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Skeletal muscle is one of the main components of lean soft tissue mass (LSTM). Low levels in children affect locomotion, posture, and increase the risk of metabolic syndrome.(1) To evaluate the association between muscle cross-sectional area (MCSA) of the lower left leg measured by peripheral quantitative computed tomography (pQCT) and total LSTM; namely, total left leg and left lower leg LSTM assessed by dual-energy X-ray absorptiometry (DXA) in a group of children, (2) to examine if MCSA is a predictor of LSTM, (3) to determine the ability of pQCT to identify children with low LSTM.Lower left leg MCSA and LSTM were measured using pQCT and DXA, respectively, in 396 children.Statistically significant positive correlations were found between the lower leg MCSA - total LSTM (Our results showed that lower left leg MCSA, measured using pQCT, could be a tool to predict low LSTM in children.

BACKGROUND: Few studies have evaluated the causes of physical inactivity in rural teachers from South America. Determining the causes and effects of physical inactivity in rural teachers could be the base for future intervention studies aiming to improve physical activity (PA) engagement in this population. OBJECTIVES: To examine the levels of PA in rural teachers and evaluate the associations between their jobs, interest in PA, body composition and practice of PA. METHODS: Body mass index (BMI) and body fat % (BF) of rural teachers from the Valparaiso Region in Chile were measured; interviews regarding PA habits, interests and PA practice were conducted. The relationship between BF% and interest in PA and the practice of sports was analysed stratifying by sex. RESULTS: Around 71% were overweight/obese and 80% of the teachers reported not practicing any PA. These figures are higher than the Chilean national average for adults (64.5% overweight/obese). Moreover, females presented a higher BF% than male teachers (35.98% vs. 26.44%, p

Background Physical fitness and body composition are important health indicators; nevertheless, their combined pattern interrelationships and their association with mortality are poorly investigated. Methods This longitudinal study is part of the Spanish EXERNET-Elder project. Person-months of follow-up were calculated from the interview date, performed between June 2008 and November 2009, until the date of death or censoring on March 2018 (whichever came first). In order to be included, participants had to fulfill the following criteria: (a) be older than 65 years, (b) live independently at home, (c) not suffer dementia and/or cancer, and (d) have a body mass index above 18.5. Body fat and weight were assessed by a bioelectrical impedance analyzer. Fitness was measured with the Senior Fitness and the one-leg static balance tests. The Spanish Death Index was consulted for the death’s identification. Cluster analysis was performed to identify Fat–Fit patterns and traditional cut-points and percentiles to create the Fat–Fit groups. Cox proportional hazards regression models were used to calculate the hazard ratios (HRs) of death in clustered Fat–Fit patterns and in traditional Fat–Fit groups. Results A total of 2299 older adults (76.8% of women) were included with a baseline mean age of 71.9 ± 5.2 years. A total of 196 deaths (8.7% of the sample) were identified during the 8 years of follow-up. Four clustered Fat–Fit patterns (Low fat–Fit, Medium fat–Fit, High fat–Unfit, and Low fat–Unfit) and 9 traditional Fat–Fit groups emerged. Using the Low fat–Fit pattern as the reference, significantly increased mortality was noted in High fat–Unfit (HR: 1.68, CI: 1.06–2.66) and Low fat–Unfit (HR: 2.01, CI: 1.28–3.16) groups. All the traditional Fit groups showed lower mortality risk when compared to the reference group (obese–unfit group). Conclusion Physical fitness is a determinant factor in terms of survival in community-dwelling older adults, independently of adiposity levels.

The present study investigated the associations between physical activity (PA) and physical fitness (PF) with lean body mass (LBM) and evaluated whether PA mediates the association between PF and LBM. 279 children (150 boys) aged 7.5 ± 0.3 years participated in the study. PA was assessed by accelerometry and PF with handgrip and the standing long jump test. Total lean soft tissue mass index (TLSTMI), muscle cross-sectional area index (MCSAI), and fat-free mass index (FFMI) were evaluated using dual-energy X-ray absorptiometry, peripheral quantitative computed tomography, and bioimpedance analysis, respectively. Total (β = 0.247) and vigorous PA (β = 0.143) were associated with TLSTMI in girls. In boys, total (β = 0.337), light (β = 0.290), vigorous (β = 0.200), and moderate-vigorous PA (β = 0.189) were associated with TLSTMI. Total PA was associated with FFMI (β = 0.299). Handgrip strength does not mediate the relationship between total PA and TLSTMI. Positive associations were found between handgrip strength and TLSTMI, MCSAI, and FFMI in both girls and boys. In children, there is a positive association between total and vigorous PA with TLSTMI. Handgrip strength does not mediate the relationship between total PA and TLSTMI. It was associated with TLSTMI, MCSAI, and FFMI.

