bluuebunny/crossref_metadata_2025 huggingface dataset:
Development and Evaluation of a Novel Computer-Based Tool for Assessing Physical Activity Levels in Schoolchildren
Authors: McLure Sally A. , Reilly John J. , Crooks Sean , Summerbell Carolyn D.
Published: August 2016

A novel computer tool (peas@tees), designed to assess habitual physical activity levels in children aged 9 and 10 years, was evaluated. Study 1 investigated agreement between peas@tees and accelerometry in 157 children. Bland-Altman limits of agreement (LOA) revealed peas@tees underestimated physical activity levels compared with accelerometry (bias −21 min; 95% LOA -146–105). Study 2 investigated stability of peas@tees in a separate sample of 42 children. Intraclass correlation coefficient was 0.75 (95% CI 0.62–0.84). Computer tools are promising as a cheap, feasible, and useful method to monitor children’s habitual levels of physical activity at the group level.
Medial Gastrocnemius Architectural Properties During Isometric Contractions in Boys and Men
Authors: Kannas Theodoros , Kellis Eleftherios , Arampatzi Fotini , de Villarreal Eduardo Saez Saez
Published: August 2016

The aim of this study was to examine the differences in muscle architecture during isometric tests between children and adults. Eight boys (age= 11.2 ± 0.26 years) and eight men (age= 22.3 ± 2.01 years) performed plantar flexion isometric efforts at angles of -15°, 0°, 15° at 0%, 40%, 60%, 80% of MVC. Analysis of variance tests indicated that adults showed greater fascicle length from rest to 80% of MVC (p < .05), greater pennation angle at 80% and 100% of MVC (p < .05) and greater aponeuroses displacement at levels of effort greater than 60% of MVC (p < .05). These differences observed in MG would appear to favor better utilization of the force-length and the force-velocity relationships, of the muscle in adults compared with children.
Paraoxonase Activity in Athletic Adolescents
Authors: Cakmak Alpay , Zeyrek Dost , Atas Ali , Erel Ozcan
Published: August 2016

Regular physical activity may play a protective role against cardiovascular disease in adults, and paraoxonase activity may serve to mediate this effect. This study compared paraoxonase activity and that of other antioxidative agents in adolescent athletes compared with inactive youth. Paraoxonase level was 177.32 ± 100.10 (U/L) in children with regular physical activity and 98.11 ± 40.92 (U/L) in the control group (P < 0.0001). The levels of total antioxidative capacity, total oxidative status, oxidative stress index, and lipid hydroperoxide were significantly higher in the athlete group compared with controls (P < 0.0001). Paraoxonase activity was found to be greater in adolescent athletes, suggesting that regular exercise might provide a cardio-protective effect by this means.
The Relationships Between Leptin and Measures of Fitness and Fatness Are Dependent Upon Obesity Status in Youth
Authors: Hosick Peter A. , McMurray Robert G. , Cooper Dan M.
Published: August 2016

The relationship between peak aerobic fitness (peakVO2) and plasma leptin was assessed in 25 normal (BMI < 85th %tile) and 25 overweight (BMI > 85th %tile) youth, ages 7–17 years. In the overall analysis peakVO2 was related to leptin when expressed in mL/kg/min (R2 = .516, p < .0001), or as ml/kgFFM/min (R2 = .127, p = .01). The relationships between peakVO2 and leptin were no longer significant when percent bodyfat was added to the models. In subanalyses by weight groups, peakVO2: leptin relationships were not evident for normal weight, but remained for overweight youth. In conclusion the relationship between aerobic fitness and leptin in youth is dependent upon weight status.
Neuromuscular Differences Between Men and Prepubescent Boys During a Peak Isometric Knee Extension Intermittent Fatigue Test
Authors: Armatas Vasilios , Bassa Eleni , Patikas Dimitrios , Kitsas Ilias , Zangelidis Georgios , Kotzamanidis Christos
Published: August 2016

The aim of this study was to examine the fatigue and recovery in boys and men during a maximal intermittent isometric fatigue test of the knee extensor muscles, by evaluating the electromyogram of vastus lateralis, vastus medialis and biceps femoris. Thirteen boys (10.0 ± 0.8yrs) and 13 men (26.1 ± 4.2yrs) were fatigued until torque reached 50% of its initial value. Three and 6 min after, a maximal isometric knee extension test was assessed. Men had faster torque decline during fatigue and slower torque recovery compared with boys. Agonist activity declined in both groups during fatigue but men had greater extent of reduction. After 6 min boys recovered fully in respect to agonist EMG, whereas this was not the case for the men. The lower level of fatigue and faster recovery in boys could be attributed to the limited inhibition that was observed in the boys’ agonist muscles, whereas the antagonist activity does not seem to play a role in the fatigue or recovery differences between the groups.
Habitual Moderate-to-Vigorous Physical Activity is Inversely Associated With Insulin Resistance in Canadian First Nations Youth
Authors: Mitchell Marc S. , Gaul Catherine A. , Naylor Patti-Jean , Panagiotopoulos Constadina
Published: August 2016

