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 a multicomponent training followed by a detraining period on metabolic syndrome profile of older adults.

AIMS: The present study sought to analyze the effects of 6-month multicomponent training (MCT) combined with a 4-month detraining on metabolic syndrome (MetS) profile among older adults with decreased functional capacity. METHODS: This quasi-experimental study included a total of 104 older adults (80.5 ± 6.0 years) and the sample was divided into a training (TRAIN, n = 55) or control group (CON). Harmonized definition was used to diagnose the MetS. Functional capacity, blood biochemical parameters, blood pressure, body composition and anthropometric measurements were assessed 3 times. Analysis of variance for repeated measures and Wilcoxon signed-rank test were used to check the differences within groups. RESULTS: TRAIN decreased diastolic blood pressure (DBP), high-density lipoprotein cholesterol (HDLC) and total fat mass during training period, whereas CON did not show any significant changes. During detraining, TRAIN increased HDLC, systolic blood pressure (SBP), waist circumference (WC) and total fat mass; and decreased glucose and fat free mass, whereas CON increased the concentration of glucose and HDLC. From baseline to post-detraining assessment, CON increased the concentration of triglycerides and the WC, while TRAIN only increased the WC (all p < 0.05). CONCLUSIONS: Exercise can be a key component in the treatment of the MetS, since MCT seems to be effective to decrease DBP and total fat mass. Nevertheless, 4-months of detraining could cause a drop of total fat mass, but no in DBP. To avoid reversibility of the benefits obtained, it could be beneficial to promote continuing exercise programs. TRIAL REGISTRATION: ClinicalTrial.gov identifier: NCT03831841.

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.

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.

Job Demands May Determine Cognitive and Physical Aging After Retirement.

During adulthood, we spend most of our time and efforts at work. However, the impact of employment in aging is poorly explored. Our study addressed how job demands can affect aging after retirement. We have developed a descriptive observational study carried out in 367 older adults with a mean age of 73.9 years (66.5% women and 33.5% men), measuring cognition and functional status. Our results demonstrate that older adults who had high mental demands in their jobs, show better scores in cognition. However, they show poor functional development of basic and instrumental activities of daily life (p< .05). In contrast, former workers who had high physical demands, display lower scores in cognition and lower functional performance in instrumental activities (p< .05). Work life activities contribute to cognitive and physical decline after retirement. Therefore, healthy aging should include interventions that consider the job influence on the age impairment.

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.

Effects of an online home-based exercise intervention on breast cancer survivors during COVID-19 lockdown: a feasibility study.

PURPOSE: The strict lockdown implemented due the COVID-19 pandemic is generating a great impact on wellbeing and health-related quality of life (HRQoL) in people with cancer. We aimed to evaluate the efficacy and feasibility of an online home-based exercise intervention performed during a lockdown period analysing its effects on body composition, physical fitness, and HRQoL in breast cancer survivors. METHODS: Fifteen women with breast cancer receiving hormonal therapy (55.5 ± 6.7 years) were included in the study. The exercise intervention consisted of two weekly sessions of remotely supervised functional training (60 min per day) and two weekly sessions of unsupervised aerobic training (20-30 min/session; 60-85% of maximum heart rate) for a total of 16 weeks. DXA absorptiometry was used for the assessment of body composition. Functional assessment included cardiorespiratory fitness (CRF) by Rockport walking test, upper and lower body strength (grip strength, arm curl test, and chair stand test), walking speed (brisk walking test), and agility (8-foot up-and-go test). The HRQoL was evaluated with the QLQ-BR23 questionnaire. The adherence to the intervention was measured as the percentage of online classes attended. RESULTS: Rate of adherence for the online exercise intervention was 90 ± 17%. The exercise intervention induced significant (p < 0.05) improvements in physical fitness: CRF (+ 9%), right arm and lower limb strength (+ 10% and + 18%, respectively) and lower limbs lean mass (+ 2% and + 3.5% for left and right leg, respectively). CONCLUSION: This feasibility study suggests that an online home-based exercise intervention during COVID-19 lockdown could improve physical fitness and body composition in breast cancer survivors even in a context of heightened concern for future health.

