Daily energy expenditure, activity patterns, and energy costs of the various activities in French 12-16-y-old adolescents in free living conditions

Late subadult ontogeny and adult aging of the human thorax reveals divergent growth trajectories between sexes

Sexual dimorphism is an important feature of adult thorax morphology, but when and how sex-related differences in the ribcage arise during ontogeny is poorly known. Previous research proposed that sex-related size differences in the nasal region arise during puberty. Therefore, we explore whether ribcage sexual dimorphism also arises at that time and whether this sexual dimorphism is maintained until old age. We measured 526 (semi)landmarks on 80 CT-based human ribcage reconstructions, on individuals ranging from 7 to 65 year-old. The 3D coordinates were submitted to the Procrustes superimposition and analyzed. Our results show that the trajectories of thorax size and shape between sexes diverge at around 12 years of age, and continue slightly diverging until old age. The differential ontogenetic trends cause adult male ribcages to become deeper, shorter, and wider than female. Our results are consistent with the evidence from the cranial respiratory system, with the development of sexual dimorphism probably related to changes in body composition during puberty combined with changes in the reproductive system.

Objective Measurement of the Mode of Commuting to School Using GPS: A Pilot Study

Background and objectives: Active commuting to school (ACS) is a promising strategy to increase the daily physical activity (PA) in youths. However, more studies are required to objectively quantify the mode of commuting to school, as well as the health impact of this behavior. Thus, the aims of this study were: (1) to objectively determine the mode of commuting to school using GPS; (2) to quantify the sedentary time, PA levels, energy expenditure, and the steps derived from each mode of commuting; and (3) to analyze the associations between ACS trips and sedentary time, PA, energy expenditure, and steps. Participants and Methods: A total of 180 trips to school were detected, which corresponded to 18 adolescents (12 girls, mean age = 15 ± 0.0 years old). Mode of commuting to school was detected using a novel method merging GPS data in the Personal Activity Location Measurement System (PALMS), whereas sedentary time, PA levels, energy expenditure, and steps were objectively evaluated through accelerometry. Logistic regressions were used to analyze the associations of these variables with walking trips. Results: A total of 115 trips were recorded. Most trips were performed by walk (49.5%), followed by vehicle (39.1%) and mixed transport (11.3%). In the active school trips, youths were less likely to spend minutes in sedentary behaviors (OR: 0.481, p = 0.038), a higher increase on Metabolic-Equivalent of Task (METs) (OR: 5.497, p = 0.013), and greater steps (OR: 1.004, p = 0.029) than in the passive school trips (both active and passive modes were objectively measured). Conclusions: ACS (mainly walking) contribute to higher METs and steps in adolescents. GPS could be an appropriate method to objectively evaluate the PA variables related to the ACS trips.

How Do Perceptions of Local Neighborhood Relate to Adolescents' Walking and Cycling?

Purpose.

To examine how perceptions of the local neighborhood relate to adolescents' walking and cycling.

Design.

Exploratory cross-sectional study.

Setting.

Birth cohort from the Nepean Hospital, Sydney, Australia.

Subjects.

Three hundred forty-seven adolescents (79.1% response rate; 49.6% boys; mean age = 13.0 ± 0.2 years) and their parents.

Measures.

Self-report and parental-report questionnaires.

Results.

Multiple linear regressions, adjusted for level of maternal education, revealed that boys who reported having many peers to hang out with locally, cycled for recreation (β = 0.242, p = .006) or for transport (β = 0.141, p = .046) more often, and walked for transport for longer (β = 0.129, p = .024) on weekdays. For girls this variable was related to cycling for recreation on weekends (β = 0.164, p = .006) and walking to school (β = 0.118, p = .002). Adolescents who waved/talked to neighbors walked for transport more often (boys, β = 0.149, p = .037; girls, β = 0.119, p = .012). Girls who perceived local roads to be safe spent more time walking for transport on weekdays (β = 0.183, p = .007) and for exercise on weekends (β = 0.184, p = .034). Parents' perception of heavy traffic was negatively associated with boys' walking for transport (β = −0.138, p = .037) and many aspects of girls' walking and cycling.

Conclusion.

Social interaction and road safety may be important predictors of adolescents' walking and cycling in their neighborhood. Limitations are the use of self-report and cross-sectional data. Longitudinal studies may clarify these relations.

