bluuebunny/crossref_metadata_2025 huggingface dataset:
Resistance Training and Youth
Authors: Kraemer William J. , Fry Andrew C. , Frykman Peter N. , Conroy Brian , Hoffman Jay
Published: August 2016

The use of resistance training for children has increased in popularity and interest. It appears that children are capable of voluntary strength gains. Exercise prescription in younger populations is critical and requires certain program variables to be altered from adult perspectives. Individualization is vital, as the rate of physiological maturation has an impact on the adaptations that occur. The major difference in programs for children is the use of lighter loads (i.e., > 6 RM loads). It appears that longer duration programs (i.e., 10-20 wks) are better for observing training adaptations. This may be due to the fact that it takes more exercise to stimulate adaptational mechanisms related to strength performance beyond that of normal growth rates. The risk of injury appears low during participation in a resistance training program, and this risk is minimized with proper supervision and instruction. Furthermore, with the incidence of injury in youth sports, participation in a resistance training program may provide a protective advantage in one’s preparation for sports participation.
Serum Creatine Kinase Activity and Delayed Onset Muscle Soreness in Prepubescent Children: A Preliminary Study
Authors: Webber Lauri M. , Byrnes William C. , Rowland Thomas W. , Foster Vicky L.
Published: August 2016

Although delayed onset muscle soreness and increased serum creatine kinase activity (SCKA) following unaccustomed exercise is common in adults, little is known concerning these responses in children. The perception of muscle soreness and SCKA in children (n = 16) (M age = 10.4±.30 yr) was compared to a control group of adults (n = 15) (M age = 27.1±.87 yr) following a single bout of downhill running (30 min − 10% grade). Preexercise SCKA was not significantly different between the children (91.7±8.5 μmol•L−1•min−1) and the adults (77.1±5.9 μmol•L−1•min−1). The difference in SCKA (pre to 24 hours post) was significantly less (p<.01) for the children (68.6±16.2 μmol•L−1•min−1) than for the adults (188.7±36.8 μmol•L−1•min−1). When the groups were adjusted for weight differences, SCKA was not significantly different between the adults and the children. Regardless of age, males demonstrated a significantly greater increase in SCKA postexercise when compared to females. Soreness ratings (verbally anchored scale from 1 to 10) 24 hours following the downhill run were not significantly different between the children (3.8±.6) and the adults (4.5±.7). Following an eccentrically biased exercise task, children exhibited less of a SCKA response compared to adults that is related to body weight.
Validation of a Weight-Bearing Physical Activity Questionnaire in a Study of Bone Density in Girls and Women
Authors: Verheul Anne-Claire M. , Prins Angelique N. , Kemper Han C.G. , Kardinaal Alwine F.M. , van Erp-Baart Marie-Agnes J.
Published: August 2016

The purpose of this study is to validate a physical activity questionnaire (PAQ) developed to classify adolescent girls and young adult women according to their level of weight-bearing activities. Twenty-six girls age 11-15 years and 29 women age 20-25 years reported average weekly times spent in several physical activities that were classified according to their weight-bearing levels. The relative validity of the PAQ was determined by comparing findings with a 3-day recording using a Caltrac accelerometer (3DCal) and a 3-day activity diary (3DAD). In the girls, no significant correlations were found between PAQ scores and either 3DCal or 3DAD. In the women, however, significant associations were observed between PAQ and both of these measures (r = .58 and .77, respectively). The validity of PAQ in women is supported by this study, but not in girls.
The Relationship of Goal Orientation and Perceived Ability to Enjoyment and Value in Youth Sport
Authors: Stephens Dawn E.
Published: August 2016

The purpose of the present study was to examine the effects of goal orientation and perceived ability on perceived enjoyment and value of playing soccer. Participants were 212 female soccer players (M age, 11.47 years) who were categorized according to one of four goal orientation profile groups. The largest difference between groups was found for valuing soccer between the high task-low ego group and the low task-high ego group, with those in the former group perceiving significantly more value in playing soccer. A median split procedure was then used to divide subjects into high and low perceived ability groups. Perceived ability was found to play a mediating role in the relationship between goal orientation profile and perceived enjoyment and value of playing soccer.
Aerobic Trainability of Prepubertal Boys and Girls
Authors: Tolfrey Keith , Campbell Ian Gordon , Batterham Alan Mark
Published: August 2016

This study examined the effect of exercise training on peak VO2 of 26 (12 boys and 14 girls) prepubertal children. Exercise training involved 12 weeks of stationary cycling for 30 min, 3 times · week−1 at 79.3 ± 1.2% (M ± SD) peak heart rate. Nineteen maturity matched controls (10 boys and 9 girls) completed all tests excluding the training. When alterations in habitual physical activity and percent body fat were included as covariates in the analyses, the exercise training did not have a significant effect on peak VO2 for boys or girls. These data may either indicate a maturity related, blunted training response or that prepubertal children require a more intense exercise stimulus.
Determinants of Children’s Self-Esteem: An Examination of Perceived Competence and Affect in Sport
Authors: Ebbeck Vicki , Weiss Maureen R.
Published: August 2016