Resumen: Objetivo: Aportar evidencias de la eficacia de una intervención comunitaria en salud a través de un programa de estimulación cognitiva (PEC) implementada con el paso del tiempo en mayores con deterioro cognitivo leve en la comunidad. Diseño: Seguimiento de un ensayo controlado aleatorizado (normas grupo CONSORT). Emplazamiento: Centro de salud San José Norte-Centro y Fundación La Caridad (Zaragoza). Participantes: Veintinueve personas ≥ 65 años, con 24-27 puntos en el MEC-35 que completaron el ensayo a los 48 meses, 15 aleatorizados en el grupo intervención y 14 en el grupo control. Intervenciones: Se realizaron 10 sesiones, 45 min/semana, durante 10 semanas, con el cuaderno rojo de activación mental que ejercita: memoria, orientación, lenguaje, praxis, gnosis, cálculo, percepción, razonamiento lógico, atención y funciones ejecutivas. Mediciones principales: MEC-35, Set-test, Barthel, Lawton-Brody, subescala de ansiedad Goldberg y Yesavage abreviado (GDS-15). Resultados: Analizando los incrementos sobre el nivel basal para MEC-35, el grupo intervención obtiene, de media: postintervención 3,14 puntos, a los 6 meses 3,76 puntos y a los 12 meses 2,26 puntos más que el grupo control, siendo estos incrementos estadísticamente significativos. A los 48 meses el grupo intervención sigue obteniendo 2 puntos más que el control, sin ser significativos. La intervención no mejoró el desempeño en fluidez verbal, actividades de la vida diaria ni estado de ánimo. Conclusiones: Nuestro PEC podría ser eficaz en la mejora de la cognición general, medida con el MEC-35, en postintervención, a los 6, 12 y 48 meses. No se evidencian mejoras en fluidez verbal, actividades de la vida diaria ni estado de ánimo.Clinicaltrials.gov Identifier: NCT03831061. Abstract: Objective: To provide evidence about the efficacy of a community health intervention through a cognitive stimulation program at long term in older people with mild cognitive impairment. Design: Randomized controlled trial (CONSORT group norms). Location: San José Norte-Centro Primary Care Center and La Caridad Foundation (Zaragoza, Spain). Participants: Twenty-nine people over 65 years old with a 24-27 MEC score that completed 48 months follow up. They were randomized between the intervention group (15) and the control group (14). Interventions: The intervention was applied in 10 sessions of 45 min for 10 weeks using the red notebook tool for mental activation that works memory, orientation, language, praxis, gnosis, calculation, perception, logical reasoning, attention and executive functions. Main measurements: The main outcome variables were MEC-35, Set-test, Barthel index, Lawton-Brody scale, Goldberg anxiety scale and Yesavage geriatric depression scale short form. Results: Increases of the main result variable over the baseline level of MEC-35 were analyzed. On average, the intervention group obtained higher scores than control: 3.14 points post intervention, 3.76 points after 6 months and 2.26 points more than control group after 12 months. All the differences were statistically significant. After 48 months the intervention group obtained 2 points more than control group. The intervention did not improve verbal fluency, activity daily living and mood. Conclusions: Our cognitive stimulation program seems to improve cognitive performance, measured with the variable MEC-35 at post intervention, 6, 12 and 48 months. There is no evidence of improvement in verbal fluency, activity daily livings and mood.Clinicaltrials.gov Identifier: NCT03831061.

There are different surfaces on which football is played, but their influence on bone mass accretion still remains unknown. The aims of this study were to compare bone mass accretion between football players and controls, and evaluate the influence of two different playing surfaces on bone accretion. A total of 27 male football players (13.2 ± 0.5 years) and 15 controls (12.6 ± 1.1 years) participated in this study. Football players were classified into two groups according to the surface they trained on: 14 on third-generation artificial turf with elastic layer and 13 on third-generation artificial turf without elastic layer. Bone mineral content and areal bone mineral density were measured using dual-energy X-ray absorptiometry. Bone mineral apparent density variables were calculated. Bone geometry and strength of the non-dominant tibia were assessed with peripheral quantitative computed tomography. For both football players and controls, bone variables measured at subtotal body, lumbar spine, legs and tibia ( p

Gomez-Bruton, A, Gabel, L, Nettlefold, L, Macdonald, H, Race, D, and McKay, H. Estimation of peak muscle power from a countermovement vertical jump in children and adolescents. J Strength Cond Res 33(2): 390-398, 2019-Several equations to predict muscle power (MP) from vertical jump height (VJH) have been developed in adults. However, few have been derived in children. We therefore aimed to: (a) evaluate the validity of existing MP estimation equations from a vertical countermovement jump (CMJ) in children and adolescents and (b) develop and validate a new MP estimation equation for use in children and adolescents. We measured peak MP (in watts) and VJH (in centimeters) during a CMJ using a force platform in 249 children and adolescents (9-17 years; 119 boys and 130 girls). We compared actual (force platform) with predicted (12 existing prediction equations) MP using repeated-measures analysis of variance and estimated bias using modified Bland-Altman plots. We developed a new prediction equation using stepwise linear regression, assessed predictive error using leave-one-out and 10-fold cross-validation, and externally validated the equation in an independent sample (n = 100). All existing prediction equations demonstrated some degree of bias, either systematic bias (mean differences ranging 178-1,377 W; 8-64%) or bias at the extremes or interactions with sex. Our new prediction equation estimates MP from VJH and body mass: Power (W) = 54.2 × VJH (cm) + 34.4 × body mass (kg) - 1,520.4. With this new equation, there was no difference between actual and predicted MP (0%) and negligible differences (0.2-0.9%) in R and root mean square error between our observed and cross-validated sets. Actual and predicted MP were not different in our external validation (p = 0.12). The new equation demonstrates excellent validity and can be used to predict MP from a CMJ in children and adolescents.

Background: Prior to the COVID-19 pandemic, teachers were already reporting a low quality of life (QoL) perception, with a significant impact on mental and physical health due to various stress factors associated with work overload. The objective of this study was to evaluate the QoL impact on Chilean teachers before and during the COVID-19 pandemic. The analysis was performed following a longitudinal design on a sample of 63 Chilean teachers in pre-pandemic and COVID-19 pandemic timeframes. QoL perception, along with teachers’ sociodemographic data, was evaluated via the Short-Form 36 Health Survey (SF-36) questionnaire. Sociodemographic variables presented no significant variations in pre-pandemic and pandemic comparisons. QoL, however, showed a significant decrease during the pandemic compared to the pre-pandemic measurement (p &lt, 0.01). In each gender, there were significant differences between pre-pandemic and pandemic timeframes, with a greater impact among women in the mental and physical component summary variables and seven of the eight QoL scales (p &lt, 0.01). Between age categories, people under 45 presented significant differences (p &lt, 0.05) between pre-pandemic and pandemic timeframes in all summary dimensions and measurements. In conclusion, Chilean teachers’ QoL perception has been affected by the COVID-19 pandemic. These findings could be related to work overload due to teleworking or feelings of uncertainty, loneliness, and fear that the pandemic and its associated confinements will worsen.

