bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of Training Status and Maturity on Pulmonary O2 Uptake Recovery Kinetics Following Cycle and Upper Body Exercise in Girls
Authors: McNarry Melitta A. , Welsman Joanne R. , Jones Andrew M.
Published: August 2016

The influence of training status on pulmonary VO2 recovery kinetics, and its interaction with maturity, has not been investigated in young girls. Sixteen prepubertal (Pre: trained (T, 11.4 ± 0.7 years), 8 untrained (UT, 11.5 ± 0.6 years)) and 8 pubertal (Pub: 8T, 14.2 ± 0.7 years; 8 UT, 14.5 ± 1.3 years) girls completed repeat transitions from heavy intensity exercise to a baseline of unloaded exercise, on both an upper and lower body ergometer. The VO2 recovery time constant was significantly shorter in the trained prepubertal and pubertal girls during both cycle (Pre: T, 26 ± 4 vs. UT, 32 ± 6; Pub: T, 28 ± 2 vs. UT, 35 ± 7 s; both p < .05) and upper body exercise (Pre: T, 26 ± 4 vs. UT, 35 ± 6; Pub: T, 30 ± 4 vs. UT, 42 ± 3 s; both p < .05). No interaction was evident between training status and maturity. These results demonstrate the sensitivity of VO2 recovery kinetics to training in young girls and challenge the notion of a “maturational threshold” in the influence of training status on the physiological responses to exercise and recovery.
Patterning of Affective Responses During a Graded Exercise Test in Children and Adolescents
Authors: Benjamin Charlotte C. , Rowlands Alex , Parfitt Gaynor
Published: August 2016

Past studies have shown the patterning of affective responses during a graded exercise test (GXT) in adult and male adolescent populations, but none have explored the patterns in adolescent girls or younger children. This study explored the patterning of affective responses during a GXT in adolescents and younger children. Forty-nine children (21 male and 28 female) aged between 8–14 years (10.8 ± 1.8 years) completed a GXT. Ventilatory threshold (VT) was identified. At the end of each incremental step, participants reported affective valence. Results revealed that affective valence assessed by the Feeling Scale (FS) significantly declined from the onset of exercise until the point of VT in the younger children, but remained relatively stable in the adolescents. Exercise above the VT brought about significant declines in affective valence regardless of age or sex, but the decrease was significantly greater in adolescents. Results suggest it may be preferable to prescribe lower exercise intensities (below VT) for children, compared with adolescents, to ensure a positive affective response.
Using the Oxygen Uptake Efficiency Slope as an Indicator of Cardiorespiratory Fitness in the Obese Pediatric Population
Authors: Breithaupt Peter G. , Colley Rachel C. , Adamo Kristi B.
Published: August 2016

The aim of the current study was to investigate the relationship between the Oxygen Uptake Efficiency Slope (OUES) and traditional measures of cardiorespiratory function in an overweight/obese pediatric sample. Maximal treadmill exercise testing with indirect calorimetry was completed on 56 obese children aged 7–18 years. Maximal OUES, submaximal OUES, VO2peak, VEpeak, and ventilatory threshold (VT) were determined. In line with comparable research in healthy-weight samples, maximal and submaximal OUES were both correlated with VO2peak, VEpeak, and VT (r2= 0.44−0.91) in the obese pediatric sample. Correlations were also found with anthropometric variables, including height (cm), body surface area (m2), body mass (kg), and fat free mass (kg). In comparing our data to a published sample of healthy weight children, maximal and submaximal exercise OUES were both higher in our obese sample. However, when we adjusted for any of body mass (kg), BSA (m2), or FFM (kg) the obese children were found to be less efficient. The results of this study suggest the use of OUES to be an appropriate measure of efficiency of ventilation and cardiorespiratory function in obese children, while also showing that our sample of obese children were less efficient on a per kilogram basis when compared with their healthy weight peers.
A Steps/Minute Value for Moderate Intensity Physical Activity in Adolescent Females
Authors: Harrington Deirdre M. , Dowd Kieran P. , Tudor-Locke Catrine , Donnelly Alan E.
Published: August 2016

The number of steps/minute (i.e., cadence) that equates to moderate intensity in adolescents is not known. To that end, 31 adolescent females walked on a treadmill at 5 different speeds while wearing an ActivPAL accelerometer and oxygen uptake was recorded by indirect calorimetry. The relationship between metabolic equivalents (METs) and cadence was explored using 3 different analytical approaches. Cadence was a significant predictor of METs (r=.70; p<.001). Moderate intensity (3 METs) corresponded to 94 or 114 steps/minute based on the mixed model and ROC analysis, respectively. These two values, and a practical value of 100 steps/minute, were cross-validated on an independent sample of 33 adolescent females during over-ground walking at 3 speeds. The sensitivity and specificity of each value correctly identifying 3 METs were 98.5% and 87.2% for 94 steps/minute, 72.9% and 98.8 for 114 steps/minute and 96.5% and 95.7% for 100 steps/minute. Compromising on a single cadence of 100 steps/minute would be a practical value that approximates moderate intensity in adolescent females and can be used for physical activity interpretation and promotion.
Locomotive and Non-Locomotive Activity as Determined by Triaxial Accelerometry and Physical Fitness in Japanese Preschool Children
Authors: Tanaka Chiaki , Hikihara Yuki , Ohkawara Kazunori , Tanaka Shigeho
Published: August 2016