Seasonal variation in physical activity and sedentary time in different European regions. The HELENA study

This report aims (1) to examine the association between seasonality and physical activity (PA) and sedentary time in European adolescents and (2) to investigate whether this association was influenced by geographical location (Central-North versus South of Europe), which implies more or less extreme weather and daylight hours. Valid data on PA, sedentary time and seasonality were obtained in 2173 adolescents (1175 females; 12.5-17.5 years) included in this study. Physical activity and sedentary time were measured by accelerometers. ANCOVA was conducted to analyse the differences in PA and sedentary time across seasons. Results showed that girls had lower levels of moderate to vigorous PA (MVPA) and average PA, and spent more time in sedentary activities in winter compared with spring (all P < 0.05). Stratified analyses showed differences in PA and sedentary time between winter and spring in European girls from Central-North of Europe (P < 0.05 for sedentary time). There were no differences between PA and sedentary time across seasonality in boys. In conclusion, winter is related with less time spent in MVPA, lower average PA and higher time spent in sedentary activities in European adolescent girls, compared with spring. These differences seem to mainly occur in Central-North Europe.

Physical activity, fitness and the energy cost of activities: implications for obesity in children and adolescents in the tropics

The tropics cover a large section of the world in which both developed and developing countries are situated. Rapid socioeconomic development, modernization, urbanization, and globalization have affected both the food market and physical activity (PA), which in turn have propelled the obesity epidemic in the tropics. There is growing concern that overweight and obesity are emerging as major health problems among children and adolescents in the tropics, despite the fact that undernutrition still exists in many of these countries. Physical inactivity, a low metabolic rate, and lack of physical fitness (PF) have been linked to overweight and obesity. Moreover, PF in several tropical countries is declining, and these changes may be a threat to future health, as low PA and PF levels are important risk factors for noncommunicable chronic diseases. Previous studies have reported that the relationships among PA, PF, overweight, and obesity are inconsistent and inconclusive. There is no indication that variances in the energy cost of physical activities lead to obesity. Despite a lack of definite evidence to prove a causal relationship, there is enough certainty that physical inactivity and low fitness levels are linked to overweight and obesity. Hence, people living in tropical countries need to be encouraged to lead a healthier lifestyle by increasing their PA levels and reducing sedentary behaviors to prevent overweight or obesity.

A Weight Reduction Program Preserves Fat-Free Mass but Not Metabolic Rate in Obese Adolescents

OBJECTIVE

To determine the effects of a multidisciplinary weight reduction program on body composition and energy expenditure (EE) in severely obese adolescents.

RESEARCH METHODS AND PROCEDURES

Twenty-six severely obese adolescents, 12 to 16 years old [mean BMI: 33.9 kg/m(2); 41.5% fat mass (FM)] followed a 9-month weight reduction program including moderate energy restriction and progressive endurance and resistance training. Body composition was assessed by DXA, basal metabolic rate by indirect calorimetry, and EE by whole-body indirect calorimetry with the same activity program over 36-hour periods before starting and 9 months after the weight reduction period.

RESULTS

Adolescents gained (least-square mean +/- SE) 2.9 +/- 0.2 cm in height, lost 16.9 +/- 1.3 kg body weight (BW), 15.2 +/- 0.9 kg FM, and 1.8 +/- 0.5 kg fat-free mass (FFM) (p < 0.001). Basal metabolic rate, sleeping, sedentary, and daily EE were 8% to 14% lower 9 months after starting (p < 0.001) and still 6% to 12% lower after adjustment for FFM (p < 0.05). Energy cost of walking decreased by 22% (p < 0.001). The reduction in heart rate during sleep and sedentary activities (-10 to -13 beats/min), and walking (-20 to -25 beats/min) (p < 0.001) resulted from both the decrease in BW and physical training.

DISCUSSION

A weight reduction program combining moderate energy restriction and physical training in severely obese adolescents resulted in great BW and FM losses and improvement of cardiovascular fitness but did not prevent the decline in EE even after adjustment for FFM.

Physical activity energy expenditure in Dutch adolescents: contribution of active transport to school, physical education, and leisure time activities

BACKGROUND

Detailed knowledge about physical activity energy expenditure (PAEE) can guide the development of school interventions aimed at reducing overweight in adolescents. However, relevant components of PAEE have never been objectively quantified in this population. This study investigated the contribution of active transport to and from school, physical education (PE), and leisure time activities to total PAEE during a regular school week in adolescents.

METHODS

Seventy-three adolescents (mean age: 15.7 years) wore an individually calibrated combined heart rate-acceleration monitor and kept an activity diary during a regular school week. Branched equation modeling was used to calculate PAEE of the specific activity categories, and their relative contribution to total PAEE was determined.

