High muscular fitness level may positively affect bone strength and body composition in children with overweight and obesity.

Muscular fitness plays a major role in bone health and body composition in overweight and obese children. It is key that the development of this muscle fitness is affected by absolute isometric strength and dynamic strength. PURPOSE: To compare bone health and body composition between overweight/obese children considering muscular fitness (MF) levels, and to investigate whether weight-bearing dynamic or absolute isometric strength, both involved in the development of this muscular fitness, are more related with bone health. METHODS: MF of 59 overweight or obese children (10.1 ± 0.9 years, 27 females) was measured by a countermovement jump (CMJ), handgrip, and maximal isometric strength of knee extension. Participants were divided into four groups depending on their MF level performing a cluster analysis: 16 children with high MF (HMF) in all tests, 18 with high performance in isometric strength (HIS), 15 with high performance in CMJ (HCMJ) and 10 low isometric and low dynamic force values (LMF). Body composition values were measured by dual energy X-ray absorptiometry, and bone strength values were assessed by peripheral quantitative computed tomography. Motor skills were evaluated using TGMD-3. Multivariate analysis of covariance test was applied to analyse bone strength differences between children in the different MF groups, using maturity offset, height and weight as covariates, and correlations were investigated. RESULTS: HMF excelled in bone health. HIS had higher cortical bone area, periosteal circumference, bone mass, polar strength strain index and fracture load than LMF, while HCMJ only showed better results in trabecular bone area than LMF. HMF had significantly better values of fracture load and periosteal and endosteal circumferences than HCMJ, but not than HIS. CONCLUSIONS: High MF level shows positive effects on bone health in overweight/obese children. Those with highest isometric strength had better bone health compared to those with higher dynamic strength. TRIAL REGISTRATION: The research project was registered in a public database Clinicaltrials.gov in June 2020 with the identification number NCT04418713.

Effects of whole-body vibration on body composition, microbiota, cardiometabolic markers, physical fitness, and quality of life after bariatric surgery: protocol for a randomized controlled trial.

BACKGROUND: Morbid obesity is a complex chronic condition characterized by a body mass index of 40 kg/m2 or higher. The incidence of the condition is on the rise in developed countries, and bariatric surgery has been proposed as a potential solution to address this trend. Nonetheless, bariatric surgery may also result in adverse effects, including a reduction in bone mineral density (BMD) and muscle mass, as well as an increased risk of fractures. The present study aims to elucidate the effects of bariatric surgery and whole-body vibration (WBV) training on body composition, microbiota, physical fitness, quality of life, and cardiometabolic markers. METHODS: Twenty-eight participants (14 females), aged 18 to 50 years, will undergo sleeve gastrectomy surgery. They will be randomly allocated into a control group or a WBV training group. The WBV group will train three times per week with increasing intensities and duration ranging from 30 to 45 min over the 4-month training period. Measurements of body composition (dual-energy X-ray absorptiometry and peripheral quantitative computed tomography), physical fitness (muscular strength, agility, cardiorespiratory fitness, and balance), gait biomechanics, cardiometabolic markers, gut microbiota, quality of life, and physical activity levels will be collected at four different time points: (1) prior to the surgery, (2) 45 days post-surgery, (3) 6 months post-surgery, and (4) 18 months post-surgery. DISCUSSION: Both groups are expected to experience improvements in most of the aforementioned variables. Nonetheless, we expect the WBV group to show larger improvements proving that the training is effective and safe. TRIAL REGISTRATION: Clinicaltrials.gov NCT05695599. Registered on January 25, 2023.

Impact of Suspected Preterm Labor during Pregnancy on Cardiometabolic Profile and Neurodevelopment during Childhood: A Prospective Cohort Study Protocol.