The aim of this study was to explore the relationship between insulin resistance (IR) and objectively measured habitual moderate-to-vigorous physical activity (MVPA) in First Nations youth. A cross-sectional study was conducted in 2 rural villages in northern British Columbia, Canada. Thirty-nine healthy youth (16 males and 23 females; age = 11.8yrs ± 2.2; range = 8.8–18.5yrs) participated. PA was measured with ActiGraph GT1M accelerometers. The homeostasis model assessment estimate of IR (HOMA-IR) was used to define IR. Duration of MVPA was inversely related to HOMA-IR (r=−.44, p < .01). From the regression model, 30 min of habitual MVPA corresponded to HOMA-IR levels that were 15% lower. In conclusion, these findings suggest that active First Nations youth have lower HOMA-IR values.
Insights Into Developmental Muscle Metabolism Through the Use of 31P-Magnetic Resonance Spectroscopy: A Review
Authors: Barker Alan R. , Armstrong Neil
Published: August 2016

31phosphorous-magnetic resonance spectroscopy (31P-MRS) has become an extremely valuable technique to investigate changes in muscle metabolism noninvasively and in vivo. The purpose of this article is to critically review how 31P-MRS has contributed to current understanding of muscle metabolic function in healthy children and adolescents. In addition, an overview of the basic principles of 31P-MRS and its application to the study of muscle metabolism is provided and discussed in relation to child-specific methodological concerns when using this technique.
Bone Speed of Sound, Bone Turnover and IGF-I in Adolescent Synchronized Swimmers
Authors: Ludwa Izabella A. , Falk Bareket , Yao Matthew , Corbett Lauren , Klentrou Panagiota
Published: August 2016

This pilot study compared bone speed of sound (SOS), bone turnover and insulin-like growth factor 1 (IGF-1) between 20 Caucasian, postmenarcheal, adolescent synchronized swimmers (SS) and 20 aged- and maturity-matched nonswimmers (NS). Daily dietary intake and physical activity levels were also assessed. Bone SOS was measured by quantitative ultrasound. Blood samples were analyzed for osteocalcin, cross-linked N-teleopeptide of type I collagen (NTx), IGF-I and 25-OH vitamin D. Although no differences in bone SOS or turnover markers were observed between groups, the lower IGF-1 and vitamin D intake found in synchronized swimmers, in combination with their higher strenuous activity levels, should be further explored.
Linking Young People’s Knowledge of Public Health Guidelines to Physical Activity Levels in England
Authors: Roth Marilyn , Stamatakis Emmanuel
Published: August 2016

Using the 2007 Health Survey for England, we examine whether knowledge of guidelines is linked to physical activity levels for 1,954 children aged 11–15, and the correlates of adhering to the guidelines. For girls, knowing the guidelines was associated with meeting them, but was weak among boys, for whom only white ethnicity was associated with meeting the guidelines. For girls, being younger, white, and from a manual social class background was associated with meeting the guidelines. Findings support the call for physical activity-promoting policy and programs aimed at specific groups of children who are prone to lower levels of activity.
Plyometric Training Does Not Affect Central and Peripheral Muscle Fatigue Differently in Prepubertal Girls and Boys
Authors: Skurvydas Albertas , Brazaitis Marius
Published: August 2016

The aim of the study was to evaluate the effect of plyometric training (PT) on central and peripheral (muscle) fatigue in prepubertal girls and boys. The boys (n = 13, age 10.3 ± 0.3 years) and girls (n = 13, age, 10.2 ± 0.3 years) performed continuous 2-min maximal voluntary contractions (MVCs) before and after 16 high-intensity PT sessions. PT comprised two training sessions per week of 30 jumps in each session with 20 s between jumps. The greatest effect of PT was on excitation–contraction coupling, (twitch force increased by 323% in boys and 21% in girls) and height of a counter–movement jump (increased by 37% in boys and 38% in girls). In contrast, the quadriceps voluntary activation index, central activation ratio, and MVC did not change significantly after PT. The thickness of the quadriceps muscle increased by 9% in boys and 14% in girls after PT. In conclusion, boys and girls demonstrated similar changes in indicators of central fatigue (50–60% decrease) and peripheral fatigue (45–55% decrease) after MVC before and after PT.
Lower Relative Bone Mineral Content in Obese Adolescents: Role of Non-Weight Bearing Exercise
Authors: Templeton Danielle L. , Kelly Aaron S. , Steinberger Julia , Dengel Donald R.
Published: August 2016

We assessed relative bone mineral content (BMC) in normal-weight (BMI < 85th percentile), overweight (BMI ≥ 85th—< 95th percentile), and obese (BMI ≥ 95th percentile) adolescents and evaluated the impact of nonweight bearing stationary cycle exercise training in a subset of obese participants. Obese and overweight adolescents had higher (p = .001) BMC than normal-weight counterparts, but after adjusting for total body mass the overweight and obese adolescents had a significantly lower (p < .001) BMC than normal-weight subjects. Although aerobic training such as cycling would seem optimal for caloric expenditure in obese adolescents, this study showed that eight weeks of cycle training did not improve BMC in obese adolescents. Weight-bearing aerobic exercise would be a better option for optimizing bone health in this population.
The Perceptual Response to Treadmill Exercise Using the Eston-Parfitt Scale and Marble Dropping Task, in Children Age 7 to 8 Years
Authors: Lambrick Danielle M. , Rowlands Ann V. , Eston Roger G.
Published: August 2016

