bluuebunny/crossref_metadata_2025 huggingface dataset:
Strength, Power, and Aerobic Exercise Correlates of 5-km Cross-Country Running Performance in Adolescent Runners
Authors: Cole Andrew S. , Woodruff Megan E. , Horn Mary P. , Mahon Anthony D.
Published: August 2016

Relationships between physiological parameters and 5-km running performance were examined in 15 male runners (17.3 ± 0.9 years). Running economy (RE) and blood lactate concentration ([BLa]) at 241.2 m/min, VO2max, velocity at VO2max (vVO2max), vertical jump height and muscle power, and isokinetic knee extension strength at 60°/sec and 240°/sec were measured. The participants’ best 5-km race time over the last month of the cross-country season (16.98 ± 0.76 min) was used in the analysis. The data were analyzed using Pearson correlation coefficients. Significant relationships to run time were observed for VO2max (r = -.53), RE (r = .55), and vVO2max (r = -.66), but not [BLa], isokinetic muscle torque, or vertical jump. Identifying the unique strength and power characteristics related to running performance in this age group is warranted.
Reliability of Assessing Indices of Isokinetic Leg Strength in Pubertal Soccer Players
Authors: Iga John , George Keith , Lees Adrian , Reilly Thomas
Published: August 2016

Using 95% limits of agreement (LOA), this study examined the reproducibility of indices of isokinetic leg strength in pubertal soccer players. Following familiarization, 23 boys performed isokinetic assessments of the knee joint muscles at 1.08, 2.16, and 4.32 rad/s during concentric exercise and at 2.16 rad/s during eccentric actions on two separate occasions. Peak torque values were recorded and reciprocal and bilateral muscle group ratios were calculated. As random error was heteroscedastic, 95% ratio LOA were employed. Systematic bias for the various measurements ranged from 0.97 to 1.07 for all data. Random variation associated with eccentric assessments of the hamstrings, concentric H:Q ratio calculated at 1.08 rad/s, and HECC:QCON ratios appeared narrow enough to be of practical use (×/÷ 1.05 to 1.20). Random errors associated with H:Q ratios calculated at high concentric velocities (4.32 rad/s) and during eccentric exercise (×/÷ 1.10 to1.37), and in all bilateral muscle group ratios (×/÷ 1.15 to 1.43) were too broad, rendering them prone to misinterpretation.
Elbow Flexor Strength, Muscle Size, and Moment Arms in Prepubertal Boys and Girls
Authors: Wood Louise E. , Dixon Sharon , Grant Chris , Armstrong Neil
Published: August 2016

The aim of this study was to examine elbow flexion torque, muscle cross-sectional area (CSA), and leverage in boys and girls. Thirty-eight prepubertal children (9.6 ± 0.3 years) volunteered to participate. All performed isometric flexion actions at 10°, 50°, and 90° of elbow flexion. Magnetic resonance imaging was used to assess elbow flexor (EF) muscle CSA and brachialis moment arm lengths. No significant gender differences were observed for any of the variables studied. EF CSA was directly proportional to isometric torque at 50° and 90°. CSA explained between 47% and 57% of torque variance. Moment arm estimates explained 19% of the variance in isometric torque at 90°. These baseline data contribute to our understanding of factors influencing strength variation during childhood.
Monitoring of Physical Activity in Young Children: How Much Is Enough?
Authors: Penpraze Victoria , Reilly John J. , MacLean Christina M. , Montgomery Colette , Kelly Louise A. , Paton James Y. , Aitchison Thomas , Grant Stan
Published: August 2016

There is limited evidence on how much and on which days accelerometry monitoring should be performed to obtain a representative measurement of physical activity (PA) in young children. We measured 76 children (40 M and 36 F, mean age 5.6 years ([SD ± 0.4]) on 7 days using Actigraph accelerometers. Mean daily PA was expressed in counts per min (cpm). Reliability increased as the number of days and hours of monitoring increased, but only to 10 hr per day. At 7 days of monitoring for 10 hr per day, reliability was 80% (95% CI [70%, 86%]). The number of days was more important to reliability than the number of hours. The inclusion or exclusion of weekend days made relatively little difference. A monitoring period of 7 days for 10 hr per day produced the highest reliability. Surprisingly short monitoring periods may provide adequate reliability in young children.
The Effect of Feedback and Information on Children’s Pedometer Step Counts at School
Authors: Butcher Zoe , Fairclough Stuart , Stratton Gareth , Richardson David
Published: August 2016

This study examined whether feedback or feedback plus physical activity information could increase the number of pedometer steps taken during 1 school week. One hundred seventy-seven students (mean age 9.124 ± 1.11 years) in three elementary schools participated. Schools were randomly assigned to control (CON), feedback (FB), or feedback plus information (FB+I) groups. Children wore pedometers during school time for 5 consecutive weekdays. The total steps of the groups were recorded at the end of each school day, with students in the FB and FB+I groups free to view their step counts. In addition, the FB+I group received information and ideas about how they could increase their daily steps. The CON group received no step-count feedback or information. Students in the FB+I group achieved significantly more steps per minute (17.17 ± 4.87) than those in the FB (13.77 ± 4.06, p = 0.003) and CON (12.41 ± 3.12, p = 0.0001) groups. Information, as well as step-count feedback, increased elementary students’ school-based physical activity (number of steps) in the short term. A longer intervention period is necessary to assess the sustained impact of this type of approach.
Precompetitive State Anxiety, Objective and Subjective Performance, and Causal Attributions in Competitive Swimmers
Authors: Polman Remco , Rowcliffe Naomi , Borkoles Erika , Levy Andrew
Published: August 2016