INTRODUCTION: Suspected preterm labor (SPL), defined as the presence of regular and painful uterine contractions and cervical shortening, represents a prenatal insult with potential long-term consequences. However, despite recent evidence demonstrating suboptimal neurodevelopment at 2 years in this population, it remains underestimated as a significant risk factor for neurodevelopmental disorders or other chronic diseases. The aim of this study is to assess the impact of suspected preterm labor during pregnancy on cardiometabolic profile and neurodevelopment during childhood (6-8 years). METHODS AND ANALYSIS: Prospective cohort study including children whose mothers suffered suspected preterm labour during pregnancy and paired controls. Neurodevelopmental, cardiovascular, and metabolic assessments will be performed at 6-8 years of age. A trained psychologist will carry out the neurodevelopment assessment including intelligence, visual perception, and behavioral assessment. Body composition and physical fitness assessment will be performed by one trained pediatrician and nurse. Finally, cardiovascular evaluation, including echocardiography and blood pressure, will be performed by two pediatric cardiologists. Data regarding perinatal and postnatal characteristics, diet, lifestyle, and weekly screen time of the child will be obtained from medical history and direct interviews with families. Primary outcome measures will include body mass index and adiposity, percentage of fat mass and total and regional lean mass, bone mineral content and density, cardiorespiratory resistance, isometric muscle strength, dynamic lower body strength, systolic and diastolic blood pressure, left ventricle (LV) systolic and diastolic function, general intelligence index, visuospatial working memory span, oculomotor control test, index of emotional, and behavioral problems.

Design of a Computer Model for the Identification of Adolescent Swimmers at Risk of Low BMD.

This paper aims to elaborate a decision tree for the early detection of adolescent swimmers at risk of presenting low bone mineral density (BMD), based on easily measurable fitness and performance variables. The BMD of 78 adolescent swimmers was determined using dual-energy X-ray absorptiometry (DXA) scans at the hip and subtotal body. The participants also underwent physical fitness (muscular strength, speed, and cardiovascular endurance) and swimming performance assessments. A gradient-boosting machine regression tree was built to predict the BMD of the swimmers and to further develop a simpler individual decision tree. The predicted BMD was strongly correlated with the actual BMD values obtained from the DXA (r = 0.960, p < 0.001; root mean squared error = 0.034 g/cm2). According to a simple decision tree (74% classification accuracy), swimmers with a body mass index (BMI) lower than 17 kg/m2 or a handgrip strength inferior to 43 kg with the sum of both arms could be at a higher risk of having a low BMD. Easily measurable fitness variables (BMI and handgrip strength) could be used for the early detection of adolescent swimmers who are at risk of suffering from low BMD.

Endocrine Evaluation and Homeostatic Model Assessment in Patients with Cornelia de Lange Syndrome.

Objective: The aim of this study was to expand knowledge about endocrine disorders in individuals with Cornelia de Lange syndrome (CdLS), a rare developmental genetic disorder with anomalies in multiple organs and systems. Methods: Hormone levels, clinical scores, anthropometric measurements, and molecular analysis were assessed in 24 individuals with CdLS. Results: Hyperprolactinemia was the most common endocrine disorder. Three patients showed subclinical hypothyroidism. In the gonadotropic axis, mildly delayed puberty was observed, as well as genital anomalies, such as cryptorchidism. Despite short stature, levels of insulin-like growth factor 1 and insulin-like growth factor-binding protein 3 were normal, on average. Three prepubertal individuals without risk factors had higher than normal values for the homeostatic model assessment of insulin resistance (HOMA-IR) and for insulinemia, suggesting insulin resistance. Furthermore, two adults had elevated BMIs associated with HOMA-IR values over the cut-off values. Conclusion: CdLS can lead to dysregulation of the endocrine system, particularly in patients with high HOMA-IR values and insulinemia who are at risk of insulin resistance. Therefore, clinical follow-ups with hormonal assessments are proposed for individuals with CdLS.

Do Serum 25-Hydroxyvitamin D Concentrations Affect Body Composition, Physical Fitness, Bone Strength and Bone Biomarkers in Female Children and Adolescent Football Players? A One-Season Study.

