels.

Non-exercise activity thermogenesis in the workplace: The office is on fire

From the second half of the previous century, there has been a shift toward occupations largely composed of desk-based behaviors. This, inevitably, has led to a workload reduction and a consequent lower energy expenditure. On this point, small increments of the non-exercise activity thermogenesis (NEAT) could be the rationale to reach health benefits over a prolonged period. Different published researches suggest solutions to reverse sitting time and new alternative workstations have been thought to increase total physical activity. Therefore, the purpose of this narrative review is to summarize the current state of the research regarding the "NEAT approach" to weight-gain prevention in work environments. This review analyzes the main evidence regarding new alternative workstations such as standing, walking workstations, seated pedal, and gymnastic balls to replace a standard office chair.

Physical activity habits and their relationship with sociodemographic factors in Chilean adolescents

Physical activity plays an important role in the well-being and development of adolescents. Physical activity habits expressed in terms of frequency and duration are consistently associated with sociodemographic factors such as age, gender, and socioeconomic status. However, there is less evidence of the relationship between the type and context of physical activity in adolescents. The aim of this article is to analyze physical activity habits and their relationship with sociodemographic factors in Chilean adolescents. The cross-sectional study consisted of 7,263 adolescents aged between 10 and 20 years old, students from both public and private schools in all regions of Chile. Physical activity habits were examined by means of a self-report questionnaire. The age groups were classified according to the three stages of adolescence (early: 10 to 13, middle: 14 to 16, and late: 17 to 20 years old). Socioeconomic level was established based on the school vulnerability index (SVI) of the school attended by each adolescent. In the study it was obvious to the level of physical activity for the adolescents was below the international recommendations. A statistically significant association can also be found between the sociodemographic factors studied and the physical activity habits reported by the young people. The multivariate regression analysis established that the risk of not achieving the physical activity recommendations was 2.8 times higher in females than in males, 2.4 times higher in the older age groups (14–16 and 17–20 years old) compared to the 10–13-year age range and 1.1 times in the medium and high vulnerability groups than in the low socioeconomic vulnerability group. These findings highlight the importance of considering all these factors holistically whenever designing programs or public policies that promote the development of healthy physical activity habits in adolescents.

The Moderating Role of Sociodemographic Factors in the Relationship between Physical Activity and Subjective Well-Being in Chilean Children and Adolescents

Background: The relationship between physical activity habits and well-being is widely recognized; however, the interaction that these variables have with sociodemographic factors throughout life is only partially addressed in the literature, particularly in children and adolescents. The aim of this article is to analyze the moderating effect of sociodemographic factors and the possible interaction of these moderations in the relationship between physical activity and subjective well-being in children and adolescents. Methods: This cross-sectional study considered a sample of 9572 children and adolescents from 10 to 19 years of age, students of primary and secondary schools in all regions of Chile. Subjective well-being and physical activity habits were measured using self-report questionnaires. Socioeconomic level was established from the school vulnerability index (SVI) of each student’s school. Results: Simple moderation analyses revealed that the higher the age and the lower the SVI, the stronger the relationship between physical activity habits and subjective well-being. From a double moderation analysis, it could be observed that the age of the subjects is the most relevant moderator in the relationship between physical activity habits and perceived well-being in young people. Conclusions: This study highlights the importance of considering these factors and their interaction when generating programs or public policies to improve physical activity habits and well-being in children and adolescents.

Gathering Is Not Only for Girls : No Influence of Energy Expenditure on the Onset of Sexual Division of Labor

In some small-scale societies, a sexual division of labor is common. For subadult hunter-gatherers, the onset of this division dates to middle childhood and the start of puberty; however, there is apparently no physiological explanation for this timing. The present study uses an experimental approach to evaluate possible energetic differences by sex in gathering-related activities. The energetic cost of gathering-related activities was measured in a sample of 42 subjects of both sexes aged between 8 and 14 years. Body mass and other anthropometric variables were also recorded. Our results show that the energetic differences in the simulated gathering activities depend only on body mass. Both sexes expend a similar amount of energy during locomotion activities related to gathering. Discarding the energetic factor, the sexual division of tasks may be explained as an adaptation to acquire the skills needed to undertake the complex activities required during adulthood as early as possible. Carrying out gathering activities during childhood and adolescence could be favored by the growth and development cycles of Homo sapiens. Moreover, if most of the energetic costs of gathering activities depend on body mass, the delayed growth in humans relative to other primates allows subadults to practice these tasks for longer periods, and to become better at performing them. In fact, this strategy could enable them to acquire adults' complex skills at a low energetic cost that can be easily subsidized by other members of the group.

Objective and subjective measurement of sedentary behavior in human adults: A toolkit

OBJECTIVES

Objectives: Human biologists are increasingly interested in measuring and comparing physical activities in different societies. Sedentary behavior, which refers to time spent sitting or lying down while awake, is a large component of daily 24 hours movement patterns in humans and has been linked to poor health outcomes such as risk of all-cause and cardiovascular mortality, independently of physical activity. As such, it is important for researchers, with the aim of measuring human movement patterns, to most effectively use resources available to them to capture sedentary behavior.

METHODS

This toolkit outlines objective (device-based) and subjective (self-report) methods for measuring sedentary behavior in free-living contexts, the benefits and drawbacks to each, as well as novel options for combined use to maximize scientific rigor. Throughout this toolkit, emphasis is placed on considerations for the use of these methods in various field conditions and in varying cultural contexts.

RESULTS

Objective measures such as inclinometers are the gold-standard for measuring total sedentary time but they typically cannot capture contextual information or determine which specific behaviors are taking place. Subjective measures such as questionnaires and 24 hours-recall methods can provide measurements of time spent in specific sedentary behaviors but are subject to measurement error and response bias.

CONCLUSIONS

We recommend that researchers use the method(s) that suit the research question; inclinometers are recommended for the measurement of total sedentary time, while self-report methods are recommended for measuring time spent in particular contexts of sedentary behavior.