This study investigated the nature of the relationship between precompetitive state anxiety (CSAI-2C), subjective (race position) and objective (satisfaction) performance outcomes, and self-rated causal attributions (CDS-IIC) for performance in competitive child swimmers. Race position, subjective satisfaction, self-confidence, and, to a lesser extent, cognitive state anxiety (but not somatic state anxiety) were associated with the attributions provided by the children for their swimming performance. The study partially supported the self-serving bias hypothesis; winners used the ego-enhancing attributional strategy, but the losers did not use an ego-protecting attributional style. Age but not gender appeared to influence the attributions provided in achievement situations.
Sex Effect on Catecholamine Responses to Sprint Exercise in Adolescents and Adults
Authors: Botcazou Maïtel , Jacob Christophe , Gratas-Delamarche Arlette , Vincent Sophie , Bentué-Ferrer Danièle , Delamarche Paul , Zouhal Hassane
Published: August 2016

The purpose of this study was to clarify the effect of sex on plasma catecholamine responses to sprint exercise in adolescents and adults. Thirty-six untrained participants took part in this study—9 girls and 10 boys (Tanner Stage 4) and 9 women and 8 men. Each participant performed a 6-s sprint test on a cycle ergometer. Plasma adrenaline (A) and noradrenaline (NA) concentrations were determined successively at rest (A0 and NA0), immediately after the 6-s sprint test (AEX and NAEX), and after 5 min of recovery (A5 and NA5). Peak power, expressed in absolute values or relative to body weight and fat-free mass, was significantly higher in boys than in girls and higher in men than in women (p < .001). No sex effect was observed in AEX in the adolescents, but the NA increase was significantly higher in boys in response to the 6-s sprint (p < .05). In adults, no sex difference was found in NAEX, but AEX was significantly higher in men than in women (p < .05). NAEX was significantly higher in women than in girls (p < .05), and AEX was significantly higher in men than in boys (p < .01). The results of this study suggest that male and female adolescents and young adults might exhibit different catecholamine responses to sprint exercise.
Effects of School-Based Cardiovascular-Fitness Training in Children with Mental Retardation
Authors: Ozmen Tarik , Yildirim Necmiye Un , Yuktasir Bekir , Beets Michael W.
Published: August 2016

The aim of this study was to investigate the effects of a school-based cardiovascular-fitness-training program in children with mental retardation (MR). Thirty boys (8−15 years old) with mild to moderate mental retardation were randomly divided into 2 groups—experimental (EX) and control (CN). The EX group underwent 10 weeks of training 3 times/week for a duration of 1 hr/session at 60-80% peak heart rate. At Week 10, significant increases in 20-m shuttle-run-test (20-MST) laps were observed for the EX group. No improvements were found in percent body fat. No changes were observed for the CN. The school-based training program might prove useful in improving the cardiovascular fitness of children with MR.
Heart-Rate Deflection Point and the Second Heart-Rate Variability Threshold during Running Exercise in Trained Boys
Authors: Buchheit Martin , Solano Roberto , Millet Grégoire Paul
Published: August 2016

The aim of the present investigation was to compare the accuracy of the heart-rate (HR) deflection point (HRDP) and the second HR variability threshold (HRVTh2) to predict anaerobic threshold in boys. HRDP was determined from slope trends of successive linear regressions. HRVTh2 was determined from the high frequency’s peak and power-density trends. The second ventilatory threshold (VTh2) corresponding to the first decrease in PETCO2, with an increase in VE/VCO2, was used as the reference measure of AnT. Results show that VO2 and HR were similar at HRDP, HRVTh2, and VTh2. HRVTh2 and HRDP were highly correlated. It appears that HRVTh2 is a good alternative to HRDP for assessing anaerobic threshold. HRVTh2 and HRDP might rely on similar mechanisms.
Accelerometer Assessment of Physical Activity in Children: An Update
Authors: Rowlands Ann V.
Published: August 2016

Accelerometry is frequently used to assess physical activity in children. The number of articles in this area has increased dramatically in the last 10 years. The aim of this article is to provide a contemporary overview of accelerometry research in children. Specifically, the review addresses the choice of monitor, choice of epoch, when and for how long activity should be measured, the lack of consensus over how to define a complete day of activity data, issues of compliance, methods for the calibration of activity output, and the richness of data available from accelerometry.
Effects of Caffeine on Physiological Responses to Exercise: Boys versus Men
Authors: Turley Kenneth R. , DeSisso Travis , Gerst Jonathan W.
Published: August 2016

We compared the influence of caffeine on physiological responses to exercise between boys and men. Fifty-two participants (26 boys and 26 men) participated in a double blind, randomized, double crossover study. Each participant received the caffeinated (5 mg/kg) drink (CAF) and placebo (PL) twice each on 4 separate days. One hour after drink consumption preexercise heart rate (HR) and blood pressure (BP) were measured. Then while the participants rode stationary cycle ergometers at two different exercise intensities, HR, BP, and oxygen consumption (VO2) were measured. Blood pressure was not significantly affected by CAF, although on average it was always higher in boys for diastolic BP (3 mmHg) and systolic BP (3–4 mmHg) and men for diastolic BP (2–3 mmHg) and systolic BP (1–6 mmHg) both at rest and during exercise. HR was significantly (p < .05) lower at rest, 25W and 50W in CAF versus PL in boys, with no change in adults. During exercise, VO2 and respiratory exchange ratio (RER) were not different in CAF versus PL in either group. In conclusion, metabolism is not affected by a moderate caffeine dose in children or adults. The same dose has a similar effect on BP in both groups. The effect on HR was different, however, with a significant (p < .05) lowering in children in CAF versus PL, with no adult effects.
Age-Related Increases in the Shoulder Strength of High School Wrestlers
Authors: Housh Terry J. , Hughes Rommie J. , Johnson Glen O. , Housh Dona J. , Wagner Loree L. , Weir Joe P. , Evans Sharon A.
Published: August 2016