This study examined the potential relationship between participation in physical activity (PA) assessed by triaxial accelerometry and physical fitness testing, including health-related and skill-related parameters of fitness, in 136 Japanese preschoolers (65 girls and 71 boys, 5.5 ± 0.6 years). In partial correlation analyses, grip strength and 20m shuttle run test were positively correlated with time spent in physical activity ratio (PAR) ≥ 4. Better scores on standing long jump distance and jump over and crawl under tests were associated with lower sedentary time and greater moderate-to-vigorous PA time and PAR ≥ 4 time, and increased physical activity level. Moreover, 25m run speed was positively correlated with time spent in PAR ≥ 4 and locomotive activity. These findings suggest that development of both health-related (muscle strength and aerobic fitness) and skill-related fitness (power, agility and speed) may make engagement in PA easier for preschool children, although further research on the cause-effect relationship is needed.
Physical Activity and Self-Concept: The SEARCH for Diabetes in Youth Case Control Study
Authors: O’Neill Jennifer R. , Liese Angela D. , McKeown Robert E. , Cai Bo , Cuffe Steven P. , Mayer-Davis Elizabeth J. , Hamman Richard F. , Dabelea Dana
Published: August 2016

In this study, the relationship between physical activity (PA) and 3 self-concept constructs (physical abilities, physical appearance, and general self-concept) was examined. Youth with type 1 diabetes (n = 304), type 2 diabetes (n = 49), and nondiabetic controls (n = 127) aged 10−20 years wore pedometers over 7 days. Youth completed the Self-Description Questionnaire and correlation coefficients were calculated. Mean steps/day were 7413 ± 3415, 4959 ± 3474 and 6870 ± 3521 for type 1, type 2 and control youth, respectively. Significant correlations were found between steps/day and perception of physical abilities (r = .29; r = .31; r = .31) for type 1, type 2, and control youth, respectively. The other correlations were not significant. Among youth with type 2 diabetes, steps/day were significantly correlated with physical appearance (r = .46). The positive correlation between PA and physical abilities suggests a reciprocal relationship between behavior and perception.
Modeling Developmental Changes in Functional Capacities and Soccer-Specific Skills in Male Players Aged 11-17 Years
Authors: Valente-dos-Santos João , Coelho-e-Silva Manuel J. , Simões Filipe , Figueiredo Antonio J. , Leite Neiva , Elferink-Gemser Marije T. , Malina Robert M. , Sherar Lauren
Published: August 2016

This study evaluates the contributions of age, growth, skeletal maturation, playing position and training to longitudinal changes in functional and skill performance in male youth soccer. Players were annually followed over 5 years (n = 83, 4.4 measurements per player). Composite scores for functional and skill domains were calculated to provide an overall estimate of performance. Players were also classified by maturity status and playing position at baseline. After testing for multicollinearity, two-level multilevel (longitudinal) regression models were obtained for functional and skill composite scores. The scores improved with age and training. Body mass was an additional predictor in both models [functional (late maturing): 13.48 + 1.05 × centered on chronological age (CA)—0.01 × centered CA2—0.19 × fat mass (FM) + 0.004 × annual volume training—1.04 × dribbling speed; skills (defenders): 7.62 + 0.62 × centered CA—0.06 × centered CA2 + 0.04 × fat-free mass—0.03 × FM + 0.005 × annual volume training—0.19 × repeated-sprint ability + 0.02 × aerobic endurance]. Skeletal maturity status was a significant predictor of functional capacities and playing position of skill performance. Sound accuracy of each multilevel model was demonstrated on an independent cross-sectional sample (n = 52).
Biomechanical Comparison in Different Jumping Tasks Between Untrained Boys and Men
Authors: Lazaridis Savvas N. , Bassa Eleni I. , Patikas Dimitrios , Hatzikotoulas Konstantinos , Lazaridis Filippos K. , Kotzamanidis Christos M.
Published: August 2016

This study examines the biomechanical differences during different vertical jump tasks in 12 prepubescent and 12 adult males. The sagittal knee kinematics, vertical ground reaction force (vGRF) and electromyographic (EMG) activity of 5 lower extremity muscles were recorded. Compared with boys, men presented higher peak vGRF during the propulsive phase in all examined jumps, but lower values during the braking phase, even when related to body mass. Normalized EMG agonist activity in all phases was higher in men (p < .05), while antagonist coactivation was enhanced in boys (p < .05). The knee joint was on average 9 degrees more flexed at touchdown in men during drop jump tasks, but boys exhibited 12 degrees and 17 degrees higher knee flexion at the deepest point when performing drop jump from 20 and 40 cm, respectively. In conclusion, the performance deficit observed in boys in all jump types is a reflection of their immature technique, which could be partly attributed to the less efficient stiffness regulation and activation of their neuromuscular system.
Objectively Measured Sedentary Time, Physical Activity and Markers of Body Fat in Preschool Children
Authors: España-Romero Vanesa , Mitchell Jonathan A. , Dowda Marsha , O’Neill Jennifer R. , Pate Russell R.
Published: August 2016