The aim was to compare changes in body composition, physical fitness, and bone biomarkers in female children and adolescent football players with different Vitamin D levels. Twenty-two players were classified into two groups according to 25(OH)D concentrations: 11 with deficient/insufficient 25(OH)D levels (IVD; <30 ng/mL) and 11 with sufficient 25(OH)D levels (SVD; ≥30 ng/mL). Body composition parameters were measured using dual-energy X-ray absorptiometry and a peripheral quantitative computed tomography scanner. The following physical fitness tests were applied: maximal isometric knee extension (MIF), long jump, 30-m sprint, and 20-m shuttle run test (VO2max). Electrochemiluminescence immunoassays were used to analyze bone biomarkers and 25(OH)D. All variables were registered at the beginning and the end of the football season. The increase in subtotal bone mineral density (BMD) was higher in players with SVD than those with IVD (p = 0.030). Only players with SVD improved their MIF of the left leg (p = 0.005); whereas, only players with IVD decreased their 30-m sprint performance (p = 0.007) and VO2max (p = 0.046). No significant between- and within-group differences were found for bone biomarkers. SVD might cause an extra improvement of subtotal BMD in female children and adolescent football players. Moreover, it seems that the 25(OH)D concentration could be an important parameter for physical fitness improvement in this population.

Effect of an Active Video Game Intervention Combined With Multicomponent Exercise for Cardiorespiratory Fitness in Children With Overweight and Obesity: Randomized Controlled Trial.

BACKGROUND: Childhood overweight and obesity have become major global health problems and are negatively related with the cardiorespiratory fitness (CRF) level in school children and adolescents. Exercise, specifically multicomponent training, is effective for CRF improvement, but the main challenge is to ensure adherence to exercise in children with overweight and obesity. Therefore, new ways of exercising that are more attractive and motivational for this population are needed and playing or training with active video games (AVGs) has been proposed as an effective alternative because they require full-body movement and therefore increase energy expenditure. OBJECTIVE: The main aim of this study was to investigate the effects of an AVG intervention combined with multicomponent training on CRF at maximal and submaximal intensities in children with overweight or obesity. METHODS: We recruited 28 children (13 girls and 15 boys) aged 9 to 11 years with overweight or obesity from medical centers and divided them into 2 groups, an intervention group (n=20) that participated in a 5-month supervised AVG exercise program combined with multicomponent exercise, and a control group (n=8) that continued daily activities without modification. A maximal stress test to measure CRF using a walking-graded protocol with respiratory gas exchange was performed by the participants. RESULTS: The AVG group showed a significant decrease in heart rate and oxygen uptake for the same intensities in the submaximal stages of the maximal treadmill test, as well as a lower oxygen uptake percentage according to the individual maximal oxygen uptake, whereas the control group did not show overall changes. No change in the peak oxygen uptake (VO2peak) was found. CONCLUSIONS: A 5-month AVG intervention combined with multicomponent exercise had positive effects on CRF at submaximal intensity, showing a lower heart rate and oxygen uptake at the same intensities and displaying a lower oxygen uptake percentage according to the individual (VO2peak). Greater benefits were found in children with the highest fat percentage. TRIAL REGISTRATION: ClinicalTrials.gov NCT04418713; https://clinicaltrials.gov/show/NCT04418713.

Active Video Games Improve Muscular Fitness and Motor Skills in Children with Overweight or Obesity.

