bluuebunny/crossref_metadata_2025 huggingface dataset:
Muscular Strength Development in Children and Adolescents
Authors: Beunen Gaston , Thomis Martine
Published: August 2016

This review builds on earlier reviews and considers the development of strength characteristics from childhood through adulthood. Since strength is associated with size and biological maturation, these associations are also discussed. Finally, genetic determinants of strength and tracking of strength components over time are also reviewed.
Effects of an Exercise Program (PEP) for Children with Asthma: Results of a Pilot Study
Authors: van Veldhoven Nicolette H.M.J. , Wijnroks Lex , Bogaard Jan M. , Vermeer Adri
Published: August 2016

To establish the feasibility of a comprehensive exercise program (PEP) a pilot study was conducted on 7 children with asthma (8 to 13 years). The program was comprised of regular group exercises and home exercises for a period of 3 months. It was based on a theoretical model describing the relationships between physical competence, perceived physical competence, self-esteem, and coping behavior. The results showed that after the program, the children’s heart rate response had improved significantly at a workload of 60 W. Although exercise indices, such as endurance time at treadmill running and maximum workload on a cycle ergometer, had improved too, they were not significant. Further, the training had a positive and significant effect on the children’s expectations of physical competence in sports and on coping with asthma. As expected, no significant changes of lung function indices were found. In conclusion, our approach seemed to be feasible, especially for coping and perceived competence in children with asthma.
Use of Heart Rate Cutpoints to Assess Physical Activity Intensity in Sixth-Grade Girls
Authors: Allor Karin M. , Pivarnik James M.
Published: August 2016

We calculated individual heart rate–oxygen consumption (HR–V̇O2) regression lines for 49 sixth-grade girls based on a treadmill test. From these data, we determined V̇O2 at HRs of 140 and 160 b · min−1 and 50%, 60%, and 75% of maximal heart rate reserve (MHRR), and the relationship between V̇O2 and %fat at given heart rates. Results indicated traditional 140 and 160 b · min−1 HR cutpoints were at the low end of exercise intensity (46 and 63% V̇O2max) and were negatively correlated with %fat. Heart rates at 50%, 60%, and 75% MHRR corresponded to 52%, 62%, and 76% of V̇O2max. Although the best method for analyzing HR data to describe physical activity intensity is unknown, use of 140 and 160 cutpoints may not describe vigorous or very hard exercise in adolescent girls as well as 75% MHRR. Researchers should also consider the effects of adiposity when using specific heart rate cutpoints.
Children’s Understanding of the Concept of Physical Activity
Authors: Trost Stewart G. , Morgan Angela M. , Saunders Ruth , Felton Gwen , Ward Dianne S. , Pate Russell R.
Published: August 2016

This study evaluated 4th-grade students’ understanding of the concept of physical activity and assessed the effects of two interventions to enhance the students’ understanding of this concept. Students were randomly assigned to 1 of 3 conditions: the video group (n = 40) watched a 5-min video describing physical activity; the verbal group (n = 42) listened to a generic description of physical activity; the control group received no instruction (n = 45). Students completed a 17-item checklist testing their understanding of the concept of physical activity. Compared to controls, students in the verbal and video group demonstrated significantly higher checklist scores, with the video group scoring significantly higher than the verbal group. Only 35.6% of the controls, compared to 52.4% and 70.0% of the verbal and video groups respectively, could classify ≥ 15 of the checklist items correctly. The results indicate that, without intervention, children have a limited understanding of the concept of physical activity.
Activity-Associated Differences in Bone Mineral Are Evident before Puberty: A Cross-Sectional Study of 130 Female Novice Dancers and Controls
Authors: Bennell Kim , Khan Karim , Matthews Bernadette , Cook Elizabeth , Holzer Karen , McKay Heather , Wark John
Published: August 2016

It is not clear at what age or maturational stage physical activity is most effective in optimizing peak bone mass in girls. We compared bone mineral of 78 pre- and early-pubertal novice female ballet dancers (mean age, 9.6 years, SD, 0.8) with that of 52 age-matched controls. Dancers had 4.5% greater total hip bone mineral density (BMD) and 4.9% greater femoral neck BMD (both p < .01) than controls. BMD at the lumbar spine and upper and lower limbs was similar between groups. These findings could not be explained by maturity, size, body composition, or dietary calcium intake differences between groups. While genetics may partially explain these findings, we propose that the mechanical loading of dance training provided appropriate skeletal stimulus to generate site-specific BMD advantage.
Left Ventricular Structure and Function in Young Elite Cyclists
Authors: Larsen Søren E. , Hansen Henrik S. , Froberg Karsten , Nielsen Jens Rokkedal
Published: August 2016

This study investigated a group of young elite cyclists at the age of 19–20 years. The cardiac characteristics, left ventricular function and structure, after long-term and high intensity endurance training, were examined by echocardiography during resting conditions. In comparison with an age-matched control group, the elite cyclists had significantly lower systolic blood pressure, heart rate, and total body fat and a significantly higher physical fitness. Left ventricular mass, left ventricular mass indexed for differences in body size, and both systolic and diastolic dimensions of the left ventricle were increased significantly in the elite cyclist group. No significant difference was found in left ventricular function. Left ventricular diastolic function was examined (E/A-ratio, E = early passive, A = late active, atriale induced transmitral diastolic flow) and showed no significant difference between the two groups in spite of the structural changes observed in the left ventricular structure. We conclude that structural but not functional cardiac changes can be observed in elite cyclists when examined during resting conditions.
Knee Extensor Muscle Strength and Vertical Jumping Performance Characteristics in Pre- and Post-Pubertal Boys
Authors: Pääsuke Mati , Ereline Jaan , Gapeyeva Helena
Published: August 2016

