Sensation‐seeking genes and physical activity in youth

Many studies examining genetic influences on physical activity (PA) have evaluated the impact of single nucleotide polymorphisms (SNPs) related to the development of lifestyle‐related chronic diseases, under the hypothesis that they would be associated with PA. However, PA is a multidetermined behavior and associated with a multitude of health consequences. Thus, examining a broader range of candidate genes associated with a broader range of PA correlates may provide new insights into the genetic underpinnings of PA. In this study, we focus on one such correlate – sensation‐seeking behavior. Participants (N = 1130 Mexican origin youth) provided a saliva sample and data on PA and sensation‐seeking tendencies in 2008–2009. Participants were genotyped for 630 functional and tagging variants in the dopamine, serotonin and cannabinoid pathways. Overall 30% of participants (males – 37.6% and females – 22.0%) reported ≥60 min of PA on 5 of 7 days. After adjusting for gender, age and population stratification, and applying the Bayesian False Discovery Probability approach for assessing noteworthiness, four gene variants were significantly associated with PA. In a multivariable model, being male, having higher sensation‐seeking tendencies and at least one copy of the minor allele for SNPs in angiotensin I‐converting enzyme gene [ACE; rs8066276 odds ratio (OR) = 1.44; P = 0.012] and tryptophan hydroxylase 2 gene (TPH2; rs11615016 OR = 1.73; P = 0.021) were associated with increased likelihood of meeting PA recommendations. Participants with at least one copy of the minor allele for SNPs in synaptosomal‐associated protein 25 gene (SNAP25; rs363035 OR = 0.53; P = 0.005) and cannabinoid receptor 1 gene (CNR1; rs6454672 OR = 0.62; P = 0.022) have decreased likelihood of meeting PA recommendations. Our findings extend current knowledge of the complex relationship between PA and possible genetic underpinnings.     

Assessment of physical activity of the human body considering the thermodynamic system

Correctly dosed physical activity is the basis of a vital and healthy life, but the measurement of physical activity is certainly rather empirical resulting in limited individual and custom activity recommendations. Certainly, very accurate three-dimensional models of the cardiovascular system exist, however, requiring the numeric solution of the Navier–Stokes equations of the flow in blood vessels. These models are suitable for the research of cardiac diseases, but computationally very expensive. Direct measurements are expensive and often not applicable outside laboratories. This paper offers a new approach to assess physical activity using thermodynamical systems and its leading quantity of entropy production which is a compromise between computation time and precise prediction of pressure, volume, and flow variables in blood vessels. Based on a simplified (one-dimensional) model of the cardiovascular system of the human body, we develop and evaluate a setup calculating entropy production of the heart to determine the intensity of human physical activity in a more precise way than previous parameters, e.g. frequently used energy considerations. The knowledge resulting from the precise real-time physical activity provides the basis for an intelligent human–technology interaction allowing to steadily adjust the degree of physical activity according to the actual individual performance level and thus to improve training and activity recommendations.     

Assessment of physical activity in older individuals: a doubly labeled water study.

We compared the accuracy of two physical activity recall questionnaires and a motion detector in 45- to 84-yr-old women (n = 35) and men (n = 32), using doubly labeled water (DLW) in conjunction with indirect calorimetry as the criterion measure. Subjects were administered the Yale Physical Activity Survey (YPAS) and Minnesota Leisure Time Physical Activity Questionnaire (LTA). Physical activity energy expenditure was determined over a 10-day period by using a Caltrac uniaxial accelerometer and DLW in conjunction with indirect calorimetry. In older women, Minnesota LTA (386 +/- 228 kcal/day) and Caltrac (379 +/- 162 kcal/day) underestimated physical activity by approximately 55% compared with DLW (873 +/- 244 kcal/day). No difference was observed between daily physical activity measured by the YPAS (863 +/- 447 kcal/day) and DLW in older women. In older men, Minnesota LTA (459 +/- 288 kcal/day) and Caltrac (554 +/- 242 kcal/day) underestimated daily physical activity by approximately 50-60% compared with DLW (1,211 +/- 429 kcal/day). No difference was found between physical activity measured by the YPAS (1,107 +/- 612 kcal/day) and DLW in older men. Despite no difference in mean physical activity levels between YPAS and DLW in women and men, Bland and Altman (Lancet 1: 307-310, 1986) analyses demonstrated poor concordance between DLW and YPAS (i.e., limits of agreement = -1,310-1,518 kcal/day). Our data suggest that the Minnesota LTA recall and Caltrac uniaxial accelerometer may significantly underestimate free-living daily physical activity energy expenditure in older women and men. Although the YPAS compares favorably with DLW on a group basis, its use as a proxy measure of individual daily physical activity energy expenditure may be limited in older women and men.     

