[The use of sports facilities for physical activity: a public health and equity perspective]. / El uso de instalaciones deportivas para promover la actividad física: una perspectiva de salud pública y equidad.

Introduction: Background: despite multimillion-dollar investments in sports facilities, there is little information on their contribution to energy expenditure of the population. In this study, participation in 71 physical activities (PAs) and 31 different types of spaces was examined. Objectives: to evaluate which types of spaces are more effective from a public health perspective. Methods: a cross-sectional sample was designed, stratified and proportional to the adult population of Gran Canaria (n = 3,000, ≥ 18 years). PA was evaluated using a validated questionnaire. The spaces used were grouped into two categories: public open spaces and sport facilities. Descriptive statistics and multiple logistic regression were used to analyze the data. Results: the open public spaces accumulated a volume of hours for PA between 1.6 and 28.4 times higher than the sport facilities depending on the socio-demographic group analyzed. The indoor sport facilities were the ones that expressed the greatest associative strength with the achievement of PA recommendations (OR = 5.45, 95 % CI: 4.01; 7.40). Conclusion: a dilemma was posed from a public health perspective because the urban open public spaces reached more population and supported most of the population's energy expenditure, particularly in the groups with the highest health risk, but the indoor sport facilities were the ones that best contributed to achieving a healthy level of physical activity. This study suggests changes in the polices of construction and management of sport facilities and open public spaces to increase PA in groups at higher health risk.

Introducción: Introducción: pese a las inversiones multimillonarias en instalaciones para la actividad física-deportiva, hay poca información acerca de su contribución en el gasto energético poblacional. En este estudio examinamos la participación en 71 actividades físicas (AF) y 31 tipos de espacios diferentes. Objetivo: valorar qué tipos de espacios son más eficaces desde una perspectiva de salud pública y equidad. Método: muestra transversal aleatoria, estratificada y proporcional en género y edad a la población de adultos de Gran Canaria (n = 3.000, ≥ 18 años). La AF fue evaluada mediante cuestionario validado. Los espacios de AF fueron agrupados en dos categorías: espacios públicos abiertos (EPA) e instalaciones deportivas. Para analizar los datos se emplearon estadística descriptiva y regresión logística múltiple. Resultados: los EPA acumularon un volumen de horas de AF entre 1,6 y 28,4 veces mayor que las instalaciones deportivas dependiendo del grupo sociodemográfico analizado. Las instalaciones deportivas cubiertas fueron las que expresaron la mayor fuerza asociativa con el logro de las recomendaciones de AF (OR = 5,45, IC 95 %: 4,01; 7,40). Conclusiones: se planteó un dilema desde una perspectiva de salud porque los EPA urbanos llegaron a más población y dieron soporte a la mayor parte del gasto energético poblacional, particularmente, en los grupos de mayor riesgo de salud, pero las instalaciones deportivas cubiertas fueron las que mejor contribuyeron a lograr un nivel saludable de actividad física. Este estudio sugiere cambios en las políticas de construcción y gestión de instalaciones deportivas y EPA para aumentar la AF en los grupos de mayor riesgo de salud.

Architectural anatomy of the human tibialis anterior presents morphological asymmetries between superficial and deep unipennate regions.