Italian Physical Fitness Decline: A True Fact or a Mindset? A 10-Year Observational Perspective Study

Evidence regarding a putative physical fitness decline remains less well documented for Italian children and adolescents. An update review of data collection articles was undertaken concerning motor performances (power, strength, speed-agility and indirect cardiorespiratory fitness) of children and adolescents worldwide and compared with 2859 11-12-year-old Italian students of both sexes, throughout a ten-year observational period. Lower limb explosive strength (standing broad jump), flexibility (sit-and-reach), endurance (Cooper) and speed (SP-30) performances of sixth grade Italian students showed nearly stable trends, with no differences during the observed decade, in both sexes. This 10-year perspective study confirmed that Italian physical fitness levels flatlined rather than actually declined. According to these study data, the decline in physical fitness of the Italian youth is ostensible and needs a further in-depth analysis.

Impact of Physical Education on Changes in Students' Emotional Competence: A Meta-analysis

The theoretical background related to how physical activity positively influences children and adolescents' brain function for social and emotional competency has been stably structured. However, according to our review of the literature, no study has synthetically analyzed physical education interventions that produce positive outcomes related to learners' emotional status. Therefore, the aim of the study was to systematically analyze the effectiveness of physical education interventions designed to improve students' emotional ability. In October 2017, we searched electronic research databases for intervention studies that analyzed the impact of school physical education on students' emotional changes. We assessed the risk of bias, extracted data, and conducted meta-analysis to determine the effectiveness of physical education intervention. From an initial pool of 1200 non-duplicate records, 12 studies fulfilled the inclusion criteria. The effectiveness of school-based physical education was analyzed by calculating standard mean difference. Based on the results of the meta-analysis, students in intervention conditions changed their psychological conditions compared with students in usual practice conditions (standardized mean difference=0.30, 95% confidence interval=- 0.05-0.66). Physical and sport education for children and adolescents has positively influenced changes in their emotional conditions.

Sitting, squatting, and the evolutionary biology of human inactivity

Recent work suggests human physiology is not well adapted to prolonged periods of inactivity, with time spent sitting increasing cardiovascular disease and mortality risk. Health risks from sitting are generally linked with reduced levels of muscle contractions in chair-sitting postures and associated reductions in muscle metabolism. These inactivity-associated health risks are somewhat paradoxical, since evolutionary pressures tend to favor energy-minimizing strategies, including rest. Here, we examined inactivity in a hunter-gatherer population (the Hadza of Tanzania) to understand how sedentary behaviors occur in a nonindustrial economic context more typical of humans' evolutionary history. We tested the hypothesis that nonambulatory rest in hunter-gatherers involves increased muscle activity that is different from chair-sitting sedentary postures used in industrialized populations. Using a combination of objectively measured inactivity from thigh-worn accelerometers, observational data, and electromygraphic data, we show that hunter-gatherers have high levels of total nonambulatory time (mean ± SD = 9.90 ± 2.36 h/d), similar to those found in industrialized populations. However, nonambulatory time in Hadza adults often occurs in postures like squatting, and we show that these "active rest" postures require higher levels of lower limb muscle activity than chair sitting. Based on our results, we introduce the Inactivity Mismatch Hypothesis and propose that human physiology is likely adapted to more consistently active muscles derived from both physical activity and from nonambulatory postures with higher levels of muscle contraction. Interventions built on this model may help reduce the negative health impacts of inactivity in industrialized populations.

OPREVENT (Obesity Prevention and Evaluation of InterVention Effectiveness in NaTive North Americans): Design of a Multilevel, Multicomponent Obesity Intervention for Native American Adults and Households

Obesity prevalence is high in Native American (NA) adults, and there is a critical need to establish and implement evidence-based social, behavioral, and policy interventions that are theoretically informed. The use of multilevel, multicomponent (MLMC) interventions has been shown to be an effective strategy for comprehensive health behavior change; however, there is little guidance available in the literature to facilitate implementation in this underserved and understudied population. To decrease obesity and related comorbidities in NA adults, an MLMC intervention called OPREVENT (Obesity Prevention and Evaluation of InterVention Effectiveness in NaTive North Americans) was implemented in 5 rural NA communities to modify the food-purchasing environment, improve diet, and increase physical activity (PA). Five NA communities across the Upper Midwest and Southwest United States were randomly assigned to Immediate (n = 3) or Delayed (n = 2) Intervention. OPREVENT was implemented in Immediate Intervention community food stores, worksites, schools, and media over 1 y. A community-randomized controlled trial was used to evaluate intervention impact in adults at the individual and institutional levels, with individual-level data being collected on diet, PA, and psychosocial variables at baseline and follow-up; and institutional-level data being collected on food stores, worksites, and schools, media, and process measures. The OPREVENT intervention was one of the first MLMC obesity interventions in this population and provides evidence-based practices for future program development. The purpose of this article is to describe the design, implementation, and evaluation of OPREVENT. This trial was registered at isrctn.com as ISRCTN76144389.

The Genetic Variability of APOE in Different Human Populations and Its Implications for Longevity

Human longevity is a complex phenotype resulting from the combinations of context-dependent gene-environment interactions that require analysis as a dynamic process in a cohesive ecological and evolutionary framework. Genome-wide association (GWAS) and whole-genome sequencing (WGS) studies on centenarians pointed toward the inclusion of the apolipoprotein E (APOE) polymorphisms ε2 and ε4, as implicated in the attainment of extreme longevity, which refers to their effect in age-related Alzheimer's disease (AD) and cardiovascular disease (CVD). In this case, the available literature on APOE and its involvement in longevity is described according to an anthropological and population genetics perspective. This aims to highlight the evolutionary history of this gene, how its participation in several biological pathways relates to human longevity, and which evolutionary dynamics may have shaped the distribution of APOE haplotypes across the globe. Its potential adaptive role will be described along with implications for the study of longevity in different human groups. This review also presents an updated overview of the worldwide distribution of APOE alleles based on modern day data from public databases and ancient DNA samples retrieved from literature in the attempt to understand the spatial and temporal frame in which present-day patterns of APOE variation evolved.