(1) Background: Childhood obesity is an important public health problem. Children with overweight or obesity often tend to show the pediatric inactivity triad components; these involve exercise deficit disorder, pediatric dynapenia, and physical illiteracy. The aim of the study was to examine the influence of an active video games (AVG) intervention combined with multicomponent exercise on muscular fitness, physical activity (PA), and motor skills in children with overweight or obesity. (2) Methods: A total of 29 (13 girls) children (10.07 ± 0.84 years) with overweight or obesity were randomly allocated in the intervention group (AVG group; n = 21) or in the control group (CG; n = 8). The intervention group performed a 5-month AVG training using the Xbox 360® with the Kinect, the Nintendo Wii®, dance mats, and the BKOOL® interactive cycling simulator, combined with multicomponent exercise, performing three sessions per week. The control group continued their daily activities without modification. Weight, PA using accelerometers, and motor competence using the Test of Gross Motor Development 3rd edition were measured. Muscular fitness was evaluated through the Counter Movement Jump height, maximal isometric strength of knee extension and handgrip strength, and lean mass using Dual-energy X-ray Absorptiometry. Mann−Whitney U and Wilcoxon signed rank tests were performed. The biserial correlation coefficients (r) were calculated. Spearman's correlation coefficients among PA, muscular fitness, and motor competence variables were also calculated. (3) Results: The AVG group significantly increased their knee extension maximal isometric strength (4.22 kg; p < 0.01), handgrip strength (1.93 kg; p < 0.01), and jump height (1.60 cm; p < 0.01), while the control group only increased the knee extension maximal isometric strength (3.15 kg; p < 0.01). The AVG group improved motor competence and light physical activity (p < 0.05) and decreased sedentary time (p < 0.05). Lean mass improved in both AVG group and CG (p < 0.05). Lastly, the percentage of improvement of motor skills positively correlated with the percentage of improvement in vigorous PA (r = 0.673; p = 0.003) and the percentage of improvement in CMJ (r = 0.466; p = 0.039). (4) Conclusions: A 5-month intervention combining AVG with multicomponent training seems to have positive effects on muscle fitness, motor competence, and PA in children with overweight or obesity.

Nonspecific Resistance Training and Swimming Performance: Strength or Power? A Systematic Review.

ABSTRACT: Muniz-Pardos, B, Gomez-Bruton, A, Matute-Llorente, A, Gonzalez-Aguero, A, Gomez-Cabello, A, Gonzalo-Skok, O, Casajus, JA, and Vicente-Rodriguez, G. Nonspecific resistance training and swimming performance: Strength or power? A systematic review. J Strength Cond Res 36(4): 1162-1170, 2022-The purpose of this systematic review was to determine the type of nonspecific resistance intervention that is more effective to enhance swimming performance and to determine the nonspecific strength- or power-related variable that better predicts swimming performance. A search was conducted on PubMed, Cochrane Plus, and SportDiscus up to June 2018. Studies were distributed into 4 categories: dry-land strength (DLS), dry-land power (DLP), combination of training methods, and strength and power in start performance. From 1,844 citations, 33 met the inclusion criteria. Cross-sectional DLS studies showed positive associations between swimming performance and DLS development (especially through upper-body isometric assessments), although the efficacy of DLS training interventions remains unclear. Dry-land power training (principally through plyometrics) was a proficient, nonspecific method to enhance swimming block start performance (SBS; the start phase off the block and during the first 5-15 m), and jump assessment was the best predictor of SBS. Some pioneering nonspecific practices such as the acute exposure to high altitude or the maintenance of a high core temperature during the transition phase before competition seem to improve performance, although more research is required to confirm their efficacy. Further high-quality intervention studies are required to clarify the effect of DLP training on sprint swimming performance.

Does Acute Caffeine Supplementation Improve Physical Performance in Female Team-Sport Athletes? Evidence from a Systematic Review and Meta-Analysis.

INTRODUCTION: Recent original research and meta-analyses suggest that acute caffeine supplementation improves exercise performance in team-sport athletes (TSA). Nonetheless, most of the studies testing the effects of caffeine on TSA included samples of male athletes, and there is no meta-analysis of the performance-enhancing effects of caffeine on female TSA. The aim of the present study was to synthesize the existing literature regarding the effect of caffeine supplementation on physical performance in adult female TSA. METHODS: A search was performed in Pubmed/Medline, SPORTDiscus and Scopus. The search was performed from the inception of indexing until 1 September 2021. Crossover randomized controlled trials (RCT) assessing the effects of oral caffeine intake on several aspects of performance in female TSA were selected. The methodological quality and risk of bias were assessed for individual studies using the Physiotherapy Evidence Database scale (PEDro) and the RoB 2 tool. A random-effects meta-analysis of standardized mean differences (SMD) was performed for several performance variables. RESULTS: The search retrieved 18 articles that fulfilled the inclusion/exclusion criteria. Overall, most of the studies were of excellent quality with a low risk of bias. The meta-analysis results showed that caffeine increased performance in specific team-sport skills (SMD: 0.384, 95% confidence interval (CI): 0.077-0.691), countermovement jump (SMD: 0.208, CI: 0.079-0.337), total body impacts (SMD: 0.488; 95% CI: 0.050, 0.927) and handgrip strength (SMD: 0.395, CI: 0.126-0.665). No effects were found on the ratings of perceived exertion, squat jumps, agility, repeated sprint ability or agility tests performed after fatigue. CONCLUSIONS: The results of the meta-analysis revealed that acute caffeine intake was effective in increasing some aspects of team-sports performance in women athletes. Hence, caffeine could be considered as a supplementation strategy for female athletes competing in team sports.

