Objectively assessed recess physical activity in girls and boys from high and low socioeconomic backgrounds.

Background: The school environment influences children's opportunities for physical activity participation. The aim of the present study was to assess objectively measured school recess physical activity in children from high and low socioeconomic backgrounds.

Methods: Four hundred and seven children (6-11 years old) from 4 primary schools located in high socioeconomic status (high-SES) and low socioeconomic status (low-SES) areas participated in the study.

Effects of a playground marking intervention on school recess physical activity in French children.

Objective: Playground interventions offer an opportunity to enhance school recess physical activity. We aimed to assess the effects of playground marking on objectively measured school recess physical activity in French children.

Methods: Participants were four hundred and twenty children (6-11years old) from 4 primary schools in Nord-Pas de Calais, France.

Is there any relationship between physical activity level and patterns, and physical performance in children?

Background: It is often assumed that physical activity (PA) and physical performance during childhood and adolescence are beneficial for health during adulthood, but a positive relationship between PA and physical performance has not been precisely clarified in children. The lack or the weakness of the relationships between PA and physical performance could be due to the measure of PA. If the use of accelerometry is considered as an objective and common measure of PA, the real patterns of children's habitual PA must be reflected.

Physical activity patterns in French youth--from childhood to adolescence--monitored with high-frequency accelerometry.

Objectives: To investigate changes in time spent in light (LPA), moderate (MPA), vigorous (VPA), very high physical activity (VHPA) from childhood to adolescence, according to age and sex, when measured with high frequency accelerometry.

Methods: Three hundred and sixty-one children, 94 preschoolers (Ps), 156 from primary schools (PS) and 111 from junior high schools (JHS)) were involved in this study. The children's physical activity was assessed with a uniaxial accelerometer over a seven-day period.

Continuous vs. interval aerobic training in 8- to 11-year-old children.

The aim of the present study was to show if the use of continuous-running training vs. intermittent-running training has comparable or distinct impact on aerobic fitness in children. At first, children were matched according to their chronological age, their biological age (secondary sexual stages), and their physical activity or training status.

Effects of a back squat training program on leg power, jump, and sprint performances in junior soccer players.

The aim of the present study was to investigate the effects of voluntary maximal leg strength training on peak power output (Wpeak), vertical jump performance, and field performances in junior soccer players. Twenty-two male soccer players participated in this investigation and were divided into 2 groups: A resistance training group (RTG; age 17 +/- 0.3 years) and a control group (CG; age 17 +/- 0.

Squat jump performance during growth in both sexes: comparison with cycling power.

The purpose of this cross-sectional study was to investigate leg muscle power and compare two activities (jumping and cycling) in 383 girls and 407 boys ages 9-19 years. Results in anthropometric characteristics and jumping performance were comparable until midadolescence, and sex differences were observed. Lean leg volume (LLV) was the reason for most of the variance (76% in girls and 88% in boys) in jumping performance.

Psychoendocrine and physical performance responses in male Tunisian rugby players during an international competitive season.

The aim was to investigate a follow-up study based on hormonal, physical, and psychological parameters among rugby players who trained during a whole season interspersed with competitions on an international level. Fitness or reciprocally tiredness as well as competitive anxiety were evaluated, respectively, using the French Society for Sports Medicine (SFMS) and the sport competition anxiety test (SCAT) questionnaires. In this study, SFMS and SCAT scores increased respectively over the competitive season.

Relationship between indicators of fitness and bone density in adolescent Brazilian children.

The purpose of the current study was to investigate the relationship between health-related physical fitness and bone mineral density (BMD) in adolescents. One hundred forty-four adolescents (65 boys and 79 girls) between 15 and 18 years of age were recruited to this cross-sectional study. Subjects were evaluated in aerobic fitness, muscular fitness, flexibility, body composition, and maturation.

High-intensity intermittent cycle ergometer exercise: effect of recovery duration and resistive force selection on performance.

The purpose of this study was to compare the exercise performance and postexercise recovery of 8 male subjects using four different maximal high-intensity intermittent cycle ergometry protocols. Resistive forces were calculated by multiplying fat-free mass (FFM) or total-body mass (TBM) by 0.75 g.

Anaerobic fitness tests: what are we measuring?

Anaerobic fitness, during growth and development, has not received the same attention from researchers as aerobic fitness. This is surprising given the level of anaerobic energy used daily during childhood and adolescence. During physical activity and sport, the child is spontaneously more attracted to short-burst movements than to long-term activities.

Upper body contribution during leg cycling peak power in teenage boys and girls.

This study investigated gender differences in upper-body contribution to cycle muscle power in 23 adolescents. All subjects performed two 5-s and one 20-s cycling sprint, using two protocols: with handgrip (WG) and without handgrip (WOG). Maximal handgrip strength was assessed for each individual.