Assessment of objectively measured physical activity levels in individuals with intellectual disabilities with and without Down's syndrome

Objective

To investigate, using accelerometers, the levels of physical activity being undertaken by individuals with intellectual disabilities with and without Down''s syndrome.

Methods

One hundred and fifty two individuals with intellectual disabilities aged 12–70 years from East and South-East England. Physical activity levels in counts per minute (counts/min), steps per day (steps/day), and minutes of sedentary, light, moderate, vigorous, and moderate to vigorous physical activity (MVPA) measured with a uni-axial accelerometer (Actigraph GT1M) for seven days.

Results

No individuals with intellectual disabilities met current physical activity recommendations. Males were more active than females. There was a trend for physical activity to decline and sedentary behaviour to increase with age, and for those with more severe levels of intellectual disability to be more sedentary and less physically active, however any relationship was not significant when adjusted for confounding variables. Participants with Down''s syndrome engaged in significantly less physical activity than those with intellectual disabilities without Down''s syndrome and levels of activity declined significantly with age.

Conclusions

Individuals with intellectual disabilities, especially those with Down''s syndrome may be at risk of developing diseases associated with physical inactivity. There is a need for well-designed, accessible, preventive health promotion strategies and interventions designed to raise the levels of physical activity for individuals with intellectual disabilities. We propose that there are physiological reasons why individuals with Down''s syndrome have particularly low levels of physical activity that also decline markedly with age.     

Promoting physical activity within under-resourced afterschool programs: A qualitative investigation of staff experiences and motivational strategies for engaging youth

Afterschool programs (ASPs) have become increasingly recognized as a key context to support youth daily physical activity (PA) accrual. Using Self-Determination Theory (SDT) as a framework, this study examined staff perspectives on the strengths and barriers within under-resourced ASPs for establishing a social-motivational climate for encouraging and supporting youth PA. Analysis of semi-structured staff interviews (28 staff; 7 ASPs) indicated that staff had knowledge and value for establishing a PA-supportive motivational climate. However, the feasibility of implementing PA curricula was identified as challenging across programs. Findings suggest increased need for staff training and supports to provide a PA climate that meets the developmental needs/interests of all youth, with particular attention toward increasing the PA of girls and older program youth. Furthermore, striking an appropriate balance between PA and other competing program demands (e.g., academics) will be required to optimize on the effectiveness of PA program components.     

Physical activity in youth with osteogenesis imperfecta type I

Introduction:

Individuals with Osteogenesis Imperfecta (OI) type I often show muscular weakness. However, it is unclear whether muscular weakness is a consequence of physical inactivity or a result of the disease itself. The aim was to assess muscle function in youth with OI type I and evaluate physical activity (PA).

Methods:

Fourteen children with OI type I (mean age [SD]: 12.75 [4.62] years) were compared to 14 age- and gender-matched controls (mean age [SD]: 12.75 [4.59] years). Muscle force and power were determined through mechanography. PA and daily energy expenditure were measured with an accelerometer and a questionnaire.

Results:

Compared to controls, children with OI type I had lower muscle force and power. OI type I children were as active as their healthy counterparts.

Conclusions:

Children and adolescents with OI type I and their healthy counterparts did not reached daily recommendations of PA. Given their muscle function deficit, youth with OI type I would benefit to reach these recommendations to prevent precocious effect of aging on muscles.     

Habitual physical activity in mitochondrial disease

Purpose

Mitochondrial disease is the most common neuromuscular disease and has a profound impact upon daily life, disease and longevity. Exercise therapy has been shown to improve mitochondrial function in patients with mitochondrial disease. However, no information exists about the level of habitual physical activity of people with mitochondrial disease and its relationship with clinical phenotype.

Methods

Habitual physical activity, genotype and clinical presentations were assessed in 100 patients with mitochondrial disease. Comparisons were made with a control group individually matched by age, gender and BMI.

Results

Patients with mitochondrial disease had significantly lower levels of physical activity in comparison to matched people without mitochondrial disease (steps/day; 6883±3944 vs. 9924±4088, p = 0.001). 78% of the mitochondrial disease cohort did not achieve 10,000 steps per day and 48%were classified as overweight or obese. Mitochondrial disease was associated with less breaks in sedentary activity (Sedentary to Active Transitions, % per day; 13±0.03 vs. 14±0.03, p = 0.001) and an increase in sedentary bout duration (bout lengths / fraction of total sedentary time; 0.206±0.044 vs. 0.187±0.026, p = 0.001). After adjusting for covariates, higher physical activity was moderately associated with lower clinical disease burden (steps / day; r_s = −0.49; 95% CI −0.33, −0.63, P<0.01). There were no systematic differences in physical activity between different genotypes mitochondrial disease.

Conclusions

These results demonstrate for the first time that low levels of physical activity are prominent in mitochondrial disease. Combined with a high prevalence of obesity, physical activity may constitute a significant and potentially modifiable risk factor in mitochondrial disease.     

