The muscle-bone unit in adolescent swimmers.

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.

Does fitness attenuate the relationship between changes in sitting time and health-related quality of life over time in community-dwelling older adults? Evidence from the EXERNET multicenter longitudinal study.

OBJECTIVE: To assess the relationship between fitness levels and components, sitting time and health-related quality of life (HRQoL), over time among community-dwelling older adults. METHODS: Three different sitting trajectories were calculated: (i) no change; (ii) decrease; and (iii) increase in ST, between baseline and follow-up. Fitness was assessed using the aerobic capacity, upper and lower limb strength, and total fitness. Participants were classified into higher (75th percentile or above) or lower (below 75th percentile) fitness levels, using the fitness tests. HRQoL scores at follow-up were compared to the three different sitting time trajectories within and across both the higher and the lower fitness groups for each of the three fitness indexes. RESULTS: Greater HRQoL scores were observed in those participants that decreased their ST as compared with those increasing their sitting time over time for participants classified in the lower end of their aerobic capacity or total fitness index. No differences were detected in HRQoL scores in people classified in the higher fitness level group for any of the fitness indexes. Participants that increased or did not change their sitting time and who were classified in the higher fitness end of aerobic capacity and total fitness index self-reported higher HRQoL scores when compared with those in the lower fitness end. CONCLUSION: Increased sitting time over time is associated with poorer HRQoL in older adults. Higher fitness levels could help attenuate the negative impact of sitting over time.

Swimming and bone: Is low bone mass due to hypogravity alone or does other physical activity influence it?

UNLABELLED: Swimming during adolescence has shown neutral or even negative effects on bone mass. Nevertheless, it is still unknown if these effects are due to swimming or to other factors, such as sedentary behaviors. INTRODUCTION: Three objectives were described (1) to measure objective physical activity (PA) additional to swimming performed by adolescent swimmers (SWI) and compare it to that performed by normo-active controls (CG), (2) to describe the relationship between objectively measured PA and bone mass, and (3) to compare bone mass of swimmers that meet the World Health Organization PA guidelines (active) WHO and those that do not (inactive). METHODS: A total of 71 SWI (33 females) and 41 CG (17 females) wore an accelerometer for at least 4 days. PA was expressed as the amount of time (minutes/day) in each intensity [sedentary/light/moderate or vigorous (VPA), and the sum of moderate and vigorous (MVPA)]. Using the cutoff points proposed by Vanhelst et al. SWI were classified as active or inactive according to whether they reached 60 min of weight-bearing MVPA per day or not. Bone mineral density (BMD) was measured by dual energy X-ray absorptiometry, and bone strength values were calculated with peripheral quantitative computed tomography. Differences in PA intensities were calculated between SWI and CG. The relation of VPA to bone mass was studied in the SWI. RESULTS: Male-SWI spend less time in VPA and MVPA than male-GC, which partly explains the lower BMD values in SWI than CG. CONCLUSION: Swimming may displace weight-bearing VPA with serious implications on bone health.

Effect of whole-body vibration training on bone mass in adolescents with and without Down syndrome: a randomized controlled trial.