The purpose of this investigation was to examine age-related differences in absolute and relative isokinetic shoulder strength of high school wrestlers. A total of 122 high school wrestlers (M age = 16.31±1.18 yrs) volunteered to be measured for arm flexion and extension strength at the shoulder joint using a Cybex II dynamometer at 30, 180, and 300°·s−1. The sample was divided into four age groups: 13.75−15.00 (n = 22), 15.08−16.00 (n = 27), 16.08−17.00 (n = 34), and 17.08−18.83 years (n = 39). The results of this study indicated significant increases in absolute and relative arm flexion and extension strength across age when covaried for BW and FFW. In addition, comparisons with previously published data indicated differences between muscle groups in the pattern of strength gains that were dependent upon the speed of muscular contraction and may have been influenced by fiber type distribution characteristics.
Longitudinal Study of Coronary Risk Factors during Adolescence and Young Adulthood—The Amsterdam Growth and Health Study
Authors: Kemper Han C.G. , Verschuur Robbert
Published: August 2016

The purpose of this longitudinal study was to identify factors for coronary artery disease (CAD) in a teenage population in the Netherlands from ages 13.5 to 21.5 years. In a follow-up study 93 boys and 107 girls were measured annually from 1977 to 1980, and a fifth measurement was made in 1985. The CAD factors assessed were total serum cholesterol (TC), high density lipoprotein cholesterol (HDL), TC/HDL ratio, systolic (Psyst) and diastolic (Pdiast) blood pressure, percentage body fat (percent fat) and aerobic fitness (VO2 max/BW). The results indicate that the percentage of subjects at risk for CAD are relatively low in both sexes for all factors except for percent fat. From 20 to 30% of the subjects remain in the upper half of risk factor distribution throughout the 8 years study for TC, TC/HDL, percent fat, and VO2max/BW, indicating stability during the teenage period. Because percent fat combines a high stability with relatively high mean values during the teenage period in both sexes, this parameter seems a particularly important CAD risk factor in youngsters.
Insulin and Weight Status in Adolescents: Independent Effects of Intensity of Physical Activity and Peak Aerobic Power
Authors: Rubin Daniela A. , McMurray Robert G. , Harrell Joanne S.
Published: August 2016

Differences in insulin concentrations between normal weight or overweight adolescents (n = 437) were determined depending on their habitual physical activity (PA) and aerobic power (pVO2max). Tertiles were computed for PA (survey) and pVO2max (submaximal predicted cycle test). Independent of their weight, adolescents in the upper 2 tertiles for vigorous PA had lower insulin concentrations than those in the bottom tertile (p < .05). Adolescents in the top tertile for pVO2max expressed per kg fat-free mass also had lower insulin concentrations than those in the medium and bottom tertiles (p = .002). In youth, vigorous physical activity and aerobic power are associated with fasting insulin independent of weight status.
Sweat Electrolyte Loss in Asthmatic Children during Exercise in the Heat
Authors: Laitano Orlando , Martins Jocelito , Mattiello Rita , Perrone Claudia , Fischer Gilberto B. , Meyer Flavia
Published: August 2016

This study assessed sweat electrolyte concentration and losses in asthmatic children during exercise in the heat. Eleven asthmatics (AG; 11 ± 2 years old) and 11 nonasthmatics (CG; 10 ± 1 year old) underwent a maximal progressive cycle-ergometer test. During a second session, participants cycled in the heat (35°C, 60% RH) of a climatic chamber for 30 min at 50–60% of maximal workload. Sweat was collected using sweat patches attached to the dorsal region. No differences were observed in sweat [Na+] (AG = 35 ± 12.9 and CG = 43.4 ± 18 mmol/L) and [Cl-] (AG = 27.3 ± 10.4 and CG = 38.5 ± 19.1 mmol/L). There was no difference in sweat Na+ losses (AG = 0.47 ± 0.36 and CG = 0.66 ± 0.68 mmol/kg/h) and Cl- losses (AG = 0.37 ± 0.29 and CG = 0.59 ± 0.62 mmol/kg/h) between groups. Asthmatic children did not differ from nonasthmatics in their sweat electrolyte concentrations and electrolyte losses.
Physical Self-Esteem of Adolescents with Regard to Physical Activity and Pubertal Status
Authors: Altintaş Atahan , Aşçi F. Hülya
Published: August 2016