The present study examined perceived sport competence and affect experienced in sport as possible determinants of children’s levels of self-esteem. The sample consisted of 183 summer sport program participants ranging in age from 8 to 13 years. The children completed self-report questionnaires that assessed the constructs of interest. Hypothesized relationships among the constructs were then examined using structural equation modeling techniques. The results revealed that both structural models tested provided an adequate fit with the sample data. For the affect mediator model, perceived competence significantly influenced positive affect and to a lesser degree negative affect, while only positive affect influenced self-esteem. For the perceived competence mediator model, only positive affect significantly influenced perceived competence, which in turn significantly influenced self-esteem. Thus, higher scores on perceived competence and positive affect were associated with higher scores in children’s self-esteem.
Reproducibility and Stability of Physical Activity in Children
Authors: Raudsepp Lennart , Päll Peep
Published: August 2016

The purpose of this study was to examine the between-day reproducibility of physical activity across 1 week and determine the stability of physical activity over 2 years. Forty-two children (19 boys, 23 girls) aged 8–9 years at the beginning of the study were followed across 1 week and over a 2-year period. Physical activity was assessed by Caltrac accelerometer. Reproducibility and stability of physical activity was analyzed using Spearman correlations. The results revealed significant Spearman rank order correlations between weekdays (r = 0.64 to 0.79) and weekend days (r = 0.53 to 0.67). Spearman rank order correlations between weekdays and weekend days during two monitoring sessions were consistently lower, ranging from 0.34 to 0.57. It was concluded that the between-day reproducibility of accelerometer monitoring was higher between similar days of the week (weekdays or weekend days). Shortterm stability of physical activity during late childhood was moderate.
A Long-Term Follow-Up of Participants in the Trois-Rivières Semi-Longitudinal Study of Growth and Development
Authors: Trudeau François , Laurencelle Louis , Tremblay Janie , Rajic Mirjana , Shephard Roy J.
Published: August 2016

The purpose of this project was to undertake a long-term follow-up of participants in the Trois-Rivières Growth and Development Study. Some 20 years after their initial involvement in the program, two groups were compared: experimental subjects (n =150) who had received 5 one-hour sessions of specialized physical education per week throughout their 6 years of primary school, and the original control group (n = 103). All subjects completed a questionnaire regarding current patterns of physical activity (PA), attitudes and beliefs about PA, and perceived barriers to PA. Principal results indicate: (a) More experimental than control women exercise 3 times or more per week, (b) experimental subjects more commonly perceived their health to be very good to excellent, (c) control subjects in general felt less psychological dependency on exercise, and (d) women in the experimental group had a lower relative risk of back problems.
Substrate Metabolism during Exercise in Children and the “Crossover Concept”
Authors: Duncan Glen E. , Howley Edward T.
Published: August 2016

This review addresses issues related to substrate metabolism in children and how this information compares and contrasts to that of adults. The relative percent of fat and carbohydrate (CHO) utilized by an individual can be estimated from respiratory exchange ratio (RER) values between 0.7 (100% fat, 0% CHO) and 1.0 (100% CHO, 0% fat). The rise in RER towards 1.0 in relation to increased exercise intensity demonstrates the augmented role of CHO as an energy source for muscle; however, fat oxidation also represents a major source of energy during exercise of moderate-to-heavy intensity. Preliminary reports suggest that children demonstrate patterns of fat and CHO use in response to exercise intensity similar to those of adults and also show a reduction in RER at submaximal exercise intensities after training. The use of the “crossover concept" may simplify the presentation of how metabolism is affected by exercise intensity and training.
The Self-Regulation and Perception of Exercise Intensity in Children in a Field Setting
Authors: Cowden Robin D. , Plowman Sharon A.
Published: August 2016

This study examined whether elementary school children (n = 104, M = 59, F = 45) could learn to self-reguiate exercise intensity and provide consistent and accurate perceptual estimates of sell-regulated exercise in the field setting of a physical education class. Five training sessions involving heart rate monitoring (HRM), introduction to the Children’s Effort Rating Table (CERT), and feedback from the researcher preceded two testing sessions (Trial 1 [Tl] and Trial 2 [T2]). Sixty-two percent of the subjects were able to set their intensity within the HR range for Tl, but only 40% did so for both trials. Validity coefficients between HR and CERT were low (r = –.10 to –.18) and intraclass reliability for CERT was only moderate (Tl, R = .67; T2, R = .56). The data indicate that elementary school children could neither consistently self-regulate exercise intensity nor provide valid or reliable CERT estimation responses for self-determined activity.
Physical Activity and Pulmonary Function in Youth: The Québec Family Study
Authors: Eisenmann Joey C. , Katzmarzyk Peter T. , Thériault Germain , Song Thomas M.K. , Malina Robert M. , Bouchard Claude
Published: August 2016