UNLABELLED: Whole-body vibration training (WBV) attracts great interest as osteoporosis prevention strategy. Twenty-six adolescents with and without Down syndrome (DS) (13 DS; 12-18 years) performed 20 weeks of WBV. The results indicate that WBV seems to provoke a lesser response in adolescents with DS than in those without DS. INTRODUCTION: This study aims to observe the differences between adolescents with and without DS in the effects of 20 weeks of WBV training, on bone mineral content (BMC) and density (BMD). METHODS: Twenty-six adolescents (13 DS; 12-18 years) were measured with dual-energy X-ray absorptiometry before and after the intervention (3/week, 10 repetitions (30-60 s) and 1-min rest, frequency 25-30 Hz and peak-to-peak displacement of 2 mm (peak acceleration 2.5-3.6 g)). Both, an intention-to-treat (ITT) analysis designed to assess the effects on bone mass and a per-protocol analysis, designed to compare poor and high compliers, were performed. RESULTS: The ITT analysis revealed significant increases in all BMC and BMD parameters (dz = 0.66 to 1.64; all p < 0.05) in the non-DS group, whilst DS group improved whole-body, subtotal (whole-body less head), upper limbs (ULIMBS), pelvis, lower limbs (LLIMBS) and spine BMC (dz = 0.75 to 1.76; all p < 0.05) and subtotal, pelvis, LLIMBS and spine BMD (dz = 0.73 to 1.28; all p < 0.05). Significantly greater increases were evident in the absolute and percent changes of the non-DS group over DS group (d = 0.88 to 3.85; all p < 0.05). ULIMBS BMD showed a tendency towards an interaction (f = 0.41 and p = 0.086) with higher increase for non-DS group. When a per-protocol analysis was considered, high-complier adolescents had 8.1 versus 5.3 % of gains in the spine BMC over poor-complier adolescents (d = 0.93; p < 0.05). CONCLUSIONS: Twenty weeks of WBV training may improve BMC and BMD in clinically relevant skeletal sites in both groups. Nevertheless, this type of training seems to provoke a lesser response in adolescents with DS than in those without DS.

Effect of whole body vibration training on bone mineral density and bone quality in adolescents with Down syndrome: a randomized controlled trial.

UNLABELLED: Adolescents with Down syndrome (DS) have poorer bone health than their peers without DS. Twenty-five adolescents with DS were randomly assigned to whole-body vibration training (WBV) or control groups. The results indicate that a 20-week WBV might be useful to improve subtotal bone mineral content and density in adolescents with DS. INTRODUCTION: This study aims to determine the effects of 20 weeks of whole body vibration training (WBV) on bone mineral content (BMC), density (BMD), and structure variables in adolescents with Down syndrome (DS). METHODS: This randomized controlled trial of 25 adolescents (12-18 years) with DS (8 females) generated 2 non-equal groups, WBV group (n = 11) and CON group (n = 14). Using an efficacy analysis, the primary outcomes were BMC and BMD by dual-energy X-ray absorptiometry and the secondary were bone structure variables by peripheral quantitative computed tomography. A synchronous vibration platform (PowerPlate®) was used (3/week, 10 repetitions (30-60 s) 1-min rest, frequency of 25-30 Hz, and peak-to-peak displacement of 2 mm (peak acceleration 2.5-3.6 g)). RESULTS: WBV group improved whole body BMC 2.8%, 95% CI [3.5, 2.1], subtotal area, BMC, and BMD by 2.8, 4.8, and 2%, respectively, 95% confidence intervals (CIs) [3.4, 2.1], [6.5, 3.1], and [2.8, 1.1], respectively (all, p < 0.05), showing group by time interactions in BMC and BMD (both p < 0.05). Lumbar spine BMC and BMD also increased in the WBV group by 6.6 and 3.3% both p < 0.05, 95 % CIs [8.6, 4.7], and [4.9, 1.7], respectively. Regarding bone structure, WBV group showed improvements in tibial BMC at 4 % (2.9 %, 95 % CI [3.0, 2.8]) and in volumetric BMD (vBMD), cortical vBMD, and cortical thickness at 66% of the radius (by 7.0, 2.4, and 10.9%; 95% CIs [7.4, 6.7], [2.6, 2.3], and [12.4, 9.3], respectively) (all, p < 0.05). CONCLUSIONS: A 20-week WBV, with this protocol, might be useful to improve subtotal BMC and BMD in adolescents with DS.

The effects of swimming training on bone tissue in adolescence.

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.

Body Composition Evolution in Elite Football Referees; an Eleven-years Retrospective Study.