This study assessed the nature of the perceived exertion response to treadmill running in 14 healthy 7–8 year-old children, using the Eston-Parfitt (E-P) Ratings of Perceived Exertion (RPE) scale and a marble dropping task. For the E-P scale and the marble dropping task, the relationships between the RPE and work rate were best described as linear (R2 = .96) and curvilinear (R2 = .94), respectively. This study further suggests that individual respiratory-metabolic cues (oxygen uptake: O2, heart rate: HR, ventilation: V̇E) may significantly influence the overall RPE to varying degrees in young children. The E-P scale provides an intuitively meaningful and valid means of quantifying the overall perception of exertion in young, healthy children during treadmill running. The marble dropping task is a useful secondary measure of perceived exertion, which provides further insight into the nature of the perceived exertion response to exercise in young children.
Association Between Light-Intensity Physical Activity and Adiposity in Childhood
Authors: Kwon Soyang , Janz Kathleen F. , Burns Trudy L. , Levy Steven M.
Published: August 2016

The purpose of this study was to examine whether the association between daily light-intensity physical activity (LPA) and total body fat mass changes during childhood. The study sample was 577 children participating in the longitudinal Iowa Bone Development Study. Body fat mass and physical activity (PA) were measured using dual energy X-ray absorptiometry (DXA) and accelerometers, respectively, at approximately 5, 8, and 11 years of age. Age- and gender-specific multivariable linear regression models were fit to predict fat mass by LPA, adjusted for actual age, birth weight, fat-free mass, height, moderate- to vigorous-intensity PA, and physical maturity (only for girls). Among boys, LPA was negatively associated with fat mass at age 11, but not age 5 or 8. Among girls, LPA was negatively associated with fat mass at ages 8 and 11, but not at age 5. LPA may have a beneficial effect against excess adiposity among older children.
Clustering of Metabolic Syndrome Risk Factors Associated With Lifestyle Factors and Serum Leptin in Korean Children
Authors: Hong Hye-Ryun , Cho Jin-Kyung , Lee Ji-Young , Park Jin-Koo , Kang Hyun-Sik
Published: August 2016

The present study investigated the relationships among metabolic risk factors, major lifestyle factors, and serum cytokines in a sample of Korean children. In a cross-sectional design, we studied a total of 275 children (130 boys and 145 girls) aged 12–13 years. Measured variables included anthropometrics, blood pressures (BP), VO2max, physical activity (PA), dietary intakes, lipids, glucose, and insulin. We explored the extent to which dietary intakes, VO2max, PA, and serum cytokines explained variance in a clustered risk score, which is a sum of Z scores for waist circumference, BP, TG, HDLC, and HOMA-IR, using a stepwise linear regression by blocks. VO2max, vigorous PA (VPA), and leptin were independent predictors for the clustered risk score while adjusting for age and Tanner stage. Our findings suggest that the clustered risk score is associated not only with low levels of VO2max and VPA, but also with elevated serum leptin in Korean children.
On Scientific Truth and Evidence-Based Practice
Authors: Rowland Thomas
Published: August 2016

Science is based on the idea that there is a truth, whether or not we have access to it. What we know depends on systems of knowledge, and we may never be able to get to specific truths, but the idea is that there is a reality; there is a way humans evolved or cancers grow, for instance. And science is a way to get to that.

Ariel Ruiz I Altaba (2010)
Effect of Rest Interval on Neuromuscular and Metabolic Responses Between Children and Adolescents
Authors: Bottaro Martim , Brown Lee E. , Celes Rodrigo , Martorelli Saulo , Carregaro Rodrigo , Vidal José Carlos de Brito
Published: August 2016

The purpose of this study was to compare the effect of different rest intervals and contraction velocities on muscle recovery following resistance exercise. 18 children (11.1 ± 0.52 yrs) and 19 adolescents (15.8 ± 0.49 yrs) performed three sets of 10 isokinetic repetitions at 60°/s and 180°/s. The work-to-rest ratio (W/R) was 1:2 and 1:4 for 60°/s, and 1:6 and 1:12 for 180°/s. ANOVA revealed that children demonstrated no significant decline in PT from the first to third set with any rest interval, but there was a significant (p < .05) decline for adolescents when a W/R of 1:2, 1:4 and 1:6 were used. Adolescents demonstrated significantly greater blood lactate (BLa) concentrations than children after three sets of resistance exercise. The present study indicates that adolescents may require longer rest intervals to recover full PT when compared with children.
Changes in Physical Activity, Self-Efficacy and Depressive Symptoms in Adolescent Girls
Authors: Neissaar Inga , Raudsepp Lennart
Published: August 2016

The purpose of this study was to examine the longitudinal relationships between naturally occurring changes in leisure-time physical activity, depressive symptoms and self-efficacy in adolescent girls. We also aimed to test whether depressive symptoms would moderate the self-efficacy-physical activity relationship. Participants were 181 urban adolescent girls. Physical activity was measured using the 3-Day Physical Activity Recall. Self-efficacy and depressive symptoms were assessed using questionnaires. Body height and body mass were measured and body mass index (BMI) was calculated. Data were collected on three occasions over a 2-year period. There was a decrease in physical activity and self-efficacy and increase in depressive symptoms across three measurement occasions. There were statistically significant and negative relationships between initial level and change for physical activity and depressive symptoms. Initially higher levels of physical activity were related with initially lower levels of depressive symptoms, and change in physical activity across time was inversely associated with change in levels of depressive symptoms across measurements. There were statistically significant and positive relationships between initial level and change for physical activity and self-efficacy after controlling effect of BMI. Latent growth modeling (LGM) also indicated a moderating effect of depressive symptoms on the self-efficacy-physical activity relationship. Girls who had high initial levels of self-efficacy and smaller increases in depressive symptoms had the lowest decline in physical activity participation. Our results encourage the design of interventions that reduce depressive symptoms and increase self-efficacy as a possible of means of increasing adolescent girls’ physical activity.
Correlations Between High Level Sport-Climbing and the Development of Adolescents
Authors: Schöffl Isabelle , Schöffl Volker , Dötsch J. , Dörr H.G. , Jüngert J.
Published: August 2016