The purpose of this study was to examine the associations between sedentary behavior and moderate to vigorous physical activity (MVPA), measured by accelerometry, with body mass index (BMI) and waist circumference in 357 preschool children. Linear mixed models were used adjusting for race/ethnicity, parental education, and preschool. Follow-up analyses were performed using quantile regression. Among boys, MVPA was positively associated with BMI z-score (b = 0.080, p = .04) but not with waist circumference; quantile regression showed that MVPA was positively associated with BMI z-score at the 50th percentile (b = 0.097, p < .05). Among girls, no associations were observed between sedentary behavior and MVPA in relation to mean BMI z-score and mean waist circumference. Quantile regression indicated that, among girls at the 90th waist circumference percentile, a positive association was found with sedentary behavior (b = 0.441, p < .05), and a negative association was observed with MVPA (b = −0.599, p < .05); no associations were found with BMI z-score. In conclusion, MVPA was positively associated with BMI z-score among boys, and MVPA was negatively associated and sedentary behavior was positively associated with waist circumference among girls at the 90th percentile.
BMI Change, Fitness Change and Cardiometabolic Risk Factors Among 8th Grade Youth
Authors: Jago Russell , Drews Kimberly L. , McMurray Robert G. , Baranowski Tom , Galassetti Pietro , Foster Gary D. , Moe Ester , Buse John B.
Published: August 2016

This paper examined whether a two-year change in fitness, body mass index (BMI) or the additive effect of change in fitness and BMI were associated with change in cardiometabolic risk factors among youth. Cardiometabolic risk factors, BMI group (normal weight, overweight or obese) were obtained from participants at the start of 6th grade and end of 8th grade. Shuttle run laps were assessed and categorized in quintiles at both time points. Regression models were used to examine whether changes in obesity, fitness or the additive effect of change in BMI and fitness were associated with change in risk factors. There was strong evidence (p < .001) that change in BMI was associated with change in cardiometabolic risk factors. There was weaker evidence of a fitness effect, with some evidence that change in fitness was associated with change in total cholesterol, HDL-C, LDL-C and clustered risk score among boys, as well as HDL-C among girls. Male HDL-C was the only model for which there was some evidence of a BMI, fitness and additive BMI*fitness effect. Changing body mass is central to the reduction of youth cardiometabolic risk. Fitness effects were negligible once change in body mass had been taken into account.
Stroke Volume Dynamics During Progressive Exercise in Healthy Adolescents
Authors: Rowland Thomas , Unnithan Viswanath
Published: August 2016

Understanding cardiac responses to exercise in healthy subjects is important in the evaluation of youth with heart disease. This review article incorporates previously published original research from the authors’ laboratory to examine changes in stroke volume during progressive exercise which are consistent with a model in which circulatory responses are controlled by alterations in the systemic vascular resistance. Stroke volume dynamics and cardiovascular responses to a progressive upright cycle test were examined in three groups of healthy, untrained adolescent subjects. These indicated a) a progressive decease in systemic vascular resistance, b) little change in stroke volume after an initial rise related to orthostatic changes in ventricular refilling, c) evidence of a constant or slightly declining left ventricular end diastolic filling pressure, d) and increases in markers of ventricular contractility. These observations are consistent with peripheral (vascular resistance) rather than central (cardiac) control of circulation with exercise. Changes in stroke volume during exercise need to be interpreted in respect to alterations in heart rate and myocardial functional capacity.
Role of Free Testosterone in Interpreting Physical Performance in Elite Young Brazilian Soccer Players
Authors: Moreira Alexandre , Mortatti Arnaldo , Aoki Marcelo , Arruda Ademir , Freitas Camila , Carling Christopher
Published: August 2016

This study investigated the contribution of salivary testosterone (sT) concentration, years from peak height velocity (YPHV) and height by body mass interaction on jumping performance (Countermovement jump; CMJ) and aerobic fitness (Yo-Yo intermittent endurance test, level 1) in young elite soccer players. Forty-five participants (age: 12.5 ± 0.5y; body mass: 48.6 ± 10.2kg, height: 155.7 ± 10.0cm) belonging to a top level Brazilian soccer club were evaluated at four time points across a single semester. None of the assessed players had reached PHV. The data from the four evaluations were averaged and multiple linear regression analysis conducted. For CMJ, the model explained 42.88% of the variance (R2 = 42.88; p < .000); sT concentration was the primary contributor (R2 = 32.84) and the YPHV contributed 9.95% of the variance. The model explained 28.50% (p < .000) of the variance in Yo-Yo. The sT was the primary and single significant contributor (R2 = 21.32). A significant difference was noted between high and low testosterone groups divided a posteriori to CMJ performance (t = 3.35; p = .001). These results suggest an important role for hormonal status in interpreting physical performance in preadolescent soccer players.
Pacing Strategies of Inexperienced Children During Repeated 800 m Individual Time-Trials and Simulated Competition
Authors: Lambrick Danielle , Rowlands Alex , Rowland Thomas , Eston Roger
Published: August 2016

Prior experience of fatiguing tasks is considered essential to establishing an optimal pacing strategy. This study examined the pacing behavior of inexperienced children during self-paced, 800 m running, both individually and within a competitive environment. Thirteen children (aged 9−11 y) completed a graded-exercise test to volitional exhaustion on a treadmill (laboratory trial), followed by three self-paced, individual 800 m time-trials (Trials 1−3) and one self-paced, competitive 800 m time-trial (Trial 4) on an outdoor athletics track. Ratings of perceived exertion (RPE) and heart rate (HR) were measured throughout all trials. Overall performance time improved from Trial 1−3 (250.1 ± 50.4 s & 242.4 ± 51.5 s, respectively, p < .017). The difference in overall performance time between Trials 3 and 4 (260.5 ± 54.2 s) was approaching significance (p = .06). The pacing strategy employed from the outset was consistent across all trials. These findings dispute the notion that an optimal pacing strategy is learned with exercise experience or training.
Resting IL-6 and TNF-α Level in Children of Different Weight and Fitness Status
Authors: Hosick Peter A. , McMurray Robert G. , Hackney A.C. , Battaglini Claudio L. , Combs Terry P. , Harrell Joanne S.
Published: August 2016