The relationship between habitual physical activity and pulmonary function were considered in 424 boys and 366 girls, 9–18 years of age. Indicators of habitual physical activity were assessed using a 3-day activity diary and included estimated daily energy expenditure (EE) and time spent in moderate-to-vigorous physical activity (MVPA) (METs ≥ 4.8). Pulmonary function was measured according to standard procedures. Relationships were examined with partial correlations and ANCOVA, comparing the highest and lowest quartiles of EE and MVPA. When age and stature are statistically controlled, relationships between EE, MVPA, and pulmonary function was generally low and not significant, with the exception of FEV1% in 16–18-year-old girls (r ≤ −0.28). Youth in the highest and lowest quartiles of EE and MVPA do not differ in pulmonary function, except for PEER in 9–12-year-old boys, and FEV1% in 16–18-year-old boys, which are slightly greater (1–3%) in the less active group. These findings indicate that lung volumes, capacities, and flow rates are not consistently related to estimated habitual physical activity in a general, free-living population of youth.
Effects of a Physical Activity Program on Children’s Activity Levels and Attraction to Physical Activity
Authors: Ernst Michael P. , Pangrazi Robert P.
Published: August 2016

The proliferation of research on physical activity paints a clear picture regarding the health benefits of increasing levels of physical activity. In the present study, the efficacy of a school-based physical activity intervention (Promoting Lifetime Activity for Youth) was examined. Twenty-eight 4th-, 5th-, and 6th-grade elementary school teachers and their students participated in this study. Treatment group classes received the P.L.A.Y. intervention. Control group classes received a placebo. Participants completed 2 questionnaires 3 times during the study. Repeated measures ANOVA was used for all analyses. Results indicate that the treatment group significantly increased physical activity levels. Control group classes did not significantly increase activity levels or attraction to activity.
Development of Aerobic Fitness during Childhood and Adolescence
Authors: Armstrong Neil , Welsman Joanne R.
Published: August 2016

Over 60 years ago, Robinson published the first investigation of boys’ aerobic fitness; almost 50 years ago, Åstrand conducted his pioneering studies of both sexes. Twenty four percent of the papers published during the first 10 years of Pediatric Exercise Science (1989-98) involved the determination of peak V̇O2. Yet, the interpretation of aerobic fitness during childhood and adolescence is still shrouded with controversy. In this paper we review peak V̇O2 in relation to age, growth, maturation, and sex. We describe the increase in peak V̇O2 with age, challenge the traditional interpretation of peak V̇O2 during growth, demonstrate the independent contribution of maturation to peak V̇O2, and address the progressive divergence of boys’ and girls’ peak V̇O2, during childhood and adolescence.
Skeletal Development during Childhood and Adolescence and the Effects of Physical Activity
Authors: Kemper Han C.G.
Published: August 2016

This paper reviews the growth and development of skeletal mass in youth and the effects of physical activity upon the bone mass in young people. The different methods to measure the bone mass are described such as anthropometrics, radiographics, dual energy X-ray absorptiometry, quantitative computed tomography, and ultrasound. Two different mechanisms are important for the formation and plasticity of bone: a central hormonal mechanism (with estrogen production) and a local mechanism (based on mechanical forces of gravity and muscle contractions). This local mechanism is closely connected to physical activity patterns and therefore discussed in more detail. Thereafter the natural course of the development of the bone mass during youth is described, taking into account the pubertal stages of boys and girls and also the age at which the maximal bone mass (peak bone mineral density) will be reached. The last part is devoted to the effects of physical activity on bone mass based on results of randomized controlled trials. Although the number of experimental studies are scarce, significant effects of weight bearing activity and high impact strength training programs are shown on the side specific bone mineral density in both boys and girls.
Arm Cranking Economy in Spastic Cerebral Palsy: Effects of Different Speed and Force Combinations Yielding the Same Mechanical Power
Authors: Maltais Désirée , Kondo Izumi , Bar-Or Oded
Published: August 2016

To determine optimal arm crank speed for subjects with cerebral palsy (CP), and whether it differs at high or low power output (PO), the cardiopulmonary cost and economy of cranking at 20, 30, and 40 rpm under a low (0.09 W · cm−1 arm span) and a high (0.12 or 0.18 W · cm−1 arm span) PO were measured in 11 adolescents (14.3 ± 2.4 years) with spastic diplegic CP. Data were analyzed using an ANOVA for repeated measures and post hoc (for between-speed differences) using Tukey’s test for honestly significant differences. Crank speed did not affect the cardiopulmonary cost nor economy at low PO. Under high PO, net economy at 30 rpm (12.2%) was significantly (p = .001) higher than at 20 rpm (10.2%), with a trend (p = .055) to also be higher than at 40 rpm (11.1%). Gross economy showed a similar pattern. These results suggest that cranking at 30 rpm under high PO may be more economical than cranking at 20 or 40 rpm.
The Effects of Goal Specificity and Goal Difficulty on the Performance of Badminton Skills in Children
Authors: Mooney Robert P. , Mutrie Nanette
Published: August 2016

