Mild to moderate hypohydration reduces boys' high-intensity cycling performance in the heat.

Purpose: To evaluate the effect of 1 and 2 % hypohydration on high-intensity cycling performance of 10- to 12-year-old boys in the heat.

Methods: In a counterbalanced order, nine boys attended three sessions in which they cycled intermittently (6 × 10-min bouts at 40-45 % [Formula: see text]) in a climate chamber. During each session, environmental conditions and water intake were individually adjusted to achieve a target hypohydration level of 0, 1 or 2 %, based on change in body weight (BW).

Influence of pubertal stage on local sweating patterns of girls exercising in the heat.

The influence of puberty on sweating patterns of girls exercising in the heat is not known. Nine- to 17-year-old girls, representing 4 stages of breast development: T1 (n = 21); T2 (n = 22); T3 (n = 25); and T4 (n = 22), cycled for 20 min at 60% in 35 °C. The population density of heat activated sweat glands was higher in T1 vs T3 and T4 and in T2 vs T4.

Body weight changes in child and adolescent athletes during a triathlon competition.

We examined young athletes during a triathlon performed in a hot climate. Complete or partial data were available for 95 athletes competing in the National Triathlon Championship in Costa Rica. Mean ± SD for age and body weight (BW) were 13.

Voluntary fluid intake, hydration status, and aerobic performance of adolescent athletes in the heat.

We determined whether beverage flavoring and composition would stimulate voluntary drink intake, prevent dehydration, and maintain exercise performance in heat-acclimated adolescent males running in the heat. Eight adolescent (age, 13.7 ± 1.

Voluntary drinking and hydration in trained, heat-acclimatized girls exercising in a hot and humid climate.

This study examined the effects of beverage composition on the voluntary drinking pattern, body fluid balance and body temperature responses of heat-acclimatized trained girls exercising intermittently in outdoor conditions (WBGT = 30.9 +/- 0.2 degrees C).

Reliability of exercise testing and functional activity questionnaires in children with juvenile arthritis.

Objective: To determine the reliability of formal exercise testing and the reliability of functional and activity questionnaires in children with juvenile idiopathic arthritis (JIA).

Methods: Children with JIA of any subtype ages 8-16 years who were recruited to a randomized trial comparing different exercise therapies participated in 2 preintervention sessions of exercise testing 2-6 weeks apart. Exercise testing included 1) submaximal oxygen uptake (VO(2submax)), 2) peak VO(2) (VO(2peak)), and 3) anaerobic power using modified Wingate tests (W(ant)).

The effects of vigorous exercise training on physical function in children with arthritis: a randomized, controlled, single-blinded trial.

Objective: To examine the effectiveness of high-intensity aerobic training compared with low-intensity training in terms of energy cost of locomotion, peak oxygen uptake, peak power, and self-reported physical function in children with juvenile idiopathic arthritis (JIA).

Methods: Eighty children with JIA, ages 8-16 years, were enrolled in a randomized, single-blind controlled trial. Both groups participated in a 12-week, 3-times-weekly training program consisting of high-intensity aerobics in the experimental group and qigong in the control group.

Voluntary drinking and hydration in non-acclimatized girls exercising in the heat.

The intent of this study was to assess the influence of drink flavor and composition on voluntary drinking and hydration status in girls exercising intermittently in the heat (35 +/- 1 degrees C, 45-50% relative humidity). Twelve physically active, nonacclimatized girls (9-12 years) performed three 3 h identical sessions, each consisting of four 20 min cycling bouts at 50% (VO(2max)), separated by 25 min of rest. One of the three beverages (chilled to 8-10 degrees C) was assigned to each session: unflavored water (W), grape-flavored water (FW) and grape-flavored water plus 6% carbohydrate and 18 mmol l(-1) NaCl (CNa).

Energy substrate utilization during prolonged exercise with and without carbohydrate intake in preadolescent and adolescent girls.

Little information is available on energy metabolism during exercise in girls, particularly the contribution of exogenous carbohydrate (CHO(exo)). The purpose of this study was to determine substrate utilization during exercise with and without CHO(exo) intake in healthy girls. Twelve-yr-old preadolescent (YG; n = 12) and 14-yr-old adolescent (OG; n = 10) girls consumed flavored water (WT) or (13)C-enriched 6% CHO (CT) while cycling for 60 min at approximately 70% maximal aerobic power (Vo(2max)).

Evidence of sex-based differences in natural killer cell responses to exercise and carbohydrate intake in children.

Distinct natural killer (NK) cell subsets (CD56bright and CD56dim) are mobilized with exercise and these cells may serve adaptive functions. We determined the distribution of NK cell subsets in response to exercise and carbohydrate (CHO) intake in young girls and compared these responses with previous findings in young boys of the same age. Twelve girls (12 years old) cycled for 60 min at 70% VO2max while drinking 6% CHO or flavoured water.

Influence of age and pubertal status on substrate utilization during exercise with and without carbohydrate intake in healthy boys.

Substrate utilization during exercise is known to differ between children and adults, but whether these differences are related to pubertal status is unclear. The objective of this study was to investigate the effects of pubertal status on endogenous (CHOendo) and orally ingested exogenous (CHOexo) carbohydrate and fat oxidation rates during exercise. Twenty boys at the same chronological age (12 y) were divided into three pubertal groups (pre-pubertal, PP: n=7; early-pubertal, EP: n=7; mid- to late-pubertal, M-LP: n=6) and consumed either a placebo or 13C-enriched 6% CHO drink while cycling for 60 min at approximately 70% of their maximal aerobic power (VO2 max).