Reports suggest children with high aerobic fitness (VO2max; mL/kg/min) have healthier profiles of TNF-α and IL-6; however, research has not accounted for differences in adiposity between high-fit and low-fit individuals. Thus, this study examined differences in inflammatory markers of obese and normal weight children of different fitness levels, using two different VO2max units: per unit of fat free mass (VO2FFM) or total body mass (VO2kg). Children (n = 124; ages 8–12) were divided into four matched groups; normal weight high-fit (NH), normal weight low-fit (NL), obese high-fit (OH), and obese low-fit (OL). Height, weight, skinfolds, body mass index (BMI), and predicted VO2max were measured and a morning, fasting blood sample taken. IL-6 was elevated in the NL and OL groups compared with the NH group, as well as the OL group compared with the OH group. No differences were found in TNF-α. The relationship between IL-6 or TNF-α and the two units of predicted VO2max did not differ suggesting that either VO2FFM or VO2kg can be used to describe aerobic power when studying inflammation and exercise in youth. The relationship between IL-6 or TNF-α and predicted VO2max, whether expressed per mass or per fat-free mass was similar, suggesting that both can be used to describe aerobic power when studying inflammation and exercise in youth. Given the polar design of this study, this relationship should be confirmed including overweight subjects.
Double Dose: The Cumulative Effect of TV Viewing at Home and in Preschool on Children’s Activity Patterns and Weight Status
Authors: Ross Sharon Taverno , Dowda Marsha , Saunders Ruth , Pate Russell
Published: August 2016

Little is known about how screen-based sedentary behavior at home and in preschool influences children’s health and activity patterns. The current study examined the individual and cumulative influence of TV viewing at home and in preschool on children’s physical activity (PA) and weight status. Children (n = 339) attending 16 preschools in South Carolina were grouped into high and low TV groups based on parent report of children’s TV viewing at home and director report of TV use/rules in preschool. T-tests and mixed model ANOVAs examined differences in weight status and PA (min/hr) by high and low TV groups. Results revealed that children who were classified as High TV both at home and in preschool had significantly lower levels of moderate-to-vigorous PA compared with their Low TV counterparts (8.3 (0.3) min/hr vs. 7.6 (0.2) min/hr, p < .05). However, there were no significant differences in weight status or physical activity between the high and low TV groups at home or in preschool when examined individually. These findings demonstrate the importance of total environmental TV exposure on preschooler’s PA. Longitudinal and observational research to assess preschoolers’ cumulative screen-based sedentary behavior and its relationship with PA and weight status is needed.
Reliability of Maximal Handgrip Strength Test in Pre-Pubertal and Pubertal Wrestlers
Authors: Gerodimos Vassilis , Karatrantou Konstantina
Published: August 2016

The purpose of this study was to evaluate the intersession and the intrasession reliability of maximal handgrip strength test in young wrestlers. Twenty-seven prepubertal (9.49 ± 0.96yrs) and twenty-seven pubertal (14.60 ± 0.50yrs) male wrestlers performed two assessment sessions separated by one day. Both assessments included a testing protocol consisted of three maximal isometric contractions, on both hands using a hydraulic dynamometer (Jamar). The intersession and intrasession reliability was high for both prepubertal and pubertal wrestlers (ICC = 0.87−0.99). The single trial as well as the best of two and three trials of handgrip strength were slightly less reliable (ICC = 0.87−0.94) than the mean of two and three trials in prepubertal (ICC = 0.95−0.97). The present results indicate that maximum handgrip strength can be measured reliably, using the Jamar dynamometer, in young wrestlers. A single trial as well as the two trials can be used as reliable, less-tiring and less time-consuming methods for the evaluation of handgrip strength than the three trials.
Pseudonephritis is Associated With High Urinary Osmolality and High Specific Gravity in Adolescent Soccer Players
Authors: Van Biervliet Stephanie , Van Biervliet Jean Pierre , Watteyne Karel , Langlois Michel , Bernard Dirk , Walle Johan Vande
Published: August 2016

The study aimed to evaluate the effect of exercise on urine sediment in adolescent soccer players. In 25 15-year-old (range 14.4–15.8 yrs) athletes, urinary protein, osmolality and cytology were analyzed by flow cytometry and automated dipstick analysis before (T0), during (T1), and after a match (T2). All athletes had normal urine analysis and blood pressure at rest, tested before the start of the soccer season. Fifty-eight samples were collected (T0: 20, T1: 17, T2: 21). Proteinuria was present in 20 of 38 samples collected after exercise. Proteinuria was associated with increased urinary osmolality (p < .001) and specific gravity (p < .001). Hyaline and granular casts were present in respectively 8 of 38 and 8 of 38 of the urinary samples after exercise. The presence of casts was associated with urine protein concentration, osmolality, and specific gravity. This was also the case for hematuria (25 of 38) and leucocyturia (9 of 38). Squamous epithelial cells were excreted in equal amounts to white and red blood cells. A notable proportion of adolescent athletes developed sediment abnormalities, which were associated with urinary osmolality and specific gravity.
Peak-Power Estimation Equations in 12- to 16-Year-Old Children: Comparing Linear with Allometric Models
Authors: Duncan Michael J. , Hankey Joanne , Nevill Alan M.
Published: August 2016