A vast amount of research has focused on the effects of physical fitness (PF) on mortality, with little research evaluating the effects of PF on future expected health related quality of life (HRQoL). Aim: To evaluate how current PF influences future HRQoL measured in a prospective 8-year study in older adults. Methods: A total of 617 (157 males) older adults (>65y) participated in the study. PF was assessed with the EXERNET battery in 2008–2009 (baseline) and 2016–2017 (follow-up). HRQoL was assessed using the EQ-5D-3L questionnaire in both evaluations. PF tertiles were developed from baseline PF variables: FIT (highest PF values), REGULAR and UNFIT (lowest PF values) taking into account age and sex. Follow-up HRQoL values were compared to sex and age-specific expected values. Logistic regressions were performed to test differences be tween PF tertiles regarding future expected quality of life. Linear regressions were developed to test whether baseline PF could predict future HRQoL scores. Results: The FIT group showed higher probabilities of an improved HRQoL when compared to the UNFIT group. All PF variables seemed to be important at some point of the study except upper extremities flexibility. Aerobic endurance was the variable that showed to be significant for most of the HRQoL predictions. Conclusion: PF influences future HRQoL in older adults who accordingly should try to remain fit to maintain an increased age-adjusted HRQoL.

The multicomponent training (MCT) effect on bone health in frail and pre-frail elders, which is influenced by dietary intake, is still unknown. The objective of this non-randomized intervention trial was to assess the effects of a 6-month MCT on bone structure in frail and pre-frail elders, and to analyse the influence of dietary intake and serum vitamin D (25(OH)D) in these changes. Thirty MCT (TRAIN) and sixteen controls (CON), frail and pre-frail completed the information required for this study. Peripheral quantitative computed tomography measurements were taken at 4% and 38% of the tibia length and dietary intake was registered. The 25(OH)D values were obtained from blood samples. Analyses of covariance (ANCOVA) for repeated measures showed significant decreases for CON in total bone mineral content at 38% of tibia length. One factor ANOVAs showed smaller decreases in bone mineral density and cortical thickness percentage of change in TRAIN compared to CON. Linear regression analyses were performed to study the influence of nutrients and 25(OH)D on bone changes. Alcohol showed a negative influence on fracture index changes, while polyunsaturated fatty acid and vitamin A showed a positive association with some bone variables. The 25(OH)D only affected positively the cortical bone mineral density. In conclusion, our MCT seems to slow down some of the bone detriments associated with ageing in frail and pre-frail older adults, with alcohol showing a negative effect on the bone and apparent limited effect of nutrients and serum 25(OH)D on training related changes.

SUMMARY: This study evaluated the effect of resistance exercise training (RET) on body composition and muscle strength in 16 older women during summer holidays (70.5 ± 8.4 years old; Range 60-87). Exercise sessions were carried out for twelve weeks, two sessions per week, with 60 minutes of exercise per session. We measured body mass index (BMI), fat mass percentage (FM%, by bioimpedance) and grip strength with a dynamometer before and after the intervention. The participants showed a significant increase in BMI (p

Blood flow partially determines specific climbing endurance (SCE) as it mediates oxygen bio-availability in the finger flexors. Blood flow is related to occlusion threshold (OT), which is defined as the contraction intensity at which intramuscular pressure exceeds perfusion blood pressure resulting in the cessation of local blood flow. The OT is represented as an inflection point on a force-time graph when isometric force is registered and applied through maximal and continuous tests. Endurance time (ET) to exhaustion is influenced by the relative isometric applied force and is different for each climber. The aim of this study was to explore whether an approximation of the finger flexors OT in sport climbers through records of ET to exhaustion at different isometric relative intensities was possible. We measured maximum finger hang ETs at 6 intensities ranging from 85% to 35% maximal force in 34 sport climbers of advanced and elite level. The values obtained were analysed by two different methods in an attempt to determine a change in the shape of the curve in the intensity-ET relationship graphs that approximated the OT for each climber. The results suggest that the finger flexors OT could be different among climbers, regardless of their strength and ability level. The presented methods do not accurately reflect the OT, but could indicate the intensity at which blood flow is restored in the active muscles. This is the first study to indirectly approximate the finger flexors OT in sport-climbers, a parameter that could be essential to assess SCE.

The aims of the present study were (1) to describe the changes in physical fitness during an 8 year follow-up in a large sample of Spanish adults aged 65 or over that are initially engaged in organized physical activity (OPA), (2) to compare fitness changes according to different age groups (65 to 69 vs. 70 to 74 vs. &ge, 75 years-old), (3) to evaluate the independent and combined effects of changes in OPA engagement and sitting time (ST) on physical fitness. A total of 642 (147 males) non-institutionalized over 65 years-old participants completed the EXERNET battery fitness tests and completed a validated questionnaire from which information regarding OPA and ST were collected. All participants completed evaluations in 2008&ndash, 2009 and in 2016&ndash, 2017. An impairment of fitness-related variables happens after 65 years of age in both males and females, with the older participants (&ge, 75), showing the largest decreases. Males who continued performing OPA demonstrated lower decreases in balance, leg flexibility and agility when compared to those who stopped performing OPA during the follow-up. Females who continued performing OPA demonstrated lower decreases of all variables except for balance when compared to those who stopped performing OPA during the follow-up.

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.

Los cuestionarios se han propuesto como una buena alternativa a los metodos objetivos (acelerometria o podometria), sin embargo, no parece existir un consenso sobre que cuestionario es el mejor para cuantificar los niveles de actividad fisica en ninos espanoles. El objetivo del presente estudio fue el de validar los cuestionarios “Physical Activity Questionnaire for Children” (PAQ-C) y el “International Physical Activity Questionnaire for Adolescents” (IPAQ-A) completados por ninos/as y sus padres. Para ello, 24 ninos/as sanos (9.1±0.6 anos) llevaron un acelerometro siete dias consecutivos, completando tanto ellos como sus padres el PAQ-C e IPAQ-A. La puntuacion del PAQ-C se comparo con la actividad fisica (AF) moderada y vigorosa obtenida por el acelerometro, mientras que en el IPAQ-A se compararon minutos por intensidades de AF con los del acelerometro. Las correlaciones obtenidas entre el PAQ-C y acelerometria fueron positivas para ninos/as (rho=0.42; p

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.

