Success of a general school-based physical activity intervention on bone mineral content depends on pubertal stage but not on gender

Aims: We performed a randomised controlled trial in children of both gender and different pubertal stages to determine whether a school-based physical activity (PA) program during a full schoolyear influences bone mineral content (BMC) and whether there are differences in response for boys and girls before and during puberty. Methods: Twenty-eight 1st and 5th grade classes were cluster randomised to an intervention (INT, 16 classes, n=297) and control (CON; 12 classes, n=205) group. The intervention consisted of a multi-component PA intervention including daily physical education during a full school year. Each lesson was predetermined, included about ten minutes of jumping or strength training exercises of various intensity and was the same for all children. Measurements included anthropometry (height and weight), tanner stages (by self-assessment), PA (by accelerometry) and BMC for total body, femoral neck, total hip and lumbar spine using dualenergy X-ray absorptiometry (DXA). Bone parameters were normalized for gender and tanner stage (pre- vs. puberty). Analyses were performed by a regression model adjusted for gender, baseline height, baseline weight, baseline PA, post-intervention tanner stage, baseline BMC, and cluster. Researchers were blinded to group allocation. Children in the control group did not know about the intervention arm. Results: 217 (57%) of 380 children who initially agreed to have DXA measurements had also post-intervention DXA and PA data. Mean age of prepubertal and pubertal children at baseline was 9.0±2.1 and 11.2±0.6 years, respectively. 47/114 girls and 68/103 boys were prepubertal at the end of the intervention. Compared to CON, children in INT showed statistically significant increases in BMC of total body (adjusted z-score differences: 0.123; 95%>CI 0.035 to 0.212), femoral neck (0.155; 95%>CI 0.007 to 0.302), and lumbar spine (0.127; 95%>CI 0.026 to 0.228). Importantly, there was no gender*group, but a tanner*group interaction consistently favoring prepubertal children. Conclusions: Our findings show that a general, but stringent school-based PA intervention can improve BMC in elementary school children. Pubertal stage, but not gender seems to determine bone sensitivity to physical activity loading.

Effect of physical activity during pregnancy on mode of delivery.

OBJECTIVE: The purpose of this study was to evaluate the effect of structured physical exercise programs during pregnancy on the course of labor and delivery. STUDY DESIGN: We conducted a systematic review and metaanalysis using the following data sources: Medline and The Cochrane Library. In our study, we used randomized controlled trials (RCT) that evaluated the effects of exercise programs during pregnancy on labor and delivery. The results are summarized as relative risks. RESULTS: In the 16 RCTs that were included there were 3359 women. Women in exercise groups had a significantly lower risk of cesarean delivery (relative risk, 0.85; 95% confidence interval [CI], 0.73-0.99). Birthweight was not significantly reduced in exercise groups. The risk of instrumental delivery was similar among groups (relative risk, 1.00; 95% CI, 0.82-1.22). Data on Apgar score, episiotomy, epidural anesthesia, perineal tear, length of labor, and induction of labor were insufficient to draw conclusions. With the use of data from 11 studies (1668 women), our analysis showed that women in the exercise groups gained significantly less weight than women in control groups (mean difference, -1.13 kg; 95% CI, -1.49 to -0.78). CONCLUSION: Structured physical exercise during pregnancy reduces the risk of cesarean delivery. This is an important finding to convince women to be active during their pregnancy and should lead the physician to recommend physical exercise to pregnant women, when this is not contraindicated.

Associations of physical activity and sport and exercise with at-risk substance use in young men: a longitudinal study.

OBJECTIVE: This study aims to measure the associations of physical activity and one of its components, sport and exercise, with at-risk substance use in a population of young men. METHOD: Baseline (2010-2012) and follow-up (2012-2013) data of 4748 young Swiss men from the Cohort Study on Substance Use Risk Factors (C-SURF) were used. Cross-sectional and prospective associations between at-risk substance use and both sport and exercise and physical activities were measured using Chi-squared tests and logistic regression models adjusting for covariates. RESULTS: At baseline, logistic regression indicated that sport and exercise is negatively associated with at-risk use of cigarettes and cannabis. A positive association was obtained between physical activity and at-risk alcohol use. At baseline, sport and exercise was negatively associated with at-risk use of cigarettes and cannabis at follow-up. Adjusted for sport and exercise, physical activity was positively associated with at-risk use of cigarettes and cannabis. CONCLUSION: Sport and exercise is cross-sectionally and longitudinally associated with a low prevalence of at-risk use of cigarettes and cannabis. This protective effect was not observed for physical activity broadly defined. Taking a substance use prevention perspective, the promotion of sport and exercise among young adults should be encouraged.