The present study examines the effects of goal specificity and goal difficulty on performance in a sports setting for children while attempting to control for the effects of social comparison. Participants (N = 46) were matched on their baseline performance on two badminton tasks (underhand serve and drop shot) and then randomly assigned to one of three goal setting conditions: (a) easy goals, (b) difficult goals, and (c) do-your-best goals. Results suggest that the easy and difficult groups showed a significant improvement in performance for both experimental tasks, whereas the do-your-best group did not display any improvement. However, no significant differences were found between easy goals and difficult goals. Further analyses reveal that age effects were not significant. Manipulation checks indicate that all children accepted their assigned goals and intended to try extremely hard to reach them. The implications of these results are discussed in terms of Locke’s (18) goal setting theory as well as previous research in physical activity settings. Future directions for research are suggested.
The Use of Uniaxial and Triaxial Accelerometers to Measure Children’s “Free-Play” Physical Activity
Authors: Ott Alise E. , Pate Russell R. , Trost Stewart G. , Ward Dianne S. , Saunders Ruth
Published: August 2016

In order to effectively measure the physical activity of children, objective monitoring devices must be able to quantify the intermittent and nonlinear movement of free play. The purpose of this study was to investigate the validity of the Computer Science and Applications (CSA) uniaxial accelerometer and the TriTrac-R3D triaxial accelerometer with respect to their ability to measure 8 “free-play” activities of different intensity. The activities ranged from light to very vigorous in intensity and included activities such as throwing and catching, hopscotch, and basketball. Twenty-eight children, ages 9 to 11, wore a CSA and a heart rate monitor while performing the activities. Sixteen children also wore a Tritrac. Counts from the CSA, Tritrac, and heart rates corresponding to the last 3 min of the 5 min spent at each activity were averaged and used in correlation analyses. Across all 8 activities, Tritrac counts were significantly correlated with predicted MET level (r = 0.69) and heart rate (r = 0.73). Correlations between CSA output, predicted MET level (0.43), and heart rate (0.64) were also significant but were lower than those observed for the Tritrac. These data indicate that accelerometers are an appropriate methodology for measuring children’s free-play physical activities.
Health Enhancing Physical Activity for Young People: Statement of the United Kingdom Expert Consensus Conference
Authors: Cavill Nick , Biddle Stuart , Sallis James F.
Published: August 2016

An expert consensus development process was initiated to make public health recommendations regarding young people (5–18 years) and physical activity. Eight commissioned review papers were discussed at a meeting of over 50 academics and experts from a range of disciplines from the UK and overseas. Participants agreed on a consensus statement that summarized the research evidence and made two core recommendations. First, to optimize current and future health, all young people should participate in physical activity of at least moderate intensity for 1 hour per day. Young people who currently do little activity should participate in physical activity of at least moderate intensity for at least half an hour per day. The subsidiary recommendation is that, at least twice a week, some of these activities should help to enhance and maintain muscular strength and flexibility and bone health. A second aspect of the consensus process, which was based on extensive consultation, outlined the practical ways in which key organizations can work together to implement these recommendations. The resultant consensus statement provides a strong basis for the planning of future policies and programs to enhance young people’s participation in health-enhancing physical activity
Determinants of Sport Commitment among Junior Tennis Players: Enjoyment as a Mediating Variable
Authors: Weiss Maureen R. , Kimmel Lissa A. , Smith Alan L.
Published: August 2016

This study examined determinants of junior tennis players’ motivation to continue involvement using the sport commitment model as the theoretical framework (20). Based on the sport enjoyment literature, a version of the original sport commitment model (i.e., all determinants directly predict commitment) and a revised model where enjoyment was a mediator of the relationships between determinants and level of commitment were tested. Tennis players (N = 198; ages 10–18 years) completed self-report questionnaires on the constructs of interest. Hypothesized relationships among variables were tested using structural equation modeling. Results provided support for both the original and mediational models, with enjoyment exerting the strongest effect on tennis commitment in both models. An alternative model was tested where both direct and indirect effects through enjoyment on commitment were specified. The alternative model was accepted as most theoretically appealing because determinants of commitment and sources and consequences of sport enjoyment were accounted for within the larger conceptual model.
Isokinetic Measurement of Maximal Muscle Power during Leg Cycling: A Comparison of Adolescent Boys and Adult Men
Authors: Williams Craig A. , Keen Peter
Published: August 2016

This study investigated the maximal isokinetic muscle power characteristics in adolescent boys and adult men by comparing voluntary maximal efforts on a novel isokinetic cycling ergometer. Thirteen boys and 12 men performed between seven and ten 6-s (unpaced, maximal) sprints at crank velocities ranging from 80–170 rev · min−1 (8.3–17.8 rad · s−1). Maximum power over a single revolution (Pmax) and mean power for the total of complete revolutions in 5 s (MP5s) were recorded, and the optimal crank velocity for both parameters was calculated for each subject. Men’s Pmax were significantly higher (P < .05) than boys. There were no significant differences in the optimal velocity at Pmax and MP5s or the theoretical maximum velocity at Pmax and MP5s for men or boys. All subjects showed a linear torque velocity relationship (r > 0.90) for both Pmax and MP5s. Absolute differences in isokinetic power between adolescent boys and adult men cannot be attributable to the differences in crank pedal velocities as optimal velocities were similar in both groups.
The “Untracking” of Sedentary Living: A Call for Action
Authors: Corbin Charles B.
Published: August 2016

