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Development of Upper-Extremity Morphological Asymmetries in Male and Female Elite Youth Tennis Players: A Longitudinal Study

Laurent Chapelle, Eva D’Hondt, Nikki Rommers, and Peter Clarys

Purpose: This 2-year longitudinal study examined the development of upper-extremity bone mineral density (BMD), bone mineral content (BMC), and lean mass (LM) asymmetry magnitudes in male and female youth tennis players. Methods: Dominant and nondominant upper-extremity BMD, BMC, and LM values of 49 male and 31 female players were measured yearly using dual X-ray absorptiometry. From these values, asymmetry magnitudes were calculated and expressed as a percentage. Maturity offset was estimated using anthropometric measurements. Linear mixed effect models examined the development of BMD, BMC, and LM asymmetry magnitudes according to players’ maturity offset, sex, and training volume. Results: Adjusted for sex and training volume, a 1-year increment in maturity offset was associated with a significant increase in BMD (1.3% [2.2%]; P < .001) and BMC (0.6% [2.4%]; P = .011) asymmetry magnitudes. Male players displayed significantly higher LM asymmetry magnitudes (Δ3.2% [8.4%]; P = .002) compared with their female counterparts. Training volume was not significantly associated with asymmetry magnitude development. Conclusion: In contrast to LM, male and female youth tennis players’ upper-extremity bones are still responsive to mechanical loading with a significant increase in BMD and BMC asymmetry magnitudes according to maturity offset.

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Motor Unit Firing Properties During Force Control Task and Associations With Neurological Tests in Children

Masamichi Okudaira, Ryosuke Takeda, Tetsuya Hirono, Taichi Nishikawa, Shun Kunugi, and Kohei Watanabe

The present study aimed to clarify the development of motor unit (MU) firing properties and the association between those neural properties and force steadiness (FS)/neurological tests in 6- to 12-year-old children. Fifty-eight school-aged children performed maximal voluntary knee extension contraction, a submaximal FS test at 10% of maximal voluntary knee extension contraction, knee extension reaction time to light stimulus test, and single-leg standing test, and data from 38 children who passed the criteria were subject to analysis. During the FS test, high-density surface electromyography was recorded from the vastus lateralis muscle to identify individual MU firing activity. FS was improved with an increase in age (r = −.540, P < .001). The MU firing rate (MUFR) was significantly decreased with an increase in age (r = −.343, P = .035). MUFR variability was not associated with age. Although there was no significant correlation between FS and MUFR, FS was significantly correlated with MUFR variability even after adjustment for the effect of age (r = .551, P = .002). Neither the reaction time nor the single-leg standing test was correlated with any MU firing properties. These findings suggest that MUFR variability makes an important contribution to precise force control in children but does not naturally develop with age.

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Volume 35 (2023): Issue 3 (Aug 2023)

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Physical Activity in Pediatric Inflammatory Bowel Disease: A Scoping Review

Lee Hill, Noushin Roofigari, Maria Faraz, Jelena Popov, Michal Moshkovich, Melanie Figueiredo, Emily Hartung, Meryem Talbo, Marie-Laure Lalanne-Mistrih, Mary Sherlock, Mary Zachos, Brian W. Timmons, Joyce Obeid, and Nikhil Pai

Background: Inflammatory bowel disease (IBD) is a chronic, systemic condition affecting the gastrointestinal tract. IBD can be severe and are associated with impairment in growth, school absences, abdominal pain, and fatigue. Physical activity (PA) could have an anti-inflammatory effect in addition to other benefits. It is important to address the possible risks, physiological effects of PA, and potential barriers, and facilitators for PA participation in pediatric IBD. However, potential barriers and facilitators to PA have yet to be adequately described. Methods: We conducted a scoping review to map and describe the current literature on PA in pediatric IBD populations between 1980 and April 2022 using Preferred Reporting Items for Systematic Reviews and Meta-analysis guidelines for Scoping reviews. Results: Nineteen articles were identified including 10 descriptive, 6 interventional, and 3 physiological responses to PA studies. Patients and healthy controls demonstrated similar responses to exercise. Barriers to participation were low self-esteem, body image, and active IBD symptoms. Facilitators included personal interest, activity with friends, and support from family. Conclusion: This review highlighted that PA participation may reduce in children with IBD-related symptoms. Short- and medium-term impacts of PA on immune modulation require further study; it is possible that regular PA does not negatively affect biomarkers of disease activity.