RESULTS

Active transport and PE contributed 30.0% and 17.4%, respectively, to school-related PAEE. Active transport to and from school contributed 15% to total PAEE. Youth with a high physical activity level (PAL) spent 4 hours less in sedentary behavior than subjects with a medium or low PAL (F = 77.415 (2.70), p < .001) and had higher PAEE during leisure time sports (F = 9.135 (2.70), p < .001) and work-related activities (F = 10.583 (2.70), p < .001) than youth with medium or low PAL values.

CONCLUSIONS

Active transport and PE contribute significantly to PAEE during school hours in adolescents. To achieve an increase in total PAEE in the least active group of adolescents, promising strategies might be to reduce inactive behavior, increase participation in leisure time sports, and possibly to replace inactive for active jobs.

Seasonal variation in physical activity among children and adolescents: a review

The purpose of this review was to examine seasonal variation in physical activity among children and adolescents. Searches were conducted of electronic databases for studies on seasonal differences in physical activity levels. A total of 35 studies, including children and adolescents between the ages of 2-19 years, were reviewed. Overall, 83% (29/35) of the studies found seasonal variation in physical activity among children and/or adolescents. The results were consistent regardless of the region, physical activity measure, or the study design but the findings were inconsistent across age categories.

Physical activity levels and estimated energy expenditure in overweight and normal-weight 11-year-old children

AIM

To objectively evaluate physical activity and energy expenditure in overweight and normal-weight 11-year-old children.

METHODS

The final sample consisted of 91 children (32 overweight and 59 normal-weight children), mean age (SD) = 11.3 (0.2) years. Energy expenditure and physical activity were assessed during two weekdays and two weekend days using a multiple-sensor body monitor (SenseWear Armband; BodyMedia Inc., Pittsburgh, PA, USA).

RESULTS

Time spent in physical activity was higher in normal-weight compared with overweight children (p = 0.002). The highest level of physical activity was noted in normal-weight boys [mean (SD) = 258 (114) min/day] and the lowest in overweight girls [mean (SD) = 136 (59) min/day] (p = 0.002). In contrast, energy expended during physical activity did not differ between normal-weight and overweight children (2.6 and 2.7 MJ/day, respectively, p = 0.89). The average decrease in physical activity at weekends was 39 min in overweight children (from 166 to 127 min/day) and 27 min in their normal-weight counterparts (from 230 to 203 min/day).

CONCLUSION

Overweight children engaged in less physical activity of both moderate and vigorous intensity compared with their normal-weight peers. Both overweight and normal-weight children were less active at weekends than on weekdays. Initiatives aiming to increase physical activity of overweight children at weekends are warranted.

Are safety-related features of the road environment associated with smaller declines in physical activity among youth?

This study examined how objective measures of the local road environment related to safety were associated with change in physical activity (including active transport) among youth. Few longitudinal studies have examined the impact of the road environment on physical activity among children/adolescents in their neighborhoods. Participants were children aged 8-9 years (n = 170) and adolescents aged 13-15 years (n = 276) in 2004. Data were collected in 2004 and 2006 during follow-up of participants recruited initially in 2001 from 19 primary schools in Melbourne, Australia. Walking/cycling to local destinations was parent-reported for children and self-reported by adolescents. Moderate-to-vigorous physical activity (MVPA) during nonschool hours was recorded using accelerometers. Road environment features in each participant's neighborhood (area within 800 m radius of their home) were measured objectively using a Geographical Information System. Linear regression analyses examined associations between road features and changes in active transport (AT) and MVPA over 2 years. Children's AT increased but MVPA levels decreased in both age groups; on average, younger girls recorded the greatest declines. The number of traffic/pedestrian lights was associated with DeltaAT among younger girls (B=0.45, p=0.004). The total length of walking tracks (in meters) was associated with AT among younger girls (B = 0.0016, p = 0.015) and adolescent girls (B = 0.0016, p = 0.002). For adolescent boys, intersection density was associated with AT (B = 0.03, p = 0.030). Slow points were associated with MVPA among younger boys before school (B = 1.55, p = 0.021), while speed humps were associated with MVPA among adolescent boys after school (B = 0.23, p = 0.015). There were many associations for adolescent girls: for example, the total length of local roads (B = 0.49, p = 0.005), intersection density (B = 0.05, p = 0.036), and number of speed humps (B = 0.33, p = 0.020) were associated with MVPA during nonschool hours. Safety-related aspects of the built environment are conducive to physical activity among youth and may help stem age-related declines in physical activity. Passive road safety interventions may promote AT and physical activity among less active girls, in particular.