Parent-offspring correlations in pedometer-assessed physical activity

Background

Physical activity is a major component of a healthy lifestyle in youth and adults. To identify determinants of this complex behavior is an important research objective in the process of designing interventions to promote physical activity at population level. In addition to individual determinants, there is evidence documenting familial influences on physical activity. However, the few studies that have addressed this issue with objective measures did not provide data on parent-offspring physical activity relationships throughout childhood and adolescence. The purpose of this study was to assess familial correlations in pedometer-assessed physical activity.

Methods

We measured ambulatory activity in 286 French nuclear families (283 mothers, 237 fathers, and 631 children aged 8–18 years) by pedometer recordings (Yamax Digiwalker DW 450) over a week. Correlations were computed with their 95% confidence intervals (CI) for spouse pairs, siblings, mother-offspring, and father-offspring. Data were expressed as steps per day and computed both for the full recording period and separately for weekdays and weekends.

Results

The correlations were the highest between siblings (r = 0.28, 95%CI: 0.17–0.38). Parent–offspring correlations were significant in mothers (r = 0.21, 95%CI: 0.12–0.30), especially between mothers and daughters (r = 0.24, 95%CI: 0.12–0.36 vs. r = 0.18, 95%CI: 0.05–0.31 for sons), but were almost nonexistent in fathers. Correlations were generally higher on weekend days compared to weekdays. Mother-offspring correlations did not decrease with increasing age of children (r = 0.17, 95%CI: 0.00–0.34 in 8–11-year-olds, r = 0.20, 95%CI: 0.07–0.33 in 12–15-year-olds, and r = 0.25, 95%CI: 0.07–0.39 in ≥16-year-olds). Finally, between-spouse correlations were significant only during weekend days (r = 0.14, 95%CI: 0.01–0.27).

Conclusion

Ambulatory activity correlated within families, with a possible mother effect. Mother-offspring correlations remained significant through the transition from childhood to adolescence. Further studies are required to better understand the respective influences of shared activities, parental modeling and support as well as genetic factors on the familial aggregation of physical activity.     

Assessment of physical activity by questionnaire and personal interview with particular reference to fitness and coronary mortality

Physical work capacity was measured by means of a symptom limited, near maximal cycle ergometer exercise test in two populations: a random sample of 95 military officers, and 2014 apparently healthy working males, 40-59 years old. Physical activity during leisure hours was assessed by means of a standardized questionnaire and by a personal interview with the officers and with 1769 of the other men. A 3 year total incidence of coronary heart disease (CHD) was recorded in the case of the officers and a 7 year CHD incidence and of CHD deaths was obtained for the 2014 working men. The data show that: A marked underestimation of the habitual levels of physical activity of the officers was obtained from the standardized questionnaire, as compared with that shown by the interview data. A far better agreement between the questionnaire and interview data on leisure time activity was observed among the mainly sedentary men. Physical work capacity was fairly well predicted from the questionnaire data in the sedentary men, but poorly predicted in the officers. CHD mortality in the sedentary men was highly correlated with working capacity in all age groups. Of 58 who died from CHD, 28 belonged to the lowest physical fitness quartile. This study indicates that questionnaires should be used with caution when assessing levels of habitual physical activity. It also suggests that a low physical work capacity is an important risk factor in CHD mortality.     

Assessment of daily life physical activities in pulmonary arterial hypertension

Background

In pulmonary arterial hypertension (PAH), the six-minute walk test (6MWT) is believed to be representative of patient''s daily life physical activities (DL_PA). Whether DL_PA are decreased in PAH and whether the 6MWT is representative of patient''s DL_PA remain unknown.

Methods

15 patients with idiopathic PAH (IPAH) and 10 patients with PAH associated with limited systemic sclerosis (PAH-SSc) were matched with 15 healthy control subjects and 10 patients with limited systemic sclerosis without PAH. Each subject completed a 6MWT. The mean number of daily steps and the mean energy expenditure and duration of physical activities >3 METs were assessed with a physical activity monitor for seven consecutive days and used as markers of DL_PA.

Results

The mean number of daily steps and the mean daily energy expenditure and duration of physical activities >3 METs were all reduced in PAH patients compared to their controls (all p<0.05). The mean number of daily steps correlated with the 6MWT distance for both IPAH and PAH-SSc patients (r = 0.76, p<0.01 and r = 0.85, p<0.01), respectively.

Conclusion

DL_PA are decreased in PAH and correlate with the 6MWT distance. Functional exercise capacity may thus be a useful surrogate of DL_PA in PAH.     

Aspects of physical activity in high altitude natives

Altitude adaptation was measured at sea level and high altitudes in sea level adapted and high altitude adapted natives. Tests of work capacity as measured by O₂ consumption, pulse rate, and ventilation rate are reported. It is noted that comparing our results with those of other investigators is difficult due to variations in terminology and procedure. This suggests the necessity of more precise definitions in studies of the physical activity of high altitude natives.     