Fitness, and specifically body composition of football referees requires attention in order to achieve the highest possible standards. The aim of the present study was to describe body composition of elite Spanish football referees over 11 years. Data from 2001 to 2012 pre-seasons were analyzed from a total of 470 referees of 1(st) and 2(nd) categories in Spanish male football (1C and 2C respectively). Body mass index (BMI), sum of 6 skinfolds (6SS) and percentage of body fat (%BF) were assessed. 2-independent samples Student's t-test between categories, and ANOVA tests with Bonferroni post-hoc analyses among seasons were applied. Overall, 1C referees were older than 2C in every season, and both 1C and 2C showed a decrease in 6SS, BMI and %BF throughout seasons (all p<0.05; from 82.5 to 62.9 mm, from 23.7 to 22.4 kg/m(2) and from 13.7 to 11.7%). No differences were observed between categories in any season. Since football referees at the highest levels need to have a low %BF for the intense matches nowadays, an improvement in their body composition profile has been observed in a highly competitive league as 'La Liga' in Spain over the last decade.

Cortical and trabecular bone at the radius and tibia in male and female adolescents with Down syndrome: a peripheral quantitative computed tomography (pQCT) study.

UNLABELLED: We aimed to describe the structure and strength of the tibia and radius of adolescents with Down syndrome. We observed that despite higher levels of volumetric bone mineral density in determined skeletal sites, they are at higher risk of developing osteoporotic fractures in the future due to their lower bone strength indexes. INTRODUCTION: The aims of the study were to describe the cortical and trabecular volumetric bone mineral density (vBMD), bone mineral content (BMC), area, and bone strength in adolescents with Down syndrome (DS) and to compare them with adolescents without disabilities. METHODS: Thirty adolescents (11 girls) with DS and 28 without disabilities (10 girls) participated in the study. Peripheral quantitative computed tomography measurements were taken at proximal and distal sites of the tibia and radius. Values of total, trabecular, and cortical BMC; vBMD; and area were obtained of each scan. Cortical thickness and endosteal and periosteal circumferences were also measured, and different bone strength indexes were calculated. Student's t tests were applied between groups. RESULTS: The DS group showed greater vBMD at distal radius, BMC at proximal radius, and total and cortical vBMD at proximal tibia. The non-DS group showed higher total and trabecular area at the distal radius and total, cortical, and trabecular BMC and area at distal tibia. Higher values of periosteal and endosteal circumference and bone strength were also found in non-DS group. CONCLUSIONS: From these results, it can be believed that even with higher vBMD in determined skeletal sites, adolescents with DS are at higher risk of suffering bone fractures due to an increased fragility by lower resistance to load bending or torsion.

Impact of methodological decisions on accelerometer outcome variables in young children.

BACKGROUND: The impact of accelerometer-related methodological decisions relating to the assessment of physical activity and sedentary time has not been conclusively determined in young children. OBJECTIVES: To determine the effects of epoch and cutoff points on the assessment of physical activity and sedentary time and to determine the accelerometer wear time required to achieve reliable accelerometer data in children. DESIGN: Children were recruited from centres at Ghent, Glasgow, Gothenburg and Zaragoza. METHODS: Physical activity was assessed for 1 week in 86 children (41 girls, 45 boys; mean age 7±2 years) by uniaxial accelerometry. The epoch was set at 15 s and reintegrated to 30 and 60 s. Time spent sedentary and in moderate and vigorous physical activity (MVPA) was assessed using a range of cutoff points. Number of days required to achieve 80% reliability was predicted using the Spearman-Brown Prophecy formula. RESULTS: The Reilly cutoff points (<1100 counts per min (CPM)) indicated less sedentary time per day when comparing 15 vs 30 s and 15 vs 60 s epochs: 570±91 vs 579±93 min and 570±91 vs 579±94 min, respectively; P<0.05. Pate cutoff points (>420 counts per 15 s) reported more MVPA time per day compared with Sirard (890 counts per 15 s) and Puyau cutoff points (>3200 counts per min) using 15 s epoch: 78 (4-197) min (median (range) vs 18 (1-80) min and 24 (1-100) min, respectively; P<0.001. Compliance with guidelines of at least 60 min MVPA was 84, 78 and 73% for Pate cutoff points using 15, 30 and 60 s epochs, respectively, but 0% for Sirard and Puyau cutoff points across epochs. The number of days required to achieve 80% reliability for CPM, sedentary and MVPA time was 7.4-8.5 days. CONCLUSION: Choice of epoch and cutoff point significantly influenced the classification of sedentary and MVPA time and observed compliance to the MVPA guidelines.