Physical activity under confinement and free-living conditions.

The objective of this study was to investigate the relationship between the physical activity (PA) and its related variables under confinement and in free-living conditions in Asian individuals, where no such information presently exists. The subjects consisted of eighty-six Japanese individuals with a mean age of 38+/-12 years. Under confinement in a large respiratory chamber, the energy expenditure (EE) was measured for 24h. In addition, two moderate walking exercises of 30 min each on a horizontal treadmill were assigned. Free-living measurements of 7 days were also performed using a validated accelerometer. The PA level in the chamber (1.47+/-0.11), expressed as a multiple of the basal EE, was lower than that in free-living conditions (1.53+/-0.12) (p<0.001). However, the two values were closely correlated (r=0.744, p<0.001). Conversely, a residual analysis showed a wide variation in the mean difference for both conditions and revealed a significant systematic error (r=-0.548, p<0.001), thus indicating an increased gap with increasing PA levels in free-living conditions. Similar results were obtained following the exclusion of the imposed exercise sessions. In contrast, the daily step counts under both conditions did not show any correlation. The PA level in the chamber (including and excluding imposed walking exercises) is compatible with the PA level in free-living conditions at the group level, although the daily step counts are unrelated. Thus, the PA level in the chamber may provide valuable information to help us achieve a better understanding of human PA in daily life as it is related to behavioral research.

Effect of a governmentally-led physical activity program on motor skills in young children attending child care centers: a cluster randomized controlled trial.

OBJECTIVE: To assess the effect of a governmentally-led center based child care physical activity program (Youp'la Bouge) on child motor skills.Patients and methods: We conducted a single blinded cluster randomized controlled trial in 58 Swiss child care centers. Centers were randomly selected and 1:1 assigned to a control or intervention group. The intervention lasted from September 2009 to June 2010 and included training of the educators, adaptation of the child care built environment, parental involvement and daily physical activity. Motor skill was the primary outcome and body mass index (BMI), physical activity and quality of life secondary outcomes. The intervention implementation was also assessed. RESULTS: At baseline, 648 children present on the motor test day were included (age 3.3 +/- 0.6, BMI 16.3 +/- 1.3 kg/m2, 13.2% overweight, 49% girls) and 313 received the intervention. Relative to children in the control group (n = 201), children in the intervention group (n = 187) showed no significant increase in motor skills (delta of mean change (95% confidence interval: -0.2 (-0.8 to 0.3), p = 0.43) or in any of the secondary outcomes. Not all child care centers implemented all the intervention components. Within the intervention group, several predictors were positively associated with trial outcomes: 1) free-access to a movement space and parental information session for motor skills 2) highly motivated and trained educators for BMI 3) free-access to a movement space and purchase of mobile equipment for physical activity (all p < 0.05). CONCLUSION: This "real-life" physical activity program in child care centers confirms the complexity of implementing an intervention outside a study setting and identified potentially relevant predictors that could improve future programs.Trial registration: Trial registration number: clinical trials.gov NCT00967460 http://clinicaltrials.gov/ct2/show/NCT00967460.

Assessment of physical activity with a pedometer and its relationship with VO2max among adolescents in Switzerland.

OBJECTIVES: In the absence of a gold standard, the assessment of physical activity in children remains difficult. To record physical activity with a pedometer and to examine to what extent it is correlated with VO2max. METHODS: Survey on physical activity and fitness; 233 Swiss adolescents aged 11 to 15 carried a pedometer (Pedoboy) during seven consecutive days. VO2max was estimated through an endurance shuttle run test. RESULTS: The physical activity recorded by the pedometer did not vary from one day to the other (p > 0.05). The physical activity was higher among boys than among girls (p < 0.001) and higher among younger adolescents (6th versus 8th grade; p < 0.001). The correlation between physical activity and estimated VO2max was 0.30 (p < 0.01). CONCLUSIONS: The use of a pedometer to assess physical activity over one entire week is feasible among adolescents. The record provided by the pedometer gives an objective measure of the usual physical activity and, as such, is relatively well correlated with aerobic capacity.