Lymphocyte expression of CD95 at rest and in response to acute exercise in healthy children and adolescents.

CD95 is essential in regulating the immune system, and its reduced expression has been associated with anthracycline resistance in some childhood leukemias. We determined whether an acute bout of exercise would influence the mixed lymphocyte expression of CD95 in healthy children and adolescents. Fifty healthy pediatric subjects (female n=25) cycled for 60 min @ 70% V O(2max).

Puberty effects on NK cell responses to exercise and carbohydrate intake in boys.

Unlabelled: Previous research has demonstrated that younger versus older animals and humans experience smaller perturbations in natural killer (NK) cells in response to physiological stress.

Purpose: To determine whether the smaller perturbations in NK cells induced by strenuous exercise and carbohydrate (CHO) intake, previously reported in children, are influenced by puberty.

Methods: Twenty 12-yr-old boys, distinguished as prepubertal (Tanner (T) 1, N = 7), early pubertal (T2, N = 7), or pubertal (T3-5, N = 6), cycled for 60 min at 70% VO(2max) while drinking 6% CHO (CT) or flavored water (WT).

Immunological changes in response to exercise: influence of age, puberty, and gender.

Purpose: This study tested the hypothesis that exercise-induced perturbation and recovery of the immune system would vary with age, puberty, and gender in healthy children and adolescents.

Methods: Twelve-year-old girls (YG; N = 14) and boys (YB; N = 20), and 14-yr-old girls (OG; N = 11) and boys (OB; N = 13) cycled for 60 min at 70% VO2max. Blood was collected before, at 30 and 60 min of exercise, and at 30 and 60 min of recovery to measure total leukocytes, leukocyte and lymphocyte subsets, and cytokines.

Sex-based effects on the distribution of NK cell subsets in response to exercise and carbohydrate intake in adolescents.

Carbohydrate (CHO) supplementation and female sex independently influence the natural killer (NK) cell response to acute exercise. Consequently, this study sought to elucidate sex-based differences in the distribution of NK cell subsets (i.e.

Overweight children reduce their activity levels earlier in life than healthy weight children.

Objective: To determine differences in the time overweight and nonoverweight youth spend on light, moderate, hard, and very hard activity plus gender and age differences in activity patterns.

Design And Setting: This study was a cross-sectional design in a primary care hospital.

Participants: A total of 197 children and adolescents (4-16 years) participated.

Aerobic and lung performance in premature children with and without chronic lung disease of prematurity.

Objective: This study intended to identify pulmonary and exercise-related effects of chronic lung disease of infancy (CLD) versus prematurity (PRE) without CLD in children 5 to 7 years old who were born prematurely (24-30 weeks of gestation) with very low and extremely low birthweight of 500 to 1500 g (VLBW, ELBW).

Subjects: Seventeen CLD and 14 PRE were compared with 24 term controls (CON). The premature children had no overt manifestations of a neuromuscular disease.

Effect of ipratropium bromide on EIB in children depends on vagal activity.

Purpose: Ipratropium bromide (IB) has been used to prevent exercise-induced bronchoconstriction (EIB), but its effect varies among individuals. We hypothesized that such variability may reflect individual differences in vagal activity (VA), and therefore determined whether a correlation exists between VA and the effect of IB on EIB in 13.0 (+/-0.

Physical activity level is associated with the O2 cost of walking in cerebral palsy.

Purpose: To determine, in children and adolescents with cerebral palsy (CP), the relationship between physical activity level (PAL) and i) oxygen cost of walking, and ii) peak VO2.

Methods: In 11 subjects (10.6-16.

Habitual physical activity levels are associated with biomechanical walking economy in children with cerebral palsy.

Objective: To evaluate in children and adolescents with cerebral palsy the relationship between habitual physical activity and biomechanical treadmill walking economy and whether treadmill belt speed or walking time affect economy.

Design: Physical activity was measured in 11 subjects (10.6-16.

Relationship between summer vacation weight gain and lack of success in a pediatric weight control program.

The purpose was to measure the effect of holidays or season on changes in body weight to determine if this was the reason for the low success rate of weight control program participants. Changes in percent ideal body weight were gathered on 73 overweight youth (average age: 10.5+/-2.

Responses of children with cerebral palsy to treadmill walking exercise in the heat.

Purpose: When metabolic rate during arm-cranking in the heat is equated between children and adolescents with cerebral palsy (CP) and matched controls (CON), there are no relevant intergroup differences in heat strain. The metabolic rate, however, is known to be higher in CP during treadmill walking. The purpose of this study was to determine if during treadmill walking in the heat, the higher oxygen uptake (VO2), and thus greater metabolic heat production in those with CP would result in greater heat strain compared with able-bodied, matched CON.

Anaerobic muscle performance of children after long-term recovery from Guillain-Barré syndrome.

The aim of this study was to evaluate anaerobic muscle performance in children after long-term recovery from Guillain-Barré syndrome (GBS). Participants were recruited from all children and adolescents with GBS admitted to The Hospital for Sick Children, University of Toronto, Canada, between 1988 and 1995. We assessed 17 children (nine males, eight females; mean age at GBS diagnosis 7 years 11 months, SD 4 years 2 months; mean age at testing 14 years 1 month) more than two years after acute GBS.