Knee extensor muscle strength and vertical jumping performance characteristics were compared between 14 pre-pubertal (11-year-old) and post-pubertal (16-year-old) boys. Post-pubertal boys had greater (p < .05) absolute values of maximal isometric force (MF) and rate of force development (RFD), absolute and body mass-related values of isokinetic peak torque of the knee extensor muscles at angular velocities of 60, 180, and 240° · s−1, as well as jumping height in squat, counter-movement, and drop jumps, than pre-pubertal boys. This study indicated an inability to use the positive effect of stretch-shortening cycle to vertical jumping performance in pre- and post-pubertal boys.
Assessment of Physical Activity and Sedentary Behavior in Preschool-Age Children: Priorities for Research
Authors: Fulton Janet E. , Burgeson Charlene R. , Perry Geraldine R. , Sherry Bettylou , Galuska Deborah A. , Alexander Maria P. , Wechsler Howell , Caspersen Carl J.
Published: August 2016

An expert panel workshop had two specific aims: (a) to review the current state of knowledge of existing methods for assessing physical activity and sedentary behavior in order to determine their reliability, validity, feasibility, strengths, and limitations and (b) to set research priorities and recommendations to enable the use of reliable and valid instruments for assessing physical activity and sedentary behavior within the context of three public health functions for children ages 2–5 years. Experts presented four major recommendations for research priorities at the conclusion of the 2-day workshop. The need to develop valid methods for measuring physical activity and sedentary behavior was considered the necessary first step to accomplish meaningful physical activity surveillance, public health research, and intervention research for children ages 2–5 years.
Differentiated Perceived Exertion during Submaximal Exercise in Children and Adults
Authors: Mahon Anthony D. , Stolen Kira Q. , Gay Julie A.
Published: August 2016

This study examined overall, leg, and chest ratings of perceived exertion (RPE) in 16 children (10.7 ± 0.8 yr) and 16 adults (24.2 ± 1.8 yr) during 16 min of exercise performed at an intensity equal to ventilatory threshold (~64% of V̇O2max for the children and 61% of V̇O2max for the adults). Physiological and perceptual responses were measured at 8 and 16 min. RPE in the children ranged from 11.6 ± 2.3 (chest) to 12.6 ± 2.6 (leg) at 8 min, and from 13.3 ± 2.8 (chest) to 15.1 ± 2.9 (leg) at 16 min. In adults, RPE ranged from 10.9 ± 1.9 (chest) to 12.0 ± 1.8 (leg) at 8 min, and from 11.8 ± 2.1 (chest) to 13.3 ± 1.6 (leg) at 16 min. Between groups, RPE tended to be higher and increased more over time in the children compared to the adults (P < .08). RPE at 8 min was less than RPE at 16 min, and overall and leg RPE were greater than chest RPE. Children were able to discriminate sensory information arising from different physiological variables; however, the specific physiological cues underlying the perception of effort remains uncertain in this age group.
Prediction of Maximal Aerobic Power in Adolescents from Cycle Ergometry
Authors: Jung Alan P. , Nieman David C. , Kernodle Michael W.
Published: August 2016

The purpose of this study was to validate an existing V̇O2max prediction equation for a graded cycle ergometer test, using adolescents as subjects (14). Healthy, active males (n = 19) and females (n = 19), ages 13–18 years old, pedaled at a rate of 60 rpm until exhaustion, with resistance increasing 15 W every minute. Oxygen uptake, ventilation, and respiratory exchange ratio were measured continuously. A significant correlation was found between predicted and actual V̇O2max for both male (r = 0.90, p < .001) and female (r = 0.91, p < .001) adolescents. For all subjects combined the correlation was r = 0.96, p < .001 with an SEE = 198 ml · min−1. Mean differences between actual and predicted V̇O2max values were 1.0 ± 0.7 ml · kg−1 · min−1 and 2.0 ± 0.7 ml · kg−1 · min−1 for the males and females, respectively (2.1% and 5.2% difference). The data indicate these cycle ergometry equations are valid for prediction of V̇O2max in male and female adolescents.
Test-Retest Reproducibility of Submaximal and Maximal Cardiac Output by Doppler Echocardiography and CO2-Rebreathing in Prepubertal Children
Authors: Nottin Stéphane , Vinet Agnès , Lecoq Anne-Marie , Guenon Patrick , Obert Philippe
Published: August 2016

The aim of this study was to examine the reproducibility of cardiac output (Q) measured by Doppler echocardiography and CO2-rebreathing in prepubertal children during exercise. Fourteen healthy children (8 girls and 6 boys aged 10.9 ± 0.9 years) underwent a progressive maximum upright cycle test until exhaustion on two separate occasions (1 week apart). Q was determined successively by the two methods at rest and during the final minutes of each workload. The reproducibility of the Doppler method was higher than the reproducibility of the CO2-rebreathing method, both at rest and during exercise. Moreover, this reproducibility was lower during high intensity exercise whatever the method used. On account of its high reproducibility, Doppler echocardiography should be preferentially used to detect changes in Q as a result of an exercise training intervention in prepubertal children.
Comparison of Hydrodensitometry, Skinfold Thickness, and Dual-Energy X-Ray Absorptiometry for Body Fat Estimation in Youth Swimmers
Authors: Tuuri Georgianna , Loftin Mark
Published: August 2016