The Effects of 10-week Integrated Neuromuscular Training on Fundamental Movement Skills and Physical Self-efficacy in 6-7-Year-Old Children

Duncan, MJ, Eyre, ELJ, and Oxford, SW. The effects of 10-week integrated neuromuscular training on fundamental movement skills and physical self-efficacy in 6-7-year-old children. J Strength Cond Res 32(12): 3348-3356, 2018-Integrated neuromuscular training (INT) has been suggested as an effective means to enhance athletic potential in children. However, few studies have reported the effects of school-based INT programs. This study examined the effect of INT on process and product fundamental movement skill measures and physical self-efficacy in 6-7-year-old children. Ninety-four children from 2 primary schools were randomized into either a 10-week INT program or a control group (CON) (n = 41). Results indicated significantly greater increases in process fundamental movement skill (FMS) scores in INT vs. CON (p = 0.001). For product measures of FMS, 10-m sprint time, counter movement jump, seated medicine ball throw and standing long jump (all p = 0.001), all significantly increased to a greater extent in the INT group vs. CON. A significant group (INT vs. CON) × time (pre vs. post) × gender interaction for physical self-efficacy revealed increased physical self-efficacy pre to post INT, compared with CON but only for boys (p = 0.001). For girls, physical self-efficacy was not significantly different before to after the 10-week period for INT and CON groups. The results of this study suggest that replacing 1 of the 2 weekly statutory physical education (PE) lessons with an INT program over a 10-week period results in positive improvements in fundamental movement skill quality and outcomes in 6-7-year-old children. Integrated neuromuscular training also appears to increase physical self-esteem to a greater extent than statutory PE but only in boys.

Exercise as a reward: Self-paced exercise perception and delay discounting in comparison with food and money

Exercise is an important health behavior. Expressed reasons for participation are often delayed outcomes i.e. health threats and benefits, but also enjoyment. However, we do not know how people evaluate exercise as a reward. The value of rewards diminish the longer we have to wait for them and the discounting effect can undermine decision-making. Here, we investigated delay-discounting of exercise perception and its valuation with time delays; we conducted self-paced exercise sessions on treadmill and compared the discounting rates of exercise (k_ex) with those of established rewards of food (k_fo) and money (k_m). Outcomes show, that young, moderately active participants (n = 70) preferred walking/running intensity with low to moderate cardiovascular strain and light perceived exertion. Delay discounting rates (k) indicated that exercise was discounted like other consumable rewards at the same rate as food and more rapidly than monetary rewards. Significant associations were detected of k_ex with preferred speed and with extrinsic exercise motivation. Exercise training (n = 16) reduced k_ex specifically, not affecting k_fo. Our studies show, that participants perceived and discounted self-paced walking/running like a consumable reward. Exercise discounting was quicker in individuals who preferred lower speeds being less physically active and exercise training reduced the decay rate of exercise specifically.

Early Holocene morphological variation in hunter-gatherer hands and feet

Background

The Windover mortuary pond dates to the Early Archaic period (6,800–5,200 years ago) and constitutes one of the earliest archaeological sites with intact and well-preserved human remains in North America. Unlike many prehistoric egalitarian hunter-gatherers, the Windover people may not have practiced a sex-based division of labor; rather, they may have shared the load. We explore how mobility and subsistence, as reconstructed from archaeological data, influenced hand and foot bone morphology at Windover.

Methods

We took length and width measurements on four carpal bones, four tarsal bones, and load-bearing tarsal areas (calcaneus load arm, trochlea of the talus). We analyzed lateralization using side differences in raw length and width measurements. For other hypothesis testing, we used log transformed length-width ratios to mitigate the confounding effects of sexual dimorphism and trait size variation; we tested between-sex differences in weight-bearing (rear foot) and shock-absorbing (mid foot) tarsal bones and between-sex differences in carpal bones.

Results

We identified no significant between-sex differences in rear and midfoot areas, suggesting similar biomechanical stresses. We identified no significant between-sex differences in carpal bones but the test was under-powered due to small sample sizes. Finally, despite widespread behavioral evidence on contemporary populations for human hand and foot lateralization, we found no evidence of either handedness or footedness.

Discussion

The lack evidence for footedness was expected due its minimal impact on walking gait but the lack of evidence for handedness was surprising given that ethnographic studies have shown strong handedness in hunter-gatherers during tool and goods manufacture. The reconstructed activity patterns suggested both sexes engaged in heavy load carrying and a shared division of labor. Our results support previous findings—both sexes had stronger weight-bearing bones. Male shock-absorbing bones exhibited a trend towards greater relative width (suggesting greater comparative biomechanical stress) than females which may reflect the typical pattern of male hunter-gatherers engaging in walking greater distances at higher speeds than females. While there were no significant between-sex differences in carpal bones (supporting a shared work load model), females exhibited greater variation in index values, which may reflect a greater variety of and specialization in tasks compared to males. Because carpals and tarsals are so well-preserved at archaeological sites, we had surmised they might be useful proxies for activity in the absence of well-preserved long bones. Tarsals provide a stronger signal of past activity and may be useful in the absence of, or in addition to, preferred bones. Carpals, however, may not be useful as the effect size of biomechanical stress (in this study at least) is low and would require larger samples than may be possible at archaeological sites.