The tibialis anterior muscle plays a critical role in human ambulation and contributes to maintaining the upright posture. However, little is known about its muscle architecture in males and females. One hundred and nine physically active males and females were recruited. Tibialis anterior muscle thickness, pennation angle, and fascicle length were measured at rest in both unipennate regions of both legs using real-time ultrasound imaging. A linear mixed model was used with muscle thickness, pennation angle, or fascicle length as the dependent variables. All models were carried out with and without total leg lean mass and shank length as covariates. Causal mediation analysis was computed to explore the effect of muscle thickness on the relationship between fascicle length and pennation angle. There were no significant differences between dominant and nondominant legs regarding muscle architecture. Muscle thickness and pennation angle were greater in the deep than the superficial unipennate region in males (1.9 mm and 1.1°, p < 0.001) and women (3.4 mm and 2.2°, p < 0.001). However, the fascicle length was similar in both regions for both sexes. The differences remained significant after accounting for differences in leg lean mass and shank length. In both regions, muscle thickness was 1-3 mm greater in males and superficial pennation angle 2° smaller in females (both, p < 0.001). After accounting for leg lean mass and shank length, sex differences remained for muscle thickness (1.6 mm, p < 0.05) and pennation angle (3.4°, p < 0.001) but only in the superficial region. In both regions, leg lean mass and shank-adjusted fascicle length were 1.4 mm longer in females than males (p < 0.05). The causal mediation analysis revealed that the estimation of fascicle length was positive, suggesting that a 10% increase in muscle thickness would augment the fascicle length, allowing a 0.38° pennation angle decrease. Moreover, the pennation angle increases in total by 0.54° due to the suppressive effect of the increase in fascicle length. The estimated mediation, direct, and total effects were all significantly different from zero (p < 0.001). Overall, our results indicate that the architectural anatomy of the tibialis anterior shows sexual dimorphism in humans. Tibialis anterior presents morphological asymmetries between superficial and deep unipennate regions in both sexes. Lastly, our causal mediation model identified a suppressive effect of fascicle length on the pennation angle, suggesting that increments in muscle thickness are not always aligned with increments in fascicle length or the pennation angle.

Validity and reliability of the International fItness scale (IFIS) in preschool children.

Objectives: Examine the validity and reliability of parent-reported International FItness Scale (IFIS) in preschoolers. Method: A cross-sectional study of 3051 Spanish preschoolers (3-5 years). Fitness was measured by PREFIT battery and reported by parents using an adapted version of the IFIS. Waist circumference was evaluated, and the waist-to-height ratio (WHtR) was calculated. Seventy-six parents of randomly selected schoolchildren completed the IFIS twice for a reliability assessment. Results: ANCOVA, adjusted for sex, age and WHtR, showed that preschoolers who were scored by their parents as having average-to-very good fitness had better levels of measured physical fitness than those preschoolers who were classified as having "very poor/poor" fitness levels (18.1laps to 22.1laps vs 15.6laps for cardiorespiratory fitness; 6.6 kg to 7.5 kg vs 5.3 kg for muscular fitness-handgrip-; 71.7 cm to 76.4 cm vs 62.0 cm for muscular fitness-standing long jump-; 17.2s to 16.2s vs 18.2s for speed/agility; and 11.2s to 15.6s vs 8.7s for balance; p < 0.001). The weighted kappa for concordance between parent-reported fitness levels and objective assessment was poor (κ ≤ 0.18 for all fitness measures). Overall, the mean values of the abdominal adiposity indicators were significantly lower in high-level fitness categories reported by parents than in low-level fitness categories (p < 0.05). The test-retest reliability ranged from 0.46 to 0.62. Conclusions: The reliability of the parent-reported IFIS are acceptable, but the concordance between parents reported and objectively measures fitness levels is poor, suggesting that parents' responses may not be able to correctly classify preschoolers according to their fitness level.HighlightsThe convergent validity and reliability (test-retest) values of the IFIS parent scale are moderately acceptable for assessing physical fitness in children aged 3-5 years.However, the results of concordance show that criterion validity is poor suggesting that parents' responses may not be able to correctly classify preschoolers according to their fitness level.Considering that the fitness level at these ages is fairly homogeneous, it seems difficult for parents to discriminate between the fitness levels of their children. Therefore, it seems necessary to recalibrate the scale in future work.

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

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

Role of CaMKII and sarcolipin in muscle adaptations to strength training with different levels of fatigue in the set.