The purpose of this study was to examine the physical activity and pubertal status differences in the multiple dimensions of physical self-esteem of Turkish adolescents. The current study also aimed to investigate the gender differences in the physical self-esteem. The pubertal status of participants was determined by a self-report questionnaire. The Children and Youth Physical Self-Perception Profile and a weekly activity checklist were administered to 803 adolescents (Mage = 13.10 ± 0.93). Analysis revealed significant main effects of physical activity on the multiple dimensions of physical self-esteem for both boys and girls. Follow-up analysis indicated that physically active boys and girls scored higher on almost all subscales of physical self-esteem than less active counterparts. The main effect of pubertal status and physical activity × pubertal status interaction were not significant either for boys or girls. Analysis also revealed significant gender differences in perceived body attractiveness, physical strength, physical condition, and physical self-worth subscales in favor of boys (p < .05).
Differences in Physical Activity Levels between White and South Asian Children in the United Kingdom
Authors: Duncan Michael J. , Woodfield Lorayne , Al-Nakeeb Yahya , Nevill Alan M.
Published: August 2016

The purpose of this study was to compare physical activity levels between white and South Asian children in the UK. The data were obtained from 606, 11–14 year old schoolchildren (397 white; 209 Asian). Physical activity was assessed using the ‘four by one day’ recall questionnaire from which the time spent in moderate and vigorous physical activity was calculated. Boys were significantly more active than girls (p = .0001), and white children reported significantly greater physical activity than south Asian children (p = .001). Mean ± SD of time spent in moderate and vigorous activity was 90.2 ± 65.4 mins and 68.2 ± 49.3 mins for white and south Asian children and 103.5 ± 63.4 mins and 65.6 ± 53.5 mins for boys and girls respectively. These findings indicate that south Asian children are significantly less active than their white peers and there may be a need for specific interventions to target South Asian children particularly.
An Algorithm for Identifying Physical Activity Patterns from Motion Data
Authors: Dorsey Karen B. , Herrin Jeph , Krumholz Harlan M.
Published: August 2016

An algorithm was developed to describe how physical activity (PA) patterns relate to overall motion counts. Thirty-five children wore an accelerometer (7-days). Each motion count was compared with the mean of surrounding counts within 21 min. Counts per minute similar to the mean were grouped into bouts. Counts that differed by more than 20% of the coefficient of variations (based on the mean and SD of the 21 min period) indicated transitions between bouts. Children with more daily motion had more and longer moderate (MPA) and vigorous (VPA) bouts, higher counts during MPA bouts, and more transitions from VPA to VPA bouts. In addition to differences in PA levels, highly active and less active children perform PA differently.
Predicting Physical Activity Intention and Behavior in School-Age Children
Authors: Foley Louise , Prapavessis Harry , Maddison Ralph , Burke Shauna , McGowan Erin , Gillanders Lisa
Published: August 2016

Two studies were conducted to predict physical activity in school-aged children. Study 1 tested the utility of an integrated model in predicting physical activity (PA) intention and behavior—the theory of planned behavior (TPB) and self-efficacy theory. Six hundred and forty-five New Zealand children (aged 11–13 years) completed measures corresponding to the integrated model and a self-reported measure of PA one week later. Perceived behavioral control (PBC) and subjective norm were the two strongest predictors of intentions. Task efficacy and barrier efficacy were the two strongest predictors of PA. A second study (Study 2) was conducted to determine whether the self-efficacy measures could discriminate objectively measured PA levels. Sixty-seven Canadian children (aged 11–13 years) completed task and barrier self-efficacy measures. The following week, children classified as ‘high’ (n = 11) and ‘lower’ (n = 7) for both task and barrier efficacy wore an Actical® monitor for seven consecutive days to provide activity-related energy expenditure (AEE) data. Results showed that children with high efficacy expended significantly greater AEE than their lower efficacious counterparts. Findings from these two studies provide support for the use of self-efficacy interventions as a potentially useful means of increasing PA levels among school-aged children.
North American Society for Pediatric Exercise Medicine
Authors: Johnson M.R. , Hopkins-Price P.
Published: August 2016

Background:

Children may undergo exercise testing for multiple reasons. Exercise testing measures multiple physiologic parameters when the body is under stress and can be performed by cycle or treadmill protocols. A higher oxygen consumption (VO2) has been noted by treadmill protocols. The oxygen uptake efficiency slope (OUES) and slope of ventilation to carbon dioxide (VE/VCO2) are newer parameters of cardiopulmonary response. Differences in OUES and VE/VCO2 slope have not been compared in regards to method of testing.

Methods:

Clinical exercise tests performed by graded treadmill (Treadmill group) were compared with those performed by cycle ergometer (Cycle controls) from a previous study carried out at a separate institution. Exercise testing of persons with cystic fibrosis (Cycle CF) was evaluated during the same study. Age, weight, height, body mass index, sex, pulmonary function, maximal heart rate, VO2max, VEmax, end tidal carbon dioxide (ET-CO2), OUES and VE/VCO2 slope were compared by unpaired student’s T-test among the three groups. Pearson product moment correlations compared VO2max, OUES and VE/VCO2 slope in all three study groups.

Results:

The Treadmill group and Cycle controls had similar age, height, weight, BMI and baseline pulmonary function. The Cycle CF group had lower height, weight and BMI but similar age and pulmonary function to the other two groups. VO2max, and VEmax were significantly higher in Treadmill group than cycle controls. OUES was higher in the Treadmill group than cycle controls (p=0.07). Correlation between VO2max and OUES was 0.89 in treadmill group, 0.96 in cycle controls and 0.93 in cycle CF.