Effects of Active Video Games on Health-Related Physical Fitness and Motor Competence in Children and Adolescents With Overweight or Obesity: Systematic Review and Meta-Analysis.

BACKGROUND: Childhood obesity is one of the most important public health problems. Active video games (AVGs) have been proposed as an attractive alternative to increase energy expenditure and are being investigated to determine their effectiveness against childhood obesity. OBJECTIVE: The aim of this study is to summarize the existing research and draw conclusions about the effects of AVGs on health-related physical fitness and motor competence in children and adolescents with overweight and obesity. METHODS: The search strategy was applied to PubMed, MEDLINE, Web of Science, and SPORTDiscus, including randomized and nonrandomized controlled trials investigating the effects of AVG programs on health-related physical fitness and motor competence in children and adolescents with overweight and obesity. To measure the risk of bias in randomized and nonrandomized controlled trials, 2 different quality assessment tools were used. In total, 15 articles met the inclusion criteria, and the variables of interest were BMI, body fat percentage, cardiorespiratory fitness (CRF), waist circumference, fat-free mass, muscular fitness, and motor competence. A meta-analysis was performed. RESULTS: Positive effects were found for BMI and body fat percentage, favoring the AVG group compared with a control group with no intervention (mean difference -0.209; 95% CI -0.388 to -0.031 vs mean difference -0.879; 95% CI -1.138 to -0.602). Positive effects seem to be observed for CRF. The effects of AVG interventions on muscular fitness, fat-free mass, waist circumference, and motor competence are unclear. CONCLUSIONS: AVG programs showed positive effects on BMI, body fat percentage, and CRF. AVG could be a good strategy to combat childhood obesity.

The Effects of Active Video Games on Health-Related Physical Fitness and Motor Competence in Children and Adolescents with Healthy Weight: A Systematic Review and Meta-Analysis.

(1) Background: Poor levels of physical fitness and motor skills are problems for today's children. Active video games (AVG) could be an attractive strategy to help address them. The aim was to investigate the effects of AVG on health-related physical fitness and motor competence in children and adolescents with healthy weight. (2) Methods: Randomized and non-randomized controlled trials investigating the effects of AVG programs on health-related physical fitness and motor competence were included. Two different quality assessment tools were used to measure the risk of bias. Twenty articles met the inclusion criteria and the variables of interest were body mass index (BMI), body fat, cardiorespiratory fitness (CRF), muscular fitness and motor competence. (3) Results: AVG interventions seem to have benefits in BMI when lasting longer than 18 weeks (SMD, -0.590; 95% IC, -1.071, -0.108) and in CRF (SMD, 0.438; 95% IC, 0.022, 0.855). AVG seems to be a promising tool to improve muscular fitness and motor competence but the effects are still unclear due to the lack of evidence. (4) Conclusions: AVG seem to be an effective tool for improving some components of health-related physical fitness and motor competence in healthy-weight children and adolescents, but the effect on some fitness components needs further research. Therefore, AVG may be included as a strategy to improve health.

Impact of the Home Confinement Related to COVID-19 on the Device-Assessed Physical Activity and Sedentary Patterns of Spanish Older Adults.