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.

Patterns of Active Commuting to School in Spanish Preschool Children and Its Associations with Socio-Economic Factors: The PREFIT Project.

The aims of this study were to describe patterns of active commuting to school (ACS) of preschool children, and to analyse the relationship between ACS and family socio-economic factors. A total of 2636 families of preschoolers (3-to-5 years old) were asked to complete a questionnaire at home about the mode of commuting to school of their children and marital status, educational level, and profession of both father and mother. Chi-square analyses were applied to compare ACS between school grades and gender of the children. To analyse the association of ACS with socio-economic factors, logistic regression analyses were performed. Almost 50% of participants reported ACS of their offspring, with a higher rate in 3rd preprimary grade (5 years old) than in 1st and 2nd preprimary grades (3- and 4-years old. All, p < 0.05). Those preschool children who had parents with lower educational level and no managerial work had higher odds to ACS than those who had parents with higher educational level and managerial work (all, p ≤ 0.001). Around half of the Spanish preschool children included in this study commuted actively to school and families with lower educational levels or worse employment situation were related to active commuting to school.

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.

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.

Lack of impact moderating movement adaptation when soccer players perform game specific tasks on a third-generation artificial surface without a cushioning underlay.

The objective of this study was to investigate how the inclusion of a cushioning underlay in a third-generation artificial turf (3G) affects player biomechanics during soccer-specific tasks. Twelve soccer players (9 males/3 females; 22.6 ± 2.3 y) participated in this study. Mechanical impact testing of each 3G surface; without (3G-NCU) and with cushioning underlay (3G-CU) were conducted. Impact force characteristics, joint kinematics and joint kinetics variables were calculated on each surface condition during a sprint 90° cut (90CUT), a sprint 180° cut (180CUT), a drop jump (DROP) and a sprint with quick deceleration (STOP). For all tasks, greater peak resultant force, peak knee extensor moment and peak ankle dorsi-flexion moment were found in 3G-NCU than 3G-CU (p < 0.05). During 90CUT and STOP, loading rates were higher in 3G-NCU than 3G-CU (p < 0.05). During 180CUT, higher hip, knee and ankle ranges of motion were found in 3G-NCU (p < 0.05). These findings showed that the inclusion of cushioning underlay in 3G reduces impact loading forces and lower limb joint loading in soccer players across game-specific tasks. Overall, players were not attempting to reduce higher lower limb impact loading associated with a lack of surface cushioning underlay.

New Evidence on Regucalcin, Body Composition, and Walking Ability Adaptations to Multicomponent Exercise Training in Functionally Limited and Frail Older Adults.

BACKGROUND: Regucalcin, or senescence marker protein-30 (SMP30), is a Ca2+-binding protein with multiple functions reported in the literature. Physical exercise has been shown to improve aging markers; nevertheless, SMP30 in humans has not been extensively researched. Older adults experience a decline in functional capacity and body composition. The purpose of this study was to examine the effects of a multicomponent training (MCT) program on SMP30 and its regulation of walking ability and body composition in functionally limited, frail, and pre-frail older adults. METHODS: A total of 34 older adults (aged 80.3 ± 6.1 years) were divided into an intervention group (IG = 20) and control group (CG = 14). The IG performed a supervised MCT (strength, endurance, balance, coordination, and flexibility) program for 6 months, 3 days per week, whereas the CG continued their normal lives without any specific physical training. SMP30 was analyzed in plasma after 3 and 6 months of MCT, while some physical fitness variables (Timed Up and Go (TUG) and 6-min walk test (6MWT)) and body composition (fat mass and lean mass) were measured at baseline, as well as after 3 months and 6 months of MCT. RESULTS: No significant changes were observed in SPM30 between the IG (877.5 a.u. to 940.5 a.u., respectively) and CG (790.4 a.u. to 763.8 a.u., respectively). Moreover, no SMP30 differences were found between groups after 3 and 6 months of MCT. The IG improved significantly in the 6MWT after 3 months (472.2 ± 84.2 m) compared to baseline (411.2 ± 75.2 m). The IG also significantly enhanced their TUG performance after 3 months (7.6 ± 1.6 s) and 6 months (7.3 ± 1.8 s) of training compared to baseline (9.3 ± 3.2 s) (all, p < 0.001). There were no significant differences in body composition between the IG and CG through the 6 months of MCT. CONCLUSIONS: The present study suggests that MCT did not change SMP30 levels from 3 to 6 months, where there were changes in neither walking ability nor body composition; however, MCT was effective in improving 6MWT and TUG performance from baseline to 3 months.