Discussion:

This study suggests OUES and VO2max, are highly correlated in healthy controls whether obtained by cycle or treadmill protocols. Variation in the level of correlation between VE/VCO2 slope and VO2max existed in the three study populations. VE/VCO2 slope correlated highest with end tidal carbon dioxide at maximal exercise and this may confound the use of the VE/VCO2 slope in healthy populations. No clear advantage to testing by treadmill or cycle ergometry was determined in this study and testing can be determined based on institutional preference.
Exercise Provocation Test for Growth Hormone Secretion: Methodologic Considerations
Authors: Eliakim Alon , Nemet Dan
Published: August 2016

The diagnosis of Growth Hormone (GH) deficiency in children with short stature is complex, and in certain cases, might be very difficult. Most of the provocative tests used to evaluate GH deficiency use pharmacological agents. The artificial nature of the pharmacological tests and the possibility that these tests might not always reflect GH secretion under normal physiological conditions provides the impetus for a more physiologic test. Exercise is one of the important GH releasing physiological stimuli. This review will summarize the current knowledge on the methods for performing laboratory exercise provocation test for GH secretion in children. In addition to recommendations of more standardized exercise protocols and environmental considerations, we will also focus on GH responses to exercise in unique populations such as obese children.
Reliability of Wingate Testing in Adolescents with Down Syndrome
Authors: Guerra Myriam , Giné-Garriga Maria , Fernhall Bo
Published: August 2016

The Wingate anaerobic test (WAnT) has not been used to assess individuals with Down syndrome (DS) and it is unknown if it is reliable in this population. We investigated the reliability of the WAnT in 19 adolescents with DS (age = 14.8 yrs; weight = 52.7 kg; height = 146.3 cm). Participants completed, on separate days, two standards WAnT using a resistance of 0.7 Nm × body weight (kg) in individuals ≥ 14 years old, and 0.5 Nm × body weight (kg) in participants < 14 years of age. Data were analyzed using intraclass correlation coefficient (ICC), dependent t tests and Bland-Altman plots. There was a significant difference between days for peak power (210.37 W vs. 236.26 W; ICC = 0.93), but not for mean power (158.72 vs. 168.71 W; ICC = 0.86), time to peak power (6.67 vs. 6.28 s; ICC = 0.69), or the fatigue index (9.33 vs. 5.43 W/sec; ICC = 0.09). Adolescents with DS exhibit low WAnT performance compared with previously published data on adolescents without DS and the reliability of WAnT is questionable in this population.
Physical Fitness, Activity, and Insulin Dynamics in Early Pubertal Children
Authors: Casazza Krista , Gower Barbara A. , Willig Amanda L. , Hunter Gary R. , Fernández José R.
Published: August 2016

The objectives of this study were to identify the independent effect of physical activity and fitness on insulin dynamics in a cohort of European-, African-, and Hispanic-American children (n = 215) age 7–12 years and to determine if racial/ethnic differences in insulin dynamics could be statistically explained by racial/ethnic differences in physical activity or fitness. An intravenous glucose tolerance test and minimal modeling were used to derive the insulin sensitivity index (SI) and acute insulin response to glucose (AIRg). Fitness was assessed as VO2-170 and physical activity by accelerometer. Multiple regression models were tested for contributions of fitness and physical activity to SI and AIRg. Fitness was a stronger predictor of SI and AIRg than physical activity regardless of ethnicity; racial/ethnic differences in insulin dynamics were not accounted for by differences in fitness and/or physical activity.
Effects of Exercise Mode on the Oxygen Uptake Kinetic Response to Severe-Intensity Exercise in Prepubertal Children
Authors: Machado Fabiana A. , Guglielmo >Luiz G. A. , Greco Camila C. , Denadai Benedito S.
Published: August 2016

The objective of this study was to verify the effect of the exercise mode on slow component of VO2 (VO2SC) in children aged 11–12 years during severe-intensity exercise. After determination of the lactate threshold (LT) and peak VO2 (VO2peak) in both cycling (CE) and running exercise (TR), fourteen active boys completed a series of “square-wave” transitions of 6-min duration at 75%∆ [75%∆ = LT + 0.75 × (VO2peak—LT)] to determine the VO2 kinetics. The VO2SC was significantly higher in CE (180.5 ± 155.8 ml • min−1) than in TR (113.0 ± 84.2 ml · min−1). We can conclude that, although a VO2SC does indeed develop during TR in children, its magnitude is considerably lower than in CE during severe-intensity exercise.
Physical Activity Assessed by Accelerometry in Rural African School-Age Children and Adolescents
Authors: Prista António , Nhantumbo Leonardo , Saranga Silvio , Lopes Vítor , Maia José , Seabra André e , Vinagre João , Conn Carole A. , Beunen Gaston
Published: August 2016

Physical activity (PA) in children/adolescents of both genders from a rural community in Mozambique was estimated by accelerometry and by questionnaire and was compared with PA of Portuguese youth. Total PA, moderate (MPA), vigorous (VPA) and very vigorous (VVPA) were evaluated. Mozambican boys were more active than girls. Intensity of PA declined significantly with age. Survival activities, such as household tasks, were the predominant mode of PA. Compared with Portuguese children/adolescents, Mozambicans had significantly higher total PA; showed less decline of PA with age and engaged in fewer minutes at higher intensity PA. Environmental factors likely explain documented differences.
Assessing Physical Activity Preferences in Latino and White Preadolescents
Authors: Olvera Norma , McCarley Kendall E. , Leung Patrick , McLeod Jessica , Rodriguez Augusto X.
Published: August 2016