Bone mass in male and female children and adolescents with Down syndrome.

SUMMARY: Children and adolescents with Down syndrome (DS) have lower levels of bone mass compared with youths without DS. Their sexual dimorphism in bone mass also differs from that observed in children and adolescents without Down syndrome. INTRODUCTION: This study aimed to compare bone mass and sexual dimorphism in bone mass between male and female youths with DS and age- and sex-matched controls without DS. METHODS: Bone mineral density (BMD), volumetric BMD, bone mineral apparent density (BMAD), BMD/height (BMDH), and total lean mass were measured or calculated from DXA. Thirty-two youths (15 females) with DS and 32 youths (13 females) without DS participated in the study. RESULTS: ANOVA tests showed lower BMAD and BMDH in females with DS compared with females without DS. ANCOVA tests revealed lower BMD in the whole body of males and females as well as BMD in the hip region of the females with DS compared with their counterparts without DS. Within the group with DS, females had greater lumbar spine BMD than the males. CONCLUSIONS: The low values of BMD and related parameters, together with the differences in the sexual dimorphism, indicate a non-standard bone development in this specific population of children and adolescents with DS.

Health-related physical fitness in children and adolescents with Down syndrome and response to training.

Physical fitness is related to health at all ages. Information about physical fitness in the Down syndrome (DS) population, however, is scarce, especially when we consider children and adolescents. A review of the current data available on this topic would be both timely and important as it would serve as a starting point to stimulate new research perspectives. The data we reviewed from the literature showed a general trend toward lower values of physical fitness parameters and worse body composition variables in children and adolescents with DS compared with the population without intellectual disability (ID) or even with the population with ID without DS. Notably, children and adolescents with DS have been described as less active or overprotected; however, these factors may not be the cause of their poor physical fitness. Many of the training programs carried out in children and adolescents with DS did not yield the desired responses, and the reasons are still unknown. The purpose of this review is to summarize the current available literature on health-related physical fitness in children and adolescents with DS, and the effect of training on these variables. From the literature available, it is clear that more data on this population are necessary.

Associations between Physical Fitness, Bone Mass, and Structure in Older People.

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 (r 2 change = 24.8% and 23.0%), while walking speed predicted cortical bone mineral density (r 2 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 (r 2 change = 4.2%) and total hip aBMD (r 2 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.

Do 6 months of whole-body vibration training improve lean mass and bone mass acquisition of adolescent swimmers?

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. PURPOSE: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.

Bone structure of adolescent swimmers; a peripheral quantitative computed tomography (pQCT) study.

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.

Combined effects of interaction between physical activity and nutrition on bone health in children and adolescents: a systematic review.

CONTEXT: Osteoporosis is a major public health concern worldwide. Understanding the roles of diet and physical activity in ensuring adequate bone mass accrual during childhood and adolescence may help identify strategies to reduce the risk of osteoporotic fractures later in life. OBJECTIVE: The present systematic review was conducted to provide an overview of the current knowledge of the combined effects of physical activity and diet on bone mass accrual in children and adolescents. DATA SOURCES: Data were obtained via searches of the PubMed, EMBASE, SPORTDiscus, and ISI Web of Science databases. STUDY SELECTION: Studies published in English and Spanish between 1887 and August 2013 were eligible for inclusion. Two investigators evaluated the studies against the inclusion and exclusion criteria. A total of 14 studies (7 cross-sectional and 7 experimental) were included in the review. DATA EXTRACTION: The Pedro score and the Black and Down's checklist were used to evaluate the methodological quality of the experimental and the cross-sectional studies, respectively. Study characteristics were summarized in accordance with the review's PICO criteria. DATA SYNTHESIS: Significant exercise-by-calcium interaction was detected at several different bone sites. CONCLUSIONS: Although the results of cross-sectional studies were inconsistent, the results of randomized controlled trials showed that exercise has the potential to improve bone health under conditions of adequate calcium intake.