Cell-Specific "Competition for Calories" Drives Asymmetric Nutrient-Energy Partitioning, Obesity, and Metabolic Diseases in Human and Non-human Animals

The mammalian body is a complex physiologic “ecosystem” in which cells compete for calories (i.e., nutrient-energy). Axiomatically, cell-types with competitive advantages acquire a greater number of consumed calories, and when possible, increase in size and/or number. Thus, it is logical and parsimonious to posit that obesity is the competitive advantages of fat-cells (adipocytes) driving a disproportionate acquisition and storage of nutrient-energy. Accordingly, we introduce two conceptual frameworks. Asymmetric Nutrient-Energy Partitioning describes the context-dependent, cell-specific competition for calories that determines the partitioning of nutrient-energy to oxidation, anabolism, and/or storage; and Effective Caloric Intake which describes the number of calories available to constrain energy-intake via the inhibition of the sensorimotor appetitive cells in the liver and brain that govern ingestive behaviors. Inherent in these frameworks is the independence and dissociation of the energetic demands of metabolism and the neuro-muscular pathways that initiate ingestive behaviors and energy intake. As we demonstrate, if the sensorimotor cells suffer relative caloric deprivation via asymmetric competition from other cell-types (e.g., skeletal muscle- or fat-cells), energy-intake is increased to compensate for both real and merely apparent deficits in energy-homeostasis (i.e., true and false signals, respectively). Thus, we posit that the chronic positive energy balance (i.e., over-nutrition) that leads to obesity and metabolic diseases is engendered by apparent deficits (i.e., false signals) driven by the asymmetric inter-cellular competition for calories and concomitant differential partitioning of nutrient-energy to storage. These frameworks, in concert with our previous theoretic work, the Maternal Resources Hypothesis, provide a parsimonious and rigorous explanation for the rapid rise in the global prevalence of increased body and fat mass, and associated metabolic dysfunctions in humans and other mammals inclusive of companion, domesticated, laboratory, and feral animals.

In Defense of Sugar: A Critique of Diet-Centrism

Sugars are foundational to biological life and played essential roles in human evolution and dietary patterns for most of recorded history. The simple sugar glucose is so central to human health that it is one of the World Health Organization's Essential Medicines. Given these facts, it defies both logic and a large body of scientific evidence to claim that sugars and other nutrients that played fundamental roles in the substantial improvements in life- and health-spans over the past century are now suddenly responsible for increments in the prevalence of obesity and chronic non-communicable diseases. Thus, the purpose of this review is to provide a rigorous, evidence-based challenge to 'diet-centrism' and the disease-mongering of dietary sugar. The term 'diet-centrism' describes the naïve tendency of both researchers and the public to attribute a wide-range of negative health outcomes exclusively to dietary factors while neglecting the essential and well-established role of individual differences in nutrient-metabolism. The explicit conflation of dietary intake with both nutritional status and health inherent in 'diet-centrism' contravenes the fact that the human body is a complex biologic system in which the effects of dietary factors are dependent on the current state of that system. Thus, macronutrients cannot have health or metabolic effects independent of the physiologic context of the consuming individual (e.g., physical activity level). Therefore, given the unscientific hyperbole surrounding dietary sugars, I take an adversarial position and present highly-replicated evidence from multiple domains to show that 'diet' is a necessary but trivial factor in metabolic health, and that anti-sugar rhetoric is simply diet-centric disease-mongering engendered by physiologic illiteracy. My position is that dietary sugars are not responsible for obesity or metabolic diseases and that the consumption of simple sugars and sugar-polymers (e.g., starches) up to 75% of total daily caloric intake is innocuous in healthy individuals.

Evidence for energetic tradeoffs between physical activity and childhood growth across the nutritional transition

Despite broad implications for understanding human life history, energetics, and health, the impact of physical activity on childhood growth remains unclear. Particularly understudied is the effect of secular changes in physical activity on child development. We address these shortcomings using data spanning the transition from traditional to semi-developed economy among Yucatec Maya agriculturalists. Anthropometric and behavioral observation data were collected from children living in a subsistence-based rural community in 1992 and again in 2012 following the introduction of a school and mechanized technologies but minimal overt dietary change. Multiple regression analyses demonstrate dramatic twenty-year transformations in how children spent their time. This behavioral change was associated with large declines in estimated physical activity level (PAL), associated activity energy expenditure savings of several hundred kilocalories/day, and sizable increases in mean height, weight, and triceps skinfold thickness. Controlling for observed frequency of market food consumption, PAL was inversely related to child body size and subcutaneous fat stores and significantly mediated the effects of data collection year on anthropometric indices. These findings indicate that physical activity can considerably influence childhood growth, highlighting the role of energy allocation tradeoffs between physical activity and competing life tasks in shaping patterns of human ontogeny and health.

Adaptive Capacity: An Evolutionary Neuroscience Model Linking Exercise, Cognition, and Brain Health

The field of cognitive neuroscience was transformed by the discovery that exercise induces neurogenesis in the adult brain, with the potential to improve brain health and stave off the effects of neurodegenerative disease. However, the basic mechanisms underlying exercise-brain connections are not well understood. We use an evolutionary neuroscience approach to develop the adaptive capacity model (ACM), detailing how and why physical activity improves brain function based on an energy-minimizing strategy. Building on studies showing a combined benefit of exercise and cognitive challenge to enhance neuroplasticity, our ACM addresses two fundamental questions: (i) what are the proximate and ultimate mechanisms underlying age-related brain atrophy, and (ii) how do lifestyle changes influence the trajectory of healthy and pathological aging?

Physical Activity, Aging, and Physiological Function

Human evolution suggests that the default position for health is to be physically active. Inactivity, by contrast, has serious negative effects on health across the lifespan. Therefore, only in physically active people can the inherent aging process proceed unaffected by disuse complications. In such individuals, although the relationship between age and physiological function remains complex, function is generally superior with health, well being, and the aging process optimized.