The purpose of this study was to assess physical activity preferences (PAP) in preadolescent children. 191 Latino and White children (M = 11.9, SD = ±0.7) participated. Demographic, anthropometric, and PAP measures were employed. Both Latino and White children reported water play, basketball, and bicycling as their most preferred activities while indoor chores were least preferred. Compared with Latino, White children reported a higher preference for baseball/softball. Exploratory factor analysis of PAP measure indicated a three-factor solution: free play, sports, and exercise. Multiple linear regression models revealed that PAP varied as a function of ethnicity, gender, age, and body mass index.
The Association between Distance to School, Physical Activity and Sedentary Behaviors in Adolescents: Project STIL
Authors: Gorely Trish , Biddle Stuart , Marshall Simon , Cameron Noel , Cassey Louise
Published: August 2016

The purpose of this research was to investigate the relationship between distance to school and levels of physical activity and sedentary behavior in UK adolescents. Participants were 1385 adolescents (boys n = 531; mean age 14.7 years). Boys living within two miles of school and girls living within 5 miles of school were more likely to report high levels (≥60 min per day) of weekday leisure time physical activity. Differences in weekday leisure time physical activity were accounted for by active travel time. There were no differences in sedentary behavior time by distance to school. Journeys, whether active or motorized, most often took place with friends. Further research should investigate wider physical and social environmental influences on active travel.
Influence of Recovery Time on Warm-Up Effects in Male Adolescent Athletes
Authors: Faigenbaum Avery D. , McFarland James E. , Kelly Neil A. , Ratamess Nicholas A. , Kang Jie , Hoffman Jay R.
Published: August 2016

The purpose of this study was to examine the influence of recovery time following a dynamic warm-up (DY) and a static stretch warm-up (SS) on power performance in adolescent athletes. Following baseline measures, 19 males (16.5 ± 1.1 yrs) performed the vertical jump (VJ) and seated medicine ball toss (MB) at the following time points after DY and SS: 2, 6, 10, 14, 18, 22 min. Analysis of variance revealed that VJ was significantly greater following DY than SS at 2, 6, 10, 14 and 18 min. Main effects indicated a significant increase in VJ from baseline at 2 and 6 min following DY (2.6–3.9%) and a significant decrease in VJ from baseline at 2, 6, 10, 14 and 18 min following SS (–3.2% to –7.0%). No significant interaction effects between DY and SS were observed for MB. These findings indicate that lower body power performance in male adolescent athletes can be enhanced following DY as compared with SS during the first 18 min of the post warm-up period.
Adolescent Biological Maturity and Physical Activity: Biology Meets Behavior
Authors: Sherar Lauren B. , Cumming Sean P. , Eisenmann Joey C. , Baxter-Jones Adam D.G. , Malina Robert M.
Published: August 2016

The decline in physical activity (PA) across adolescence is well established but influence of biological maturity on the process has been largely overlooked. This paper reviews the limited number of studies which examine the relationship between timing of biological maturity and PA. Results are generally inconsistent among studies. Other health-related behaviors are also considered in an effort to highlight the complexity of relationships between biological maturation and behavior and to provide future research directions.
Modeling the Links Between Young Swimmers’ Performance: Energetic and Biomechanic Profiles
Authors: Barbosa Tiago M. , Costa Mário , Marinho Daniel A. , Coelho Joel , Moreira Marc , Silva António J.
Published: August 2016

The aim was to develop a path-flow analysis model for young swimmers’ performance based on biomechanical and energetic parameters, using structural equation modeling. Thirty-eight male young swimmers served as subjects. Performance was assessed by the 200-m freestyle event. For biomechanical assessment the stroke length, the stroke frequency and the swimming velocity were analyzed. Energetics assessment included the critical velocity, the stroke index and the propulsive efficiency. The confirmatory model explained 79% of swimming performance after deleting the stroke index-performance path, which was nonsignificant (SRMR = 0.06). As a conclusion, the model is appropriate to explain performance in young swimmers.
A Validation Study of Assessing Physical Activity and Sedentary Behavior in Children Aged 3 to 5 Years
Authors: Wen Li Ming , van der Ploeg Hidde P. , Kite James , Cashmore Aaron , Rissel Chris
Published: August 2016

Assessing young children’s physical activity and sedentary behavior can be challenging and costly. This study aimed to assess the validity of a brief survey about activity preferences as a proxy of physical activity and of a 7-day activity diary, both completed by the parents and using accelerometers as a reference measure. Thirty-four parents and their children (aged 3–5 years) who attended childcare centers in Sydney (Australia) were recruited for the study. Parents were asked to complete a 9-item brief survey about activity preferences of their child and a 7-day diary recording the child’s physical activity and sedentary behaviors. Both measures were compared with accelerometer data collected from the child over the same period as the diary survey. The findings suggest that parent completed diaries have acceptable correlation coefficients with accelerometer measures and could be considered in future research assessing physical activity and sedentary behavior of children aged 3–5 years.
Energy Expenditure and Perceived Effort During Brisk Walking and Running in 8- to 10-Year-Old Children
Authors: Ford Paul , Bailey Richard , Coleman Damian , Stretch Daniel , Winter Edward , Woolf-May Kate , Swaine Ian
Published: August 2016

There are no previous reports of energy expenditure and perceived effort during brisk-walking and running at speeds self-selected by young children. Fifty four participants (age 8–11 years old) performed 1500 m of brisk-walking and running in a marked school playground, and were given simple instructions to either ‘walk quickly’ or to ‘jog’. During the running the children achieved higher mean speeds and a greater total energy expenditure (p < .001). However, there was no difference in the perceived effort between the two activities (p > .05). These findings suggest that under certain conditions children find it just as easy to run as they do to walk briskly, even though the speed and energy expenditure is significantly higher.
Size and Maturity Mismatch in Youth Soccer Players 11- to 14-Years-Old
Authors: Figueiredo António J. , e Silva Manuel J. Coelho , Cumming Sean P. , Malina Robert M.
Published: August 2016