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.

Is Playing Soccer More Osteogenic for Females Before the Pubertal Spurt?

The aims of this study were to assess bone mass in children and adolescent soccer players and to evaluate the influence of both gender and pubertal status on bone mass. A total of 110 soccer players (75 males / 35 females; 12.73 ± 0.65 / 12.76 ± 0.59 years) participated in this cross-sectional study. They were divided into two groups according to their pubertal status. Bone and lean masses were measured with Dual-energy X-ray Absorptiometry. An independent t-test and an adjusted by subtotal lean and training experience multivariate analysis of covariance were used to analyse the differences in bone mass values between genders and maturity status. Female soccer players presented higher bone mass values than their male counterparts in most of the measured weight-bearing sites. Moreover, when stratifying by pubertal status, peripubertal and postpubertal females had higher subtotal body and lumbar spine bone mass than males. Comparing between pubertal status groups before adjustment, both male and female postpubertal players showed higher bone mass than their pubertal counterparts. After adjusting, these differences disappeared and, in fact results were inverted as bone mass at the femoral neck was higher in both male and female peripubertal soccer players than in postpubertal players. Bone mass seems to be more intensely stimulated by playing soccer in female than male players, particularly in the lumbar spine. The results of peripubertal players showing higher bone mass at the femoral neck after adjusting suggest that playing soccer during the peripubertal stage could be an effective activity to achieve optimal bone mass values.

Agreement of body composition methods in elite male football referees / Concordancia entre diferentes métodos de composición corporal en árbitros de fútbol de élite / Concordância entre diferentes métodos de composição corporal em árbitros de futebol de elite

OBJECTIVE: The current literature about the body composition of elite football referees is scarce and almost non-existent. Therefore, and in order to establish the level of agreement between bioelectrical impedance analysis (BIA) and dual energy X-ray absorptiometry (DXA) in elite football referees, the aim of this study was to compare fat mass (FM) and fat-free mass (FFM) values measured with these two different methods. METHOD: A total of 30 male referees belonging to 1st, 2nd and 2ndB categories, and 36 assistant referees from 1st and 2nd categories in the Spanish national league participated in this study. Total and regional FM and FFM were assessed using a portable BIA analyser TANITA BC 418-MA (Tanita Corp., Tokyo, Japan) and DXA (Hologic Corp. Software version 12.4, Bedford, MA 01730). Agreement between methods was assessed by plotting the results in Bland-Altman graphs and the presence of heteroscedasticity was also examined. Differences between methods were analysed by two-paired samples t-test. RESULTS: For the whole group, BIA underestimated body fat percentage in 3.87 points (CI 95%=3.22-4.52; p=<0.01) and overestimated kg of total FFM in 3.56 points (CI 95%=3.08-4.05; p=<0.01), however, no heteroscedasticity was shown in any case (all p > 0.05). CONCLUSIONS: The present study suggests that according to DXA, BIA values calculated with a non-specific equation are underestimating total FM and, consequently, overestimating total FFM in male elite football referees