Assessment of sympathoneural activity in clinical research

The assessment of autonomic nervous activity is a frequent and challenging goal of clinical research. The diverse current approaches are reviewed. Direct recording from the sympathetic input to muscle has the advantage of excellent time resolution and directness, but gives no information on the sympathetic input to the internal organs. Plasma noradrenaline concentration has limitations of specificity, some of which are overcome by single isotope radiotracer kinetic techniques. Other chemical markers are less satisfactory. End organ responses are generally limited to cardiovascular and cutaneous autonomic assessment, but sophisticated information is obtainable using power spectral analysis of heart rate variability. Assessment of receptor systems, of first and second messengers and radionuclide imaging of adrenergic nerves all give complimentary information. It is likely that a combination of these diverse techniques will advance understanding of the role of the autonomic nervous system in many disease states.     

Anthropometric indices and physical fitness in university undergraduates with different physical activity.

Physical activity and fitness have important health promoting effects with respect to arterosclerosis and coronary heart disease in particular. An intervention study of physical status and physical activity in university undergraduates (University of Tartu) has been carried out. The physically inactive (Group I) consisted of 310 undergraduates (235 females and 75 males) of the Faculty of Medicine. The physically active (Group II) was recruited from among undergraduates (22 females and 23 males) of the Faculty of Exercise and Sport Sciences, who participated in training sessions regularly, 3 to 5 times per week. Anthropometric body measurements, arm force, vital capacity and exercise test on the bicycle ergometer (PWC170) were performed. There were no statistically significant differences between the mean values of anthropometric indices in case of physically inactive and physically active female subjects. In the group of physically active male undergraduates, weight and shoulder width were larger than in students with physically sedentary life style (p < 0.05). Most of the female and male students had normal BMI. There were statistically significant differences in the mean values of vital capacity, arm force and aerobic working capacity between the study groups, while physically active students had higher physical capacity (p < 0.001). Mean anthropometric indices demonstrated a statistically significant increase in both female and male university undergraduates after the interval of 30 years. Normal BMI and anthropometric indices do not serve a as guarantee of physical fitness for university undergraduates who are involved in sedentary life style. Regular physical activity has a strong positive impact on physical fitness, particularly on aerobic capacity which is the most important health promoting component of physical fitness with respect to coronary heart disease.     

Assessment of inhomogeneities in an E. coli physical map.

A statistical method based on r-fragments, sums of distances between (r + 1) consecutive restriction enzyme sites, is introduced for detecting nonrandomness in the distribution or too markers in sequence data. The technique is applicable whenever large numbers of markers are available and will detect clumping, excessive dispersion or too much evenness of spacing of the markers. It is particularly adapted to varying the scale on which inhomogeneities can be detected, from nearest neighbor interactions to more distant interactions. The r-fragment procedure is applied primarily to the Kohara et al. (1) physical map of E. coli. Other applications to DAM methylation sites in E. coli and NotI sites in human chromosome 21 are presented. Restriction sites for the eight enzymes used in (1) appear to be randomly distributed, although at widely differing densities. These conclusions are substantially in agreement with the analysis of Churchill et al. (3). Extreme variability in the density of the eight restriction enzyme sites cannot be explained by variability in mono-, di- or trinucleotide frequencies.     

Lifestyle and patterns of physical activity in Hadza foragers

Objectives

Physically active lifestyles are associated with several health benefits. Physical activity (PA) levels are low in post-industrial populations, but generally high throughout life in subsistence populations. The Hadza are a subsistence-oriented foraging population in Tanzania known for being physically active, but it is unknown how recent increases in market integration may have altered their PA patterns. In this study, we examine PA patterns for Hadza women and men who engage in different amounts of traditional foraging.

Materials and Methods

One hundred and seventy seven Hadza participants (51% female, 19–87 years) wore an Axivity accelerometer (dominant wrist) for ~6 days during dry season months. We evaluated the effects of age, sex, and lifestyle measures on four PA measures that capture different aspects of the PA profile.

Results

Participants engaged in high levels of both moderate-intensity PA and inactivity. Although PA levels were negatively associated with age, older participants were still highly active. We found no differences in PA between participants living in more traditional “bush” camps and those living in more settled “village” camps. Mobility was positively associated with step counts for female participants, and schooling was positively associated with inactive time for male participants.

Conclusions

The similarity in PA patterns between Hadza participants in different camp types suggests that high PA levels characterize subsistence lifestyles generally. The sex-based difference in the effects of mobility and schooling on PA could be a reflection of the Hadza's gender-based division of labor, or indicate that changes to subsistence-oriented lifestyles impact women and men in different ways.