The main aim was to analyse the associations between several physical fitness variables and bone parameters in a sample of elderly people. 129 participants (94 females and 35 males, 76.2±5.4 y) from the EXERNET cohort of Zaragoza (Spain) were included in the study. Physical fitness was assessed using the Senior Fitness Test Battery. Peripheral quantitative computed tomography (pQCT) at the tibia and dual-energy X-ray absorptiometry (DXA) at the hip and lumbar spine were used to assess bone and muscle parameters. Partial correlations were used to describe the associations between fitness and bone parameters. A stepwise regression analysis was used to determine the influence of fitness variables on bone parameters. In males, significant correlations were found between lower body strength and agility with bone total mineral density (Tt.BMD) (r=0.41 and -0.50) and cortical thickness (r=0.40 and -0.50, respectively) and walking speed with total and cortical density (r=−0.41 and -0.40, respectively), all measured at tibia (all p<0.05). Regarding DXA, neck areal bone mineral density (aBMD) correlated with flexibility (r=−0.37) and walking speed (r=0.39) and Ward’s triangle with walking speed (r=0.39). Agility predicted Tt.BMD and cortical thickness (r2 change=24.8% and 23.0%), while walking speed predicted cortical bone mineral density (r2 change=19.5%) (all p<0.05). Females showed correlations between balance and total hip aBMD (r=0.27) and trochanter aBMD (r=0.25). Balance predicted trochanter (r2 change=4.2%) and total hip aBMD (r2 change=4.9%) (both p<0.05). In conclusion, bone mass in elderly males seems to be more influenced by physical fitness than in females, being agility and walking speed the variables showing greater associations. Other variables should be taken into account in females for future research.

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.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.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; P0.05). Nevertheless, no significant bone geometry and strength differences were found between soccer groups and between SOC-LP and CG (P0.05).Developing high MP when training and playing soccer might be favorable to bone development.

Hanging ability on small depth edges is one of the most limiting factors in climbing. The aim of this study was to assess the reliability and validity of a hanging ability indicator measured on an ...

Background Swimming has no effect on bone mass or structure. Therefore, adolescent swimmers present similar bone strength values when compared to normo-active controls, and lower values when compared to weight-bearing athletes. It thus seems necessary to try to improve bone structure and strength of adolescent swimmers through a weight-bearing intervention in order to reduce the risk of suffering osteoporosis later in life. Objective To evaluate the effects of a 6-month whole body vibration (WBV) intervention on bone strength and structure of adolescent swimmers. Design Randomized controlled trial. Setting Research center. Participants A total of 51 swimmers (14.4 ± 2.0 years) participated in the study. Methods Swimmers were randomly allocated into 2 groups: 20 swimmers (9 females) who only performed their swimming training, and 31 swimmers (15 females) who performed their swimming training and received a WBV intervention (3.6-11.6 g) 3 times per week during 6 months (VIB). Outcome measurements Peripheral quantitative computed tomography was performed in the nondominant tibia of all swimmers at 4%, 38%, and 66% of the tibia length before and after the intervention. Results No differences between groups in any bone structure variable were found at pre- or postintervention. Both groups presented similar improvements in time, and no group by time interactions were found, suggesting that the WBV intervention was not intense enough to achieve positive changes in bone strength or structure. Conclusion WBV, at the chosen intensities and durations, had no effect on adolescent swimmers’ bone strength or structure. Future studies should test other weight-bearing interventions aiming to improve bone strength and structure of adolescent swimmers. Level of Evidence II

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 Sep-tember 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 hand-grip 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. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.

This meta-analysis aims to determine the effects of regular swimming on bone mineral density (BMD) in young adults (18-30 years). A systematic search was performed in Pubmed, SPORTDiscus and the Cochrane Library from the earliest possible year to March 2016. Swimmers were compared to non-athletic controls (CG) and to high-impact athletes (HIGH). Effect sizes with the Hedges g in random effects models were developed. Fourteen studies met the inclusion criteria and were included in the meta-analyses. Swimmers presented similar BMD values to CG in whole-body (g = -0.20; P = 0.251), femoral neck (g = -0.05; P = 0.818) and lumbar spine (g = 0.18; P = 0.492); and lower BMD in the whole-body (g = -1.21; P 0.001), femoral neck (g = -1.51; P 0.001) and lumbar spine (g = -0.84; P = 0.017) than the HIGH. For the whole-body differences, the higher the latitude the smaller the differences between swimmers and HIGH (B = 0.10; P = 0.001). For the femoral neck differences, age also seemed to reduce the differences between groups (B = 0.19; P = 0.020). Young adult swimmers present similar BMD values than CG and lower values than HIGH.

BackgroundWhole-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.MethodsThe 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.ResultsStatistically 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 ConclusionsThe 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.

Muniz-Pardos, B, Gomez-Bruton, A, Matute-Llorente, A, Gonzalez-Aguero, A, Gomez-Cabello, A, Gonzalo-Skok, O, Casajus, JA, and Vicente-Rodriguez, G. Swim-specific resistance training: A systematic review. J Strength Cond Res 33(10): 2875-2881, 2019-The purpose of this systematic review was to determine which type of swim-specific training is most beneficial to enhance swimming performance and to determine which specific strength- or power-related tests better predict swimming performance. A search was conducted on PubMed, Cochrane Plus, and SPORTDiscus up to June 2018. Studies were distributed into 2 main categories: swim-specific dry land resistance training (SDLRT) and specific in-water swimming power training (SSWPT). From 1,844 citations, 25 met the inclusion criteria. It was determined that SSWPT was the most appropriate method to improve swimming performance, with tethered swimming protocols being the most studied and effective. In addition, SDLRT was a competent method to enhance swimming performance, and specifically, the inclusion of inertial training might evoke greater improvements in both strength/power capacities and swimming performance, than traditional resistance training. In conclusion, tether forces showed the greatest associations with swimming performance, although the efficacy of tethered swimming as an SSWPT method is yet to be confirmed. Further research should focus on the effects of SDLRT to verify the greater transfer of dry land resistance practices to swimming performance, with inertial training being potentially more beneficial than traditional resistance training.