Physical activity patterns and biomarkers of cardiovascular disease risk in hunter-gatherers

OBJECTIVES

Time spent in moderate-to-vigorous physical activity (MVPA) is a strong predictor of cardiovascular health, yet few humans living in industrialized societies meet current recommendations (150 min/week). Researchers have long suggested that human physiological requirements for aerobic exercise reflect an evolutionary shift to a hunting and gathering foraging strategy, and a recent transition to more sedentary lifestyles likely represents a mismatch with our past in terms of physical activity. The goal of this study is to explore this mismatch by characterizing MVPA and cardiovascular health in the Hadza, a modern hunting and gathering population living in Northern Tanzania.

METHODS

We measured MVPA using continuous heart rate monitoring in 46 participants recruited from two Hadza camps. As part of a larger survey of health in the Hadza, we measured blood pressure (n = 198) and biomarkers of cardiovascular health (n = 23) including C-reactive protein, cholesterol (Total, HDL, and LDL), and triglycerides.

RESULTS

We show that Hadza participants spend large amounts of time in MVPA (134.92 ± 8.6 min/day), and maintain these activity levels across the lifespan. In fact, the Hadza engage in over 14 times as much MVPA as subjects participating in large epidemiological studies in the United States. We found no evidence of risk factors for cardiovascular disease in this population (low prevalence of hypertension across the lifespan, optimal levels for biomarkers of cardiovascular health).

CONCLUSIONS

Our results provide evidence that the hunting and gathering foraging strategy involves high levels of MVPA, supporting the evolutionary medicine model for the relationship between MVPA and cardiovascular health.

Physical Activity Patterns in the Elderly Kashan Population

Background

Physical activity is an important component of health in old age that provides personal independence, physical ability, and quality of life.

Objectives

The current study aimed to evaluate physical activity and associated factors among the elderly population in Kashan, Iran.

Patients and Methods

This is a descriptive cross-sectional study. The sample was 400 elderly people (aged more than 60 years) living in Kashan, Iran in 2014. The subjects randomly selected via multi-stage cluster sampling from healthcare centers in three regions of Kashan. The sample size differed by gender and residence type. Each participant’s demographic characteristics and level of physical activity were recorded in a questionnaire, and the data were analyzed by SPSS version 16. Descriptive statistics, chi-square tests, Pearson correlations, and ordinal regression were used in the data analysis. The significance level for all the tests was P < 0.05.

Results

237 (59.2%) of the subjects were female. The average age of the study population was 67.6 ± 6.8 years. Their average physical activity energy consumption was 326.21 ± 364.84 according to the metabolic equivalent of hours per week. 20 subjects (5%) reported no physical activity. 320 (80%) and 59 (14.8%) subjects had low and moderate physical activity levels, respectively. Only 1 subject (0.2%) had extreme levels of physical activity. Men (n = 43, 26.4%) were more likely to be moderately or extremely physically active than women were (n = 17, 7.2%). There was a significant relationship between physical activity and sex (P < 0.0001), marital status (P < 0.0001), educational status (P < 0.002), current occupation (P < 0.0001), and personal independence (P < 0.00001). Of course, effective predictive variations included age (P = 0.034), gender (P = 0.001), marital status (P = 0.033), independent status (P = 0), and local environment (P =0.001).

Conclusions

The study revealed low physical activity in the elderly population in Kashan. The pattern of physical activity in the elderly depends on their lifestyle. A promotion of active lifestyles should be a part of health care planning for the elderly.

Workplace exercise for changing health behavior related to physical activity

BACKGROUND

Physical Activity in the workplace has received special attention from researchers who are looking to promote lifelong health and well-being. The workplace is being investigated as a possible place to assess and create strategies to help people to become healthier. The transtheoretical model and stages of change has been adapted as a tool to assess the stages of behavioral change towards exercising.

OBJECTIVE

To assess the change in health behavior following a three-month exercise program based in the workplace.

METHODS

A quasi-experimental study design was used in which 165 employees participated in the study. An intervention program of workplace exercise was applied for three months. Participants were assessed through the transtheoretical model and stages of change questionnaire before and after intervention to understand changes in their position on the behavioral change continuum.

RESULTS

The number of employees who were physically active increased after the workplace exercise intervention (13.9% , 95% CI 9.5 to 20.1; P = 0.009). There was a significant decrease in the proportion of employees in the pre-contemplation stage (-6.1% , 95% CI 3.3 to 10.8; P = 0.045) and contemplation stage (-11.5% , 95% CI 7.5 to 17.3; P = 0.017), and a significant increase in the action stage (10.9% , 95% CI 7.0 to 16.6; P = 0.003).

CONCLUSIONS

Engaging in workplace exercise has a significant positive effect on health behavior and willingness to become more physically active.

Physical activity and dietary habits among Moroccan adolescents

OBJECTIVE

The study aimed to detail the lifestyle (physical activity and dietary habits) of Moroccan adolescents.

DESIGN

Cross-sectional study undertaken in the framework of the ATLS (Arab Teens Lifestyle Study).

SETTING

Physical activity and dietary habits were determined using a validated questionnaire in public secondary schools.

SUBJECTS

A total of 669 adolescents aged 15.0-19.9 years were randomly recruited from Kenitra, Morocco.

RESULTS

Physical activity patterns and intensity differed between genders. As anticipated, male adolescents were more active than female adolescents across a typical week and engaged in more vigorous-intensity physical activity than female adolescents, who spent more time than male adolescents in moderate-intensity physical activity. Of particular concern was that one in five of the adolescents surveyed was inactive, with almost 45% of the sample reporting television viewing for more than 2 h/d and 38% engaged in computer use for a similar period. From a dietary perspective, most adolescents reported that they do not take breakfast or consume milk and dairy products, fruits and vegetables on a daily basis. In contrast, most reported consumption of doughnuts, cakes, candy and chocolate more than three times per week and approximately 50% consumed sugary drinks more than three times per week.

CONCLUSIONS

Based on a continuation of the self-reported lifestyle behaviours, adolescents in the present study are at risk of developing chronic diseases. Education programmes are urgently needed to assist in the promotion of a healthy lifestyle and reduce the likelihood of overweight and obesity and related health risks among young people.