Strength training promotes a IIX-to-IIA shift in myosin heavy chain (MHC) composition, likely due to changes in sarcoplasmic [Ca2+ ] which are sensed by CaMKII. Sarcoplasmic [Ca2+ ] is in part regulated by sarcolipin (SLN), a small protein that when overexpressed in rodents stimulates mitochondrial biogenesis and a fast-to-slow fiber type shift. The purpose of this study was to determine whether CaMKII and SLN are involved in muscle phenotype and performance changes elicited by strength training. Twenty-two men followed an 8-week velocity-based resistance training program using the full squat exercise while monitoring repetition velocity. Subjects were randomly assigned to two resistance training programs differing in the repetition velocity loss allowed in each set: 20% (VL20) vs 40% (VL40). Strength training caused muscle hypertrophy, improved 1RM and increased total CaMKII protein expression, particularly of the δD isoform. Phospho-Thr287 -CaMKII δD expression increased only in VL40 (+89%), which experienced greater muscle hypertrophy, and a reduction in MHC-IIX percentage. SLN expression was increased in VL20 (+33%) remaining unaltered in VL40. The changes in phospho-Thr287 -CaMKII δD were positively associated with muscle hypertrophy and the number of repetitions during training, and negatively with the changes in MHC-IIX and SLN. Most OXPHOS proteins remained unchanged, except for NDUFB8 (Complex I), which was reduced after training (-22%) in both groups. The amount of fatigue allowed in each set critically influences muscle CaMKII and SLN responses and determines muscle phenotype changes. With lower intra-set fatigue, the IIX-to-IIA MHC shift is attenuated.

Hypertrophy of Lumbopelvic Muscles in Inactive Women: A 36-Week Pilates Study.

BACKGROUND: The use of Pilates in various fields of sport sciences and rehabilitation is increasing; however, little is known about the muscle adaptations induced by this training method. HYPOTHESIS: A standardized Pilates training program for beginners (9 months; 2 sessions of 55 minutes per week) will increase the muscle volume and reduce potential side-to-side asymmetries of the quadratus lumborum, iliopsoas, piriformis, and gluteus muscles (gluteus maximus, medius, and minimus). STUDY DESIGN: Controlled laboratory study. LEVEL OF EVIDENCE: Level 3. METHOD: A total of 12 inactive, healthy women (35.7 ± 5.4 years) without previous experience in Pilates were randomly selected to participate in a supervised Pilates program (36 weeks, twice weekly). Muscle volume (cm3) was determined using magnetic resonance imaging at the beginning and end of the intervention program. Side-to-side asymmetry was calculated as [(left - right volume) × 100/right volume]. RESULTS: Small, nonsignificant (P > 0.05) differences in the volume of the quadratus lumborum, iliopsoas, piriformis, and gluteus muscles were observed between pre- and post-Pilates program timepoints. Before and after Pilates, side-to-side asymmetry was less than 6% and nonsignificant in all muscles analyzed. CONCLUSION: Modern Pilates performed twice weekly for 9 months did not elicit substantial changes in the volume and degree of asymmetry of the selected lumbopelvic muscles in inactive women. CLINICAL RELEVANCE: The benefits of Pilates in rehabilitation or training are likely elicited by neuromuscular rather than morphological adaptations. Pilates has no significant impact on muscle volume and does not alter side-to-side ratios in muscle volume (degree of asymmetry) of the lumbopelvic muscles.

Prevalence of severe/morbid obesity and other weight status and anthropometric reference standards in Spanish preschool children: The PREFIT project.

BACKGROUND: Childhood obesity has become a major health problem in children under the age of 5 years. Providing reference standards would help paediatricians to detect and/or prevent health problems related to both low and high levels of body mass and to central adiposity later in life. Therefore, the aim of this study was to examine the prevalence of different weight status categories and to provide sex- and age-specific anthropometry reference standards for Spanish preschool children. METHODS: A total of 3178 preschool children (4.59±0.87 years old) participated in this study. Prevalence of different degrees of obesity (mild, severe, and morbid) and other weight status categories were determined. RESULTS: Reference standards were obtained. Prevalence of overweight and obese preschool children in the Spanish population ranged from 21.4 to 34.8%. Specifically, the obesity prevalence was 3.5, 1.2, and 1.3% of these subjects were categorized as mild, severe, and morbid obese. Sex- and age-specific reference standards for anthropometric parameters are provided for every 0.25 years (i.e. every trimester of life). CONCLUSION: Our results show a high prevalence of overweight/obese preschoolers. The provided sex- and age-specific anthropometric reference standards could help paediatricians to track and monitor anthropometric changes at this early stage in order to prevent overweight/obesity.

Greater Reduction in Abdominal Than in Upper Arms Subcutaneous Fat in 10- to 12-Year-Old Tennis Players: A Volumetric MRI Study.