ObjectivesThis 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.MethodsBone mineral status of 78 adolescent swimmers was determined using DXA scans at the hip and subtotal body. Participants also underwent physical fitness (upper and lower body strength, running speed and cardiovascular endurance) and performance (swimming history, speed and ranking) assessments. A gradient boosting machine regression tree was built in order to predict BMD of the swimmers and to further develop a simpler individual decision tree, using a subtotal BMD height-adjusted Z-score of −1 as threshold value.ResultsThe predicted BMD using the gradient boosted model was strongly correlated with the actual BMD values obtained from DXA (r=0.960, p2. According to a simple decision tree, that showed a 73.9% of classification accuracy, swimmers with a body mass index (BMI) lower than 17 kg/m2 or a handgrip strength inferior to 43kg with the sum of both arms could be at higher risk of having low BMD.ConclusionEasily measurable fitness variables (BMI and handgrip strength) could be used for the early detection of adolescent swimmers at risk of suffering from low BMD. The presented decision tree could be used in training settings to determine the necessity of further BMD assessments.Summary boxWhat are the new findings?Adolescent swimmers with a low BMI or handgrip strength seem more likely to be at higher risk of having low BMD.Subtotal BMD values predicted from our regression model are strongly correlated with DXA measurements.How might it impact on clinical practice in the futureHealthcare professionals could easily detect adolescent swimmers in need of a DXA scan.The computer-based regression tree could be included in low BMD management and screening strategies.

Background: Many jumping interventions have been performed in children and adolescents in order to improve bone-related variables and thus, ensure a healthy bone development during these periods and later in life. This systematic review aims to summarize and update present knowledge regarding the effects that jumping interventions may have on bone mass, structure and metabolism in order to ascertain the efficacy and durability (duration of the effects caused by the intervention) of the interventions. Methods: Identification of studies was performed by searching in the database MEDLINE/PubMed and SportDiscus. Additional studies were identified by contacting clinical experts and searching bibliographies and abstracts. Search terms included “bone and bones”, “jump*”, “weight-bearing”, “resistance training” and “school intervention”. The search was conducted up to October 2014. Only studies that had performed a specific jumping intervention in under 18-year olds and had measured bone mass were included. Independent extraction of articles was done by 2 authors using predefined data fields. Results: A total of 26 studies were included in this review. Twenty-four studies found positive results as subjects included in the intervention groups showed higher bone mineral density, bone mineral content and bone structure improvements than controls. Only two studies found no effects on bone mass after a 10-week and 9-month intervention. Moreover, those studies that evaluated the durability of the effects found that some of the increases in the intervention groups were maintained after several years. Conclusion: Jumping interventions during childhood and adolescence improve bone mineral content, density and structural properties without side effects. These type of interventions should be therefore implemented when possible in order to increase bone mass in early stages of life, which may have a direct preventive effect on bone diseases like osteoporosis later in life.

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.

The anthropometric and somatotype evaluation is an essential tool in the selection and control of high-performance athletes. The aim of this study was to describe the somatotype and body composition of male elite race walkers (20 k modality), and its relationship with athletic performance. Twenty-four race walkers participated in this study. The sample was divided into two groups: the race walkers with the best performance (upper 25 percentile; n=7) and the second group (n=17) that corresponds to the rest of the participants. Weight (kg), height (cm), seven skinfolds, two diameters and five perimeters were measured. Body fat percentage (BF%) were estimated with the Yuhasz formula, and the somatotype was used applying the Heath-Carter method. The best performing athletes were taller (178.3 +/- 4.4 cm vs. 173.7 +/- 5.6 cm, p

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.

This study examined (1) the association of dietary energy density from solid (EDS) and solid plus liquids (EDSL) with adiposity and cardiometabolic risk factors (CRF) in children with overweight and obesity, (2) the effect of under-reporting on the mentioned associations and (3) whether the association between ED and body composition and CRF is influenced by levels of physical activity. In a cross-sectional design, 208 overweight and obese children (8-12-year-old; 111 boys) completed two non-consecutive 24 h recalls. ED was calculated using two different approaches: EDS and EDSL. Under-reporters were determined with the Goldberg method. Body composition, anthropometry and fasting blood sample measurements were performed. Moderate to vigorous physical activity (MVPA) was registered with accelerometers (7-d-register). Linear regressions were performed to evaluate the association of ED with the previously mentioned variables. Neither EDS nor EDSL were associated with body composition or CRF. However, when under-reporters were excluded, EDS was positively associated with BMI (P=0 019), body fat percentage (P=0 005), abdominal fat (P=0 008) and fat mass index (P=0 018), while EDSL was positively associated with body fat percentage (P=0 008) and fat mass index (P=0 026). When stratifying the group according to physical activity recommendations, the aforementioned associations were only maintained for non-compliers. Cluster analysis showed that the low-ED and high-MVPA group presented the healthiest profile for all adiposity and CRF. These findings could partly explain inconsistencies in literature, as we found that different ED calculations entail distinct results. Physical activity levels and excluding under-reporters greatly influence the associations between ED and adiposity in children with overweight and obesity. The research leading to these results has received funding from la Caixa Foundation and Triptolemos Foundation, the Ministry of Health (FIS PI081297), the Research Network on Preventative Activities and Health Promotion (RD06/0018/ 0038), the Henning and Johan Throne-Holst Foundation (F. B. O.), the Spanish Ministry of Education, Culture and Sport (FPU14/03329 to M. M.), the Spanish Ministry of Economy and Competitiveness (DEP2013-47540 and DEP2016-78377-R; BES-2014-068829 to C. C.-S.), Fondo de Investigacion Sanitaria del Instituto de Salud Carlos III (PI13/01335), Fondos Estructurales de la Union Europea (FEDER), Una manera de hacer Europa, the Spanish Ministry of Science and Innovation (RYC-2011-09011 to F. B. O.), the University of Granada, Plan Propio de Investigacion 2016, Excellence Actions: Units of Excellence, Unit of Excellence on Exercise and Health (UCEES), Programa de Captacion de Talento - UGR Fellows (L. G.-M.), the SAMID III network, RETICS (PN I +D+ I 2017-2021). This study has been partially funded by the University of Granada, Plan Propio de Investigacion 2016, Excellence actions: Units of Excellence; Unit of Excellence on Exercise and Health (UCEES), and by the Junta de Andalucia, Consejeria de Conocimiento, Investigacion y Universidades and European Regional Development Fund (ERDF), reference SOMM17/6107/UGR. ISCIII-Sub-Directorate General for Research Assessment and Promotion, the European Regional Development Fund (RD16/ 0022), the EXERNET Research Network on Exercise and Health in Special Populations (DEP2005-00046/ACTI), and the University of the Basque Country (GIU14/21). J. M.-G. is supported by the Spanish Ministry of Education, Culture and Sport (FPU14/06837). J. H. M. is supported by the Spanish Ministry of Education, Culture and Sport (FPU15/02645).