Hydrodensitometry (HD), skinfold thickness measurements (SK), and dual-energy X-ray absorptiometry (DXA) were compared for estimating percent body fat (%BF) in youth competitive swimmers. Agreement was assessed using Bland-Altman plots and linear regression of the differences between methods compared to method means. Limits of agreement between the three techniques were large. Hydrodensitometry and SK demonstrated no difference in precision. Variance was observed between DXA and the other two techniques, with DXA demonstrating a wider distribution of measurement scores than HD or SK. These methods do not appear to be interchangeable when measuring percent body fat in youth swimmers.
Leisure-Time Internet Use Does Not Correlate with Physical Activity or Physical Fitness Level of Ninth Grade African-American Girls
Authors: Kerner Matthew S. , Kalinski Michael , Kurrant Anthony B. , Small Eric , Spatz Eugene , Gropack Stacy
Published: August 2016

We assessed leisure-time Internet use (IU) and its relationship to physical fitness (PF) and leisure-time physical activity (PA) among 295 adolescent African-American girls. In addition, scales measuring variables in the Theory of Reasoned Action (TRA) were administered to elucidate PA data. Based on responses to the IU Questionnaire, participants were placed into either an Internet Nonuser (n = 184) or Internet User (n = 111) group. PF was assessed using body mass index (BMI) and AAHPERD Youth Fitness Tests. There were no correlations found between the fitness test scores and IU, PA, or BMI. No correlation was found between IU and PA, and similar findings were noted between PA and each variable constituting the TRA. As expected, within the TRA variables studied, significant moderate to high correlations were found between both Attitude to Exercise and Subjective Norm with Intention to Exercise, r = .43 and r = .53, respectively. The remarkably low scores among participants on the fitness tests and TRA scales suggest that IU would have no appreciable influence on the PF of this population, irrespective of IU.
Bone Mass and Somatic Development in Young Female Gymnasts: A Longitudinal Study
Authors: Courteix Daniel , Jaffré Christelle , Obert Philippe , Benhamou Laurent
Published: August 2016

The aim of this study was to assess the effects of vigorous activity on the somatic and skeletal growths in young females reaching puberty. From a group of 41 prepubertal girls, 24 remained in this study: 10 gymnasts training 15 to 22 hr a week and 14 non-exercising controls. At the start and during the study period, bone age, height, weight, fat and lean mass were significantly lower in the gymnasts vs. the controls (p < .05). These variables had increased in the same way for both groups. At each investigation, the gymnasts had significantly higher BMC, BMD, and BMAD at all the sites (p < .01) except the whole body. The strong correlation between somatic measurements at the start and at the end of the study indicated that physical exercise does not disrupt the normal growth in these children.
Ventilatory Threshold in Children: A Review
Authors: Mahon Anthony D. , Cheatham Christopher C.
Published: August 2016

Ventilatory threshold (VT) is an important index of aerobic exercise function. The non-invasive nature of assessing VT and the fact that VT can be determined without obtaining a maximal exertion makes it broadly appealing to study in both healthy and diseased populations. Much of the understanding of the physiological and biochemical events underlying the occurrence and significance of VT is based on research involving adults. Several conclusions can be made from the studies which have examined VT in children. First, VT can be determined in a reliable manner. Second, heart rate deflection has been used as an alternative method to estimate VT and, based on limited information, appears to have reasonable accuracy. Third, although there is some evidence suggesting that VT (relative to maximal oxygen uptake [V̇O2max]) declines with maturation, the evidence is not overwhelming and it is based primarily on cross-sectional comparisons. Fourth, endurance training will increase VT in children to a greater extent than the increase in V̇O2max. Lastly, the physiological significance of VT and the metabolic consequences when exercise intensities exceeds VT are not well understood in children and are fruitful areas of research.
Heart Rate and Blood Pressure Responses to Static Handgrip Exercise of Different Intensities: Reliability and Adult versus Child Differences
Authors: Turley Kenneth R. , Martin D. Eric , Marvin Eric D. , Cowley Kelley S.
Published: August 2016

To determine the reliability of cardiovascular responses to isometric exercise of different intensities, and to compare adult versus child responses, 27 boys (7–9 years old) and 27 men (18–26 years old) performed static handgrip exercise at 10, 20, and 30% of previously determined maximal voluntary contraction (MVC) for three min each on different days, while heart rate (HR) and blood pressure (BP) were measured. HR reliability was moderately high at all intensities in both boys and men ranging from R = 0.52–0.87. BP reliability was moderate in men and boys at 30% MVC while at 10% and 20% MVC reliability was very low for boys and only moderate for men. HR response from pre- to 3-min of static exercise was not different between boys versus men at any intensity. At 30% MVC diastolic (20.2 vs. 29.3 mmHg), systolic (17.4 vs. 36.2 mmHg) and mean (19.2 vs. 31.6 mmHg) BP responses were lower in boys versus men, respectively. At 20% MVC SBP (6.8 vs. 14.3 mmHg) and MBP (8.4 vs. 12.6 mmHg) responses were lower in boys versus men, respectively. In conclusion, the reliability of cardiovascular response to isometric exercise is low at low contraction intensities and moderate at higher contraction intensities. Further, BP response in men at 30% MVC is higher than boys, while responses are similar at lower contraction intensities.
Student Physical Activity Levels during a Season of Sport Education
Authors: Hastie Peter A. , Trost Stewart G.
Published: August 2016