Seasonal variations in physical activity and implications for human health

This review explores the implications of seasonal changes in physical activity for fitness and human health. Photosensitivity and nutrient shortages mediate animal hibernation via the hypothalamus and changes in leptin and ghrelin concentrations. Opportunities for hunting and crop cultivation determine seasonal activity in under-developed human societies, but in developed societies temperature and rainfall are dominant influences, usually over-riding innate rhythms. Both questionnaire data and objective measurements show that many groups from children to the elderly increase their physical activity from winter to spring or summer. Measurements of maximal oxygen intake and muscle strength commonly show parallel seasonal changes. However, potential effects upon body mass and body fat may be counteracted by changes of food intake; subsistence agriculturists sometimes maintain or increase physical activity at the expense of a decrease in body mass. In developed societies, body fat commonly increases during the winter, with parallel changes in blood lipids, blood pressure and blood coagulability; moreover, these changes are not always fully reversed the following summer. Most developed societies show increased all-cause and cardiac mortalities in the winter. Health consequences of seasonal variations in physical activity including an increased vulnerability to cardiac catastrophe and a year-by-year increase in total body fat seem most likely if the average level of physical activity for the year is low. Public health recommendations should underline the importance of maintaining physical activity during adverse environmental conditions by adapting clothing, modifying behaviour and exploiting any available air-conditioned indoor facilities.

Development of a compendium of energy expenditures for youth

BACKGROUND

This paper presents a Compendium of Energy Expenditures for use in scoring physical activity questionnaires and estimating energy expenditure levels in youth.

METHOD/RESULTS

Modeled after the adult Compendium of Physical Activities, the Compendium of Energy Expenditures for Youth contains a list of over 200 activities commonly performed by youth and their associated MET intensity levels. A review of existing data collected on the energy cost of youth performing activities was undertaken and incorporated into the compendium. About 35% of the activity MET levels were derived from energy cost data measured in youth and the remaining MET levels estimated from the adult compendium.

CONCLUSION

The Compendium of Energy Expenditures for Youth is useful to researchers and practitioners interested in identifying physical activity and energy expenditure values in children and adolescents in a variety of settings.

Effects of an eight-month weight-control program on body composition and lipid oxidation rate during exercise in obese children

OBJECTIVE

To investigate the effects of an 8-month multidisciplinary weight-control program, including 2 h/week of moderate physical activity, nutritional education lessons and psychological follow-up, on body composition and lipid oxidation rate during exercise in obese children.

DESIGN

Nineteen (7 boys and 12 girls) obese children, aged 8-12 yr [mean body mass index (BMI) z-score: 2.3 and fat mass: 35.8%] participated in this study. Before and at the end of the weight-control period body composition was assessed by bioelectrical impedance, lipid oxidation rate by indirect calorimetry during a graded exercise test, and time devoted to various activities and energy intake in free-living conditions by questionnaire.

RESULTS

All children completed the study, at the end of which BMI decreased significantly by mean 0.6+/-0.5 and 0.5+/-0.8 kg/m2, in boys and girls, respectively (p<0.05), and fat mass (FM) decreased by 1.7+/-2.8 and 1.4+/-1.3 kg in boys and girls, respectively (p<0.05). In addition, lipid oxidation rate during exercise increased significantly throughout the graded exercise test up to 21% at maximal lipid oxidation rate which happened at 48+/-5% of maximal oxygen uptake (VO2max), corresponding to 64+/-5% of maximal heart rate. Time spent at sedentary and very light physical activities decreased (p<0.001) to the benefit of recreational activities at home.

CONCLUSIONS

Multidisciplinary weight-control program, with moderate-intensity physical activities, induced decreases in FM without decreases in free FM, increases in VO2max, lipid oxidation rate during exercise, and time devoted to recreational activities in free-living conditions.