Improving physical activity assessment in prepubertal children with high-frequency accelerometry monitoring: a methodological issue.

Objective: The aim of this study was to examine the duration of physical activity (PA) bouts in prepubertal children with high-frequency accelerometry monitoring.

Methods: Thirteen boys and thirteen girls (aged 8-10 years) from one school in North of France had their PA recorded during 7 days using a uniaxial Actigraph accelerometer. To examine PA behavior patterns, the epoch was set at 2 s.

Critical velocity during continuous and intermittent exercises in children.

The purpose of this study was to apply the "critical velocity" concept to short intermittent high-intensity running exercises in prepubescent girls and boys and to compare the running performances obtained either by intermittent or continuous exercise runs. Eleven 8 to 11-year-old children underwent a maximal graded field test to determine peak oxygen uptake (peakVO2) and maximal aerobic velocity (MAV). During the six following sessions, they randomly performed three continuous runs (90, 100, and 110% of MAV) and three intermittent runs (120, 130, and 140% of MAV) until exhaustion.

Lower-limb and whole-body tissue composition assessment in healthy active older women.

Aim: The study evaluated, in active elderly women, the accuracy and bias of anthropometry and bioelectrical impedance analysis (BIA) for lower-limb and whole-body tissue composition measures using dual-energy X-ray absorptiometry (DXA) as the criterion method.

Methods: Nineteen individuals (66.1 +/- 4.

Longitudinal changes of maximal short-term peak power in girls and boys during growth.

Purpose: The aims of this study are twofold: first, to analyze the influence of age, body mass, and lean leg volume (LLV) on short-term leg peak power (Pmax) of young females and males during growth using multilevel regression analysis and, second, to compare the regression results of boys and girls.

Methods: The individuals were 100 girls and 109 boys aged 7.5-17.

Endurance training and aerobic fitness in young people.

Training-induced adaptations in aerobic fitness have been extensively studied in adults, and some exercise scientists have recommended similar training programmes for young people. However, the subject of the response to aerobic training of children and adolescents is controversial. The effects of exercise training on prepubertal children are particularly debatable.

Short-term peak power changes in adolescents of similar anthropometric characteristics.

Purpose: The present study was undertaken to examine changes of cycling peak power (P(max)), optimal pedaling frequency (Vopt), and optimal pedaling force (Fopt) with age in subjects with the same lean leg volume (LLV), leg length (LL), and percentage body fat (%BF).

Method: A total of 132 males aged 9.5-16.

Influence of two pedalling rate conditions on mechanical output and physiological responses during all-out intermittent exercise.

The purpose of this study was to investigate the effect of two cycling velocities on power output and concomitant metabolic and cardiorespiratory responses to repeated all-out exercises. Mean power output (P(m)), total work ( W(tot)), total oxygen consumption (VO(2tot)) and blood lactate accumulation (delta[La](b)) were evaluated in 13 male subjects who performed two series of twelve 5-s bouts of sprint cycling. Recovery periods of 45-s were allowed between trials.

Measurement error in short-term power testing in young people.

The aim of this study was to examine the consistency or reproducibility of measuring cycling peak power in children and adults. Twenty-seven pre-pubertal girls and boys and 27 female and male physical education students (age 9.8 +/- 0.

Are intensified physical education sessions able to elicit heart rate at a sufficient level to promote aerobic fitness in adolescents?

The purpose of this study was to determine the effects of intensified physical education sessions on adolescents ages 11-16 years. They were divided into two experimental groups--high-intensity running group (HIRG) and high-intensity jumping group (HlJG)--and a control group (C). During the sessions, heart rate (HR) was monitored.

Short-term muscle power during growth and maturation.

During growth and maturation, the study of very brief high-intensity exercise has not received the same attention from researchers as, for instance, aerobic function. In anaerobic tasks or sports events such as sprint cycling, jumping or running, the children's performance is distinctly lower than that of adults. This partly reflects children's lesser ability to generate mechanical energy from chemical energy sources during short-term intensive activity.

Comparison of peak muscle power between Brazilian and French girls.

This study examined the muscle power of Brazilian circumpubertal girls and extended the analysis to a cross-cultural dimension. A total of 462 children, 123 Brazilian girls and 339 French girls, 9-18 years, participated in this investigation. Anthropometric data included body mass (BM), height, skinfold thicknesses, and estimated lean leg volume (LLV).

Gender Difference in the Relationship of Anaerobic Power Output to Body Composition in Children.

This study was done to determine the extent to which body composition accounts for differences in anaerobic characteristics between 12-year-old girls and boys. Peak leg power (PP), mean leg power (MP), percent body fat, fat free mass (FFM), and lean thigh volume (LTV) were determined by various tests. Pubertal stages and salivary testosterone concentration (in boys) were used to assess sexual maturation.