The main objective of this study was to device-assess the levels of physical activity and sedentary behaviour patterns of older adults during the situation prior to the COVID-19 pandemic, home confinement, and phase-0 of the deescalation. We also aimed to analyse the effectiveness of an unsupervised home-based exercise routine to counteract the potential increase in sedentary behaviour during the periods within the pandemic. A total of 18 noninstitutionalized older adults(78.4 ± 6.0 y.), members of the Spanish cohort of the EXERNET-Elder 3.0 project, participated in the study. They were recommended to perform an exercise prescription based on resistance, balance, and aerobic exercises during the pandemic. Wrist triaxial accelerometers (ActiGraph GT9X) were used to assess the percentage of sedentary time, physical activity, sedentary bouts and breaks of sedentary time. An ANOVA for repeated measures was performed to analyse the differences between the three different periods. During home quarantine, older adults spent more time in sedentary behaviours (71.6 ± 5.3%) in comparison with either the situation prior to the pandemic (65.5 ± 6.7%) or the ending of isolation (67.7 ± 7.1%) (all p < 0.05). Moreover, participants performed less bouts of physical activity and with a shorter duration during home quarantine (both p < 0.05). Additionally, no differences in the physical activity behaviours were found between the situation prior to the pandemic and the phase-0 of deescalation. According to our results, the home confinement could negatively affect health due to increased sedentary lifestyle and the reduction of physical activity. Therefore, our unsupervised exercise program does not seem to be a completely effective strategy at least in this period.

25-Hydroxyvitamin D and Cardiorespiratory Fitness in Prepubertal Overweight and Obese Children.

Childhood obesity has become a major global health problem. Vitamin D deficiency and poor cardiorespiratory fitness are highly prevalent in children with overweight or obesity, but little is known about their relationships. In this study, we aimed to analyze the relationship between serum 25-hydroxyvitamin D (25(OH)D) and cardiorespiratory fitness parameters in prepubertal obese and overweight children. A cross-sectional design with a sample of 57 prepubertal children, aged 9-11 years, with overweight or obesity was used. The fasting concentration of 25(OH)D was analyzed with a chemiluminescent microparticle immunoassay. Fat and lean body masses were determined by using DXA. Maximal oxygen uptake (VO2max) was measured with the maximal treadmill test. A total of 68.4% of the sample had sufficient levels of 25(OH)D. As expected, their cardiorespiratory fitness was poor compared with that of normal-weight children, but 60% of the group exceeded the median obesity-specific reference values. No differences were found between the sexes for relative VO2max or 25(OH)D levels. Moreover, no correlations were found between 25(OH)D and body composition or cardiorespiratory parameters for sex or vitamin D groups. Vitamin D status seems not to be directly related to body composition or cardiorespiratory fitness in prepubertal overweight or obese children.

Injuries of a Spanish top-level sample of football referees. A retrospective study

OBJECTIVE: To analyze the incidence and injury pattern in Spanish football (soccer) referees. METHOD: In this retrospective study, Spanish referees filled out an online survey during a training camp organized by the Referees Technical Committee of the Real Federación Española de Fútbol. The survey included questions on aspects of refereeing qualifications, training and matches, injury patterns (type, location, and circumstances), and absence of the 2018-2019 season. RESULTS: A total of 28 elite referees (24.1%) out of 116 reported having suffered one injury during the season. Significant differences in the frequency of injuries between match (MRs) and assistant referees (ARs) were observed. MRs were 1.90 (95% CI 1.008-3.582) times as likely to suffer an injury compared to ARs. The incidence of match injuries for MRs officiating in the top division of the Spanish Football League was 1.30 (95% CI 0.0-3.82) per 1000 match hours while for ARs was 0.7 (95% CI 0.0-2.1); the incidence of training injuries was considerably lower in both groups (0.4 (95% CI 0.0-0.9) vs. 0.3 (95% CI 0.0-0.6). Hamstring- and calf-related muscle problems were the most common injury diagnoses in elite referees. Injured referees had, on average, 2 weeks of absence from training and competition. CONCLUSION: Elite MRs had a 90% increase in the risk of suffering an injury in comparison with elite ARs. The incidence of match injury or training injury was very low in both groups, despite that, they should continue carrying out preventive programs specially targeted for hamstring- and calf-related muscle problems

No disponible

Assessment of Active Video Games' Energy Expenditure in Children with Overweight and Obesity and Differences by Gender.