Swimming training repercussion on metabolic and structural bone development; benefits of the incorporation of whole body vibration or pilometric training; the RENACIMIENTO project.

INTRODUCTION: Enviromental factors such as exercise participation and nutrition have often been linked to bone improvements. However, not all sports have the same effects, being non-osteogenic sports such as swimming defined as negative or neutral sports to practice regarding bone mass by some authors, similarly exercise-diet interaction in especific groups is still not clear. OBJECTIVE: To present the methodology of the RENACIMENTO project that aims to evaluate body composition and more specifically bone mass by several techniques in adolescent swimmers and to observe the effects and perdurability of whole body vibration (WBV) and jumping intervention (JIN) on body composition and fitness on this population and explore posible diet interactions. DESIGN: Randomized controlled trial. METHODS: 78 swimmers (12-17 y) and 26 sex- and age-matched controls will participate in this study. Dual energy X-ray, peripheral Quantitative Computed Tomography, Quantitative Ultrasound, Bioelectrical Impedance Analysis, and anthropometry measurements will be performed in order to evaluate body composition. Physical activity, nutrition, pubertal development and socio-economical status may act as confounders of body composition and therefore will also be registered. Several fitness factors regarding strength, endurance, performance and others will also be registered to evaluate differences with controls and act as confounders. A 7-month WBV therapy will be performed by 26 swimmers consisting of a training of 15 minutes 3 times per week. An 8 month JIM will also be performed by 26 swimmers 3 times per week. The remaining 26 swimmers will continue their normal swimming training. Four evaluations will be performed, the first one in order to describe differences between swimmers and controls. The second one to describe the effects of the interventions and the third and fourth evaluations to describe the perdurability of the effects of the WBV and JIN. CONCLUSION: The RENACIMIENTO project will allow to answer several questions regarding body composition, fitness, bone mass and interaction with diet of adolescent swimmers, describe swimming as a positive, negative or neutral sport to practice regarding these parameters and elucidate the effects and perdurability of WBV and JIM on body composition.

Introducción: En la actualidad se ha demostrado que el ejercicio físico y la nutrición mejoran la masa ósea. Sin embargo, existen deportes de bajo impacto como la natación que no presentan efectos positivos en su desarrollo. Además, la interacción ejercicio-dieta y su efecto osteogénico sigue sin estar clara. Objetivo: Presentar la metodología del proyecto RENACIMIENTO que tiene por objetivo evaluar la composición corporal del nadador adolescente y más concretamente la masa ósea a través de diversas técnicas. Además se pretenden determinar los efectos y la perdurabilidad que pueden tener el entrenamiento vibratorio (WBV) y una intervención con saltos (JIN) sobre la composición corporal y condición física de estos adolescentes, explorando la posible interacción con la dieta. Diseño: Ensayo clínico aleatorizado. Metodología: 78 nadadores (12-17 años) y 26 controles del mismo sexo y edad participarán en el estudio. Se utilizarán absorciometría dual de rayos-x, tomografía axial computerizada, ultrasonidos cuantitativo, bioimpedancia eléctrica, y medidas antropométricas para evaluar la composición corporal. La actividad física, nutrición, desarrollo puberal y status socio-económico podrían actuar como covariables de la composición corporal y por lo tanto también serán registradas. Se evaluarán diversos factores de la condición física relacionados con la fuerza, resistencia, rendimiento y otros para definir las diferencias con los controles y para que sirvan como covariables. 26 nadadores realizarán una intervención de WBV 7 meses 15 minutos 3 veces por semana. Además otros 26 nadadores realizarán una JIN 3 veces por semana durante 8 meses. Los 26 nadadores restantes continuarán con su entrenamiento habitual de natación. Se realizaran 4 evaluaciones, la primera de ellas para describir las diferencias existentes entre nadadores y controles, la segunda para describir los efectos de las intervenciones realizadas y la tercera y cuarta para evaluar la perdurabilidad de estas intervenciones. Conclusión: El proyecto RENACIMIENTO permitirá contestar a diversas preguntas relacionadas con la composición corporal, condición física y masa ósea de los nadadores adolescentes y el posible efecto combinado dieta-ejercicio en esta población. Definirá la natación como un deporte positivo, neutral o negativo en relación con estos parámetros y esclarecerá los efectos y perdurabilidad de la WBV y JIN sobre la composición corporal.