The purpose of this study was to determine the extent to which sport education can provide students with sufficient opportunities for developing moderate-to-vigorous physical activity (MVPA). Nineteen seventh-grade boys (average age = 12.9 yrs.) participated in a 22-lesson season of floor hockey. For all students (both higher and lower skilled), students averaged a total of 31.6 min of MVPA during the season, or 63.2% of lesson time. Further, there was no significant difference according to skill level {33.4 min (Higher) vs. 30.4 min (Lower), nor were there any significant differences in MVPA levels across the phases of the season.
The Physical Activity Participation–Academic Performance Relationship Revisited: Perceived and Actual Performance and the Effect of Banding (Academic Tracking)
Authors: Lindner Koenraad J.
Published: August 2016

This study examined the relationship between academic performance and physical activity participation using objective measures of scholastic achievement, and the effect of banding (academic tracking). The sample comprised 1,447 students (aged 13–17 years) in secondary grades 2, 4, and 6 (736 boys; 711 girls). Academic records were collected from the schools, and a participation questionnaire was administered to the students. School banding was found to be a significant predictor of participation time, and students from higher-banded schools had generally greater participation time than lower-band students. Conversely, perceived academic performance and potential tended to be higher for students with more participation time in physical activity, particularly so for the males. However, for actual academic grades this positive association was not found when banding was taken into consideration. No relationship was found for the middle- and high-band students, while a slight negative relationship was observed for the low-band students.
Reliability of the Visually Identified Ventilatory Threshold and V-Slope in Children
Authors: Fawkner Samantha G. , Armstrong Neil , Childs David J. , Welsman Joanne R.
Published: August 2016

The purpose of this study was to assess the reliability of the ventilatory threshold using visual analysis (TVent) and a computerised v-slope method (TV - slope) with children. Twenty-two children completed 2 ramp incremental cycling tests to voluntary exhaustion. Oxygen uptake (V̇O2) at TVent was derived independently by two observers using plots of V̇E/V̇CO2, V̇E/V̇O2, PETO2 and PETCO2, V̇E and RER as a function of time. V̇O2 at TV - slope was determined by both observers using linear regression analysis of the plot of V̇CO2 against V̇O2. A TV – slope was determined for each test, although a TVent could not be found by one of the observers in 7 of the 44 tests. Inter-observer reliability was slightly better for TV - slope, and both methods had similar test-retest coefficients of repeatability (0.19 and 0.22 L • min−1, TVent and TV - slope, respectively). Although TV slope may be the method of choice, investigators should consider the 95% limits of agreement when interpreting their data.
Reliability of Maximum Isometric Force-Time Parameters during a Leg Press Test in Pubertal Basketball Players
Authors: Ioakimidis Panagiotis , Gerodimos Vasilios , Kellis Eleftherios , Kellis Spiros
Published: August 2016

Fifteen young basketball players (aged 14.4 – 0.5 yrs) underwent two identical testing sessions spaced one week apart, to determine the reliability of maximum isometric force and force-time parameters during a maximal bilateral isometric leg press effort. The maximal isometric force (MIF), the ratio of maximal force to time (TMIF) to attain maximal force (ARMIF), starting strength (F50), and on a relative scale the time taken to increase the force from 10% to 30%, 60%, and 90% of maximal force were calculated. High intraclass correlation coefficients (ICC) were found for MIF (0.96), ARMIF (0.85), and F50 (0.90). On the relative scale, the ICCs for the times to produce 30%, 60%, and 90% of maximum force were 0.94, 0.95, 0.95, respectively. The present results indicate that maximum isometric force and the force-time parameters during a bilateral leg press can be measured reliably in pubertal basketball players.
Validation of a Physical Activity Self-Report Questionnaire in a Portuguese Pediatric Population
Authors: Mota Jorge , Santos Paula , Guerra Sandra , Ribeiro José C. , Duarte José A. , Sallis James F.
Published: August 2016

The goal of this study was to validate an adapted version of the “weekly checklist” in a Portuguese population. The validity was assessed by comparing self-reports against the Computer Science and Application, Inc (CSA) monitor. The sample comprised 109 children (boys, n = 42; girls, n = 67), aged 8 to 16 years old. All subjects were volunteers from local schools (Oporto region). The weekly activity checklist was modestly (r = 0.30) but significantly (p < .01) correlated with the CSA. Girls (r = 40; p < .01) had higher correlations than boys (0.28; p < .05). When the values were analyzed by age, excluding the young subjects (<10 years old), the correlation values were slightly higher (r = 0.38; p < .01). The Portuguese version of the “weekly activity checklist” had similar reliability and validity as the original version. The measure appears to have lower validity in 8- and 9-year-old children.
Physical Activity Levels of Hong Kong Chinese Children: Relationship with Body Fat
Authors: Rowlands Ann V. , Eston Roger G. , Louie Lobo , Ingledew David K. , Tong Kwok K. , Fu Frank H.
Published: August 2016