Over the last years concerns have been raised about the health effects particulary on young climbers due to the observation of short stature with low body weight and body fat in sports climbers. The aim of this study was to investigate anthropometric and hormonal data for climbers of the German Junior national team. 16 climbers were compared with 14—age matched nonclimbers with respect to several anthropometric variables, leptin level, and climbing characteristics. Height, weight and body mass index (BMI) standard deviation scores (SDS) for boys were not significantly different from the controls, whereas girls had significantly lower SDS-values for weight and BMI. In comparison with the control group boys and girls had a lower skinfold thickness. The leptin values were lower than the calculated leptin levels but only reached significance for the girls. The young athletes of the GJNT were neither of short stature nor thin when compared with a physically active control group. The low body fat in boys and girls was within expected limits. The lower leptin levels might be attributed to a decrease in total body fat.
Effects of Integrative Neuromuscular Training on Fitness Performance in Children
Authors: Faigenbaum Avery D. , Farrell Anne , Fabiano Marc , Radler Tracy , Naclerio Fernando , Ratamess Nicholas A. , Kang Jie , Myer Gregory D.
Published: August 2016

The aim of this study was to evaluate the effects of integrative neuromuscular training (INT) during physical education (PE) class on selected measures of health- and skill-related fitness in children. Forty children from two 2nd grade PE classes were cluster randomized into either an INT group (n = 21) or a control (CON) group (n = 19). INT was performed 2x/wk during the first ~15 min of each PE class and consisted of body weight exercises. INT and CON participants were assessed for health- and skill-related fitness before and after 8 wks of PE with or without INT, respectively. A significant interaction of group by time was observed in INT participants with improvements noted in push-ups, curl-ups, long jump, single leg hop, and 0.5 mile (0.8 km) run performance (p < .05). These data indicate that INT is an effective and time-efficient addition to PE as evidenced by improvements in health- and skill-related fitness measures in children.
Assessing Children’s Physical Activity Behaviors at Recess: A Multi-Method Approach
Authors: Saint-Maurice Pedro F. , Welk Gregory J. , Silva Pedro , Siahpush Mohammad , Huberty Jennifer
Published: August 2016

To better understand and promote youth physical activity (PA) it is important to determine settings and characteristics that promote or influence behavior. This study evaluated the utility of a multi-method approach (accelerometers plus direct observation) to better understand youth PA at recess. A total of 100 third through fifth grade children (52 males and 48 females) wore an Actigraph accelerometer during school recess for five consecutive days in both Fall and Spring. Trained observers coded PA behaviors at the same recess periods using the System for Observing Play and Leisure Activities (SOPLAY). Overall, gender comparisons based on both instruments indicated that boys were more active than girls. MVPA levels were higher during climbing/sliding activities (40–50%) and when the activity setting was supervised and equipped (30%). Both assessments indicated that boys were more active but the contextual data from the SOPLAY indicate that differences may vary according to the environmental context.
Variation in Sport Participation, Fitness and Motor Coordination With Socioeconomic Status Among Flemish Children
Authors: Vandendriessche Joric B. , Vandorpe Barbara F.R. , Vaeyens Roel , Malina Robert M. , Lefevre Johan , Lenoir Matthieu , Philippaerts Renaat M.
Published: August 2016

Socioeconomic status (SES) is often indicated as a factor that influences physical activity and associated health outcomes. This study examined the relationship between SES and sport participation, morphology, fitness and motor coordination in a sample of 1955 Flemish children 6–11 years of age. Gender, age and SES-specific values for morphologic dimensions, amount and type of sport participation and fitness and motor coordination tests were compared. SES was positively and significantly associated with sport participation and sports club membership in both sexes. Although differences were not consistently significant, morphologic dimensions and tests of fitness and motor coordination showed a trend in favor of children from higher SES. The results suggest that public and local authorities should consider providing equal opportunities for children in all social strata and especially those in the lower SES to experience the beneficial effects of sport participation through which they can enhance levels of physical fitness and motor coordination.
Measuring and Validating Physical Activity and Sedentary Behavior Comparing a Parental Questionnaire to Accelermeter Data and Diaries
Authors: Bringolf-Isler Bettina , Mäder Urs , Ruch Nicole , Kriemler Susi , Grize Leticia , Braun-Fahrländer Charlotte
Published: August 2016

Accurately measuring children’s physical activity and their sedentary behavior is challenging. The present study compared 189 parental responses to a questionnaire surveying physical activity and sedentary behavior of children aged 6–14 years, to accelerometer outputs and time activity diaries for the same group. Responses were analyzed taking age, sex and maternal education into account. Correlation coefficients between questionnaire reports and accelerometer-based physical activity across all age groups were acceptable (up to r = .55). Yet, adjustment for age markedly attenuated these associations, suggesting concomitant influences of biological and behavioral processes linked to age. The comparisons of general time indications in the questionnaire with 24h-diary records suggested that parents tended to under- and over-report single activities, possibly due to social desirability. We conclude that physical activity questionnaires need to be designed for specific age groups and be administered in combination with objective measurements.
The Influence of Maturation on the Oxygen Uptake Efficiency Slope
Authors: Rogowski Michael P. , Guilkey Justin P. , Stephens Brooke R. , Cole Andrew S. , Mahon Anthony D.
Published: August 2016