espanolObjetivo: La literatura cientifica existente sobre la composicion corporal en arbitros de futbol es todavia escasa. Por lo tanto y para establecer el nivel deconcordancia entre el analisis de impedancia bioelectrica y la absorciometria de rayos X de doble energia en arbitros de futbol de elite, el objetivo de esteestudio fue comparar los valores de masa grasa (MG) y la masa libre de grasa (MLG) medidos con ambos metodos.Metodo: Un total de 30 arbitros pertenecientes a las categorias de 1a, 2a y 2a division B, y 36 asistentes de 1a y 2a division de la liga espanola participaronen este estudio. La MG y la MLG tanto a nivel total como regional se evaluo utilizando la impedancia bioelectrica TANITA BC 418-MA (Tanita Corp., Tokyo,Japan) y absorciometria de rayos X de doble energia (Hologic Corp. Software version 12.4, Bedford, MA 01730). La concordancia entre metodos se evaluocon graficos de Bland-Altman y tambien se examino la presencia de heterocedasticidad. Las diferencias entre metodos se analizaron con la prueba T deStudent para muestras relacionadas.Resultados: Para el total de la muestra, la impedancia bioelectrica infraestimo el porcentaje de MG en 3.87 puntos (IC 95%=3.22-4.52; p=0.05). Conclusion: El presente estudio sugiere que, tomando como referencia la absorciometria de rayos X de doble energia, la impedancia bioelectrica calculadaa partir de una ecuacion no especifica para arbitros, infraestima la MG y consecuentemente, sobreestima la MLG en arbitros de futbol de elite. portuguesObjetivo: A literatura atual sobre a composicao corporal de arbitros de futebol de elite e escassa e quase inexistente. Portanto, afim de estabelecer o nivelde concordância entre a bioimpedância eletrica (BIA) e a absorciometria por raios-X de dupla energia (DXA) em arbitros de futebol de elite, o objetivodeste estudo foi comparar os valores de massa gorda (FM) e massa livre de gordura (FFM) valores mensurados com estes dois diferentes metodos.Metodo: Um total de 30 arbitros pertencentes as categorias 1st, 2nde 2ndB, e 36 arbitros assistentes da 1ste 2nd categorias da Liga Nacional Espanhola. A FMtotal e regional e a FFM foram avaliadas atraves de um analisador BIA portatil TANITA BC 418-MA (Tanita Corp., Toquio, Japao) e DXA (Hologic Corp.Software versao 12.4, Bedford, MA 01730). A concordância entre os metodos foi avaliada atraves da plotagem dos resultados nos graficos de Bland-Altman e a presenca de heteroscedasticidade tambem foi examinada. As diferencas entre os metodos foram analisadas pelo teste t para duas amostraspareadas.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 = 0.05).Conclusoes: O presente estudo sugere que, de acordo com a DXA, os valores da BIA calculados com uma equacao nao especifica estao subestimando a FMtotal e, consequentemente, superestimando a FFM total em arbitros de futebol de elite do sexo masculino. EnglishObjective: The current literature about the body composition of elite football referees is scarce and almost non-existent. Therefore, and in order toestablish 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 nationalleague 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=0.05). 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.

Whole-body vibration (WBV) intervention studies and reviews have been increasing lately. However, the results regarding its effects on bone tissue in different populations are still inconclusive. The goal of this overview was to summarize systematic reviews assessing the effects of WBV training on bone parameters. Three electronic databases were scanned for systematic reviews and meta-analyses evaluating the effects of WBV on bone tissue. The search had no time restrictions and was limited to articles written in English. Vibration protocols and the main bone parameters included in each review were extracted. Methodological quality was assessed and analyses were conducted stratifying by age. 17 reviews and meta-analyses fulfilled the inclusion criteria. No increase or small improvements in bone mineral density (BMD) after WBV interventions were observed in reviews regarding postmenopausal women. One intervention study regarding young adults was included and reported no bone-related benefits from WBV. Most reviews including children and adolescents with compromised bone mass showed an improvement of BMD at lower limbs, lumbar spine, and whole body. In conclusion, WBV interventions seem to help children and adolescents with compromised bone mass to increase their BMD, but these improvements are limited in postmenopausal women and there is insufficient evidence for young adults. Further research is also needed to identify the ideal parameters of WBV training focused on bone health.