Effects of a short-term whole body vibration intervention on physical fitness in elderly people.

We aimed to clarify whether a short-term whole body vibration (WBV) training has a beneficial effect on physical fitness in elderly people. Forty-nine non-institutionalized elderly (75.0 ± 4.7 years) participated in the study. Twenty-four of them trained on a vibration platform for 11 weeks. Physical fitness included balance, lower- and upper-body strength and flexibility, agility, walking speed and endurance. In the WBV group most of the physical tests improved through the intervention (all P < 0.01) while in the control group only an increment was detected in lower-body strength (P < 0.05). In conclusion, a short-term WBV training is beneficial for physical fitness among elderly people.

Physical activity and cardiorespiratory fitness in adolescents with Down syndrome.

AIMS: To determine if adolescents with and without Down syndrome (DS) accomplish the physical activity (PA) guidelines and to evaluate relationships between PA and cardiorespiratory variables. METHODS: 42 adolescents (27 with DS) participated in this study. PA was measured using accelerometers. Walking-graded treadmill protocol with a breath-by-breath gas analyzer was employed to assess cardiorespiratory fitness. RESULTS: Adolescents with DS spent less time in sedentary PA, moderate PA (MPA), vigorous PA (VPA) and moderate to vigorous PA (MVPA) than those without DS. VO2peak was correlated with total minutes spent in light PA, MPA, VPA and MVPA in the control group (from r = 0.55 to r = 0.61, p < 0.05) and with MPA and MVPA in the DS group (from r = 0.38 to r = 0.41, p < 0.05). CONCLUSION: Nor DS neither control groups achieved at least 60 minutes of MPA daily. Engaging more time in MPA was associated with greater cardiorespiratory fitness in adolescents with DS.

Objetivos: Comprobar si los adolescentes con síndrome de Down (SD) cumplen las guías de actividad física (AF) y evaluar la relación entre AF y la condición cardiorrespiratoria. Métodos: 42 adolescentes (27 con SD) participaron en este estudio. La AF se midió usando acelerometría. La condición cardiorrespiratoria se evaluó mediante ergoespirometría en tapiz rodante con un protocolo progresivo continuo. Resultados: Los adolescentes con SD pasaron menos tiempo en AF sedentaria, moderada (MAF), vigorosa (VAF) y moderada-vigorosa (MVAF) que los adolescentes sin SD. El VO2peak mostró correlación con minutos totales en AF ligera, MAF, VAF y MVAF en el grupo control (desde r = 0,55 hasta r = 0,61, p < 0,05) y con MAF y VAF en el grupo de adolescentes con SD (desde r = 0,38 hasta r = 0,41, p < 0,05). Conclusión: Ningún grupo alcanzó 60 minutos de MAF diaria. La capacidad cardiorrespiratoria en adolescentes con SD se asoció con una mayor participación en MAF.

Do calcium and vitamin D intake influence the effect of cycling on bone mass through adolescence?