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Physical Activity Levels During School Recess in a Nationally Representative Sample of 10- to 11-Year-Olds

Lan Sum Wong, John J. Reilly, Paul McCrorie, and Deirdre M. Harrington

Purpose: School recess provides a valuable opportunity for children’s daily moderate- to vigorous-intensity physical activity (MVPA). This study aimed to quantify MVPA during school recess in a representative sample of Scottish children and examine whether recess MVPA varied by gender, socioeconomic status, season, urban/rural residency, and recess length. Method: Five-day accelerometry MVPA data were analyzed from 773 children (53.9% girls, 46.1% boys, 10- to 11-y-olds) from 471 schools. Binary logistic regression explored associations between meeting/not meeting the recommendation to spend 40% of recess time in MVPA and the aforementioned risk factors. Descriptive recess data were also analyzed. Results: Participants spent an average of 3.2 minutes (SD 2.1) in MVPA during recess. Girls engaged in 2.5 minutes (SD 1.7) of MVPA compared with 4.0 minutes (SD 2.2) for boys. Only 6% of children met the recess MVPA recommendation. The odds of girls (odds ratio 0.09; 95% confidence interval, 0.04–0.25) meeting the recommendation was lower (P < .001) compared with boys. No statistically significant differences were observed in meeting the recommendation for the other risk factors. Conclusion: Levels of MVPA during school recess are very low in Scottish children, and interventions aimed at increasing MVPA during recess are needed.

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A Pilot Study of Exercise Training for Children and Adolescents With Inflammatory Bowel Disease: An Evaluation of Feasibility, Safety, Satisfaction, and Efficacy

Mila Bjelica, Rachel G. Walker, Joyce Obeid, Robert M. Issenman, and Brian W. Timmons

Background: Children with inflammatory bowel disease (IBD) experience extraintestinal side effects including altered body composition, impaired muscle strength, and aerobic capacity. Exercise training may remedy these issues. Purpose: To assess the feasibility, safety, participant satisfaction, and efficacy of a training program for youth with IBD. Methods: Children with IBD completed 16 weeks of training (2 supervised + 1 home sessions per week). Feasibility was assessed by tracking recruitment, adherence, and compliance rates. Safety was assessed by tracking symptoms and adverse events. Posttraining interviews gauged satisfaction. Circulating inflammatory markers, body composition, muscle strength, aerobic fitness, and habitual physical activity were measured at baseline, midtraining (8 wk), and posttraining. Results: Eleven youth were recruited and 10 completed the study. Participants adhered to 28 (1) of 32 prescribed supervised sessions and 8 (4) of 16 prescribed home sessions. There were no adverse events, and overall feedback on training was positive. Posttraining, we observed an increase in lean mass (+2.4 [1.1] kg), bone density (+0.0124 [0.015] g·cm−2), aerobic fitness (+2.8 [5.7] mL·kg LM−1· min−1), and vigorous physical activity levels (+13.09 [8.95] min·h−1) but no change in inflammation or muscle strength. Conclusion: Supervised exercise training is feasible, safe, and effective for youth with IBD and should be encouraged.