The aim of this study was to investigate the relationship between habitual physical activity and body fatness in Hong Kong Chinese children. Fifty children aged 8–11 yrs wore a uniaxial accelerometer for 7 days to determine physical activity levels. The sum of seven skinfolds was used to estimate body fatness. Activity counts summed over 1 day (299384 – 140427, mean – SD) were similar to activity counts recorded in previous studies. Activity correlated significantly negatively with sum of skinfolds in boys (r = –.50, N = 24, P < .05) but not girls. In conclusion this study supports a negative relationship between physical activity and body fatness in Hong Kong Chinese boys.
Increasing Children’s School Time Physical Activity Using Structured Fitness Breaks
Authors: Scruggs Philip W. , Beveridge Sandy K. , Watson Doris L.
Published: August 2016

Fifth-grade students’ physical activity levels were examined via heart rate telemetry and pedometry during school fitness and recess breaks. Twenty-seven students with a mean age of 11.03 (-.32) years participated in morning recess (MR), lunch recess (LR), and fitness breaks (FB) for three days. Structured FB’s consisted of students engaging in locomotor and nonlocomotor activities within an obstacle course framework, while recess breaks followed a traditional model. Results from repeated measures ANOVAs indicated students engaged in significantly more physical activity during FB than MR and LR. Fitness breaks provided a viable method for increasing children’s school time activity levels.
Does Exercise Testing Affect the Bioelectrical Impedance Assessment of Body Composition in Children?
Authors: Goss Fredric L. , Robertson Robert J. , Dube John , Rutkowski Jason , Andreacci Joseph , Lenz Brooke , Ranalli Julie , Frazee Krisi
Published: August 2016

This investigation examined the impact of a cycle ergometry exercise test (CET) on body composition determined using leg-to-leg bioelectrical impedance analysis (BIA; Tanita Model TPF-305). Fifty three children (25 males, 28 females) aged 10-12 yr participated. BIA measures of body fat (BF) were obtained immediately before and within five min of a multistage CET administered to assess peak oxygen consumption. Correlations (P = 0.01) of 0.99 were noted between the pre and post CET measures of BF. A systematic difference was not found in BIA measures obtained before and after CET. BF decreased by 0.4 and 1.2% following CET in the male and female subjects, respectively.
Effects of an Oral Glucose Challenge on Metabolic and Hormonal Responses to Exercise in Active Prepubertal Girls
Authors: Foricher Jean-Marc , Boisseau Nathalie , Ville Nathalie S. , Berthon Phanélie M. , Bentué-Ferrer Dominique , Gratas-Delamarche Arlette , Delamarche Paul
Published: August 2016

To examine hormonal and metabolic effects of an oral challenge in glucose (≈ 16 g), 15 prepubertal girls performed a 30-min ergocycle test at 60% of Wmax. Among them, 8 ingested an oral glucose challenge between 2 and 3 min after the beginning of the exercise whereas the other 7 girls received no fluid intake. Plasma glucose is influenced by the oral challenge, as the values obtained at the 15th and 30th min are higher than those of the control group. Plasma FFA, catecholamines, and insulin are not significantly modified by the oral challenge. Therefore, it seems that a challenge in glucose at the beginning of a prolonged exercise could avoid a fall in plasma glucose.
Personal, Social, and Environmental Correlates of Physical Activity in a Bi-Ethnic Sample of Adolescents
Authors: Morgan Charles F. , McKenzie Thomas L. , Sallis James F. , Broyles Shelia L. , Zive Michelle M. , Nader Philip R.
Published: August 2016

We examined associations of demographic/biological, psychological, social, and environmental variables with two different measures (self-reported and accelerometer) of physical activity (PA) in Mexican-American (56 boys; 64 girls) and European-American (49 boys; 45 girls) children (mean age = 12.1 years). Among 32 potential correlates, 4 gender and 16 ethnic differences were found. Percent of variance explained from 3% to 24% for self-reported PA and from 7% to 16% for accelerometer-measured PA. Physical self-perception was the only variable with a significant association across all subgroups and both measures. Less favorable levels of psychosocial variables among Mexican-Americans may explain ethnic differences in PA.
Short-Term Power Output in 9-Year-Old Children: Typical Error between Ergometers and Protocols
Authors: Williams Craig A. , Doré Eric , Alban James , Van Praagh Emmanuel
Published: August 2016

This study investigated the differences in short-term power output (STPO) using three different cycle ergometers in 9-year-old children. A total of 31 children participated in three cycle ergometer sprint tests of 20 s duration: a modified friction braked Monark, a modified friction braked Ergomeca cycle ergometer, and a SRM isokinetic ergometer. Common indices of peak and mean power, peak pedal rate, time to peak power, and pedal rate were recorded. Indices of peak power 1 s for the Monark, Ergomeca and SRM ergometer were found to be 299 ± 55, 294 ± 55, 297 ± 53 W and mean power 20 s to be 223 ± 40, 227 ± 43 and 216 ± 34 W, respectively. The time to peak power was found to be 3 ± 2, 6 ± 2, 5 ± 3 s, respectively. The standard error of measurement was lower in mean 20-s power compared to 1-s peak power. Despite instrumentation and protocol differences these results demonstrate reproducibility in 9-year-old children that will allow researchers confidence in comparing STPO data obtained from different ergometers.
The Reliability of an Isokinetic Knee Muscle Endurance Test in Young Children
Authors: De Ste Croix Mark B.A. , Armstrong Neil , Welsman Joanne R.
Published: August 2016