Background: Little is known about the impact of long term participation in sports and subcutaneous fat volume in children. This study aimed at determining whether tennis participation is associated with lower subcutaneous adipose tissue volume (SATv) in the abdominal and upper extremities in children. Methods: Magnetic resonance imaging (MRI) was used to determine the SATv stored in the abdominal region and upper arms in seven tennis players and seven inactive children matched by height and age (147 cm and 10.9 years). All participants were in Tanner stage 1 or 2. Results: Playing tennis was associated with 48% (P = 0.001) lower abdominal SATv and 17-18% (P > 0.05) lower upper arms SATv compared to controls. The ratio between abdominal/upper arms SATv was larger in the controls vs. tennis players (69% P = 0.001). The SATv was similar in the dominant and non-dominant arm within each group. Conclusion: Playing tennis during childhood is associated with reduced SATv in the abdominal region and a more favorable regional distribution of fat. Despite the large amount of contractile activity of the playing (dominant) arm, there was no indication of between-arms differences in SATv.

Domain and intensity of physical activity are associated with metabolic syndrome: A population-based study.

INTRODUCTION: Little is known on how the domain and intensity of physical activity (PA) associates with metabolic syndrome (MetS). The aim of this study was to examine associations between PA domains (leisure-time, domestic, active transport, total walking and total PA), PA intensities (light, moderate and vigorous) and PA levels with MetS in the general adult population. METHODS: Cross-sectional study. Anthropometry, blood biochemistry, 79-item PA-questionnaire, lifestyle and medical history were evaluated in a representative sample of Canary Island adults (n = 6,729). MetS was diagnosed using the harmonized IDF-NHLBI-AHA criteria. T-test and multivariable logistic regression was used to analyse associations between PA domains and intensities with MetS vs. no MetS, controlling for socio-demographic, lifestyle, family antecedents and body mass index (BMI). RESULTS: For each MET-h/day spent in moderate-vigorous PA intensities, as well as in recreational domain, active transport, total walking and total PA, the odds of MetS decreased between 3-10%. Energy expenditure exclusively in light and domestic PAs was not associated with MetS, however it was important to achieve a total PA level of 3 MET-h/day, which reduced the odds of MetS by 23%. This reduction was blunted in those with more than 2 h/d of TV watching time. A PA level of 3 MET-h/d also nullified the risk of MetS in those with low PA and high TV consumption. CONCLUSIONS: Some types of leisure time PAs may contribute more than others to reducing MetS. Light and domestic PA play a complementary role in enhancing energy expenditure in the general population. TV watching time above 2 h/d counteracted the MetS risk reduction associated with PA level, but PA level also reduced the risk of METs presented by those with a low level of PA and an excess TV watching time. Physical activity explains a greater amount of the variance of MetS than any other factors of lifestyle, education, sex and family history, and substantially mitigates the strong association of age and BMI with MetS.

Physical fitness reference standards for preschool children: The PREFIT project.

OBJECTIVES: Reference values are necessary for classifying children, for health screening, and for early prevention as many non-communicable diseases aggravate during growth and development. While physical fitness reference standards are available in children aged 6 and older, such information is lacking in preschool children. Therefore, the purposes of this study were (1) to provide sex-and age-specific physical fitness reference standards for Spanish preschool children; and (2) to study sex differences across this age period and to characterise fitness performance throughout the preschool period. DESIGN: Cross-sectional. METHODS: A total of 3179 preschool children (1678 boys) aged 2.8-6.4 years old from Spain were included in the present study. Physical fitness was measured using the PREFIT battery. RESULTS: Age- and sex-specific percentiles for the physical fitness components are provided. Boys performed better than girls in the cardiorespiratory fitness, muscular strength, and speed-agility tests over the whole preschool period studied and for the different percentiles. In contrast, girls performed slightly better than boys in the balance test. Older children had better performance in all fitness tests than their younger counterparts. CONCLUSIONS: Our study provides age- and sex-specific physical fitness reference standards in preschool children allowing interpretation of fitness assessment. Sexual dimorphism in fitness tests exists already at preschool age, and these differences become larger with age. These findings will help health, sport, and school professionals to identify preschool children with a high/very low fitness level, to examine changes in fitness over time, and to analyse those changes obtained due to intervention effects.