An important national health goal is to decrease the rate of sedentary living among Americans. Current baseline data suggest that 40% of those 18 and over do no regular leisure physical activity. Many studies suggest that there is a low to moderate relationship among youth activity and sedentary living. Some believe that getting the physical activity patterns of youth to “track” to adulthood could be the solution to reducing adult sedentary living. However, because activity generally decreases with age, a more important goal is to “untrack” activity. Specifically, steps must be taken in adolescence to help teens get “untracked” from their ever-decreasing activity levels. To accomplish this we must teach activities that will “track” to adulthood and teach self-management skills that can lead to a lifetime of active living.
Validation of the CSA Accelerometer in Adolescent Boys during Basketball Practice
Authors: Coe Dawn , Pivarnik James M.
Published: August 2016

Junior high school male basketball players (n = 10) were assessed during a 55-min practice to evaluate the validity of the Computer Science and Applications, Inc. (CSA) accelerometer for estimating physical activity (PA). Direct observation (Five-Level Children’s Activity Rating Scale [CARS]) and heart rate monitoring (HR) were used as criterion measures. CSA, CARS, and HR values were recorded during each minute of practice. Correlation using group data showed a moderate to good (r = 0.60; P < .001) relationship between CSA and HR. Individual participant analyses revealed a significant correlation (range 0.54–0.81; P < .001) between CSA and HR in nine of ten subjects. ANOVA revealed significant differences (P < .001) in CSA and HR in values associated with CARS levels 2–4. The CSA provides valid estimates of PA intensity (compared to CARS and HR) during basketball played by adolescent boys. It appears that CSA is sufficiently sensitive to quantify physical activity level as well as to discriminate between various intensity levels that exist during a typical basketball practice session.
Does Reactivity Exist in Children When Measuring Activity Levels with Pedometers?
Authors: Vincent Susan D. , Pangrazi Robert P.
Published: August 2016

Reactivity is defined as a change in normal activity patterns when people are aware that their activity levels are being monitored. This study investigated reactivity in elementary school children. The step counts of forty-eight participants in second, fourth and sixth grades were monitored with sealed pedometers for eight days. A factorial repeated measures ANOVA revealed no significant differences among days for all participants (F(7,294) = 1.25, p = .279) and no interactions among Sex, Grade, and Day. There is no reactivity in children monitored with a sealed pedometer. Intraclass correlations found that three to four days of monitoring are needed to determine habitual activity levels with a coefficient alpha level of .70 and five days of monitoring are needed to obtain a .80 coefficient alpha. This study demonstrates that there appears to be no reactivity period when sealed pedometers are used to measure physical activity.
Physical Activity Level, Sport Participation, and Parental Education Level in Turkish Junior High School Students
Authors: Koçak Settar , Harris Mary B. , Kin İşler Ayşe , Çiçek Şeref
Published: August 2016

This study examined physical activity level, sport participation, and parental education level in 333 female and 359 male Turkish junior high school students. Student’s physical activity level, sport participation, and parental education level were determined by a questionnaire with three sections. Independent samples t-test results revealed higher physical activity level and chi-square results indicated higher sport participation for boys when compared with girls. In addition significant negative correlations have been found between MET values and father and mother education for the total sample and for female students; however, negative correlations between MET values and parental education were not significant for boys.
Physical Activity and Cancer in Youth: A Review of Physical Activity’s Protective and Rehabilitative Functions
Authors: Culos-Reed S. Nicole
Published: August 2016

This paper examines the evidence between physical activity and cancer in youth populations, both in terms of physical activity as a risk-reduction and rehabilitation behavior. The association between cancer and physical activity as a risk-reducing health behavior is receiving increasing support; however, research on youth participation and subsequent adult cancer incidence is fairly limited, and future research must address numerous design and measurement issues. Specifically, the designs, methods, and measurement vary, highlighting the need for the standardization of measures in future research. Four studies were located that examined physical activity as a means of rehabilitation for youth cancer survivors. All four studies, focusing only on the physical and physiological changes associated with physical activity, found physical activity interventions to be beneficial. Given the positive physical and psychosocial impact that physical activity programs have had in adult cancer survivors, additional research is warranted with children survivors.
Measuring Children’s Vertical Ground Reaction Forces with Accelerometry during Walking, Running, and Jumping: The Iowa Bone Development Study
Authors: Janz Kathleen F. , Rao Smita , Baumann Hope J. , Schultz Jaime L.
Published: August 2016

Ground reaction forces (GRF) are associated with bone hypertrophy; therefore, they are important to understanding physical activity’s role in children’s bone health. In this study, we examined the ability of accelerometry to predict vertical GRF in 40 children (mean age 8.6 yr) during slow walking, brisk walking, running, and jumping. Correlation coefficients between accelerometry-derived movement counts and GRF were moderate to high and significant during walking and running, but not during jumping. Given a large proportion of children’s daily physical activity involves ambulation, accelerometry should be useful as a research method in bone-related research. However, this method underestimates GRF during jumping, an important physical activity for bone modeling and remodeling.
Validation of the Computer Science and Applications (CSA) Activity Monitor as an Objective Measure of Activity Energy Expenditure in Vietnamese Adolescents
Authors: Chu Binh Ba , Lawson David , Naughton Geraldine
Published: August 2016