(1) Background: Childhood obesity has become a main global health problem and active video games (AVG) could be used to increase energy expenditure. The aim of this study was to investigate the energy expenditure during an AVG intervention combined with exercise, differentiating by gender. (2) Methods: A total of 45 children with overweight or obesity (19 girls) performed an AVG intervention combined with exercise. The AVG used were the Xbox Kinect, Nintendo Wii, dance mats, BKOOL cycling simulator, and Nintendo Switch. The energy expenditure was estimated from the heart rate recorded during the sessions and the data from the individual maximal tests. (3) Results: The mean energy expenditure was 315.1 kilocalories in a one-hour session. Participants spent the most energy on BKOOL, followed by Ring Fit Adventures, Dance Mats, Xbox Kinect, and the Nintendo Wii, with significant differences between BKOOL and the Nintendo Wii. Significant differences between boys and girls were found, but were partially due to the difference in weight, VO2max, and fat-free mass. (4) Conclusions: The energy expenditure with AVG combined with multi-component exercise was 5.68 kcal/min in boys and 4.66 kcal/min in girls with overweight and obesity. AVG could be an effective strategy to increase energy expenditure in children and adolescents with overweight and obesity.

Association Between Physical Fitness and Bone Strength and Structure in 3- to 5-Year-Old Children.

BACKGROUND: The positive association between physical fitness and bone structure has been widely investigated in children and adolescents, yet no studies have evaluated this influence in young children (ie, preschoolers). HYPOTHESIS: Fit children will present improved bone variables when compared with unfit children, and no sex-based differences will emerge in the sample. STUDY DESIGN: Cross-sectional study. LEVEL OF EVIDENCE: Level 3. METHODS: Handgrip strength, standing long jump (SLJ), speed/agility, balance, and cardiorespiratory fitness (CRF) were assessed using the Assessing FITness levels in PREschoolers (PREFIT) test battery in 92 children (50 boys; age range, 3-5 years). A peripheral quantitative computed tomography scan was performed at 38% of the length of the nondominant tibia. Cluster analysis from handgrip strength, SLJ, speed/agility, and CRF was developed to identify fitness groups. Bone variables were compared between sexes and between cluster groups. The association between individual physical fitness components and different bone variables was also tested. RESULTS: Three cluster groups emerged: fit (high values on all included physical fitness variables), strong (high strength values and low speed/agility and CRF), and unfit (low strength, speed/agility, and CRF). The fit group presented higher values than the strong and unfit groups for total and cortical bone mineral content, cortical area, and polar strength strain index (all P < 0.05). The fit group also presented a higher cortical thickness when compared with the unfit group (P < 0.05). Handgrip, SLJ, and speed/agility predicted all bone variables except for total and cortical volumetric bone mineral density. No differences were found for bone variables between sexes. CONCLUSION: The results suggest that global fitness in preschoolers is a key determinant for bone structure and strength but not volumetric bone mineral density. CLINICAL RELEVANCE: Physical fitness is a determinant for tibial bone mineral content, structure, and strength in very young children. Performing physical fitness tests could provide useful information related to bone health in preschoolers.

Effects of whole-body vibration training on bone density and turnover markers in adolescent swimmers.