This study examined the influence of maturation on the oxygen uptake efficiency slope (OUES) in healthy male subjects. Seventy-six healthy male subjects (8–27 yr) were divided into groups based on maturation status: prepubertal (PP), midpubertal (MP), late-pubertal (LP), and young-adult (YA) males. Puberty status was determined by physical examination. Subjects performed a graded exercise test on a cycle ergometer to determine OUES. Group differences were assessed using a one-way ANOVA. OUES values (VO2L·min1/log10VEL·min−1) were lower in PP and MP compared with LP and YA (p < .05). When OUES was expressed relative to body mass (VO2mL·kg−1·min−1/log10VEmL·kg−1·min−1) differences between groups reversed whereby PP and MP had higher mass relative OUES values compared with LP and YA (p < .05). Adjusting OUES by measures of body mass failed to eliminate differences across maturational groups. This suggests that qualitative factors, perhaps related to oxidative metabolism, account for the responses observed in this study.
Tracking of Health-Related Physical Fitness for Middle School Boys and Girls
Authors: Liu Wenhao , Zillifro Traci D. , Nichols Randall A.
Published: August 2016

This study tracked health-related physical fitness in 11 year-old youths over their three-year middle school period. The Fitnessgram test battery was administered four times to 116 boys and 129 girls in the US during the period. Results indicated that BMI and estimated %BF tracked best, followed by PACER, sit and reach, push-up, and curl-up. Fitness levels in the estimated %BF and curl-up in the least fit quartiles (at baseline) tracked better than those in the fittest quartiles, and initially at-risk youths had higher probabilities of falling into at-risk categories three years later than those initially in healthy groups. In addition, boys became healthier in the estimated %BF and girls tracked poorer than boys in the PACER. Further, the numbers of girls in the at-risk categories increased considerably in four fitness measures (estimated %BF, BMI, PACER, and push-up) during the middle school period, whereas boys’ corresponding numbers either dropped or did not change in all the fitness measures.
Accuracy of a New Time-Resolved Step Counter in Children
Authors: Dueker Donna , Gauderman W. James , McConnell Rob
Published: August 2016

Most pedometers record cumulative steps, limiting ability to assess level of physical activity or nonwear periods. The SportBrain iStep X1 has potential to overcome this limitation by recording and storing step count data in 60-s epochs. We evaluated accuracy of this instrument in children and the duration of consecutive zero step count minutes that indicated nonwear time periods. Seventeen children walked or ran on a treadmill at 2, 3, 4 and 5 miles/hour and walked around a track while wearing the SportBrain and Digiwalker SW-701 pedometer. We compared percent error in step counts for each pedometers relative to observer counts. A subsample wore a SportBrain pedometer during up to 5 days of usual activity. The SportBrain pedometer performed with acceptable accuracy at all evaluated treadmill speeds and during self-paced walking, recording steps within an average of 4% of observed step counts. It outperformed the Digiwalker, especially at slower speeds and in overweight children. During normal wear only 1% of zero count periods were more than 60 min. We conclude that the SportBrain iStep X1 pedometer provides a valid measure of step counts in short averaging times useful for assessing patterns of physical activity in population studies and periods of nonwear.
Cardiorespiratory Fitness, But Not Central Obesity or C-Reactive Protein, Is Related to Liver Function in Obese Children
Authors: Martins Clarice , Freitas Ismael , Pizarro Andréia , Aires Luísa , Silva Gustavo , Santos Maria Paula , Mota Jorge
Published: August 2016

Nonalcoholic fatty liver disease (NAFLD) is one of the most frequent complications associated with excess adiposity. Its pathogenesis is complex and there are multiple factors that may contribute to it. AIM: To analyze whether cardiorespiratory fitness (CRF), waist circumference (WC), and C-reactive protein (CRP) are associated with alanine aminotransferase (ALT) in children with obesity. METHODS: 79 overweight/obese children of both genders, 11–13 year-olds, with abnormal serum ALT from Porto public schools comprised the sample. Measurements included CRF (20-m Shuttle Run Test), WC (NHANES protocol), CRP and ALT (Cholestech LDX analyzer). Logistic regression adjusted for gender, maturation, and weight with ALT levels as dependent variable (risk vs. non risk), and WC (risk vs. non risk), CRP (risk vs. non risk), and CRF (fit vs. unfit) as independent variables. Level of significance was set at 95%. RESULTS: Logistic regression showed that obese fit children were less likely to have abnormal ALT values (OR=.031) CONCLUSION: In obese children, higher cardiovascular fitness appears to reduce the chance of decreased liver function.
Scaling of VO2max and Its Relationship With Insulin Resistance in Children
Authors: Ahn Bumsoo , McMurray Robert , Harrell Joanne
Published: August 2016