Exercise, APOE genotype, and the evolution of the human lifespan

Humans have exceptionally long lifespans compared with other mammals. However, our longevity evolved when our ancestors had two copies of the apolipoprotein E (APOE) ɛ4 allele, a genotype that leads to a high risk of Alzheimer's disease (AD), cardiovascular disease, and increased mortality. How did human aging evolve within this genetic constraint? Drawing from neuroscience, anthropology, and brain-imaging research, we propose the hypothesis that the evolution of increased physical activity approximately 2 million years ago served to reduce the amyloid plaque and vascular burden of APOE ɛ4, relaxing genetic constraints on aging. This multidisciplinary approach links human evolution with health and provides a complementary perspective on aging and neurodegenerative disease that may help identify key mechanisms and targets for intervention.

The role of sports clubs in sports activity of students

Objective: Exercise is a recognised means for improving quality of life. In general, students perform less sports activity than previous generations. In contrast, however, children’s participation in competitive sports has increased. The present study therefore aimed to assess how many students participate in sports clubs, how active in sports student (non)members are, and what actual effect sports clubs have on enabling sufficient sports activity.

Methods: Students (N=213) in the first year of university studies (19-20 years) were recruited for a study approved by the Slovenian Ethics Committee. They answered a questionnaire on their sports club membership and on their sports activity during organised sports training and/or in their free time. Results were statistically analysed and compared to our previous results obtained from primary and secondary school children (1).

Results: Only 16% of students participate in sports clubs, which is less (p<0.001) than in primary and secondary school children. The average (SD) sports activity of student sports-club members is 11.7 (6.8) h/week, with students non-members being significantly (p<0.001) less active with 4.6 (3.0) h/week. Participation in sports clubs is lower (p<0.001) in female (15%) than in male (21%) students, which is similar to children.

Conclusions: The results of the study demonstrate that sports clubs in Slovenia are important for promoting sufficient sports activity. Namely, most of the student members participate in sports activity more than the recommended 1 h/day and are more than two times more active than their peers. Females, however, participate less often in sports clubs, which calls for further attention.

Free-living physical activity and energy expenditure of rural children and adolescents in the Nandi region of Kenya

PURPOSE

To examine the relationship between physical activity and energy demands in children and adolescents with highly active lifestyles.

METHODS

Physical activity patterns of 30 rural Kenyan children and adolescents (14 ± 1 years, mean ± SD) with median body mass index (BMI) z-score = -1.06 [-3.29-0.67] median [range] were assessed by accelerometry over 1 week. Daily energy expenditure (DEE), activity-induced energy expenditure (AEE) and physical activity level (PAL) were simultaneously determined using doubly-labelled water (DLW). Active commuting to school was assessed by global positioning system.

RESULTS

Mean DEE, AEE and PAL were 12.2 ± 3.4, 5.7 ± 3.0 MJ/day and 2.3 ± 0.6, respectively. A model combining body mass, average accelerometer counts per minute and time in light activities predicted 45% of the variance in DEE (p < 0.05) with a standard error of DEE estimate of 2.7 MJ/day. Furthermore, AEE accounted for ∼47% of DEE. Distance to school was not related to variation in DEE, AEE or PAL and there was no association between active commuting and adiposity.

CONCLUSION

High physical activity levels were associated with much higher levels of energy expenditure than observed in Western societies. These results oppose the concept of physical activity being stable and constrained in humans.

Patterns of senescence in human cardiovascular fitness: VO2 max in subsistence and industrialized populations

OBJECTIVES

This study explores whether cardiovascular fitness levels and senescent decline are similar in the Tsimane of Bolivia and Canadians, as well as other subsistence and industrialized populations. Among Tsimane, we examine whether morbidity predicts lower levels and faster decline of cardiovascular fitness, or whether their lifestyle (e.g., high physical activity) promotes high levels and slow decline. Alternatively, high activity levels and morbidity might counterbalance such that Tsimane fitness levels and decline are similar to those in industrialized populations.

METHODS

Maximal oxygen uptake (VO2 max) was estimated using a step test heart rate method for 701 participants. We compared these estimates to the Canadian Health Measures Survey and previous studies in industrialized and subsistence populations. We evaluated whether health indicators and proxies for market integration were associated with VO2 max levels and rate of decline for the Tsimane.

RESULTS

The Tsimane have significantly higher levels of VO2 max and slower rates of decline than Canadians; initial evidence suggests differences in VO2 max levels between other subsistence and industrialized populations. Low hemoglobin predicts low VO2 max for Tsimane women while helminth infection predicts high VO2 max for Tsimane men, though results might be specific to the VO2 max scaling parameter used. No variables tested interact with age to moderate decline.

CONCLUSIONS

The Tsimane demonstrate higher levels of cardiovascular fitness than industrialized populations, but levels similar to other subsistence populations. The high VO2 max of Tsimane is consistent with their high physical activity and few indicators of cardiovascular disease, measured in previous studies.

Linking brains and brawn: exercise and the evolution of human neurobiology

The hunting and gathering lifestyle adopted by human ancestors around 2 Ma required a large increase in aerobic activity. High levels of physical activity altered the shape of the human body, enabling access to new food resources (e.g. animal protein) in a changing environment. Recent experimental work provides strong evidence that both acute bouts of exercise and long-term exercise training increase the size of brain components and improve cognitive performance in humans and other taxa. However, to date, researchers have not explored the possibility that the increases in aerobic capacity and physical activity that occurred during human evolution directly influenced the human brain. Here, we hypothesize that proximate mechanisms linking physical activity and neurobiology in living species may help to explain changes in brain size and cognitive function during human evolution. We review evidence that selection acting on endurance increased baseline neurotrophin and growth factor signalling (compounds responsible for both brain growth and for metabolic regulation during exercise) in some mammals, which in turn led to increased overall brain growth and development. This hypothesis suggests that a significant portion of human neurobiology evolved due to selection acting on features unrelated to cognitive performance.