The purpose of this study was to examine the reliability of repeated isokinetic knee extension and flexion in young children and to examine sex differences in 30 untrained subjects (16 boys and 14 girls) aged 12.2 ± 0.3 years. Total work and the percentage decline in average torque and work were recorded during 50 repetitions. Intra-class correlation coefficients indicated a strong positive correlation between test 1 and 2 for all parameters ranging from 0.36–0.95. Coefficient of variation data ranged from ± 0% to ± 5.4%. Repeatability coefficients and limits of agreement indicated that the extensors were more reliable than the flexors for both torque and work. There were no significant sex differences in any of the parameters measured. This study suggests that repeated isokinetic muscle actions of the knee, as a function of muscle endurance, can be reliably assessed in young people.
Correlates of Physical Activity in a Cypriot Sample of Sixth-Grade Children
Authors: Loucaides Constantinos A. , Chedzoy Sue M. , Bennett Neville , Walshe Karen
Published: August 2016

This study examined the association between self-reported physical activity and a number of potential correlates in a sample of 256 Grade-6 children. Physical activity was assessed in both summer and winter, and children and parents completed questionnaires assessing potential correlates of physical activity. Analyses revealed that gender, time spent playing outside, self-efficacy in overcoming barriers, and number of items of exercise equipment at home were variables associated with physical activity in both seasons. School location was a variable associated with physical activity only in the summer, whereas private-lesson attendance, sports-club attendance, and best friend’s physical activity were variables associated with physical activity only in winter. Variance explained in physical activity were 42% and 51% in winter and summer, respectively.
Knee Flexor: Extensor Isokinetic Ratios in Young Male Gymnasts and Swimmers
Authors: Siatras Theophanis , Mameletzi Dimitra , Kellis Spiros
Published: August 2016

The purpose of the study was to determine young male gymnasts’ and swimmers’ knee flexor:extensor (F:E) ratios during isokinetic testing at different velocities. Nine gymnasts (10.3 ± 0.5 years) and 14 swimmers (10.5 ± 0.5 years) participated. Concentric isokinetic peak torque was measured by a Cybex® Norm dynamometer at different angular velocities (60,120, and 180°/s) during unilateral knee extensions and flexions after gravity correction. Significant differences were found only in gymnasts’ knee F:E peak-torque ratios between the angular velocities of 60 and 120°/s (p < 0.01), as well as 60–180°/s (p < .01), whereas swimmers’ ratios were unchanged. Gymnasts presented significantly higher F:E ratios than swimmers did at the angular velocities of 120°/s (p < .01) and 180°/s (p < .001). The reciprocal ratios provided some indication that the training context of young athletes can influence the balance between agonistic and antagonistic activity of the lower limbs’ major muscle groups.
Free-Living Pedometer Step Counts of High School Students
Authors: Wilde Bridgette E. , Corbin Charles B. , Le Masurier Guy C.
Published: August 2016

The purpose of this study was to examine the pedometer-measured physical activity levels of high school students (Grades 9–12). Comparisons were made between sexes, among grades, among groups based on level of participation in sport and physical education, and among groups based on levels of self-reported physical activity (based on questions from the National Youth Risk Behavior Surveillance System). Participants wore sealed pedometers for 4 consecutive school days. Results indicated no differences among days of monitoring but did show significant differences in mean steps per day between sexes, among grades, and among activity levels. Males took more steps per day than females did, and 10th graders took more steps than 12th graders did. Teens involved in sport and physical education took more steps than did those not involved. Teens who reported meeting both moderate and vigorous activity recommendations were most active, followed by teens meeting recommendations for moderate activity.
Stability of Physical Self-Perceptions during Early Adolescence
Authors: Raudsepp Lennart , Kais Kristjan , Hannus Aave
Published: August 2016

This study was undertaken to examine the stability of adolescents’ physical self-perceptions across short (4 days) and longer (6 and 12 months) periods of time. Boys and girls (n = 195) from 12 to 13 years of age completed the Children’s Physical Self-Perception Profile for 4 consecutive days; follow-up measurements were performed 6 and 12 months later. Results for the short term revealed relatively high stability of physical self-perceptions for the group, although most individuals showed fluctuations in self-perceptions over the 4 days. As expected, adolescents’ self-perceptions were less stable when follow-up measurements were administered.
Effects of a Three-Year Intervention on Children’s Physical Activity from Age 4 to 7
Authors: Sääkslahti Arja , Numminen Pirkko , Salo Pia , Tuominen Juhani , Helenius Hans , Välimäki Ilkka
Published: August 2016

This study focused on the physical activities of 228 children over 3 years. Children were divided into control (n = 112) and intervention (n = 116) groups. Parents of intervention-group children received information and concrete suggestions on how, when, and where to encourage their child’s physical activity. Children in the intervention group spent more time playing outdoors (p = .041) than did children in the control group, and play in the high-activity category increased with age (p < .001), whereas no change occurred in the control group. Our study showed that children’s physical activity could be increased via family-based intervention.
Are Changes in Distance-Run Performance of Australian Children between 1985 and 1997 Explained by Changes in Fatness?
Authors: Olds Tim , Dollman Jim
Published: August 2016

The aim of this study was to determine whether changes in fitness performance could be explained by changes in body fatness. Two hundred seventy-nine 10- to 12-year-old children were tested in 1985 as part of a national survey. They were matched for age, sex, body-mass index, and triceps skin-fold thickness with 279 children from a 1997 survey. Average speeds on the 1.6 km walk/run test were compared. Children from the 1997 survey performed significantly worse than their matched peers from the 1985 survey. The decline in performance was evident for boys, girls, and all children. Matching for fatness reduced performance differences by about 61% in boys, and 37% in girls. Declines in fitness performance in this population have not been entirely due to increases in fatness.
The Relationship between Socioeconomic Status and Adolescents’ Organized and Nonorganized Physical Activities
Authors: Santos Maria Paula , Esculcas Carlos , Mota Jorge
Published: August 2016