The relationship between insulin resistance (HOMA-IR), percent body fat, and aerobic fitness (VO2max per unit fat free mass; mL/kgFFM/min) was examined in 1,710 children. Percent body fat was estimated from sum of skinfolds, and VO2max was estimated from submaximal cycle ergometer tests. Overnight fasting blood samples were obtained. VO2max (mL/kgFFM/min) and percent body fat were correlated with HOMA-IR (r=-0.076, p < .002; r=.420, p < .001, respectively); as was VO2max in units of mL/kg/min (r=-0.264, p < .001). When VO2max in mL/kg/min was used, a progressive increase in HOMA-IR was found with decreasing fitness (p < .05). However, when mL/kgFFM/min was used, HOMA-IR scores remained similar between moderate-fit and low-fit group. The stronger association between aerobic fitness (mL/kg/min) and HOMA-IR is partially due to the significant association of fat mass to HOMA-IR. Therefore, our recommendation is to express aerobic fitness in units of mL/kgFFM/min to eliminate the confounding factor of adiposity and better understand the influence of muscle on insulin resistance.
Differences in Health Behavior, Physical Fitness, and Cardiovascular Risk in Early, Average, and Late Mature Children
Authors: Drenowatz Clemens , Wartha Olivia , Klenk Jochen , Brandstetter Susanne , Wabitsch Martin , Steinacker Jürgen
Published: August 2016

This study examined the association between biological maturity, CVD risk, fitness and health behavior in 709 (359 male, 350 female) 8-year-old children (range: 6.3–8.9 years). Sports participation and sedentary behavior was assessed via parent questionnaire. Height and weight was measured and maturity status was predicted based on % of adult-height reached. Fitness was assessed via a test battery and CVD risk was determined using mean arterial pressure, cholesterol and intra-abdominal fat. BMIpercentiles (BMIPCT) differed significantly among early, average and late maturing children. Early maturing children displayed a higher CVD risk profile (0.5 vs. -0.2), lower fitness scores (-0.4 vs. 0.2), and spent more time watching TV (51 vs. 43 min/day) compared with their peers. After controlling for BMIPCT differences remained only for fitness in boys and TV time in girls.
Maximal Oxygen Uptake Validation in Children With Expiratory Flow Limitation
Authors: Robben Katherine E. , Poole David C. , Harms Craig A.
Published: August 2016

A two-test protocol (incremental/ramp (IWT) + supramaximal constant-load (CWR)) to affirm max and obviate reliance on secondary criteria has only been validated in highly fit children. In girls (n = 15) and boys (n = 12) with a wide range of VO2max (17–47 ml/kg/min), we hypothesized that this procedure would evince a VO2-WR plateau and unambiguous VO2max even in the presence of expiratory flow limitation (EFL). A plateau in the VO2-work rate relationship occurred in 75% of subjects irrespective of EFL There was a range in RER at max exercise for girls (0.97–1.14; mean 1.06 ± 0.04) and boys (0.98−1.09; mean 1.03 ± 0.03) such that 3/15 girls and 2/12 boys did not achieve the criterion RER. Moreover, in girls with RER > 1.0 it would have been possible to achieve this criterion at 78% VO2max. Boys achieved 92% VO2max at RER = 1.0. This was true also for HRmax where 8/15 girls’ and 6/12 boys’ VO2max would have been rejected based on HRmax being < 90% of age-predicted HRmax. In those who achieved the HRmax criterion, it represented a VO2 of 86% (girls) and 87% (boys) VO2max. We conclude that this two-test protocol confirms VO2max in children across a threefold range of VO2max irrespective of EFL and circumvents reliance on secondary criteria.
Variables Associated With Active and Inactive Behavior During the After-School Period
Authors: Wickel Eric
Published: August 2016

This study analyzed time-use interviews to report levels of active and inactive behavior during the after-school period (3–6 pm). Interviews were conducted on random days from three separate seasons during third and fourth grade. Youth with at least two interviews during third (356 completed 2 interviews; 506 completed 3 interviews [9 yrs; 50% boys]) and fourth (186 completed 2 interviews; 768 completed 3 interviews [10 yrs; 50% boys]) grade were included to report levels of moderate-to-vigorous physical activity (MVPA), light physical activity, inactive screen time, inactive nonscreen time, and travel by location and who the activity was undertaken with. Reporting time outside the home and with peers (single or group) was related to higher levels of MVPA. While inside the home, screen and nonscreen proportions were comparable (38% and 40%, respectively), despite unique patterns (screen: boys > girls; nonscreen: girls > boys). Reporting time with both parents was associated with more nonscreen time; whereas reporting time with peer groups was associated with lower screen time. Understanding active and inactive patterns of children’s behavior outside of school hours can be very important in contributing toward the development of innovative interventions for increasing physical activity.
Commentary on “Child-Adult Differences in Muscle Activation—A Review”
Authors: Bassa Eleni , Patikas Dimitrios , Hatzikotoulas Konstantinos , Kotzamanidis Christos
Published: August 2016

We would like to comment on the paper by Dotan et al. (8) entitled “Child-adult differences in muscle activation—a review.” Dotan et al.’s review (8) in conjunction with the commentary of O’Brien et al. (20) constitutes an important contribution to the question “who are stronger: children or adults?” based on specific force comparisons between children and adults and not on absolute values. For simplification reasons, we would like to limit the context of this question to single-joint isometric and isokinetic contractions only. Hence, we will not discuss multi-joint dynamic actions.
Effects of Two Different Resistance-Training Programs on Mean Tennis-Serve Velocity in Adolescents
Authors: Behringer Michael , Neuerburg Sebastian , Matthews Maria , Mester Joachim
Published: August 2016