Health and adult productivity: the relation between adult nutrition, helminths, and agricultural, hunting, and fishing yields in the Bolivian Amazon

OBJECTIVES

Infectious disease and nutritional stress have both been associated with reductions in adult work productivity and work capacity in the context of wage labor, but less research has investigated their effects among groups relying on more traditional subsistence practices of horticulture and foraging. In this article, we examine the relations among measures of adult nutritional status (BMI, skinfold measurements, and fat-free mass) and infection (presence of soil transmitted helminth infections) and measures of adult work productivity.

METHODS

As part of a larger panel study among Tsimane', a foraging-horticulturalist group in the Bolivian Amazon, health surveys, anthropometric information, and the quantity of products (both crops and game) brought into the household were collected for 320 Tsimane' adults over a four-month period in 2003. In addition, a single fecal sample was collected for a sub-sample of 86 adults.

RESULTS

Our analysis shows mixed associations between either BMI or the presence of parasitism and reported adult productivity. Muscularity was not clearly related to adult productivity. In contrast, body fatness (Skinfold z-score) was inversely associated with the average quantity of fish and game brought into the household, especially for men.

CONCLUSIONS

These findings suggest that the effects of adult infection and nutritional stress may be less clearly identified outside of the context of wage labor. Further research linking adult physical activity levels and metabolic rates to productivity in diverse contexts is needed.

Physical activity, fitness and the metabolic syndrome in rural youths from Mozambique

BACKGROUND

Except for North America and Europe, few studies have reported the association among physical activity (PA), cardiorespiratory fitness (CRF) and metabolic syndrome (MetS) in youths, especially for rural African youth.

AIM

The aims of this study were to determine the prevalence of PA levels, CRF, MetS and its indicators, and examine the association between these variables in a school-aged sample of youth from rural Mozambique.

SUBJECTS AND METHODS

The sample included 209 children and adolescents aged 7-15 years old from Calanga, a rural community in Mozambique. PA was estimated with a culturally-specific questionnaire. CRF was determined by 1-mile run test. Indicators of the MetS included fasting glucose, triglycerides, total cholesterol, blood pressure and body mass index. A continuous metabolic risk score was computed.

RESULTS

Results showed high levels of PA and CRF and a low prevalence of MetS ( < 2%) among children and adolescents from Calanga. However, there was a moderately high prevalence of elevated blood pressure (81.8%) and triglycerides (18.7%), respectively. There were no significant associations between PA, CRF and MetS.

CONCLUSION

Youths from Calanga are physically active and possess high CRF and their lifestyle may be a protective effect against MetS.

Correlates of physical activity: why are some people physically active and others not?

Physical inactivity is an important contributor to non-communicable diseases in countries of high income, and increasingly so in those of low and middle income. Understanding why people are physically active or inactive contributes to evidence-based planning of public health interventions, because effective programmes will target factors known to cause inactivity. Research into correlates (factors associated with activity) or determinants (those with a causal relationship) has burgeoned in the past two decades, but has mostly focused on individual-level factors in high-income countries. It has shown that age, sex, health status, self-efficacy, and motivation are associated with physical activity. Ecological models take a broad view of health behaviour causation, with the social and physical environment included as contributors to physical inactivity, particularly those outside the health sector, such as urban planning, transportation systems, and parks and trails. New areas of determinants research have identified genetic factors contributing to the propensity to be physically active, and evolutionary factors and obesity that might predispose to inactivity, and have explored the longitudinal tracking of physical activity throughout life. An understanding of correlates and determinants, especially in countries of low and middle income, could reduce the eff ect of future epidemics of inactivity and contribute to effective global prevention of non-communicable diseases.

Wired to run: exercise-induced endocannabinoid signaling in humans and cursorial mammals with implications for the 'runner's high'

Humans report a wide range of neurobiological rewards following moderate and intense aerobic activity, popularly referred to as the 'runner's high', which may function to encourage habitual aerobic exercise. Endocannabinoids (eCBs) are endogenous neurotransmitters that appear to play a major role in generating these rewards by activating cannabinoid receptors in brain reward regions during and after exercise. Other species also regularly engage in endurance exercise (cursorial mammals), and as humans share many morphological traits with these taxa, it is possible that exercise-induced eCB signaling motivates habitual high-intensity locomotor behaviors in cursorial mammals. If true, then neurobiological rewards may explain variation in habitual locomotor activity and performance across mammals. We measured circulating eCBs in humans, dogs (a cursorial mammal) and ferrets (a non-cursorial mammal) before and after treadmill exercise to test the hypothesis that neurobiological rewards are linked to high-intensity exercise in cursorial mammals. We show that humans and dogs share significantly increased exercise-induced eCB signaling following high-intensity endurance running. eCB signaling does not significantly increase following low-intensity walking in these taxa, and eCB signaling does not significantly increase in the non-cursorial ferrets following exercise at any intensity. This study provides the first evidence that inter-specific variation in neurotransmitter signaling may explain differences in locomotor behavior among mammals. Thus, a neurobiological reward for endurance exercise may explain why humans and other cursorial mammals habitually engage in aerobic exercise despite the higher associated energy costs and injury risks, and why non-cursorial mammals avoid such locomotor behaviors.

Attenuated inheritance of body weight by running in monozygotic twins

PURPOSE

Genetic factors account for 40%-70% of the population variation in body mass index (BMI), suggesting that genetic predisposition is a major risk factor for excess weight. The purpose of this study was to test whether exercise attenuates the inherited risk for excess body weight.

METHODS

Survey questionnaires of exercise (usual running distance) and BMI were obtained from a national sample of 582 female and 344 male self-identified monozygotic (MZ) twins. Regression analyses were used to test whether running disparity diminished the inheritance of BMI when adjusted for age, education, cigarette use, and selected dietary variables.