This study considered the validation of the Computer Science Applications (CSA) activity monitor (model 7164) for predicting activity energy expenditure (EE). A group of 34 Vietnamese adolescents (aged 11 to 15) performed three 5-minute treadmill trials at 4.5, 6.6, and 8.8 km · h−1. Mean activity counts and heart rate (HR) were significantly changed with the three-speed trials (p > 0.05). An equation to predict EE (kcal · min−1) was developed from activity counts and body mass (BM) from the 24 random subjects in Vietnam and was validated on the remaining 10 subjects. This equation explained 72% of the variability in kcal · min−1 (adjusted R2 = 0.72, SEE = 0.91 kcal · min−1). Consistent with previous studies, the relatively high SEE indicates that the equation is more suited for groups of Vietnamese adolescents rather than individuals.
Acute Static Stretching Reduces Lower Extremity Power in Trained Children
Authors: McNeal Jeni R. , Sands William A.
Published: August 2016

Several studies utilizing adult subjects have indicated that static stretching may reduce subsequent strength and power production, possibly for as long as an hour following the stretch. This observation has not been evaluated in children, nor in athletes accustomed to performing static stretches during strength/power type training sessions. The purpose of this investigation was to determine if an acute bout of passive, static stretching of the lower extremity would affect jumping performance in a group of young, female gymnasts. Thirteen competitive gymnasts (age 13.3 − 2.6 yrs) performed drop jumps under two conditions: immediately following stretching and without prior stretching. The jumps were performed on separate days. The conditions were randomly ordered among the subjects. Time in the air (AIR) and ground contact time (CT) were measured during the drop jumps using a timing mat. Three different stretches of the lower extremity were conducted on each gymnast twice, each stretch being held for 30 seconds. Following the stretching condition, AIR was significantly reduced (.44 vs .46 sec, p < .001), while CT was not different (.130 for both conditions, p > .05). This study demonstrates that children’s lower extremity power is reduced when the performance immediately follows passive, static stretching, even in children accustomed to static stretching during training sessions involving explosive power.
The Relationship between Physical Activity and Cognition in Children: A Meta-Analysis
Authors: Sibley Benjamin A. , Etnier Jennifer L.
Published: August 2016

The purpose of this study was to quantitatively combine and examine the results of studies pertaining to physical activity and cognition in children. Studies meeting the inclusion criteria were coded based on design and descriptive characteristics, subject characteristics, activity characteristics, and cognitive assessment method. Effect sizes (ESs) were calculated for each study and an overall ES and average ESs relative to moderator variables were then calculated. ESs (n = 125) from 44 studies were included in the analysis. The overall ES was 0.32 (SD = 0.27), which was significantly different from zero. Significant moderator variables included publication status, subject age, and type of cognitive assessment. As a result of this statistical review of the literature, it is concluded that there is a significant positive relationship between physical activity and cognitive functioning in children.
Influence of Step Frequency on Movement Intensity Predictions with the CSA Accelerometer: A Field Validation Study in Children
Authors: Brage Søren , Wedderkopp Niels , Andersen Lars Bo , Froberg Karsten
Published: August 2016

Four Computer Science and Applications (CSA, Model 7164) accelerometers were validated against speed and heart rate in a field trial, consisting of two walking and two preset running speeds, and 3 min of running at freely chosen speeds. Fifteen children (9–11 years) were recruited from a suburban school in Denmark. Mean CSA output was calculated and converted to acceleration by calibration to sinusoidal accelerations in a mechanical setup, the latter variable being independent of frequency-based filtering. Mean CSA output and estimated acceleration both correlated significantly with speed (r2 = 0.55 and r2 = 0.76, respectively) and heart rate (r2 = 0.60 and r2 = 0.81, respectively), controlled for gender. ANOVA post hoc test failed to show significant differences in accelerometer output between running speeds. Inter-individual variability of CSA output and acceleration could not be explained by differences in step frequency in walking but running values correlated significantly with step frequency (r = −0.86 and r = −0.47 for CSA output and acceleration, respectively). Conversion of CSA output to average acceleration provides more precise estimates of intensity with less inter-individual variability than raw CSA output. Different running intensities, however, are generally not well differentiated with vertical accelerometry.
Exploring Recall of Physical Activity in Young People Using Qualitative Interviewing
Authors: McKenna James , Foster Lucy Jane , Page Angela
Published: August 2016

Recall of physical activity is a known problem affecting all forms of self-report. Participants age 8–16 years contributed to 16 focus groups and 24 interviews based on cognitive interviewing (n = 8) and think-aloud (n = 8) and general probing (n = 8) techniques. When unassisted, participants readily described physical activity mode but gave vague descriptions of daily activities. In contrast, the close detail of frequency, intensity, and duration of these activities was only more fully developed through prompting. Talk-based methods can provide considerable insight into developing more reliable and valid physical activity self-reports.
Determination of Ventilatory Threshold in Adolescents with Mental Retardation, with and Without Down Syndrome
Authors: Baynard Tracy , Unnithan Viswanath B. , Pitetti Kenneth H. , Fernhall Bo
Published: August 2016