The physical activity patterns of European youth with reference to methods of assessment

This article reviews the habitual physical activity of children and adolescents from member countries of the European Union in relation to methods of assessing and interpreting physical activity. Data are available from all European Union countries except Luxembourg and the trends are very similar. European boys of all ages participate in more physical activity than European girls and the gender difference is more marked when vigorous activity is considered. The physical activity levels of both genders are higher during childhood and decline as young people move through their teen years. Physical activity patterns are sporadic and sustained periods of moderate or vigorous physical activity are seldom achieved by many European children and adolescents. Expert committees have produced guidelines for health-related physical activity for youth but they are evidence-informed rather than evidence-based and where there is evidence of a relationship between physical activity during youth and health status there is little evidence of a particular shape of that relationship. The number of children who experience physical activity of the duration, frequency and intensity recommended by expert committees decreases with age but accurate estimates of how many girls and boys are inactive are clouded by methodological problems. If additional insights into the promotion of health through habitual physical activity during youth are to be made, methods of assessment need to be further refined and recommended guidelines re-visited in relation to the existing evidence base.

Changes in physical activity explain paradoxical relationship between baseline physical activity and adiposity changes in adolescent girls: the FLVS II study

OBJECTIVE

To investigate in adolescents relationships between habitual physical activity (PA) and changes in several indicators of adiposity.

DESIGN

Longitudinal population-based study. The Fleurbaix-Laventie Ville Sante II (FLVS II) study in Northern France.

SUBJECTS

A total of 222 boys and 214 girls aged 8-18 y, not obese at inclusion.

MEASUREMENTS

PA (Modifiable Activity Questionnaire) and adiposity (body mass index (kg/m2), percent body fat by bioimpedance analysis, sum of four skinfolds, waist circumference) were assessed in 1999 and 2001. Adiposity indicators adjusted for age and pubertal stage were compared between groups of baseline PA and between groups of PA changes, separately by sex.

RESULTS

At baseline, PA was not associated with adiposity indicators in both sexes. In girls only, being in the group with the highest age-relative level of moderate PA at baseline predicted the highest adiposity gain from baseline to follow-up, for all indicators. After adjustment for baseline values, all adiposity indicators were higher at follow-up in girls who had decreased their relative level of moderate PA during follow-up. In boys, changes in adiposity during follow-up were not significantly different across groups of PA changes. However, the sum of skinfolds at follow-up, adjusted for baseline value, tended to be higher in those who decreased their vigorous PA level and lower in those who increased it.

CONCLUSION

In adolescent girls, a decrease in PA rather than inactivity per se may result in increased adiposity over time.

Comparison of accuracy and precision of heart rate calibration methods to estimate total carbon dioxide production during 13C-breath tests

BACKGROUND

13C-breath tests are noninvasive tools to measure gastrointestinal function and nutritional interventions. Calculation of percentage dose recovered of 13C in exhaled breath requires knowledge of CO2 production rate (VC02). A resting value is usually assumed, but this can underestimate VC02 because subjects are unlikely to remain at rest during tests that last for many hours. There is a need for a method to estimate nonresting VC02 during 13C-breath tests.

OBJECTIVE

To calibrate a heart rate monitor to continually estimate VC02 during 13C-breath tests.

DESIGN

Proof of concept study.

SUBJECTS

Eight healthy adults, 10 healthy children and six children with cystic fibrosis.

METHODS

Heart rate and VC02 were measured simultaneously at resting and nonresting levels. A new calibration method (smoothing heart rate and fitting a sigmoid function) was compared with published methods. A [ 3C]acetate breath test was used to demonstrate the range of physical activity during breath tests.

RESULTS

The new calibration method was more accurate than existing methods (mean bias -0.0002%, 95% confidence interval (CI) -0.0007, 0.0003% of the mean measured VC02). Smoothing heart rate gave a more precise estimate of VC02 and a more accurate estimate of resting energy expenditure (mean bias -0.09, 95% Cl -0.22, 0.05 mmol CO2 min-' m-2 body surface area) than using raw data (mean bias -0.21, 95% Cl -0.38, -0.04 mmol CO2 min' m-2 body surface area). Physical activity level ranged from 1.0 to 2.5 in children, and 1.0 to 1.5 in adults.

CONCLUSION

Use of smoothed HR with a sigmoid function provides an accurate method of estimating nonresting VC02 during 13C-breath tests.