The purpose of the study was to compare the anthropometric, functional and sport-specific skill characteristics and goal orientations of male youth soccer players at the extremes of height and skeletal maturity in two competitive age groups, 11–12 and 13–14 years. The shortest and tallest players, and least and most skeletally mature players (n = 8 per group) within each age group were compared on chronological age; skeletal age (Fels method); pubertal status (pubic hair); size, proportions and adiposity; four functional capacities; four soccer-specific skills; and task and ego orientation. The tallest players were older chronologically, advanced in maturity (skeletal, pubertal) and heavier, and had relatively longer legs than the shortest players in each age group. At 11–12 years, the most mature players were chronologically younger but advanced in pubertal status, taller and heavier with more adiposity. At 13–14 years, the most mature players were taller, heavier and advanced in pubertal status but did not differ in chronological age compared with the least mature players. Players at the extremes of height and skeletal maturity differed in speed and power (tallest > shortest; most mature > lest mature), but did not differ consistently in aerobic endurance and in soccer-specific skills. Results suggested that size and strength discrepancies among youth players were not a major advantage or disadvantage to performance. By inference, coaches and sport administrators may need to provide opportunities for or perhaps protect smaller, skilled players during the adolescent years.
Prediction of Peak Oxygen Uptake From a Maximal Treadmill Test in 12- to 18-Year-Old Active Male Adolescents
Authors: Tsiaras Vassilis , Zafeiridis Andreas , Dipla Konstantina , Patras Kostas , Georgoulis Anastasios , Kellis Spiros
Published: August 2016

The aims were to develop and validate a VO2peak prediction equation from a treadmill running test in active male adolescents. Eighty-eight athletes (12–18 yrs.) performed a maximal exercise test on a treadmill to assess the actual VO2peak and a 20m Shuttle-Run-Test (20mST). A step-wise linear regression analysis was used and the following equation for estimation of VO2peak (mL·kg−1·min−1) = 35.477 + 1.832 × duration in min - 0.010 × duration × body mass in kg was developed. The cross-validation statistics were: R = .54, CE = 0.1 mL·kg−1·min−1, SEE = 2.5 mL·kg−1·min−1 (4.6%), and TE = 2.6 mL·kg−1·min−1 (4.9%). The cross-validation values (CE, SEE, and TE) were lower compared with those of previously published equations in adolescents that estimated VO2peak using anthropometric data, performance in 20mST, and energy cost at submaximal speeds.
Associations Between Selected Demographic, Biological, School Environmental and Physical Education Based Correlates, and Adolescent Physical Activity
Authors: Hilland Toni A. , Ridgers Nicola D. , Stratton Gareth , Fairclough Stuart J.
Published: August 2016

The study investigated associations between selected physical activity correlates among 299 adolescents (90 boys, age 12–14 years) from 3 English schools. Physical activity was assessed by self-report and accelerometry. Correlates represented biological, predisposing, and demographic factors as described in the Youth Physical Activity Promotion Model. Boys engaged in more self-reported (p < .01) and accelerometer assessed physical activity than girls (p = .02). Positive associations between sex (male), BMI, Perceived PE Ability, Perceived PE Worth, number of enrolled students, and physical activity outcomes were evident (p < .05). School-based physical activity promotion should emphasize sex-specific enhancement of students’ perceived PE competence and enjoyment.
Joint Association of Fatness and Physical Activity on Resting Blood Pressure in 5- to 9-Year-Old Children
Authors: Hayes Heather M. , Eisenmann Joey C. , Heelen Kate A. , Welk Greg J. , Tucker Jared M.
Published: August 2016

The purpose of this study was to determine the joint association of fatness and physical activity on resting blood pressure in children. Subjects included 157 children (age 5.5–9.5 years). Moderate-to-vigorous physical activity (MVPA, min/day), body fatness, and resting blood pressure were measured. Four categories were created by cross tabulation of high/normal levels of fatness and high/low levels of MVPA. There were significant differences in systolic blood pressure and mean arterial pressure across the fat/MVPA groups (p < .05). Regardless of participating in an acceptable level of MVPA, overfat children had higher resting systolic blood pressure than normal fat children. MVPA did not significantly attenuate blood pressure within a fat category.
Reliability of Fitness Measures in 3- to 5-Year-Old Children
Authors: Nguyen Thanh , Obeid Joyce , Timmons Brian W.
Published: August 2016

The purpose of this study was to determine the reliability of short-term power output, heart rate (HR) response during and after a treadmill test, and time to complete a 25-m dash in healthy preschool children. Thirty-two 3- to 5-year-old boys and girls completed two sessions approximately one week apart. Intraclass correlation coefficient (ICC) and coefficient of variation (CV) were calculated to evaluate reliability. Power output was found to be reliable with ICCs ranging from 0.83 to 0.93 and CVs from 8.1 to 9.7%. Time to complete the 25-m dash was highly reliable (ICC = 0.91, CV = 3.7%). Reliability for HR at submaximal exercise (ICC = 0.28, CV = 18.8%) and HR recovery (ICC = 0.42, CV = 14.0%) was not as strong. These findings should assist in determining appropriate fitness tests for preschoolers.
The Effect of Pre-Exercise Carbohydrate Supplementation on Anaerobic Exercise Performance in Adolescent Males
Authors: Lee Jonah D. , Sterrett Lauren E. , Guth Lisa M. , Konopka Adam R. , Mahon Anthony D.
Published: August 2016