The purpose of the current study was to evaluate the transferability of 2 different resistance training protocols on service velocity and its precision consistency in junior tennis players. Thirty-six male athletes (15.03 ± 1.64 years) were randomly assigned to a machine-based resistance-training group (RG, n = 12), a plyometric training group (PG, n = 12), and a control group (CG, n = 12). For a period of 8 weeks, both intervention groups resistance trained 2 days per week in addition to their regular tennis training, whereas the CG had no extra training. Mean service velocity over 20 maximum-velocity serves increased significantly more in PG (3.78%; p < .05) when compared with CG, whereas no such changes could be found in the RG (1.18%; p > .05). Service precision did not change from pre- to posttest in all three groups (p > .05). Only the plyometric training program tested, improved mean service velocity over 20 maximum-velocity serves in junior tennis players but did not affect service precision.
Feasibility, Validity, and Reliability of the Plank Isometric Hold as a Field-Based Assessment of Torso Muscular Endurance for Children 8–12 Years of Age
Authors: Boyer Charles , Tremblay Mark , Saunders Travis , McFarlane Allison , Borghese Michael , Lloyd Meghann , Longmuir Pat
Published: August 2016

This project examined the feasibility, validity, and reliability of the plank isometric hold for children 8–12 years of age. 1502 children (52.5% female) performed partial curl-up and/or plank protocols to assess plank feasibility (n = 823, 52.1% girls), validity (n = 641, 54.1% girls) and reliability (n = 111, 47.8% girls). 12% (n = 52/431) of children could not perform a partial curl-up, but virtually all children (n = 1066/1084) could attain a nonzero score for the plank. Plank performance without time limit was influenced by small effects with age (β = 6.86; p < .001, η2 = 0.03), flexibility (β = 0.79; p < .001, η2 = 0.03), and medium effects with cardiovascular endurance (β = 1.07; p < .001, η2 = 0.08), and waist circumference (β = −0.92; p < .001, η2 = 0.06). Interrater (ICC = 0.62; CI = 0.50, 0.75), intrarater (ICC = 0.83; CI = 0.73, 0.90) and test-retest (ICC = 0.63; CI = 0.46, 0.75) reliability were acceptable for the plank without time limit. These data suggest the plank without time limit is a feasible, valid and reliable assessment of torso muscular endurance for children 8–12 years of age.
Changes in Aerobic Fitness in Boys and Girls Over a Period of 25 Years: Data From the Amsterdam Growth and Health Longitudinal Study Revisited and Extended
Authors: Kemper Han C.G. , Twisk Jos W.R. , van Mechelen Willem
Published: August 2016

In the Amsterdam Growth And Health Longitudinal Study (AGAHLS), a group of approximately 650 12- to 14-year-old boys and girls was followed in their growth, and development of their health their lifestyle including diet, physical activity and smoking. One of the main interests was the change in their aerobic fitness. From 12 to 36 years of age in total, eight repeated measurements were performed to measure peak oxygen uptake (peak VO2). In this study the data of peak VO2 are revisited and extended: We made use of all collected data as a mixed longitudinal design including cross-sectionally measured subjects as well as longitudinally measured subjects. This led to the availability of 1,194 boys and 1356 girls. With generalized estimating equations (GEE) the longitudinal changes with chronological age and differences between boys and girls were analyzed. Teenage boys and girls increased their peak VO2 (ml/min) significantly (p < .001) until age 14 in girls and until age 17 in boys. However peak VO2 relative to bodyweight (peak VO2/BW) had significantly (p < .001) decreased over the whole age range from 12 to 36 in both sexes. Vigorous physical activity (VPA) also showed a decrease and was significantly (p < .001) related with lower peak VO2/BW (Beta = 0.001). This relation was stronger in boys than in girls. Because at the start of AGAHLS no fast responding metabolic instruments were available, future longitudinal studies about aerobic fitness should include also measurement of VO2 kinetics.
Aerobic Fitness and Physical Activity in Children
Authors: Armstrong Neil
Published: August 2016

In Volume 1 of Pediatric Exercise Science (PES), a paper by Fenster et al. (25) investigated the relationship between peak oxygen uptake (peak V̇O2) and physical activity (PA) in 6- to 8-year-old children. They used both questionnaires and large-scale integrated activity monitors (LSIs) to estimate daily PA and determined peak V̇O2 using an incremental treadmill test to volitional exhaustion. They concluded that peak V̇O2 correlated well with PA as measured by LSIs but commented that questionnaire data were only weakly and nonsignificantly associated with LSI and peak V̇O2 data. Peak V̇O2 and PA are the most researched and reported variables in the 25-year history of PES. Yet, the assessment and interpretation of young people’s aerobic fitness and PA remain problematic and any meaningful relationship between them during childhood and adolescence is shrouded with controversy. The present paper uses Fenster et al.’s (25) report as an indicator of where we were 25 years ago, outlines how far we have advanced since then, and suggests future directions of research in the study of aerobic fitness and PA.

In the first volume of PES, Fenster et al. (25) investigated the relationship between 6- to 8-year-old children’s peak oxygen uptake (peak V̇O2) and physical activity (PA). Five boys and 13 girls participated in the study and their data were pooled for analysis. Peak V̇O2 was determined during an incremental treadmill test to voluntary exhaustion and PA was estimated using both questionnaires and large-scale integrated activity monitors (LSIs). On the basis of a significant interclass correlation coefficient of r = .59 between peak V̇O2 and the log of LSI average counts per hour Fenster et al. (25) concluded that “aerobic capacity, as measured by peak V̇O2 correlated well with physical activity as measured by LSI” (p.134).