The aim of this study was to explore the relationship between adolescents’ choices regarding physical activity—both organized and nonorganized—and their parents’ socioeconomic status (occupation and education level) and to characterize those differences. The sample comprised 594 adolescents (304 girls and 290 boys) between 13 and 20 years old (mean age of 15.9). Physical activity was assessed by questionnaire and was classified as organized or nonorganized. The findings showed that adolescents from families of higher socioeconomic status chose significantly more organized activities, whereas, for those choosing nonorganized activities, only mothers’ education was statistically significant. Participants who engaged in organized physical activity reported more moderate-intensity, moderate-frequency team activities, whereas adolescents’ in nonorganized physical activities reported more low-intensity, moderate-frequency individual activities.
Feasibility of the Tritrac R3D Accelerometer to Estimate Energy Expenditure in Youth
Authors: McMurray Robert G. , Baggett Christopher D. , Harrell Joanne S. , Pennell Michael L. , Bangdiwala Shrikant I.
Published: August 2016

The purpose of this study was to determine whether an equation could be developed to predict energy expenditure from Tritrac output, body mass, stature, and age in youth. The participants were 308 young people, 8–18 yrs of age, similarly dispersed across ages and genders. Stature (cm) and body mass (kg) were measured. Participants completed 10 min of nine activities, ranging from light to vigorous intensity. Simultaneous measures of Tritrac vector magnitude counts (VMAG) and oxygen uptake (Cosmed K4b2) were obtained. Mixed model analysis using VMAG, sex, age, stature, and body mass fit well, and all variables were significant (p ≤ .012). The model concordance correlation was Rc = .812; standard deviation = 305ml/min. A slightly less complex model was also adequate: VO2 (ml/min) = (0.32·VMAG) + (6.97·cm) + (6.19·kg) − 858; standard deviation = 306 ml/min; Rc =.809. These results indicate that the Tritrac R3D can be used with some success to assess energy expenditure in 8- to 18-year olds.
A Pilot Study Comparing Pedometer Counts with Reported Physical Activity in Elementary Schoolchildren
Authors: Cardon Greet , De Bourdeaudhuij Ilse
Published: August 2016

In this study pedometer counts were recorded for 6 consecutive days for 92 children (mean age = 9.6 years; range 6.5–12.7) and were compared with the number of minutes per day in which the participants engaged in moderate-to-vigorous physical activity (MVPA). Diaries filled out with the assistance of one of the children’s parents were used to determine minutes of MVPA. The average daily step count was significantly higher in boys than in girls, although the average daily MVPA engagement in minutes did not vary significantly between genders. Based on the regression equations, 60 min of MVPA was equivalent to 15,340 step counts in boys, 11,317 step counts in girls, and 13,130 step counts when results for both genders were combined. A moderate correlation (r = .39, p < .001) was found between pedometer step counts and reported minutes of MVPA. According to the present study findings, however, predictions and promotion of daily MVPA engagement in children based on pedometer counts per day should be made with caution.
Pulmonary Function in Children and Adult Scuba Divers: A Longitudinal Study
Authors: Lemaître Frédéric , Bedu Mario , Coudert Jean
Published: August 2016

Pulmonary function was measured in 48 air divers (age range: 8–38 yr) and 56 control participants (age range: 8–34 yr). Static lung volumes, dynamic lung volumes and flows, and the pulmonary diffusing capacity for carbon monoxide were measured twice, 29 months apart. At both times the adult divers (>18 yr) had higher forced vital capacity, forced expiratory volume in 1 s and maximal expiratory flow rate at 50%, as well as lower pulmonary diffusing capacity for carbon monoxide, than did the adult controls. Whatever the age, mean annual changes in these parameters did not differ between groups. Our results indicate that there were no significant changes in pulmonary function in the young (8–12 yr), adolescent, or adult divers compared with healthy controls over the 29-month period. The mean annual changes in forced expiratory flow and volume, however, were negatively correlated with number of years of diving experience in adult divers and with maximal diving depth in adolescent (13–18 yr) divers (p < .05 and p < .001, respectively). Deep diving during the teenage years coupled with years of recreational diving might increase the risk of airway obstruction.
Peak Heart Rates in Youth with Mental Retardation: Pacer vs. Treadmill
Authors: Beets Michael W. , Pitetti Kenneth H. , Fernhall Bo
Published: August 2016

The purpose of this study was to twofold: to determine reliability of peak performance as measured by peak heart rate (HRpeak) during the Progressive Cardiovascular Endurance Run (PACER) and a treadmill stress test (TM); and to compare the PACER and the TM. The sample consisted of 42 participants 8 to 21 years old with mild mental retardation. Participants completed two PACERs followed by two TMs separated by a minimum of 48 hr. Data collected were HR for the PACER and TM; PACER laps completed; and TM endurance time (min). Intraclass correlations were computed separately for males and females in order to assess the reliability of PACER laps, HRpeak, and TM time. Results indicated high reliability for both males and females on PACER laps and TM HRpeak, and for males on PACER HR and TM time; moderate reliability was observed for females on PACER HRpeak and TM time. No significant differences were detected within or among trials. These findings indicate that youth with mild mental retardation exhibit consistent peak performance on the PACER and TM tests; therefore, PACER can be used for surveillance of aerobic fitness in this population.
Physical Fitness as a Predictor of Cardiovascular Disease Risk Factors in 6- to 7-Year-Old Danish Children: The Copenhagen School-Child Intervention Study
Authors: Eiberg Stig , Hasselstrom Henriette , Grønfeldt Vivian , Froberg Karsten , Cooper Ashley , Andersen Lars Bo
Published: August 2016