This study examined the efficacy of peak-power estimation equations in children using force platform data and determined whether allometric modeling offers a sounder alternative to estimating peak power in pediatric samples. Ninety one boys and girls aged 12–16 years performed 3 countermovement jumps (CMJ) on a force platform. Estimated peak power (PPest) was determined using the Harman et al., Sayers SJ, Sayers CMJ, and Canavan and Vescovi equations. All 4 equations were associated with actual peak power (r = 0.893−0.909, all p < .01). There were significant differences between PPest using the Harman et al., Sayers SJ, and Sayers CMJ equations (p < .05) and actual peak power (PPactual). ANCOVA also indicated sex and age effect for PPactual (p < .01). Following a random two-thirds to one-third split of participants, an additive linear model (p = .0001) predicted PPactual (adjusted R2 = .866) from body mass and CMJ height in the two-thirds split (n = 60). An allometric model using CMJ height, body mass, and age was then developed with this sample, which predicted 88.8% of the variance in PPactual (p < .0001, adjusted R2 = .888). The regression equations were cross-validated using the one-third split sample (n = 31), evidencing a significant positive relationship (r = .910, p = .001) and no significant difference (p = .151) between PPactual and PPest using this equation. The allometric and linear models determined from this study provide accurate models to estimate peak power in children.
A Comparison of Physical Abilities and Match Performance Characteristics Among Elite and Subelite Under-14 Soccer Players
Authors: Waldron Mark , Murphy Aron
Published: August 2016

This study aimed to identify characteristics of match performance and physical ability that discriminate between elite and subelite under-14 soccer players. Players were assessed for closed performance and movement, physiological responses, and technical actions during matches. Elite players covered more total m·min−1 (115.7 ± 6.6 cf. 105.4 ± 7.7 m·min−1) and high-intensity m·min−1 (elite = 14.5 ± 2.3 cf. 11.5 ± 3.7 m·min−1) compared with subelite players. Elite players also attempted more successful (0.41 ± 0.11 cf. 0.18 ± 0.02) and unsuccessful ball retentions·min−1 (0.14 ± 0.04 cf. 0.06 ± 0.02) compared with subelite players. Elite players were faster over 10 m (1.9 ± 0.1 cf. 2.3 ± 0.2 s) and faster dribblers (16.4 ± 1.4 cf. 18.2 ± 1.1 s) compared with subelite players. Speed (10 m) and successful ball retention·min−1 contributed to a predictive model, explaining 96.8% of the between-group variance. The analysis of match performance provides a more thorough understanding of the factors underlying talent among youth soccer players.
Tracking of Accelerometer-Measured Physical Activity in Early Childhood
Authors: Edwards Nicholas M. , Khoury Philip R. , Kalkwarf Heidi J. , Woo Jessica G. , Claytor Randal P. , Daniels Stephen R.
Published: August 2016

Establishing and maintaining healthy physical activity (PA) levels is important throughout life. The purpose of this study was to determine the extent of PA tracking between ages 3 and 7 y. Objective measures of PA (RT3, triaxial accelerometer) were collected every 4 mo from ages 3–7; data from 234 children with PA measures available during each year of age were analyzed. Mean PA (total, moderate/vigorous (MV), and inactivity [IA]) was calculated for each year of age and adjusted for wear time. Correlations with age 3 PA were moderate at age 4 (r = .42−.45) but declined by age 7 (r = .19−.25). After classification into sex-specific tertiles of PA at age 3, boys in the high age 3 MVPA tertile maintained significantly higher PA at all subsequent ages, while girls in the high age 3 MVPA tertile were not significantly higher at age 6 and 7. Boys and girls in the high age 3 IA tertile had significantly higher IA at multiple subsequent years of age (p < .05 at ages 5 and 6). In conclusion, boys who were relatively more active at age 3 remained more active for several subsequent years. These findings highlight early-childhood differences in physical activity patterns between boys and girls.
Youth Resistance Training: Past Practices, New Perspectives, and Future Directions
Authors: Faigenbaum Avery D. , Lloyd Rhodri S. , Myer Gregory D.
Published: August 2016

Since the publication of the seminal review on youth resistance training by Kraemer and colleagues in 1989, a compelling body of evidence has found that resistance training can be a safe, effective, and worthwhile method of conditioning for children and adolescents. New perspectives for promoting resistance exercise as part of a long-term approach to youth physical development highlight the importance of integrating resistance training into youth fitness programs. Youth who do not enhance their muscular strength and motor skill proficiency early in life may not develop the prerequisite skills and abilities that would allow them to participate in a variety of activities and sports with confidence and vigor later in life. The identification of asymptomatic children with muscular weaknesses or imbalances may facilitate the development of a management plan which should rectify movement limitations and educate children and their families about the importance of daily physical activity.
Exercise and Cystic Fibrosis (CF) 2.0
Authors: Cerny Frank
Published: August 2016