RESULTS

The active twins ran between 0 and 10.7 km · d(-1) more than their less active twins if female (mean ± SD = 1.61 ± 1.50 km · d(-1)) and between 0 and 13.7 km · d(-1) more if male (1.88 ± 1.78 km · d(-1)). Average BMIs of the less active twins were 22.38 ± 3.56 and 24.59 ± 3.08 kg · m(-2) in females and males, respectively. Within-twin correlations were significant (P < 0.0001) for usual distance run (females: r = 0.64; males: r = 0.61) and BMI (females: r = 0.67; males: r = 0.71). Greater running differences (Δkm · d(-1)) attenuated the effect of the less active twins' BMIs on their active MZ twins' BMI (females: -14.3% per Δkm · d(-1), P < 10(-7); males: -7.4% per Δkm · d(-1), P = 0.004), such that by 4 Δkm · d(-1), the inherited risk was reduced by 58.8% in females and 29.6% in males.

CONCLUSIONS

These results are consistent with the attenuation of the inherited risk of excess body weight by running, which is remarkable because BMI regulation is assumed to be multifactorial, its genetic inheritance is polygenic, and no single genetic polymorphism currently explains >1% of the BMI variance.

Can we modulate physical activity in children?

There is concern that interventions that use physical activity to prevent obesity in children might be undermined by an 'Activitystat', which exerts an effect to maintain a low set point for physical activity. The present critique summarises evidence from systematic reviews of interventions, from empirical tests of the Activitystat hypothesis, from studies on the heritability of physical activity in childhood and the physical activity of children of and adolescents across a wide range of physical and cultural environments. This body of evidence is inconsistent with the Activitystat hypothesis in its current form, and suggests that the emphasis on physical activity in obesity prevention interventions in children should be increased, not reduced.

Addressing childhood obesity through increased physical activity

Obesity is affecting an increasing proportion of children globally. Despite an appreciation that physical activity is essential for the normal growth and development of children and prevents obesity and obesity-related health problems, too few children are physically active. A concurrent problem is that today's young people spend more time than previous generations did in sedentary pursuits, including watching television and engaging in screen-based games. Active behavior has been displaced by these inactive recreational choices, which has contributed to reductions in activity-related energy expenditure. Implementation of multifactorial solutions considered to offer the best chance of combating these trends is urgently required to redress the energy imbalance that characterizes obesity. The counterproductive 'shame and blame' mentality that apportions responsibility for the childhood obesity problem to sufferers, their parents, teachers or health-care providers needs to be changed. Instead, these groups should offer constant support and encouragement to promote appropriate physical activity in children. Failure to provide activity opportunities will increase the likelihood that the children of today will live less healthy (and possibly shorter) lives than their parents.

Low levels of objectively measured physical activity in preschoolers in child care

BACKGROUND

Physical activity (PA) undertaken at child care could assist in the achievement of PA recommendations across a large proportion of the population in early childhood.

PURPOSE

To review recent evidence on volume of PA and amount of moderate- to vigorous-intensity PA (MVPA) in preschool children within child care centers.

METHODS

Literature search for studies published in 2000-2008 in which objective methods (accelerometry, direct observation, pedometers, HR monitoring) were used to measure typical levels of PA and MVPA of preschool children while within child care.

RESULTS

Twelve eligible articles were identified, describing 13 studies, involving 96 different child care centers and >1900 children. In all six of the accelerometry studies that quantified MVPA and in three of the four studies that used direct observation to quantify MVPA, typical levels of PA within the child care center would have led to the accumulation of <60 min x d MVPA during a full 8-h child care day.

CONCLUSIONS

A body of high-quality evidence is consistent in suggesting that PA levels within child care centers are typically very low, and levels of sedentary behavior are typically high.

The meta-volition model: organizational leadership is the key ingredient in getting society moving, literally!

This paper argues that substantive and sustainable population-wide improvements in physical activity can be achieved only through the large scale adoption and implementation of policies and practices that make being active the default choice and remaining inactive difficult. Meta-volition refers to the volition and collective agency of early adopter leaders who implement such changes in their own organizations to drive productivity and health improvements. Leaders, themselves, are motivated by strong incentives to accomplish their organizational missions. The meta-volition model (MVM) specifies a cascade of changes that may be sparked by structural integration of brief activity bouts into organizational routine across sectors and types of organizations. MVM builds upon inter-disciplinary social ecological change models and frameworks such as diffusion of innovations, social learning and social marketing. MVM is dynamic rather than static, integrating biological influences with psychological factors, and socio-cultural influences with organizational processes. The model proposes six levels of dissemination triggered by organizational marketing to early adopter leaders carried out by "sparkplugs," boisterous leaders in population physical activity promotion: initiating (leader-leader), catalyzing (organizational-individual), viral marketing (individual-organizational), accelerating (organizational-organizational), anchoring (organizational-community) and institutionalizing (community-individual). MVM embodies public-private partnership principles, a collective investment in the high cost of achieving and maintaining active lifestyles.

Physical activity, obesity and risk for esophageal adenocarcinoma

Over the past three decades, an increasing incidence of esophageal adenocarcinoma (EADC) has been reported throughout North America and Europe at a rate exceeding that of any other human solid tumor. Recent studies have clearly implicated chronic gastroesophageal reflux disease and several lifestyle risk factors, including tobacco consumption, diet and obesity, to be associated with increased risk of EADC. Although physical inactivity is now recognized as a risk factor for several chronic diseases including cancer, only a very limited number of studies have specifically evaluated the association between physical activity and esophageal malignancy. Furthermore, the precise biological mechanisms underlying the association between physical activity, obesity and cancer risk remain unclear. Since successful promotion of healthy body weight and exercise may substantially reduce the future incidence of cancer in the population, the purpose of this review is to explore current evidence linking physical activity, obesity and risk of malignancy – specifically EADC.