Relação entre diferentes índices de atividade física e preditores de adiposidade em adolescentes de ambos os sexos

OBJETIVO: Determinar a relação entre diferentes índices de atividade física e preditores de adiposidade em adolescentes de ambos os sexos. MÉTODOS: Foram avaliadas 111 crianças (57 meninos e 54 meninas), com idade média de 11,62 ± 0,72. Como preditores de adiposidade foram determinados o IMC, percentagem de gordura corporal e a relação cintura/quadril (RCQ). Quanto aos indicadores de atividade física, calcularam-se o gasto energético total (GET), nível de atividade física habitual (NAFH), nível de atividade física (NAF) e gasto energético com atividade física (GEat) através do questionário de Bouchard e, para a taxa metabólica basal (TMB), a equação de Schofield-HW. RESULTADOS: A amostra apresentou diferenças significativas entre os sexos para idade, % de gordura corporal, RCQ, NAFH, NAF, TMB com p < 0,05. Para os meninos o GET, NAF, TMB e GEat apresentaram correlação significativa com o IMC (r = 0,86; r = 0,70; r = 0,91; r = 0,78) e % de gordura (r = 0,78; r = 0,61; r = 0,90; r = 0,70) com p < 0,01, respectivamente, e o GET, TMB, GEat apresentaram correlação significativa com o RCQ (r = 0,28; r = 0,45 e r = 0,28) com p < 0,05. Para as meninas o GET, NAF, TMB, GEat apresentaram valores significativos com o IMC (r = 0,86; r = 0,82; r = 0,78; r = 0,85); em % de gordura todos os indicadores GET, NAFH, NAF, TMB e GEat foram significativos (r = 0,73; r = -0,29; r = 0,66; r = 0,74; r = 0,70) com p < 0,05. CONCLUSÃO: Os diferentes indicadores de nível de atividade física apresentaram significativa correlação com os preditores de adiposidade com exceção do RCQ para as meninas. O aumento da massa corporal demonstrou relação significância com o aumento do dispêndio energético em função da maior necessidade de energia para movimentar o corpo.

Longitudinal changes in activity patterns, physical capacities, energy expenditure, and body composition in severely obese adolescents during a multidisciplinary weight-reduction program

OBJECTIVE

To determine the longitudinal changes in body composition, physical capacities, and time and energy expenditure (EE) devoted to various activities in the course of a 9-month weight-reduction period.

DESIGN

Longitudinal, clinical intervention including lifestyle education, moderate energy restriction, progressive training, and psychological follow-up.

SUBJECTS

A total of 27 (13 boys and 14 girls) severely obese adolescents (mean BMI: 33.9 kg/m2; 41.5% fat mass (FM)), aged 12-16 y.

MEASUREMENTS

Before the beginning and after the weight-reduction program, body composition was assessed by dual-energy X-ray absorptiometry (DXA), physical capacities by multistage treadmill test, and EE both by whole-body calorimetry and in free-living conditions using the heart rate-recording method. During 8 months of the weight-reduction period, type and duration of each activity were recorded using a daily controlled activity diary.

RESULTS

One boy resigned after 5 months. Body weight (BW) and FM decreased (-19 and -42%, respectively, P<0.001) both in boys and in girls, but fat-free mass (FFM) decreased only in girls (-6%, P<0.001). VO2max (l/min) did not vary significantly, but strength and fitness were improved (P<0.001). Time and EE spent at sedentary activities decreased significantly (P<0.001) to the benefit of moderate (recreational) activities and total physical activities (P<0.001) at the institution during the weekdays, and at home during the weekends and holidays.

CONCLUSION

The great BW and FM losses, preservation of FFM, and improvement of physical capacities of obese adolescents obtained under experimental conditions were associated with increases in leisure physical activities in free-living conditions at the expense of sleep and sedentary activities.

Energetic cost of physical activity in cystic fibrosis children during Pseudomonas aeruginosa pulmonary exacerbation