The aim of this study was to investigate whether risk factors for cardiovascular disease cluster in 6- to 7-year-old children and whether low physical fitness is a predictor of risk factor clustering. The study included 369 boys (6.8 ± 0.4 years) and 327 girls (6.7 ± 0.4 years). VO2max was directly measured during a treadmill test. The ratio of total cholesterol to high-density cholesterol, triglyceride levels, the ratio of insulin to glucose, systolic blood pressure, and the sum of four skinfolds were selected as risk factors. A child was considered at risk for individual factors if he or she had values in the least favorable quartile. The number of children with more than three cardiovascular disease cluster risk factors was not significantly different from a binominal distribution. This lack of clustering could be a result of the fact that these young children have not yet developed insulin resistance. Children in the lowest quartile of fitness had an odds ratio of 2.1 (CI: 1.0–4.4) for having three or more risk factors compared with the most fit. This is interesting with regard to prevention because it indicates that an intervention involving increased physical activity might postpone or even prevent the development of risk factors.
Activation of Antagonist Knee Muscles during Isokinetic Efforts in Prepubertal and Adult Males
Authors: Bassa Eleni , Patikas Dimitrios , Kotzamanidis Christos
Published: August 2016

The deficit of muscle-force production observed in children can be partly attributed to neural factors, such as an increased level of coactivation. This hypothesis, however, has not been thoroughly investigated under concentric and eccentric isokinetic conditions at different angular velocities. Thus, the purpose of this study was to examine whether prepubescent children present higher levels of activation of the antagonist knee muscles during isokinetic, concentric, and eccentric knee efforts compared with adults. Eighteen prepubertal and 13 young adult males (age: 10.9 ± 0.5 and 18.1 ± 0.1 years, respectively) performed maximal concentric and eccentric knee extensions and flexions at 45, 90, and 180 degrees/s. The vastus lateralis and biceps femoris electromyogram was recorded and the antagonist activation (coactivation) was calculated. Concentric contractions for both groups revealed significantly higher coactivation values (p < .05) compared with the eccentric conditions. Furthermore, increasing the angular velocity increased the level of coactivation significantly only during the concentric efforts for both groups. No significant difference in the antagonistic activity of the vastus lateralis and biceps femoris, however, was found between groups. Therefore, increased antagonist knee-muscle activation, which enhances joint stabilization during isokinetic concentric and eccentric effort, is similar in both prepubescent and adult males.
Early Muscular Fitness Adaptations in Children in Response to Two Different Resistance Training Regimens
Authors: Faigenbaum Avery D. , Milliken Laurie , Moulton Lucas , Westcott Wayne L.
Published: August 2016

The purpose of this study was to compare early muscular fitness adaptations in children in response to low repetition maximum (LRM) and high repetition maximum (HRM) resistance training. Twenty-three girls and 20 boys between the ages of 8.0 and 12.3 years (mean age 10.6 ± 1.3 years) volunteered to participate in this study. Children performed one set of 6 to 10 RM (n = 12) or one set of 15 to 20 RM (n = 19) on child-size exercise machines twice weekly over 8 weeks. Children in the control group (n = 12) did not resistance train. Maximum strength (1 RM) on the chest press, local muscular endurance (15 RM) on the leg press, long jump, vertical jump, and v-sit flexibility were assessed at baseline and posttraining. The LRM and HRM groups made significantly greater gains in 1-RM strength (21% and 23%, respectively) as compared with the control group (1%). Only the HRM group made significantly greater gains in 15-RM local muscular endurance (42%) and flexibility (15%) than that recorded in the control group (4% and 5%, respectively). If children perform one set per exercise as part of an introductory resistance training program, these findings favor the prescription of a higher RM training range.
Quantifying and Characterizing Physical Activity among 5- to 6- and 10- to 12-Year-Old Children: The Children’s Leisure Activities Study (CLASS)
Authors: Telford Amanda , Salmon Jo , Timperio Anna , Crawford David
Published: August 2016

The aim of this study was to describe the type, frequency, duration, and intensity of children’s physical activity and to examine differences by sex, age, and SES. Participants consisted of 5- to 6-year-old (n = 291) and 10- to 12-year-old (n = 919) children and their parents taking part in the Children’s Leisure Activities Study (CLASS). Parents completed proxy questionnaires about their child’s activity, and all children wore an accelerometer for 8 days. Accelerometry data showed that younger children accumulated approximately 4 hrs of moderate- to vigorous-intensity physical activity (MVPA) per day, and older children accumulated approximately 2 hrs per day. Fewer than three- quarters of 10- to 12-year-old boys and less than half of 10- to 12-year-old girls recorded 120 min of MVPA per day. Significant differences in the number of activities, as well as the type and frequency of activities performed, were observed by age and sex. The findings indicate that physical activities that appeal to older girls, such as lifestyle, noncompetitive activities, should be considered in the development of physical activity promotion strategies.