This study evaluated detection of ventilatory threshold (VT) in adolescents with mental retardation (MR) (17 with MR, 13 with MR and Down Syndrome (DS), mean age 17.5 years). Subjects performed an individualized treadmill VO2peak test. Two evaluators reviewed the same VT plots 6 weeks apart, using 5 different methods. VE vs. time elicited the most detectable cases (83%), but significantly fewer youth with DS exhibited a detectable VT using any combination of methods (62% vs. 100%). Only VE vs. time yielded acceptable detection rate, although this may have been influenced by the protocol used. Intra-evaluator correlation coefficients ranged from 0.91-0.97, and interevaluator reliability coefficients ranged from 0.81-0.93. These findings suggest determination of VT is difficult in this population when using an individualized treadmill protocol, especially in adolescents with DS.
Physical Fitness, Physical Activity, and Self-Reported Back and Neck Pain in Elementary Schoolchildren
Authors: Cardon Greet , De Bourdeaudhuij Ilse , De Clercq Dirk , Philippaerts Renaat , Verstraete Stefanie , Geldhof Elisatbeth
Published: August 2016

The present study investigates whether physical fitness, physical activity, and determinants of physical activity are associated with reports of back and neck pain in children. A total of 749 children (mean age: 9.7 years ± 0.7) were evaluated, using a standardized physical fitness test (Eurofit), a physical activity questionnaire, and a pain prevalence questionnaire. Results indicate that physical fitness levels are not associated with back pain reports, but pain reports are lower in girls reporting higher frequencies of moderate physical activity and better estimates for attitude toward physical activity. Therefore, in girls, increased levels of physical activity might contribute to better back health.
A Comparison of 20-M Shuttle-Run Performance of us Midwestern Youth to Their National and International Counterparts
Authors: Beets Michael W. , Pitetti Kenneth H.
Published: August 2016

This study was undertaken to initiate a standardized methodology model for reporting cardiovascular fitness (CVF) for youths in the US and to compare the CVF of youths from a Midwestern metropolitan area to their international and US peers. Participants were 795 youths 8–18 yrs old. The 20-m shuttle-run test (20MST) was used to determine CVF and body composition was determined by body mass index (BMI). Comparative analysis was made by sex and age. Participants in this study showed similar CVF levels with their US peers, but when compared with their international counterparts, they demonstrated considerably lower CVF and higher BMI.
Predictors of Dietary Supplement Use among Adolescent Athletes
Authors: Bartee R. Todd , Grandjean Burke , Dunn Michael S. , Eddy James M. , Wang Min Qi
Published: August 2016

This study sought to predict the use of dietary supplements marketed to enhance athletic performance among 1,737 adolescent athletes. An anonymous, paper-and-pencil, self-report survey was administered to the participants. Grade level, participation in multiple sports, and scales representing attitudes, subjective norms, and intention were all significant predictors of current dietary supplement use. The results of this study allow for the development of more appropriate prevention and intervention strategies that can target specific groups of adolescent athletes. We recommend that attitudes of adolescent athletes be addressed in interventions and that salient others be included in program planning.
The Effect of Cycle Ergometer Strength Training in Prepubertal Untrained Males
Authors: Zakas Athanasios
Published: August 2016

The aim of the present study was to investigate whether cycle training offers an effective and safe means for improving muscle strength in young people. Eighteen 10-year-old boys formed the training group and 17 age-matched boys participated as controls in the study. Participants took part in a strength-training program that included cycle training 3 times per week for a period of 12 weeks, whereas controls participated only in the school’s physical activities. Maximum knee extension and flexion was evaluated at various angular velocities using an isokinetic dynamometer. Significant increases (p < .001) were observed for both extensors and flexors in all angular velocities of the training group and only in the middle and high angular velocities of the control group (p < .05 to p < .001). The findings suggest that cycle training appears to be an effective means for improving muscle strength in prepubertal untrained males.
The Obesity Epidemic: A Challenge to Pediatric Work Physiologists?
Authors: Shephard Roy J.
Published: August 2016

The pediatric sports physician faces an epidemic of obesity. A preliminary triage of individual patients can be based on the body mass index (BMI). The 80th and 95th percentiles of age-specific BMI suggest overweight and obesity, respectively; the diagnosis is confirmed by measurements of triceps and subscapular skinfolds. Over the last twenty years, the proportions of overweight and obese children have increased in both indigenous populations and most developed societies. The increase in body fat content seems to be associated with a decline in daily energy expenditure. Immediate health consequences include an increased prevalence of atherosclerotic plaques, hypertension, and an adverse lipid profile; in addition, the resulting poor self-image limits sport participation. Many obese children become obese adults, facing increased risks of cardiovascular and all-cause deaths. A combination of increased lifestyle activities, behavioral modification techniques to reduce sedentary behavior, and an appropriate diet seems to be the most effective approach to both prevention and treatment of obesity. Such initiatives should be supported by quality daily physical education and changes in the urban environment that encourage an active lifestyle.
Physical Activity Levels in Middle and High School Physical Education: A Review
Authors: Fairclough Stuart , Stratton Gareth
Published: August 2016