Chronic pulmonary infection by Pseudomonas aeruginosa is observed in 50% of patients with cystic fibrosis and requires the use of recurrent intravenous therapy. A decrease of resting energy expenditure (REE) and an increase of physical activity (PA) after intravenous anti-P. aeruginosa therapy (IVAT) is observed while total energy expenditure (TEE) does not change. A decrease in the energetic cost of physical activity (ECPA) could be hypothesized but has never been studied. Our aim was to assess the evolution of ECPA after home IVAT in both standardized condition at hospital and in free-living condition twice before and after IVAT. Sixteen CF patients (nine boys, seven girls) chronically colonized by P. aeruginosa with a mean age of 12.1+/-2.3 years (range 7.1-14.6) were studied before and after IVAT. Each patient passed throughout a visit in hospital: weight, height and fat-free mass were measured. Then, energy expenditure (EE) measured by indirect calorimetry and heart rate (HR) were simultaneously recorded at different levels of PA: REE, and at different intensity of physical activities on a cycloergometer using an incremental increase of the power brake force. Physical activity energy expenditure (PAEE) was computed in laboratory condition using PAEE=EE-BEE (basal energy expenditure). Linear regression between PAEE and power brake force was fitted for each patient before and after IVAT. ECPA in standardized conditions was compared at different range of power brake force using area under the curve (AUC). After coming back at home, 24 h TEE using the heart rate monitoring technique and PA by triaxial accelerometry were simultaneously measured in free-living condition for 24 h during a school day. ECPA in free-living conditions was compared by the ratio PAEE:PA where PAEE=DEE-REE (DEE=daily energy expenditure). After IVAT, median AUC between 60 and 90 W in standardized condition decreased significantly by -15.4% (median 14.9, range 8.8-30.3 vs. median 12.6, range 8.5-17.6; P<0.05, Wilcoxon rank test) while the decrease for lower range of power work load did not reach significance. Spearman correlation was significant between variations of forced expiratory volume in 1 s and variation of AUC at 30-60 W before and after IVAT in standardized condition. In free-living conditions, ratio PAEE/PA did not vary significantly (median 3.4, range 1.6-6.4 vs. median 2.8, range 1.4-4.8; NS). Our data demonstrate a decrease of ECPA after IVAT in standardized conditions for moderate level of PA (60-90 W), but not in free-living conditions. The decrease of ECPA was probably due to a decrease in the energetic cost of breathing after IVAT, that is particularly relevant to promote PA in CF patients.

Évaluation de l’activité physique habituelle des adolescents en surpoids ou obèses

OBJECTIVES

To develop a simple, rapid, and unbiased test to assess usual physical activity in overweight adolescents during a routine medical consultation.

METHODS

Adolescents were selected. Their heart rate (HR) and blood pressure (BP) were measured at rest and when standing, before the beginning of the test. Subjects went up and down a 2-step apparatus during 4 minutes at a rate of 92 steps/min. HR was monitored. At the end of the test, the HR was noted and BP measured immediately. The effects of usual physical activity and gender on HR and BP were tested by ANOVA. In addition, an activity questionnaire was filled in by 43 subjects over 7 days and given to the doctor who completed the information during the visit and assessed usual physical activity.

RESULTS

56 adolescents of both sexes, aged 10-17 years (31 sedentary [S] overweight, and 25 active [A] post-obese subjects) underwent a step-test. The increase in HR during the test was significantly higher in S than in A subjects (66.2 +/- 2.3 vs 52.3 +/- 2.5 bpm, p < 0.001). However, the variations in BP did not supply reliable assessment of usual physical activity. The activity questionnaire had been filled in satisfactorily by 72% of subjects. In 95% of cases, the classification of subjects as S or A by the step-test agreed with the classification based on the questionnaire.

CONCLUSION

The step-test provided the rapid and reliable assessment of usual physical activity of the children (from 6-7 years of age) in 95% of cases during a routine consultation (30 min), and the activity questionnaire enabled the doctor to check the conclusions of the step-test and recommend to the parents physical activities adapted to the physical capacities of their children.

Effects of a multidisciplinary weight loss intervention on body composition in obese adolescents

OBJECTIVE

To investigate if a multidisciplinary weight loss program in adolescents suffering severe obesity allows adequate growth and development and avoid lean mass loss.

DESIGN

A total of 55 adolescents (33 girls and 22 boys) suffering severe obesity were enrolled in an interdisciplinary weight reduction program lasting 6-12 months. Progressive submaximal physical activity was performed and national dietary allowances for adolescents with low levels of physical activity energy were provided.

MEASUREMENTS

Total and segmental body composition was assessed by means of dual-energy X-ray absorptiometry.

RESULTS

The mean height significantly increased (P<0.001). The mean body mass index (BMI) dropped in boys from 34.5+/-3.2 to 25.5+/-2.3 kg/m(2) and in girls from 38.4+/-4.1 to 28.4+/-4.1 kg/m(2). Height increased according to the expected pattern (P<0.001). Total lean mass (LM) did not vary and was positively correlated to pubertal development in both sexes before and after weight loss. Steepest drop in fat mass (FM) was observed in the trunk (-63.2+/-10.1% in boys and -51.5+/-11.4% in girls). Decrease in BMI and FM was tightly correlated in both sexes. However, slopes significantly differed (P<0.0005) so that a decrease of 1 kg/m(2) in BMI corresponded to a decrease of 3.92 kg in FM in girls and of 5.44 kg in boys. In each sex, FM at baseline and duration of the treatment were the main determinants of the decrease in FM.