In 1989 we knew that exercise, including regular prescribed physical activity, could be safely performed and described some of the physiological responses to exercise in patients with cystic fibrosis (CF). Also in 1989, the genetic defect causing cystic fibrosis (CF) was identified leading to improvements in treatment that greatly extended the life span for these patients. Increased understanding of the factors limiting exercise capacity and of the important role of regular exercise in slowing the progression of CF and in modulating some of the effects of the genetic defect on airway function has led to the consensus that regular exercise should be part of the standard of care for this disease.
Description of the Physical Activity of Young Children Using Movement Sensor and Observation Methods
Authors: Danner Fred , Noland Melody , McFadden Molly , DeWalt Kathleen , Kotchen J. Morley
Published: August 2016

This study examined the validity of the Caltrac motion sensor for measuring physical activity in young children and described change over time in physical activity among 47 preschool children from obese and nonobese families. Children were videotaped in a controlled setting while wearing Caltrac motion sensors and also wore Caltracs at home. Caltrac readings and an observational measure of physical activity were significantly related in both Year 1 (r= .86) and Year 2 (r= .83), and outside play was associated with higher Caltrac scores (r=.43). In addition, physical activity among young girls with obese parents decreased significantly from Year 1 to Year 2.
Use of the Rating of Perceived Exertion to Control Exercise Intensity in Children
Authors: Williams John G. , Eston Roger G. , Stretch Clare
Published: August 2016

This study examined the ability of 40 children (20 boys and 20 girls), ages 11 to 14 years, to regulate the intensity of their effort using perceived effort ratings during cycling. The Borg Rating of Perceived Exertion 6 to 20 Scale was learned and used as a perceptual frame of reference. Maximal oxygen uptake and power output were predicted from telemetered heart rate data collected during a submaximal graded exercise test. Subjects were then fully familiarized with the RPE scale and attended three consecutive sessions of cycling during which they adjusted the workloads themselves so as to produce effort intensities for scale ratings of 9 (very light), 13 (somewhat hard), and 17 (very hard). Heart rates were sampled during the final half minute of each session and the data were submitted to a mixed factorial analysis of variance. This showed highly significant differences (p<.001) between the three RPE levels but no significant effects for age, gender, or trials. It was concluded that the RPE is readily learned by older children and adolescents and is a potentially useful frame of reference when self-regulating effort intensity during vigorous exercise.
Sports Participation: A Physiological Profile of Children in Four Sports Over a 12-Week Season
Authors: Naughton Geraldine , Carlson John
Published: August 2016

This study examined the changes in the physiological profile of children engaged in organized sporting activity compared to a group of normally active children. Eight children (mean age 11.4 yrs) from each of four popular sports in Australia (badminton, basketball, netball, and tennis) and an equal number of nontraining children were monitored over a 12-week season. Very few differences occurred between the sporting groups and the control group. No change was reported between groups in peak oxygen uptake at the start and completion of the season. Changes occurring within each group did not consistently reflect any sport-specific characteristics over the season. Flexibility improved significantly, with an average gain of 3.76 cm in all groups except basketball players, who gained only 0.69 cm for the 12 weeks. Anaerobic power demonstrated significant improvement only within those sporting groups whose training specifically included explosive based activity. It is suggested that the active nature of the control children and use of only 12 weeks of data collection could have contributed to the limited physiological differences observed between active sporting and nonsporting children.
Walking Cadence of 9-Year-Olds Predictable as Resonant Frequency of a Force Driven Harmonic Oscillator
Authors: Holt Kenneth G. , Jeng Suh Fang , Fetters Linda
Published: August 2016

Preferred stride frequency (PSF) of adult human walking has been shown to be predictable as the resonant frequency of a force driven harmonic oscillator (FDHO). The purpose of this study was to determine whether the PSF of 9-year-old children was predictable using the same resonance formula as that of adults. Subjects walked around a gymnasium at a rate at which they felt comfortable. Stride frequency was measured as the time for 20 strides and the stride period was calculated. The best-fit prediction based on resonance was then calculated using the overall center of mass of three segments (foot, shank, thigh) to determine the simple pendulum equivalent (SPE) length. Results indicated that a constant of 2 applied to the gravitational constant of the resonance formula, the same formulation used for adults, can be used to predict the cadence of children.
Exercise Intensity Reproduction: Children versus Adults
Authors: Ward Dianne S. , Jackman Julie D. , Galiano Floyd J.
Published: August 2016

Seventeen children, ages 8-14 years, were compared to an adult group (n = 19) in their ability to execute prescriptive exercise using the Borg 6-20 rating of perceived exertion (RPE) scale. Subjects cycled at a controlled pace (setting resistance) for 2 minutes or traveled one lap of a 400-meter track at four RPE levels: 7, 10, 13, and 16. Results indicated that for pace-controlled cycling, children were similar to adults, reproducing four incremental intensities. Adults were closer to the laboratory determined criterion than the children were. For the self-paced walk/run tasks, both groups overexerted compared to the criterion. Children could only discriminate RPE 7 from the other levels. Based on these observations, it is recommended that exercise prescriptions for children using self-monitored intensity be preceded by adequate practice or be adjusted to account for different modes of activity.
Validity of Anthropometry and Bioimpedance with 4- to 8-Year-Olds Using Total Body Water as the Criterion
Authors: DeLozier Mollie G. , Gutin Bernard , Wang Jack , Basch Charles E. , Contento Isobel , Shea Steven , Zybert Matilde Irigoyen Patricia , Rips Jill , Pierson Richard
Published: August 2016