Forty studies reporting physical activity during middle and high school physical education (PE) classes were reviewed. Students engaged in moderate-to-vigorous physical activity (MVPA) for 27% to 47% of class time. Intervention strategies were successful in increasing MVPA. During nonintervention classes the highest levels of MVPA occurred in invasion games and fitness activities. Movement activities stimulated the lowest levels. Boys and girls spent 40% of class time in MVPA. Differences in MVPA during PE were also methodology dependent. PE classes can complement other school-based opportunities to contribute to young people’s daily physical activity.
Seasonal Variations in Portuguese Adolescents’ Organized and Nonorganized Physical Activities
Authors: Santos Maria Paula , Matos Margarida , Mota Jorge
Published: August 2016

This study aimed to describe seasonal variations in Portuguese adolescents’ physical activity, in organized and nonorganized physical activities, according to gender and age group. Data from the Portuguese second wave of the Health Behaviour in School-Aged Children (HBSC) study was used. The sample comprised 6,131 public school students ages 10 to 17 years (age = 14.0 ± 1.85 years old), and 51% were girls. Physical activity was measured by questionnaire and participants were categorized as “active” or “low active” according to their reported weekly participation in physical activity sessions. Participation in organized and nonorganized physical activities of all age groups was more frequent during the spring and summer period. Results suggest that appropriate strategies should be developed to promote involvement in sports and other physical activity, particularly organized physical activity programs, among adolescents throughout the year.
Ventilatory Breakpoints in Boys and Men
Authors: Klentrou Panagiota , Nishio Mary Lou , Plyley Michael , University Brock
Published: August 2016

The purpose of this study was to compare the ventilatory breakpoints during exercise between young boys and adult men. Twenty-four active volunteers, 12 boys (10.8 ± 0.3 years of age) and 12 men (24.6 ± 1.1 years of age) with similar aerobic power (53.6 ± 4.2 to 55.7 ± 3.5 mlkg−1min−1), participated in the study. Each participant completed a standardized Physical Activity Questionnaire and anthropometric variables were measured. The exercise testing consisted of two graded tests to exhaustion on a treadmill. Heart rates were recorded every minute and gas exchange parameters were obtained every 30 s throughout the tests. Each ventilatory breakpoint was determined using a three-part model. Although the relative VO2peak values were not significantly different between the boys and the young adults, the boys reported significantly (p < .05) higher total activity than the adults. The boys had a significantly higher (p > .05) first ventilatory breakpoint expressed as a percentage of VO2peak than the adults (64.9% vs. 57.7%). Only 50% of the boys demonstrated a discernable VB2, and the VB2 of this group was not significantly different from that of the adults.
Physical Activity, Fitness, and Physical Self-Concept in Adolescent Females
Authors: Dunton Genevieve Fridlund , Schneider Margaret , Graham Dan J. , Cooper Dan M.
Published: August 2016

Cross-sectional research examined whether physical activity or physical fitness was more closely linked to physical self-concept in adolescent females ages 14 to 17 (N = 103, 63% Caucasian). Moderate physical activity and vigorous physical activity were measured through a 3-day physical activity recall. Physical fitness was assessed using highly accurate measures of peak oxygen consumption (via cycle ergometer) and percent body fat (via dual X-ray absorptiometer). The Physical Self-Description Questionnaire (PSDQ) assessed self-concept in 11 domains (e.g., health, endurance, appearance). Pearson’s correlations showed that vigorous physical activity was positively associated with scores on most of the PSDQ scales (p < .005). Peak oxygen consumption was positively related to all of the selfconcept domains (p < .001), and percent body fat was negatively related on most of the PSDQ scales (p < .005). Multiple-regression analyses found that physical fitness (i.e., peak oxygen consumption and percent body fat) was more closely related to physical self-concept than was physical activity. In addition to the possibility that genetically determined fitness levels may influence physical selfconcept, these findings suggest that programs designed to elevate self-perceptions may require physical activity levels sufficient to improve cardiovascular fitness and decrease body fat.
Secular Changes in Shuttle-Run Performance: A 23-Year Retrospective Comparison of 9- to 11-Year-Old Children
Authors: Reed Katharine E. , Warburton Darren E.R. , Whitney Crystal L. , McKay Heather A.
Published: August 2016

Low physical fitness is associated with increased risk of cardiovascular disease (CVD) in adults and a higher incidence of CVD risk factors in children. Our aim was to compare the aerobic performance of Canadian children in 2004 with that of children measured 2 decades ago. We conducted a cross-sectional comparison of 2 data sets: (a) a 2004 cohort (n = 252) and (b) data from Leger’s 1981 cohort (n = 2,151). Performance was assessed using Leger’s 20 m Shuttle Run Test. First, we compared VO2max by cohort (in age and sex subgroups). Second, we used 1981 derived data, to re-create the original distribution curves, then calculated a 1981 equivalent percentile for each 2004 cohort child. We found that aerobic performance was lower at all ages in 2004 compared with 1981 (p < .01). Thus, the 50th percentile for fitness of children in 2004 was equivalent to that of children in the lowest 20% of fitness in 1981. We support the view that the performance of children on aerobic fitness tests is declining.