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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.

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.

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.

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.

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.

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 ...

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.

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.

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.

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.

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.

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.

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 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.

Objectives The aims of the present study were: (1) to characterize vBMD, bone structure and strength with peripheral quantitative computerized tomography (pQCT) in adolescent swimmers and compare it to normo-active controls (CG); and (2) to evaluate the possible interaction that weight-bearing sports might have on swimmers bone. Design Cross-sectional. Methods The non-dominant radius and tibia of 79 (32 females) swimmers and 49 (22 females) CG (both 11–18 years old) were evaluated at proximal and distal sites with a pQCT scanner. Values of total, trabecular and cortical volumetric bone mineral density (vBMD) were obtained from each scan. Cortical thickness, endosteal and periosteal circumferences were also measured and bone strength indexes were calculated. Analyses of covariance were used to compare variables between groups adjusting for age, tanner stage and bone length. Three different analyses were performed according to present and past sport participation in addition to swimming in order to determine differences among swimmers who had performed or were performing other sports (OTHER-SP) (10 females/17 males) and swimmers who had not performed other sports (NO-OTHER-SP) (22 females/22 males). Both of these groups were compared to each other and to a CG (22 females/27 males). Results No differences were found between swimmers and CG for bone strength indexes, structure or vBMD (independently of the compared sample). Conclusions These results indicate that swimmers present similar bone strength and structure than CG who did not present high physical activity levels.

Julian-Almarcegui, C., Huybrechts, I., Gomez-Bruton, A., Matute-Llorente, A., Bel-Serrat, S., Gonzalez de Aguero, A., Cabello, A. G., Moreno, L. A., Casajus , J,. Vicente-Rodriguez , G. (2015). Underreporting of energy intake in an athlete adolescent population. Revista Andaluza de Medicina del Deporte, 8 (1), 31-31