Carbohydrate (CHO) consumption before anaerobic exercise was studied in 13 adolescent boys (15.2 ± 0.9 yrs). A within subjects design was employed where subjects consumed a 22% CHO or volume-matched placebo (PL) beverage 30-min before anaerobic exercise on two separate days. Exercise consisted of a Wingate Anaerobic Test (WAnT), ten by 10-s-sprints, and a second WAnT. Fatigue index and peak power (PP) were similar while mean power (MP) was higher (p < .025) in CHO trial; however this difference was ascribed to initial WAnT performance. PP and MP for the 10-s sprints were similar between trials. Intravenous blood glucose and insulin concentrations were higher (p < .05) in the CHO trial while lactate and catecholamine concentrations were similar. Improved performance on a single WAnT was apparent with CHO consumption before exercise; however, this strategy did not attenuate fatigue over time in adolescent boys.
Multivariate Association Among Morphology, Fitness, and Motor Coordination Characteristics in Boys Age 7 to 11
Authors: Vandendriessche Joric B. , Vandorpe Barbara , Coelho-e-Silva Manuel J. , Vaeyens Roel , Lenoir Matthieu , Lefevre Johan , Philippaerts Renaat M.
Published: August 2016

Discussions of growth and motor performance of children are often set in the context of physical fitness. Although there is a clear theoretical concept or definition of fitness comprising motor coordination, the latter is not systematically considered. This study determined to what extent the variance in motor coordination might be explained by morphological and fitness characteristics. To postulate understanding of this association during childhood, 613 boys aged 7–11 years completed the morphological measurements, the Körperkoordinationstest für Kinder (KTK) and different fitness tests. The results demonstrated a substantial interrelationship among morphology, fitness and motor coordination in elementary school boys. The magnitude of explained variance and the loadings of the canonical correlation between the several constructs are strongly pronounced during childhood indicating that these constructs should be well considered given their contribution to a child’s general development.
Feasibility and Reliability of a Repeated Sprint Test in Children Age 6 to 8 Years
Authors: Temfemo Abdou , Lelard Thierry , Carling Christopher , Mandengue Samuel Honoré , Chlif Mehdi , Ahmaidi Said
Published: August 2016

This study investigated the feasibility and reliability of a 12 × 25-m repeated sprint test with sprints starting every 25-s in children aged 6–8 years (36 boys, 41 girls). In all subjects, total sprint time (TST) demonstrated high test-retest reliability (ICC: r = .98; CV: 0.7% (95% CI: 0.6–0.9)). While sprint time varied over the 12 sprints in all subjects (p < .001) with a significant increase in time for the third effort onwards compared with the first sprint (p < .001), there was no difference in performance between genders. In all subjects, TST decreased with age (p < .001) and was accompanied by an increase in estimated anaerobic power (p < .001) but also in sprint time decrement percentage (p < .001). Gender did not effect these changes. The present study demonstrates the practicability and reliability of a repeated sprint test with respect to age and gender in young children.
Weight Status Associations With Physical Activity Intensity and Physical Self-Perceptions in 10- to 11-Year-Old Children
Authors: Fairclough Stuart J. , Boddy Lynne M. , Ridgers Nicola D. , Stratton Gareth
Published: August 2016

The study examined associations between children’s weight status, physical activity intensity, and physical self-perceptions. Data were obtained from 409 children (224 girls) aged 10–11 years categorized as normal-weight or overweight/obese. Physical activity was assessed using accelerometry, and children completed the Physical Self-Perception Profile. After controlling for the effects of age, maturation, and socioeconomic status vigorous physical activity was significantly associated with normal-weight status among boys (OR = 1.13, p = .01) and girls (OR = 1.13, p = .03). Normal-weight status was significantly associated with perceived Physical Condition (Boys: OR = 5.05, p = .008; Girls: OR = 2.50, p = .08), and Body Attractiveness (Boys: OR = 4.44, p = .007; Girls: OR = 2.56, p = .02). Weight status of 10–11 year old children was significantly associated with time spent in vigorous physical activity and self-perceptions of Body Attractiveness and Physical Condition.
Modeling Longitudinal Changes in Maximal-Intensity Exercise Performance in Young Male Rowing Athletes
Authors: Mikulic Pavle , Blazina Tomislav , Nevill Alan M. , Markovic Goran
Published: August 2016

The purpose of the current study was to examine the effect of age and body size upon maximal-intensity exercise performance in young rowing athletes. Male participants n = 171) aged 12–18 years were assessed using an “all-out” 30-s rowing ergometer test, and reassessed after 12 months. The highest rate of performance development, which amounts to [mean(SD)] +34%(23%) and +32%(23%) for mean and maximal power output, respectively, is observed between the ages of 12 and 13, while this rate of development gradually declines as the athletes mature through adolescence. Performance increases with body size, and mass, stature and chronological age all proved to be significant (all p < .05) explanatory variables of mean power output, with respective exponents [mean(SE)] of 0.56(0.08), 1.84(0.30) and 0.07(0.01), and of maximal power output, with respective exponents of 0.54(0.09), 1.76(0.32) and 0.06(0.01). These findings may help coaches better understand the progression of rowing performance during adolescence.