Anthropometric and bioimpedance regression equations were developed for young children using total body water (TBW) as the criterion. Ninety-six boys and girls, 4-8 years of age, served as subjects. Measures included height, weight, five skinfold thicknesses, three circumferences, total body bioimpedance, and separate bioimpedance measures of the arm, trunk, and leg. Height and weight alone accounted for .70 of the variance in TBW. Adding other measures did not significantly increase the R2. Standard errors of estimate for TBW were similar to those reported for older individuals (1.39-1.44 1) but may be too large relative to the small size of the subjects for the equations to be acceptable.
Syncope during Athletic Participation: A Diagnostic Case Study
Authors: Rowland Thomas W. , McFaul Richard C. , Burton David A.
Published: August 2016

Syncope during sports participation may serve as the first manifestation of cardiovascular disease that poses a risk for athletic training and competition. Other causes of syncope (vasovagal, dehydration) during physical activity may be more benign. The athlete who faints during sports deserves a comprehensive diagnostic evaluation that addresses the wide-ranging differential diagnosis involved. The case of a 14-year-old male with two syncopal spells during athletic training is presented to review the components of such a workup and subsequent management implications.
The Fat-Free Body and Subcomponents of the Fat-Free Body to Height Relationship between Swimmer and Nonswimmer Children
Authors: Slaughter Mary H. , Christ Constance B. , Stillman Rachel J. , Boileau Richard A.
Published: August 2016

This study was designed to determine whether there were differences in the relationships between fat-free body (FFB) to height and the subcomponents of the FFB—bone mineral content, bone width, bone mineral index, and total body water (TBW)—to height relationships among male and female age-group swimmers and nonswimmers. The 178 subjects (ages 8-16 yrs) were grouped by gender and activity level. Least-squares regression analysis was used to test the above relationships. Although there were no statistically significant differences in the FFB to height or the subcomponents of the FFB to height relationships between swimmers and nonswimmers in the male sample, the swimmer lines depicting the relationships typically fell above those of their nonswimmer counterparts. In the female sample, the FFB and TBW to height2.4 relationships differed significantly between the two groups, with the swimmers having greater values per unit of height than the non-swimmers.
Youth Sport Participation and Withdrawal: Is It Simply a Matter of FUN?
Authors: Petlichkoff Linda M.
Published: August 2016

In 1990 the Athletic Footwear Association (AFA) (1) released a report entitled “American Youth and Sports Participation” that examined teenagers’ (ages 10-18 years) feelings about their sport involvement. This report was the culmination of an extensive study of more than 10,000 young people from 11 cities across the U.S. in which issues related to why teenagers participate, why they quit, and their feelings about winning were addressed.1 The results highlighted in the AFA report indicate that (a) participation in organized sports declines sharply as youngsters get older, (b) “fun” is the key reason for involvement and “lack of fun” is one of the primary reasons for discontinuing, (c) winning plays less of a role than most adults would think, and (d) not all athletes have the same motivations for their involvement.
Ambulatory Minute Ventilation Estimated from Heart Rate Monitoring in Girls
Authors: Haines Douglas A. , Raizenne Mark E.
Published: August 2016

Models to indirectly estimate minute ventilation (V̇E) from heart rate (HR) monitored during normal activity were developed. VE-to-HR relationships were established from V̇E and HR measured in a graded cycle ergometer test performed by 99 girls, 7-14 years of age. The regression In V̇E = a + (b × HR) was a better predictor of V̇E, when individually determined, than were generalized prediction equations. V̇E, estimated by applying individual VE-to-HR regressions to HR monitored over 10 daytime hours, ranged between 11.5 and 14.5 L·min−1. This is a practical method of estimating V̇E, but further validation of the relationships with HR under various modes of exercise are necessary to improve the prediction in everyday settings.
Bone Density and Bone Mineral Content of Adolescent Soccer Athletes and Competitive Swimmers
Authors: McCulloch Robert G. , Bailey Donald A. , Whalen Robert L. , Houston C. Stuart , Faulkner Robert A. , Craven Bruce R.
Published: August 2016

This cross-sectional study compared differences in os calcis bone density and distal radius bone mineral content (BMC) among adolescent soccer players, competitive swimmers, and control subjects. Sixty-eight males and females (23 soccer players, 20 swimmers, 25 controls) ages 13 to 17 served as subjects. The results for os calcis trabecular density indicate a trend that may be of clinical significance and that may warrant further study. The swimmers had the lowest os calcis density in both sexes whereas the soccer players had the highest bone density at this weight-bearing site (F=2.54, p<.08). No differences with respect to distal radius BMC were observed among activity groups or between sexes.
Applicability of Criteria for V̇O2max in Active Adolescents
Authors: Rivera-Brown Anita M. , Rivera Miguel A. , Frontera Walter R.
Published: August 2016

This study examined the applicability of criteria for maximal oxygen consumption (V̇O2max) in adolescents. Active females (n=38) and males (n=196) who were students at a sports-technical junior high school performed a treadmill Bruce protocol to volitional fatigue. The criteria for V̇O2max were R ≥1.0, HR ≥95% of predicted maximal for age, and an increase in V̇O2 ≤2.1 ml·kg−1·min−1 with an increase in workload. The first criterion was met by 97% of the females and 93% of the males, while 81% of the females and 75% of the males met the second criterion. Only 8% of the females and 13% of the males met the third criterion. Those who achieved a plateau showed higher HR at peak exercise compared to those who did not (204 ±7.0 vs. 200.6 ±7.2, P≤0.05). Our data indicate that a high proportion of adolescents exhibit subjective and objective indicators of maximal performance without showing a plateau in V̇O2. Age-specific criteria for V̇O2max should be developed.
Reliability of the Nicholas Manual Muscle Tester on Upper Body Strength in Children Ages 8-10
Authors: Dawson Cynthia , Croce Ron , Quinn Tim , Vroman Neil
Published: August 2016