Unraveling dynamics of human physical activity patterns in chronic pain conditions.

Chronic pain is a complex disabling experience that negatively affects the cognitive, affective and physical functions as well as behavior. Although the interaction between chronic pain and physical functioning is a well-accepted paradigm in clinical research, the understanding of how pain affects individuals' daily life behavior remains a challenging task. Here we develop a methodological framework allowing to objectively document disruptive pain related interferences on real-life physical activity. The results reveal that meaningful information is contained in the temporal dynamics of activity patterns and an analytical model based on the theory of bivariate point processes can be used to describe physical activity behavior. The model parameters capture the dynamic interdependence between periods and events and determine a 'signature' of activity pattern. The study is likely to contribute to the clinical understanding of complex pain/disease-related behaviors and establish a unified mathematical framework to quantify the complex dynamics of various human activities.

Physical activity level and health-related quality of life in the general adult population: a systematic review.

OBJECTIVE: Little is known regarding health-related quality of life and its relation with physical activity level in the general population. Our primary objective was to systematically review data examining this relationship. METHODS: We systematically searched MEDLINE, EMBASE, CINAHL, and PsycINFO for health-related quality of life and physical activity related keywords in titles, abstracts, or indexing fields. RESULTS: From 1426 retrieved references, 55 citations were judged to require further evaluation. Fourteen studies were retained for data extraction and analysis; seven were cross-sectional studies, two were cohort studies, four were randomized controlled trials and one used a combined cross sectional and longitudinal design. Thirteen different methods of physical activity assessment were used. Most health-related quality of life instruments related to the Medical Outcome Study SF-36 questionnaire. Cross-sectional studies showed a consistently positive association between self-reported physical activity and health-related quality of life. The largest cross-sectional study reported an adjusted odds ratio of "having 14 or more unhealthy days" during the previous month to be 0.40 (95% Confidence Interval 0.36-0.45) for those meeting recommended levels of physical activity compared to inactive subjects. Cohort studies and randomized controlled trials tended to show a positive effect of physical activity on health-related quality of life, but similar to the cross-sectional studies, had methodological limitations. CONCLUSION: Cross-sectional data showed a consistently positive association between physical activity level and health-related quality of life. Limited evidence from randomized controlled trials and cohort studies precludes a definitive statement about the nature of this association.

Energy balance, physical activity, and thermogenic effect of feeding in premature infants.

In order to assess the contribution of the thermogenic effect of feeding and muscular activity to total energy expenditure, nine premature infants were studied for 2 consecutive days during which time repeated measurements of energy expenditure by indirect calorimetry were performed throughout the day, combined with a visual activity score based on body movement. The infants were growing at 16.6 +/- 4.0 g/kg/day (mean +/- SD) and received 110 +/- 8 kcal/kg/day metabolizable energy (milk formula) and 522 +/- 40 mgN/kg/day. Their total energy expenditure was 68 +/- 4 kcal/kg/day indicating that 41 +/- 7 kcal/kg/day was retained for growth. Based on the combination of energy + N balances it was estimated that 80% of the weight gain was fat-free tissue and 20% was fat tissue. The rate of energy expenditure measured minute-by-minute was significantly and linearly correlated with the activity score in both the premeal (r = 0.75;p less than 0.001) and the postmeal periods (r = 0.74; p less than 0.001) with no difference in the regression slope, but with a significant difference in intercept. In preset feeding schedules the latter allowed an estimation of the thermogenic effect without the confounding effect of activity. This was found to be 3.1 +/- 1.8% when expressed as a percentage of metabolizable energy intake. However when the "classical" approach was used as a comparison (integration of extra energy expenditure induced by the meal), the thermogenic effect was found to be greater, i.e. 9.5 +/- 3.8% of the meal's metabolizable energy, due to the superimposed effect of physical activity in the postprandial state.(ABSTRACT TRUNCATED AT 250 WORDS)

Physical activity in free-living, overweight white and black women: divergent responses by race to diet-induced weight loss.