OBJETIVO: La literatura científica existente sobre la composición corporal en árbitros de fútbol es todavía escasa. Por lo tanto y para establecer el nivel de concordancia entre el análisis de impedancia bioeléctrica y la absorciometría de rayos X de doble energía en árbitros de fútbol de elite, el objetivo de este estudio fue comparar los valores de masa grasa (MG) y la masa libre de grasa (MLG) medidos con ambos métodos. MÉTODO: Un total de 30 árbitros pertenecientes a las categorías de 1ª, 2ª y 2ª división B, y 36 asistentes de 1ª y 2ª división de la liga española participaron en este estudio. La MG y la MLG tanto a nivel total como regional se evaluó utilizando la impedancia bioeléctrica TANITA BC 418-MA (Tanita Corp., Tokyo, Japan) y absorciometría de rayos X de doble energía (Hologic Corp. Software versión 12.4, Bedford, MA 01730). La concordancia entre métodos se evaluó con gráficos de Bland-Altman y también se examinó la presencia de heterocedasticidad. Las diferencias entre métodos se analizaron con la prueba T de Student para muestras relacionadas. RESULTADOS: Para el total de la muestra, la impedancia bioeléctrica infraestimó el porcentaje de MG en 3.87 puntos (IC 95%=3.22-4.52; p=<0.01) y sobreestimó los kg de MLG en 3.56 puntos (IC 95%=3.08-4.05; p=<0.01), sin embargo, en ningún caso se observó heterocedasticidad (todos p > 0.05). CONCLUSIÓN: El presente estudio sugiere que, tomando como referencia la absorciometría de rayos X de doble energía, la impedancia bioeléctrica calculada a partir de una ecuación no especifica para árbitros, infraestima la MG y consecuentemente, sobreestima la MLG en árbitros de fútbol de elite

OBJETIVO: A literatura atual sobre a composição corporal de árbitros de futebol de elite é escassa e quase inexistente. Portanto, afim de estabelecer o nível de concordância entre a bioimpedância elétrica (BIA) e a absorciometria por raios-X de dupla energia (DXA) em árbitros de futebol de elite, o objetivo deste estudo foi comparar os valores de massa gorda (FM) e massa livre de gordura (FFM) valores mensurados com estes dois diferentes métodos. MÉTODO: Um total de 30 árbitros pertencentes as categorias 1st, 2nd e 2ndB, e 36 árbitros assistentes da 1st e 2nd categorias da Liga Nacional Espanhola. A FM total e regional e a FFM foram avaliadas através de um analisador BIA portátil TANITA BC 418-MA (Tanita Corp., Tóquio, Japão) e DXA (Hologic Corp. Software versão 12.4, Bedford, MA 01730). A concordância entre os métodos foi avaliada através da plotagem dos resultados nos gráficos de Bland-Altman e a presença de heteroscedasticidade também foi examinada. As diferenças entre os métodos foram analisadas pelo teste t para duas amostras pareadas. RESULTADOS: Para o grupo como um todo, a BIA subestimou o percentual de gordura corporal em 3.87 pontos (IC 95% = 3.22-4.52; p = <0.01) e superestimou a kg total de FFM em 3.56 pontos (IC 95% = 3.08-4.05; p = <0,01), no entanto, nenhuma heteroscedasticidade foi mostrada em nenhum caso (todos p> 0.05). CONCLUSÕES: O presente estudo sugere que, de acordo com a DXA, os valores da BIA calculados com uma equação não específica estão subestimando a FM total e, consequentemente, superestimando a FFM total em árbitros de futebol de elite do sexo masculino

Plantar pressures in male adolescent soccer players and its associations with bone geometry and strength.

BACKGROUND: Mechanical loads exerted by soccer-specific actions increase bone remodeling activity. Nevertheless, little is known about the relationship between plantar pressure and bone structure. Therefore, the aim of this study was to compare bone geometry and strength between soccer players who exhibited different maximum values of the average pressures (MP) when performing a combination of soccer-specific tasks. METHODS: Forty male adolescent soccer players (mean age 13.2±0.5 years) and 13 controls (mean age 13.1±0.9 years) participated in this study. Biofoot® system was used to measure MP at the non-dominant foot during a circuit of soccer-specific tasks. Cluster analysis was performed to classify players into groups of similar MP profiles resulting two different groups as follows: 15 players with high MP (SOC-HP; mean MP: 392.7±68.2 kPa) and 25 with low MP (SOC-LP; mean MP: 261.0±49.6 kPa). Total and cortical volumetric bone mineral content (Tt.BMC/Ct.BMC), cross-sectional area (Tt.Ar/Ct.Ar), cortical thickness (Ct.Th), fracture load in X-axis, and polar strength index (SSIp) were measured at 38% of the non-dominant tibia by peripheral quantitative computed tomography. Bone geometry and strength comparisons between SOC-HP and SOC-LP were performed using analyses of covariance controlling by weight and tibia length. RESULTS: Greater Tt.BMC, Ct.BMC and Tt.Ar. were found in SOC-HP compared to CG (Tt.BMC: 3.22vs2.95 g, Ct.BMC: 2.95vs2.68 g, Ct.Ar: 280vs253 mm2; P<0.05). Nevertheless, no significant bone geometry and strength differences were found between soccer groups and between SOC-LP and CG (P>0.05). CONCLUSIONS: Developing high MP when training and playing soccer might be favorable to bone development.