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Acute and Long-Term Changes in Blood-Borne Biomarkers in Response to Dynamic Standing in Nonambulant Children With Cerebral Palsy

Tibor V. Varga, Åsa Andersson, Katarina Lauruschkus, and Åsa B. Tornberg

Purpose: To investigate acute and long-term changes in hormonal and inflammatory biomarkers in nonambulant children with cerebral palsy in response to dynamic standing exercise. Methods: Fourteen children with severe cerebral palsy were recruited. Anthropometrics and body composition measures were obtained. Physical activity levels before the study were assessed using hip-worn accelerometry. All children underwent a 30-minute dynamic standing exercise using the Innowalk standing aid. Respiratory data during exercise were collected using indirect calorimetry. Blood samples were collected before and after exercise. Blood samples were also obtained after two 16-week exercise protocols, in a resting state. Hormonal and inflammatory metabolites were measured from blood serum/plasma, and acute and long-term changes in biomarker levels were assessed using Wilcoxon signed-rank tests. Results: Of the 14 children at baseline, all had slightly/moderately/severely elevated C-reactive protein and cortisol levels. C-reactive protein levels were decreased following a 30-minute bout of dynamic standing (before exercise: 53 mg/L [interquartile range: 40–201]; after exercise: 39 mg/L [interquartile range: 20–107]; P = .04). Conclusions: We show that several hormonal and inflammatory biomarkers are dysregulated in children with cerebral palsy. Our preliminary results from a small, but deep-phenotyped prospective cohort indicate acute and long-term alterations of several biomarkers in response to exercise.

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Editor’s Notes

Craig A. Williams

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Mediolateral Postural Control Mechanisms and Proprioception Improve With Kicking Sports Training During Adolescence

Mariève Blanchet and François Prince

Sensorimotor stimulation during the sensitive period is crucial for proper brain development. Kicking sports (KS) training stimulates these sensorimotor functions. The purpose of this study was to investigate if incorporating specific sensorimotor stimulation in mediolateral axis and proprioceptive inputs during KS training will improve the specific sensorimotor performance in adolescents. We assessed stability limits in 13 KS practitioners and 20 control participants. Starting from an upright position, subjects were asked to lean as far as possible (forward, backward, rightward, and leftward). Three sensory conditions were tested: (1) eyes open, (2) eyes closed, and (3) eyes closed while standing on a foam mat. We analyzed the maximal center of pressure excursion and the root means square of the center of pressure displacements. Results showed that KS group had smaller root means square and larger maximal center of pressure excursions than those of control participants in mediolateral axis in all sensory conditions. Furthermore, the results also revealed a significant smaller root means square excursion in KS group under foam mat condition compared to control group ML axis. This study provides evidence that KS training improved the lateral balance control and proprioceptive integration.

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Physical Activity Questionnaire for Children: Validity and Cut-Points to Identify Sufficient Levels of Moderate- to Vigorous-Intensity Physical Activity Among Children and Adolescents Diagnosed With HIV

João Antônio Chula de Castro, Luiz Rodrigo Augustemak de Lima, Richard Larouche, Mark S. Tremblay, and Diego Augusto Santos Silva

Purpose: To investigate the validity of the Physical Activity Questionnaire for Older Children (PAQ-C) to assess the moderate- to vigorous-intensity physical activity (MVPA) level of children and adolescents diagnosed with HIV and propose cut-points, with accelerometer measures as the reference method. Method: Children and adolescents, aged 8–14 years (mean age = 12.21 y, SD = 2.09), diagnosed with HIV by vertical transmission, participated in the study. MVPA was investigated through the PAQ-C and triaxial accelerometer (ActiGraph GT3X+). Receiver operating characteristic curve and sensitivity and specificity values were used to identify a cut-point for PAQ-C to distinguish participants meeting MVPA guidelines. Results: Fifty-six children and adolescents participated in the study. Among those, 16 met MVPA guidelines. The PAQ-C score was significantly related to accelerometry-derived MVPA (ρ = .506, P < .001). The PAQ-C score cut-point of 2.151 (sensitivity = 0.625, specificity = 0.875) was able to discriminate between those who met MVPA guidelines and those that did not (area under the curve = 0.751, 95% confidence interval, 0.616–0.886). Conclusion: The PAQ-C was useful to investigate MVPA among children and adolescents diagnosed with HIV and to identify those who meet MVPA guidelines.