BACKGROUND: Black women are at greater risk of obesity than are white women, perhaps because of their lower levels of physical activity. OBJECTIVE: We compared free-living activity energy expenditure (AEE) in sedentary white and black women (in overweight and normal-weight states) and in never-overweight control subjects. DESIGN: Subjects included 46 women (23 white, 23 black) studied while overweight and after reaching a normal weight and 38 female control subjects (23 white, 15 black). Diet, without exercise training, resulted in a mean weight loss of 13 kg and a body mass index (in kg/m(2)) < 25. Body composition, sleeping energy expenditure, free-living total energy expenditure, and the energy cost of activity and aerobic capacity were assessed before and after weight loss under 4-wk, diet-controlled, weight-stable conditions and in the control subjects. AEE was defined as above-sleep energy expenditure. RESULTS: No significant racial differences in body composition, before or after weight loss, were found. After weight loss, AEE and aerobic capacity increased in the white women and decreased in the black women (P < 0.05 and P < 0.02, respectively). After weight loss, but not before, the white women had a significantly higher mean AEE than did the black women (2448 +/- 979 and 1728 +/- 1373 kJ/d, respectively; P < 0.05), approximating AEEs in the white (2314 +/- 1105) and black (2310 +/- 1251) control subjects. CONCLUSIONS: Relative to the responses of the white women to diet-induced weight loss, the black women became less fit and less physically active. Induction of a normal body weight in overweight black women appeared to produce a more obesity-prone state, favoring weight relapse.

Physical activity and energy expenditure in rheumatoid arthritis patients and matched controls.

OBJECTIVES: To compare daily energy expenditure between RA patients and matched controls, and to explore the relationship between daily energy expenditure or sedentariness and disease-related scores. METHODS: One hundred and ten patients with RA and 440 age- and sex-matched controls were included in this study. Energy expenditure was assessed using the validated physical activity (PA) frequency questionnaire. Disease-related scores included disease activity (DAS-28), functional status (HAQ), pain visual analogue scale (VAS) and fatigue VAS. Total energy expenditure (TEE) and the amount of energy spent in low- (TEE-low), moderate- (TEE-mod) and high-intensity (TEE-high) PAs were calculated. Sedentariness was defined as expending <10% of TEE in TEE-mod or TEE-high activities. Between-group comparisons were computed using conditional logistic regression. The effect of disease-related scores on TEE was investigated using linear regression. RESULTS: TEE was significantly lower for RA patients compared with controls [2392 kcal/day (95% CI 2295, 2490) and 2494  kcal/day (2446, 2543), respectively, P = 0.003]. A significant difference was found between groups in TEE-mod (P = 0.015), but not TEE-low (P = 0.242) and TEE-high (P = 0.146). All disease-related scores were significantly poorer in sedentary compared with active patients. TEE was inversely associated with age (P < 0.001), DAS-28 (P = 0.032) and fatigue VAS (P = 0.029), but not with HAQ and pain VAS. CONCLUSION: Daily energy expenditure is significantly lower in RA patients compared with matched controls, mainly due to less moderate-intensity PAs performed. Disease activity and fatigue are important contributing factors. These points need to be addressed if promoting PA in RA patients is a health goal. Trial registration. ClinicalTrials.gov, http://clinicaltrials.gov, NCT01228812.

Nonlinear analysis of human physical activity patterns in health and disease.

The reliable and objective assessment of chronic disease state has been and still is a very significant challenge in clinical medicine. An essential feature of human behavior related to the health status, the functional capacity, and the quality of life is the physical activity during daily life. A common way to assess physical activity is to measure the quantity of body movement. Since human activity is controlled by various factors both extrinsic and intrinsic to the body, quantitative parameters only provide a partial assessment and do not allow for a clear distinction between normal and abnormal activity. In this paper, we propose a methodology for the analysis of human activity pattern based on the definition of different physical activity time series with the appropriate analysis methods. The temporal pattern of postures, movements, and transitions between postures was quantified using fractal analysis and symbolic dynamics statistics. The derived nonlinear metrics were able to discriminate patterns of daily activity generated from healthy and chronic pain states.