Accurate Prediction Equation to Assess Body Fat in Male and Female Adolescent Football Players.

The aims of this study were (a) to determine which of the most used anthropometric equations was the most accurate to estimate percentage of body fat (%BF), (b) to develop a new specific anthropometric equation, and (c) to validate this football-specific equation. A total of 126 (13.3 ± 0.6 years) football players (86 males and 40 females) participated in the present study. Participants were divided into two groups: 98 players were included in the assessment of existing equations and in the development of the new prediction equation, and 28 players were used to validate it. %BF was measured with dual-energy X-ray absorptiometry (DXA) and also estimated with six different %BF anthropometric equations: Johnston, Slaughter, Carter, Faulkner, Deurenberg, and Santi-Maria. Paired t tests were used to analyze differences between methods. A football-specific equation was developed by a stepwise linear regression. The existing anthropometric equations showed significant bias for %BF when compared with DXA (p < .001; constant error ranged from -4.57% to 9.24%; standard error of estimate ranged from 2.46 to 4.20). On the other hand, the developed football-specific equation was %BF = 11.115 + 0.775 (triceps skinfold) + 0.193 (iliac crest skinfold) - 1.606 (sex). The developed equation demonstrated neither %BF differences (p = .121; constant error = 0.57%; standard error of estimate = 0.36) when compared with DXA, presenting a high cross-validation prediction power (R2 = .85). Published anthropometric equations were not accurate to estimate %BF in adolescent football players. Due to the fact that the developed football-specific equation showed neither differences nor heteroscedasticity when compared with DXA, this equation is recommended to assess %BF in adolescent football players.

Bone geometry in young male and female football players: a peripheral quantitative computed tomography (pQCT) study.

The present study shows that football practice during growth may improve bone geometry in male and female football players. However, only females had better bone strength in comparison with controls. PURPOSE: The aim of this study was to compare bone geometry in adolescent football players and controls. METHODS: A total of 107 football players (71 males/36 females; mean age 12.7 ± 0.6/12.7 ± 0.6 years) and 42 controls (20 males/22 females; mean age 13.1 ± 1.4/12.7 ± 1.3 years) participated in this study. Total and trabecular volumetric bone mineral content (Tt.BMC/Tb.BMC), cross-sectional area (Tt.Ar/Tb.Ar), and bone strength index (BSI) were measured at 4% site of the non-dominant tibia by peripheral quantitative computed tomography (pQCT). Moreover, Tt.BMC, cortical BMC (Ct.BMC), Tt.Ar, cortical Ar (Ct.Ar), cortical thickness (Ct.Th), periosteal circumference (PC), endosteal circumference (EC), fracture load in X-axis, and polar strength strain index (SSIp) were measured at 38% site of the tibia. Multivariate analyses of covariance were used to compare bone pQCT variables between football players and controls using the tibia length and maturity offset as covariates. RESULTS: Female football players demonstrated 13.8-16.4% higher BSI, Ct.Th, fracture load in X-axis, and SSIp than controls (p < .0036). Males showed no significant differences in bone strength when compared to controls (p > .0036). In relation to bone mineral content and area, male football players showed 8.8% higher Tt.Ar and Tb.Ar at the 4% site of the tibia when compared to controls; whereas 13.8-15.8% higher Tt.BMC, Ct.BMC, and Ct.Ar at the 38% site of the tibia were found in female football players than controls (p < .0036). CONCLUSIONS: In this study, female adolescent football players presented better bone geometry and strength values than controls. In contrast, only bone geometry was higher in male football players than controls.