The effects of swimming on bone mineral density (BMD) have been studied by several researchers, with inconsistent results. This meta-analysis aims to determine whether systematic swimming training may influence BMD during childhood and adolescence. A systematic search was performed in PubMed, SPORTDiscus and ClinicalTrials.gov from the earliest possible year to March 2015, with data extraction and quality assessment performed independently by two researchers following the PRISMA methodology. Swimmers were compared to sedentary controls and to athletes performing highly osteogenic sports. Therefore, a total of two meta-analyses were developed. Fourteen studies met the inclusion criteria and were included in the meta-analyses. Swimmers presented similar BMD values to sedentary controls and lower than other high-impact athletes. Femoral neck and lumbar spine BMD differences between swimmers and sedentary controls and between swimmers and athletes practicing osteogenic sports appeared to increase with age and favored the non-swimming groups. There were no differences by sex. While swimming is associated with several health benefits, it does not appear to be an effective sport for improving BMD. Swimmers might be in need of additional osteogenic exercises for increasing BMD values.

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 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.

Most researchers adjust bone by lean mass when comparing swimmers with controls. This adjustment is done under the assumption that lean affects bone similarly in both groups. Nonetheless, we found that the muscle-bone association is uncoupled in swimmers, and consequently, researchers should avoid this adjustment when evaluating swimmers’ bone. Introduction: To examine the functional and structural muscle-bone unit in adolescent swimmers. Methods: Sixty-five swimmers (34 girls/31 boys) and 119 controls (51 girls/68 boys) participated in the study. Muscle cross-sectional area (MCSA), bone mineral content (BMC), and polar strength-strain index (SSIPOL) were measured in the non-dominant radius by peripheral quantitative computed tomography (pQCT). Subtotal BMC and lean mass were evaluated with dual-energy X-ray absorptiometry (DXA). Handgrip and isometric knee extension (IKE) tests were performed to determine muscle force. The effect of MCSA, lean and force on SSIPOL, and BMC were tested, and the functional and structural muscle-bone ratios of swimmers and controls were compared. Results: Both muscle size (MCSA and lean) and muscle force (handgrip and IKE) influenced BMC and SSIPOL in swimmers and controls similarly. Swimmers presented normal MCSA and lean values for their height, but when compared with controls, swimmers presented a higher amount of lean and MCSA for the same BMC or SSIPOL (structural muscle-bone unit). For the functional muscle-bone unit, different results were found for the lower and upper limbs, as no differences were found for the upper limbs, while for the lower limbs, swimmers presented higher muscle force for the same amount of BMC. Conclusions: The contradictory results regarding BMC in swimmers found in previous studies could partly be explained with the findings of the present study that reinforce the idea that swimming is not an effective sport to practice regarding bone mass and that the muscle-bone unit is different in swimmers than in controls.

Context The numbers of vegans and vegetarians have increased in the last decades. However, the impact of these diets on bone health is still under debate. Objective This systematic review and meta-analysis sought to study the impact of vegetarian and vegan diets on bone mineral density (BMD) and fracture risk. Data sources A systematic search was conducted of PubMed, Scopus, and Science Direct, covering the period from the respective start date of each database to November 2017. Data extraction Two investigators evaluated 275 studies against the inclusion criteria (original studies in humans, written in English or Spanish and including vegetarian or vegan diets and omnivorous diets as factors with BMD values for the whole body, lumbar spine, or femoral neck and/or the number of fractures as the outcome) and exclusion criteria (articles that did not include imaging or studies that included participants who had suffered a fracture before starting the vegetarian or vegan diet). The quality assessment tool for observational cohort and cross-sectional studies was used to assess the quality of the studies. Results Twenty studies including 37 134 participants met the inclusion criteria. Compared with omnivores, vegetarians and vegans had lower BMD at the femoral neck and lumbar spine and vegans also had higher fracture rates. Conclusions Vegetarian and vegan diets should be planned to avoid negative consequences on bone health. Systematic review registration PROSPERO registration no. CRD42017055508.

The aim was to analyze bone mineral content (BMC) and density (BMD) in regular swimming trained adolescents and the interaction that weigh-bearing sports may have on these values. Bone mass was evaluated by dual energy x-ray absorptiometry (DXA) and quantitative ultrasound (QUS) in 77 swimmers (34 females/43 males) and 52 normoactive controls (CG; 23 females/29 males) from 11 to 18 years. Swimmers who had performed or were performing other sports (OSP; 11 females/20 males) were compared with pure swimmers (PSW; 23 females/23 males). Both groups were compared with CG. Bone values were compared using analyses of covariance adjusting for height, calcium intake, subtotal lean (whole body lean minus head), and pubertal status. Male PSW showed lower BMD and BMC at several sites than male CG. However, for male OSP, only lumbar spine BMC was lower in OSP than male CG. Male PSW showed lower BMD and BMC when compared with male OSP. Female PSW showed higher arm BMD and lower leg BMC than female CG, while female OSP only presented lower leg BMC than female CG. Contrary to males, female-PSW presented higher BMD and BMC than female OSP. No differences in QUS values were found between swimmers and CG. To summarize, although more information is needed for females, it seems that for males, swimming is associated with lower BMC and BMD.

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.The aim of this study was to compare bone geometry in adolescent football players and controls.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.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).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.

Swimming has little effect on bone mass. Therefore, adolescent swimmers should complement their water training with a short and intense weight-bearing training, aiming to increase their bone acquisition. Forty swimmers performed a six-month whole-body vibration (WBV) training. WBV had no effect on adolescent swimmers’ bone mass or lean mass. The aims of the present study were to evaluate the effects of a whole-body vibration (WBV) intervention on bone mineral density (BMD), bone mineral content (BMC) and lean mass (LM) in adolescent swimmers. Forty male and female adolescent swimmers (VIB; mean age 14.2 ± 1.9 years) completed the WBV protocol that consisted of 15 min of training 3 days per week during a 6-month period (ranging from 3.6 to 11.6 g), while 23 swimmers (SWI; mean age 15.0 ± 2.2 years) continued with their regular swimming training alone. VIB were divided into tertiles according to training compliance in order to evaluate if any dose-effect relation existed. BMD, BMC and LM were measured longitudinally by dual energy X-ray at the whole body, lumbar-spine and hip. No group by time interactions and no differences in change percentage were found for BMD, BMC or LM in any of the measured variables. The mean change percentage of the subtotal body (whole body minus the head) for VIB and SWI, respectively, was 2.3 vs. 2.4% for BMD, 5.7 vs 5.7% for BMC and 7.3 vs. 8.0% for lean mass. Moreover, no indication for dose-response was observed. The proposed WBV protocol had no effect on BMD, BMC and LM in adolescent swimmers. Other types of training should be used in this population to improve both bone and lean mass.