They also commented that questionnaire data were only weakly and nonsignificantly associated with LSI and peak V̇O2 data. Young people’s peak V̇O2 and PA are the most researched and reported variables in the 25-year history of PES and yet the assessment and interpretation of peak V̇O2 and PA and any meaningful relationship between them during growth and maturation are still shrouded with controversy. The present paper uses Fenster et al.’s (25) work as an indicator of our understanding of young people’s peak V̇O2 and PA in 1989, briefly reviews what we know in 2013, and suggests future directions of research.
Muscular Power of High School Wrestlers
Authors: Housh Terry J. , Johnson Glen O. , Housh Dona J.
Published: August 2016

The purpose of this investigation was to examine age related changes in muscular power of high school wrestlers. A total of 155 high school wrestlers (M age±SD = 16.5±2.4 yrs) volunteered as subjects for this investigation. The sample included only wrestlers who were ≤ 16.00 years (younger group, n=75) or >17.00 years (older group, n=80). All subjects completed a Wingate anaerobic test to determine mean (MP) and peak (PP) power as well as underwater weighing for body composition assessment. The results indicated significant (p<0.05) group differences for absolute MP and PP but no differences when adjusted for BW and FFW. Thus the enhanced muscular power in the older group of high school wrestlers was associated with increases in BW and FFW.
The Influence of Age and Sexual Maturation on Children’s Blood Lactate Responses to Exercise
Authors: Williams Joanne R. , Armstrong Neil
Published: August 2016

A total of 100 boys and 91 girls, ages 11 to 16 years, completed a discontinuous treadmill test to voluntary exhaustion to determine the oxygen uptake/blood lactate relationship. Maturational stage was assessed in 72 boys and 47 girls using Tanner’s indices. Mean blood lactate at peak VO2 was significantly higher in the girls compared to the boys (6.1 vs. 5.8 mmol•l-1, P<0.01). Lactate at peak VO2 and percent peak VO2 at 4.0 mmol•l-1 were not significantly correlated with chronological age (p>0.05) in either sex, although a relationship was obtained between chronological age and percent peak VO2 at 2.5 mmol•l-“1 for boys (r= ‒0.226, p<.05) and girls (r= ‒0.272, p0.05). Analysis of variance revealed no significant changes (p>0.05) in any of the lactate variables examined with progression through the Tanner stages of maturity.
Validity of the Caltrac Accelerometer in Estimating Energy Expenditure and Activity in Children and Adults
Authors: Maliszewski Ann F. , Freedson Patty S. , Ebbeling Chris J. , Crussemeyer Jill , Kastango Kari B.
Published: August 2016

The Caltrac accelerometer functions as either an activity monitor that provides activity counts based on vertical acceleration as the individual moves about, or as a calorie counter in which the acceleration units are used in conjunction with body size, age, and sex to estimate energy expenditure. This study compared VO2 based energy expenditure with Caltrac estimated energy expenditure during three speeds of treadmill walking in children and adults. It also tested the validity of the Caltrac to differentiate between high and low levels of walking activity (activity counts). Ten boys and 10 men completed three randomly assigned walks while oxygen consumption was monitored and Caltrac estimates were obtained. The results indicate that the Caltrac does not accurately predict energy expenditure for boys and men across the three speeds of walking. Although there were no significant differences between actual and predicted energy expenditure values, the standard errors of estimate were high (17-25%) and the only significant correlation was found for men at the fastest walking speed (r=.81). However, the 95% confidence intervals of the activity counts and energy expenditure estimates from the Caltrac support its use as an activity monitor during walking.
Cardiopulmonary Fitness, Physical Activity Patterns, and Selected Coronary Risk Factor Variables in 11- to 16-Year-Olds
Authors: Armstrong Neil , Williams Joanne , Balding John , Gentle Peter , Kirby Brian
Published: August 2016

The peak oxygen uptake (VO2) of 199 boys and 164 girls (mean age 13.2±1.3 yrs) was examined in relation to their body fatness, blood pressure, and serum cholesterol level. Peak VO2 was significantly correlated with skinfold thickness in both sexes (range r = −0.41 to −0.56). When the common effects of skinfold thickness were removed, no significant relationships were observed between peak VO2 and either serum cholesterol or blood pressure. The habitual physical activity (HPA) of 92 boys and 132 girls (mean age 13.0+1.3 yrs) was examined in relation to their body fatness, blood pressure, and serum cholesterol. No significant relationships were observed. The results of this study indicate that although skinfold thickness is negatively related to peak VO2, favorable relationships between children’s peak VO2 or HPA and either blood pressure or serum cholesterol remain to be proven.
Automated Exercise Blood Pressure Measurements in Children: A Preliminary Study
Authors: Treiber Frank A. , McCaffrey Francis , Strong William B. , Davis Harry , Baranowski Tom
Published: August 2016

This study compared blood pressure and heart rate measurements provided by the Quinton 410 automated exercise monitor with simultaneous auscultatory and electrocardiograph readings during rest, postural change, immediately after each treadmill exercise workload, and during active recovery in a sample of young children (mean age 7.9 yrs). The Quinton 410 provided highly accurate heart rates under all conditions (average mean difference <1.0 bpm). The Quinton systolic readings correlated well with and were similar to auscultation across conditions except for the initial treadmill workload. Slightly weaker relationships were observed between the Quinton and K4 diastolic comparisons. Compared with K4 auscultatory readings, the Quinton 410 provided slightly lower diastolic pressures across conditions (average mean difference = 3.1 mmHg). These findings provide preliminary evidence that for group comparisons with children, the Quinton 410 provides acceptable blood pressure estimates resulting from a variety of events, including exercise.