Background Whole-body vibration training has recently been proposed as a complementary training modality to improve the bone health of adolescent swimmers. However, there is no longitudinal study regarding the effects of this training combination on bone metabolism. Therefore, the main goal was to analyze the effects of swimming and vibration training on bone turnover markers during adolescence. Methods The present study included 68 adolescent swimmers and 41 normoactive controls (CON). Swimmers were randomly selected to either continue with their regular swimming training (SWI) or participate in an additional vibration protocol (VIB). Anthropometric measurements and serum level determinations of osteocalcin (OC), procollagen type 1 N-terminal propeptide (P1NP) and C-terminal telopeptide crosslaps (CTX) were performed before and after the 6-month intervention. Results Statistically significant group by time interactions were found for both bone formation markers. VIB showed a decrease over time in OC (baseline: 101.4 µg/mL, follow-up: 82.8 µg/mL, p < 0.05) and P1NP (baseline: 528.4 µg/mL, follow-up: 389.0 µg/mL, p < 0.05) and SWI had analogous reductions in P1NP (baseline: 685.8 µg/mL, follow-up: 542.0 µg/mL, p < 0.05), whereas CON experienced an increase in OC levels (baseline: 94.4 µg/mL, follow-up: 103.4 µg/mL, p < 0.05). After stratifying the sample according to the pubertal status, similar interactions were observed. Conclusions The combination of swimming training and this particular vibration protocol led to a decrease in bone formation markers, especially during early puberty. Whole-body vibration might not induce an osteogenic stimulus in adolescent swimmers.

Adaptation of Proximal Femur to Mechanical Loading in Young Adults: Standard Vs Localized Regions Evaluated by DXA.

Regions of the proximal femur with less adaptive protection by mechanical loading may be at increased risk of structural failure. Since the size and location of these regions diverge from those defined by the dual-energy X-ray absorptiometry manufacturers the purpose of this study was to compare areal bone mineral density (aBMD) of different regions of the proximal femur considering impact loads from physical activity (PA). The participants were 134 young adults divided into 2 groups according to the impact of PA performed in the last 12 mo: high-impact PA and low-impact PA. The aBMD of the proximal femur was assessed by dual-energy X-ray absorptiometry at the standard femoral neck, intertrochanter, and trochanter, and at specific locations of the superolateral femoral neck and intertrochanteric region. The bone-specific physical activity questionnaire was used to estimate the impact load of PA. Comparisons between groups were adjusted for body height and body lean mass. Interaction analysis between sex and PA groups were conducted with analysis of variance. Comparisons of aBMD between bone regions were analyzed separately for men and women with repeated measures analysis of variance. In the high-impact PA group, men benefit more than women at all bone regions, except the aBMD at intertrochanteric region. Analyses of repeated measures did not reveal any significant interaction effect between bone regions (standard vs specific) and PA groups (low vs high-impact). In conclusion, aBMD differences due to mechanical loading were more pronounced in men than in women; the magnitude of the aBMD differences as a result of different levels of PA was similar between standard and localized regions.

Long-Term Effects of Whole-Body Vibration in Trained Adolescent Swimmers: Does It Increase Strength, Power, and Swimming Performance?

PURPOSE: To examine the effects of a 6-month whole-body vibration (WBV) training on lower-body strength (LBS), lower-body power (LBP), and swimming performance in adolescent trained swimmers. METHODS: Thirty-seven swimmers (23 males and 14 females; 14.8 [1.3] y) were randomly assigned to the WBV (n = 20) or the control group (n = 17). Isometric LBS (knee extension and half squat) and LBP (vertical and horizontal jumps and 30-m sprint) tests were performed before and after the intervention period. Swimming performance times in 100 m were collected from official competitions. As time × sex interaction was not found for any variable (P > .05), males and females were analyzed as a whole. RESULTS: Within-group analyses showed a most likely beneficial moderate effect of WBV on isometric knee extension (effect size [ES] = 0.63), 30-m sprint test (ES = 0.62), and 100-m performance (ES = 0.25), although these were corresponded with comparable small to moderate effects in the control group (ES = 0.73, 0.71, and 0.20, respectively). The control group obtained a small possibly beneficial effect of swimming-only training on vertical jump performance, whereas no effect was observed in the WBV group. Unclear effects were observed for the rest of the variables assessed. Between-group analyses revealed unclear effects of WBV training when compared with the control condition in all studied variables. CONCLUSIONS: There is no current evidence to support the use of WBV training, and therefore, coaches and sports specialists should select other methods of training when the aim is to increase LBS, LBP, or swimming performance.