Purpose: The aim of the present study was to determine which of the published anthropometric equations is the most appropriate to estimate body-fat percentage (BF%) in adolescent swimmers. Method: Eighty-eight swimmers (45 boys, 43 girls) participated in this study. Following the recommendations of the International Society of the Advancement of Kinanthropometry, biceps, triceps, subscapular, iliac-crest, supraspinale, front-thigh, and medial calf skinfold thicknesses were measured. Waist, hip, midthigh, calf, relaxed arm, and arm flexed and tensed girths were also registered. BF% was measured with dual-energy X-ray absorptiometry (DXA) to obtain the reference value. Existing anthropometric equations were applied, and BF% results obtained from anthropometric equations were compared to DXA BF% results with the modified Bland-Altman. Results: The Flavel, Durnin-Rahaman-Siri, and Durnin-Rahaman-Brozek were the only equations that did not demonstrate statistically significant differences when compared with DXA. Conclusion: The present study showed that the best anthropometric equation from existing literature to estimate BF% in swimmers is that proposed by Durnin-Rahaman (independently of applying the Siri or Brozek equation).

The aims of the present study were, firstly, to evaluate areal bone mineral density (aBMD), bone strength and structure during a swimming season and compare them to those of normo-active controls (CG), and secondly to ascertain whether practising an additional weight-bearing sport other than swimming might improve bone. Twenty-three swimmers who only swam (SWI-PURE; 14 males, 9 females), 11 swimmers who combined swimming with an additional weight-bearing sport (SWI-SPORT; 8 males, 3 females) and 28 controls (CG; 16 males, 12 females) participated in the present study. aBMD was assessed with dual energy X-ray (DXA). Bone mass, area, structure and strength of the non-dominant tibia and radius were measured with peripheral quantitative computed tomography (pQCT). Measurements were performed at the beginning of the swimming season and 8 months later. The only difference among groups for DXA and pQCT variables was found for arm aBMD, which was higher in the SWI-SPORT than in the CG group at both pre- and post-evaluation. Group by time interactions (GxT) were found for trochanter aBMD when comparing SWI-SPORT to CG and SWI-SPORT to SWI-PURE, favouring in both cases SWI-SPORT. No GxT were found for the radius. For the tibia, GxT were found between SWI-SPORT and CG and between SWI-PURE and CG, in both cases favouring the swimmers. A season of swimming does not confer any additional benefits to aBMD, but may confer minor benefits to structure and mass. Complementing swimming with a weight-bearing activity is beneficial to bone.

Introduction: Dual X-ray absorptiometry (DXA), air displacement plethysmography (ADP), bioelectrical impedance analysis (BIA) and anthropometry are four body composition methods that have been frequently used for the assessment of body fat percentage (%BF) in athletes. However, the agreement between these methods has not been studied yet in adolescent football players. Objectives: The aim of this study was to compare %BF calculated by DXA, ADP, BIA and anthropometry in 92 participants. Methods: Sixty-four males (13.4 ± 0.6 years of age) and 28 females (13.4 ± 0.6 years) participated in this study. %BF was measured with four methods: DXA, ADP, BIA, and anthropometry. ADP %BF was calculated by using Siri’s equation. The equation proposed by Slaughter et al. was used to calculate %BF by anthropometry. Paired t-test was used to compare %BF means. The heteroscedasticity was calculated by Bland-Altman analyses. Results and conclusions: Both in males and females, DXA, ADP, BIA and Slaughter et al. equation demonstrated significant %BF differences when compared to each other (p < 0.05); 95% limits of agreements ranged from 5.13 to 15.09% points. Only BIA showed heteroscedasticity compared to the other methods in both genders (p < 0.05). Although DXA, ADP, BIA, and anthropometry have been used in the scientific literature in order to assess %BF in adolescent football players, these results demonstrate that these body composition methods are not interchangeable in this population.

Aim To ascertain the effects of 21 weeks of circuit training, including plyometric jumps, on cardiorespiratory fitness of youths with Down's syndrome (DS). Methods Twenty-seven children and adolescent aged 10 to 19 years with DS participated in this study and were divided in two groups: exercise (EXE, n=14) and control (CON, n=13). Work time, peak values of oxygen consumption, respiratory exchange ratio, heart rate and minute ventilation of the participants were measured pre- and post-training with a graded exercise treadmill test. Results EXE group increased all their cardiorespiratory parameters compared to baseline after 21 weeks of training (all P Conclusion It may be concluded that youths with Down syndrome can achieve improvements in several cardiorespiratory parameters when performing 21 weeks of training including plyometric exercises.

Resumen Objetivo Determinar los efectos de 21 semanas de entrenamiento en circuito, incluyendo saltos pliometricos, sobre la resistencia cardiorrespiratoria de jovenes con sindrome de Down (SD). Metodo Veintisiete jovenes con SD de entre 10 y 19 anos participaron en este estudio. Los participantes se dividieron en dos grupos: ejercicio (EJE; n = 4) y control (CON; n = 13). Antes y despues de la realizacion del programa de entrenamiento se midieron los siguientes parametros: tiempo de trabajo, valores maximos de consumo de oxigeno, cociente respiratorio, frecuencia cardiaca y ventilacion minuto de los participantes mediante una prueba de esfuerzo progresiva en tapiz rodante. Resultados Los participantes del grupo EJE aumentaron todos los parametros cardiovasculares en comparacion con su valor basal, despues del entrenamiento (todos p p Conclusion Se puede concluir que los jovenes con SD pueden conseguir mejoras en diversos parametros cardiorrespiratorios tras la ejecucion de 21 semanas de entrenamiento con ejercicios pliometricos.