Hand-held dynamometry has proven reliable in assessing adult strength. The primary purpose of this study was to determine its reliability in children. Secondary purposes included investigating strength differences between males and females and between dominant (D) and nondominant (ND) sides. Subjects were 8-, 9-, and 10-year-old boys (n=63) and girls (n=54). The Nicholas Manual Muscle Tester (NMMT) was used to measure maximum isometric force of D and ND elbow flexors, elbow extensors, and shoulder abductors. Retest measurements were taken 4 to 7 days later. Results indicated that (a) correlation coefficients ranging from .72 to .90 were statistically significant; (b) except for males’ ND elbow extensor strength, a series of paired t tests revealed no significant differences between test and retest strength values; (c) a series of paired t tests revealed no significant strength differences between D and ND sides other than for males’ elbow extensor strength for the test phase; and (d) a series of unpaired t tests revealed statistically significant differences between males and females on a majority of the muscle groups. The NMMT appears to be a quick and reliable testing instrument for determining maximal isometric force in children.
Association of Exercise-Induced Bronchospasm with Obesity
Authors: Kaplan Ted A. , Campbell-Shaw Mary Helen , Moccia Gina
Published: August 2016

Exercise-induced bronchospasm (EIB) is present in many patients with asthma or with a family history of atopy. A review was made of exercise provocation testing performed on 37 children ages 5 to 17 years. Maximal forced expiratory maneuvers were performed before and serially every 3 minutes after a 7-min run/walk. A positive result was defined as a fall of at least 15% in FEV, or PEFR or 25% in FEF25-75 at some point within 20 min postexercise. A total of 27 out of 37 patients in this select group had positive tests (73%), with a mean fall in FEF25-75 of 31.9%. Of these 27 children with EIB, 16 had a history of atopy, 23 had clinical symptoms of EIB, and 21 were overweight. Of the 12 nonatopic children with EIB, 9 were overweight, with a mean fall in FEF25-75 of 32.1%. These 9 came from a total pool of 10 overweight, nonatopic children (90%). Being overweight was associated with a high incidence of EIB independent of a history of atopic disease.
Physiological Profiles of Performing and Recreational Early Adolescent Female Dancers
Authors: Padfield James A. , Eisenman Patricia A. , Luetkemeier Maurie J. , Fitt Sally S.
Published: August 2016

A physiological profile of 40 early adolescent female dancers was completed to investigate the characteristics of dancers this age and the possible physical fitness benefits of high levels of dance training. Of those physical fitness variables studied, the only significant difference between performing (high level) and recreational (low level) dancers was the degree of hip flexibility (p<.01). Both groups exhibited lean body density (combined mean of 1.069 g ml−1) as well as moderate aerobic (combined mean of 45.8 ml kg−1 min−1) and anaerobic power (combined mean of 6.5 Watt kg−1). These data suggest that early adolescent dance training encourages a certain level of physical fitness, but higher levels or duration of dance training do not result in or demand exceptional aerobic or anaerobic power.
Muscular Power of the Arms in High School Wrestlers
Authors: Evans Sharon A. , Eckerson Joan M. , Housh Terry J. , Johnson Glen O.
Published: August 2016

This investigation examined age related differences in the muscular power of the arms in high school wrestlers. Seventy-five volunteers (M age ±SD = 16.3 ±1.2 yrs) were stratified into four age groups (≤15.00; 15.01−16.00; 16.01−17.00, and ≥17.01 yrs) corresponding approximately to the freshman through senior years of high school. Mean power (MP) and peak power (PP) were measured using an arm crank Wingate Anaerobic Test, and body composition was assessed via underwater weighing. The results indicated significant (p<0.05) group differences for absolute MP and PP as well as for relative MP and PP (covaried for body weight). No significant differences were found when MP and PP were adjusted for fat-free weight (FFW). The results suggested that the age related increases in muscular power of the arms were a function of increases in FFW across age.
Estimation of Body Composition in Black Adolescent Male Athletes
Authors: Thorland William G. , Johnson Glen O. , Housh Terry J.
Published: August 2016

Twenty national class, junior level, track and field competitors were measured for body density (BD) via underwater weighing corrected for residual lung volume, and for skinfold (SF) thicknesses, to determine the accuracy of anthropometric estimations of body composition in athletic adolescent black males. BD was transformed to fat-free body (FFB) weight values using the formulas of Brozek, Lohman (age-adjusted), and Schutte (young black men), respectively. For each SF equation, total error (TE) was highest with the formula of Lohman (2.31–4.14 kg) and lowest with the formula of Schutte (2.02–3.62 kg). TE was further reduced when SF estimates of BD were transformed to FFB via the formula of Brozek and were compared to criterion values of FFB based on the formula of Schutte (2.05–3.10 kg). Therefore, racial influences affecting hydrostatically determined FFB differed from those affecting anthropometric estimations.