CONCLUSION

During adolescence, despite a major weight loss, adequate growth and preservation of LM can be achieved. Weight loss kinetics markedly differs between boys and girls. Low-calorie diets are unnecessary to achieve a marked reduction of severe obesity during puberty.

Assessment of energy expenditure in children and adolescents

PURPOSE OF THE REVIEW

This is a review on recent studies regarding methodological aspects of assessment of energy expenditure in children and adolescents.

RECENT FINDINGS

A variety of methods used for assessment of different components of energy expenditure has been validated and used in children and adolescents. Reference values derived from representative groups of healthy children and adolescents are now available. Variations in the different components of energy expenditure and physical activity have been proposed to be associated with weight gain, and the prevalence of overweight and obesity. However, recent cross-sectional and longitudinal data in children and adolescents do not provide strong evidence for this idea. In contrast, hypermetabolism, which is frequently seen in critically ill children, may contribute to their tissue catabolism. In this case beta blockade seems to be a way to increase 'metabolic economy' and thus to reduce tissue catabolism. In chronically ill children and adolescents (e.g. patients with cystic fibrosis and sickle cell anemia) energy expenditure is also frequently increased and group specific algorithms are needed for predicting energy expenditure when measurement facilities are not available.

SUMMARY

Methods for assessment of the different components of energy expenditure have been validated in children and adolescents. The combined use of these methods together with detailed analyses of body composition is recommended for future studies. In patients with acute or chronic illness measurements of energy expenditure are necessary if disease-specific algorithms are not available.

Assessment of energy expenditure associated with physical activities in free-living obese and nonobese adolescents

BACKGROUND

Information on activity patterns and the energy cost of activities is critically missing.

OBJECTIVE

We measured the energy cost of and time devoted to various activities in obese and nonobese adolescents.

DESIGN

Daily energy expenditure (DEE) and its main components were determined in 27 obese and 50 nonobese adolescents aged 12-16 y by using whole-body calorimetry with the same activity program and the heart rate-recording method in free-living conditions.

RESULTS

In whole-body calorimetry, energy expenditures (EEs) during sleep and sedentary activities were 18.9% and 21.5%, respectively, higher in obese subjects than in nonobese subjects (P < 0.001), but not significantly different after adjustment for fat-free mass (FFM). EEs during walking and DEEs were significantly higher in obese than in nonobese subjects, both absolutely (71% and 33%, respectively) and after adjustment for body weight or FFM (16% and 11%, respectively). In free-living conditions, EEs associated with physical activities did not differ significantly between obese and nonobese subjects, but they were 51% lower in obese subjects after adjustment for body weight (P < 0.001). The obese adolescents spent more time in light physical activities but much less time in moderate activities and sports than did the nonobese subjects. The activity-related time equivalent corrected for sedentary EE (ARTE EE(2)) averaged 69 and 122 min/d in obese and nonobese subjects, respectively (P < 0.01).

CONCLUSION

Physical activity is low in obese subjects and can be assessed satisfactorily in both obese and nonobese adolescents by using ARTE EE(2) when DEE and the basal metabolic rate are known.

The extent to which breakfast covers the morning energy expenditure of adolescents with varying levels of physical activity

BACKGROUND

Energy intake at breakfast affects the performance of creativity tests, memory recall and voluntary physical endurance in children before lunch, and food craving during the whole day.

OBJECTIVES

To assess the adequacy of breakfast energy supply (BES) and energy expenditure (EE) in adolescents during a schoolday without or with 2 h of physical education lesson (PEL) in the morning.

DESIGN

Sixty adolescents (four groups of 14-16 boys and girls aged 12-16 y) participated in a cross-sectional study. Activity patterns and EE were determined by whole-body calorimetry during 36 h and in free-living conditions during 5 days using both a diary and the validated heart rate recording method. BES was determined by weighing individual foods. The pyloric energy flow was assessed using a model of fractional stomach emptying.

RESULTS

BES averaged 24.9% (s.d.=6.1) of daily EE in the four groups of subjects. It covered the mean morning EE on a schoolday without PEL, but not in a schoolday with 2 h of PEL in any group. When PEL took place from 8-10 am the cumulative EE exceeded the cumulative pyloric energy flow after 105-150 min, that is during the PEL session, and the energy deficit increased until lunch. With a light breakfast (BES-1 s.d.) energy deficiency happened after 90 min.

CONCLUSION

The results stress the need for a heavy breakfast for children and adolescents on the days with PEL in the morning, and a carbohydrate rich snack at 10 am to improve attention, memory and willing participation in physical activities.