INTRODUCTION: Cycling has been associated with decreased bone mass during adolescence. Calcium (Ca) and vitamin D (VitD) intake are associated to bone mass and may be important confounders when studying bone mass. AIM: To clarify the effect that Ca and VitD may have on bone mass in adolescent cyclists. METHODS: Bone mineral content (BMC) and density (BMD) of 39 male adolescents (20 cyclists) were measured. Ca and VitD intake were also registered. Different ANCOVA analyses were performed in order to evaluate the influence of Ca and VitD on BMC and BMD. RESULTS: Cyclists showed lower values of BMC and BMD than controls at several sites and when adjusting by Ca, Wards triangle BMD appeared also to be lower in cyclists than controls. CONCLUSION: Nutritional aspects might partially explain differences regarding bone mass in adolescent cyclists and should be taken into account in bone mass analysis as important confounders.

Introducción: El ciclismo se ha asociado con un descenso de la masa ósea durante la adolescencia. La ingesta de calcio (Ca) y vitamina D (VitD) repercute sobre la masa ósea llegando a ser factores de confusión importantes al estudiarla. Objetivo: Clarificar el efecto que el Ca y la VitD pueden tener sobre la masa ósea de ciclistas adolescentes. Métodos: se midió el contenido mineral óseo (CMO) y la densidad mineral ósea (DMO) de 39 varones adolescentes (20 ciclistas). También se registró la ingesta de Ca y VitD. Se realizaron distintos análisis ANCOVA para evaluar la influencia del Ca y la VitD sobre el CMO y la DMO. Resultados: Los ciclistas mostraron menores valores de CMO y DMO que los controles en diversas zonas y, cuando se ajustó por Ca, la DMO del triángulo de Wards también pasó a ser menor en los ciclistas que en los controles. Conclusión: Los aspectos nutricionales podrían explicar en parte las diferencias de masa ósea en ciclistas adolescentes y deberían tenerse en cuenta en el análisis de masa ósea como factores de confusión importantes.

The nutritional status in adolescent Spanish cyclists.

INTRODUCTION: Adolescence is an important period of nutritional vulnerability due to the increased dietary requirements. OBJECTIVE: To describe the nutritional status of adolescent cyclist and a group of normoactive controls. METHODS: The HELENA Dietary Assessment Tool was used to evaluate the nutritional intake of 20 adolescent cyclists and 17 controls. Total energy intake, resting energy expenditure (REE), total energy expenditure (TEE), macronutrients and several micronutrients were registered and compared with dietary guidelines. RESULTS: REE was lower and TEE higher in cyclists than in controls (both P < 0.01). Significant differences were observed in phosphorus and vitamin B1 being higher in cyclists (P < 0.05). Most participants, both cyclist and controls, did not reach the diet requirements for macronutrients, vitamins and minerals. CONCLUSION: Nutritional status of adolescent cyclists and controls seems not to fulfil the requirements in quantity and quality. Possible implications for actual and future health especially in athlete adolescents need further research.

Introducción: La adolescencia es un periodo importante de vulnerabilidad nutricional dados las mayores demandas alimentarias. Objetivo: Describir el estado nutritivo de ciclistas adolescentes y de un grupo de controles con actividad normal. Métodos: Se utilizó la Herramienta de Evaluación Alimentaria HELENA para evaluar la ingesta nutricional de 20 ciclistas adolescentes y 17 controles. Se registraron la ingesta total de energía, el gasto de energía en reposo (GER), el gasto de energía total (GET), los macronutrientes y diversos micronutrientes y se compararon con las guías dietéticas. Resultados: El GER fue menor y el GTE mayor en los ciclistas que en los controles (ambos P < 0,01). Se observaron diferencias significativas en el fósforo y la vitamina B1, siendo mayores en los ciclistas (P < 0,05). La mayor parte de los participantes, tanto ciclistas como controles, no alcanzó los requerimientos en macronutrientes, vitaminas ni minerales. Conclusión: El estado nutritivo de los adolescentes ciclistas y de los controles parece no adecuarse a las recomendaciones de cantidad y calidad. Deberían investigarse las posibles implicaciones de la salud actual y futura, especialmente en los adolescentes atletas.