The core musculature in male prepubescent tennis players and untrained counterparts: a volumetric MRI study.

The effects of exercise on the core musculature have not been investigated in prepubescents. The main purpose of the present study was to determine the volume and degree of asymmetry of rectus abdominis, obliques and transversus abdominis, quadratus lumborum, iliopsoas, gluteus and paravertebralis muscles in prepubescent tennis players and in untrained boys. The muscle volume was determined using magnetic resonance imaging (MRI) in 7 male prepubescent tennis players and 10 untrained controls (mean age 11.0 ± 0.8 years, Tanner 1-2). After accounting for height and body weight as covariates, the tennis players had 14-34% greater volume than the controls in all the muscles analysed (P < 0.05) except in paravertebralis, dominant quadratus lumborum and non-dominant gluteus, which had similar volumes in both groups (P = NS). Compared to controls, the tennis players displayed a greater degree of asymmetry in quadratus lumborum and rectus abdominis (3% vs. 15%, P < 0.01 and 8% vs. 17%, P = 0.06, respectively). The level of asymmetry of obliques and transversus abdominis, iliopsoas, gluteus and paravertebralis muscles was similar in both groups (P = NS). In conclusion, tennis playing at prepubertal ages induces a selective hypertrophy of the core musculature and exaggerates the degree of asymmetry of quadratus lumborum and rectus abdominis compared to untrained boys.

The asymmetry of pectoralis muscles is greater in male prepubertal than in professional tennis players.

It is generally accepted that preadolescents have a limited capacity to develop muscle hypertrophy in response to exercise compared with older populations; however, studies are scarce and conflicting. The main aim of the present study was to assess if playing tennis is associated with the hypertrophy of dominant pectoralis muscles (PM) in professional (PRO) and in prepubescent tennis players (PRE). A secondary aim was to assess if the degree of asymmetry of PM is greater in PRO than PRE. The volume of PM of both sides was determined using magnetic resonance imaging in 8 male PRO (21.9 years), 6 male PRE (11 years, Tanner 1-2) and 12 male non-active controls (6 adults: 23.5 years; and 6 prepubescents: 10.7 years, Tanner 1-2). PRO and PRE had 15 and 30% greater volume, respectively, in the dominant than in the contralateral PM (P < .01). No significant side-to-side differences in PM volume were observed in the non-active controls (3%, P = .34 in adults and 5%, P = .17 in children). The degree of side-to-side asymmetry in PM volume was greater in PRE than in PRO (P < .05). In conclusion, tennis practice is associated with marked hypertrophy of dominant PM in tennis players, even at prepubertal age, whilst non-active age-matched control subjects display similar volumes in both sides. The larger asymmetry observed in PRE than in PRO may indicate a greater relative loading in the children or increased contralateral hypertrophy in the professionals. This study demonstrates that prepubertal children respond with marked hypertrophy to loading by tennis.

Physical fitness, adiposity and testosterone concentrations are associated to playing position in professional basketballers.

UNLABELLED: The effects of basketball on basal concentrations of testosterone and cortisol and its associations to body composition and physical performance remain to be determined. AIM: The main aim of this study was to determine the effects of playing position on physical fitness, percentage of body fat and hormonal profile in professional basketball players (BP). METHOD: Jump performance (SJ, CMJ and ABK), 30 m running speed and treadmill VO2max tests were conducted in 12 male BP (24.1 years) from the first division league of Spain (ACB). The percentage of body fat was determined from anthropometry, and hemoglobin, glucose, testosterone and cortisol concentrations were measured from fasting blood samples. BP were divided into 3 groups depending on playing positions: guards (GU), forwards (FW) and centers (CE) (n = 4 in each group). RESULTS: GU had greater percentage of body fat (%BF) than CE (p < 0.05). CE developed greater positive mechanical impulse than GU in all jump types (p < 0.05) and achieved higher maximal instantaneous power than GU and FW in the SJ and ABK (p < 0.05). Centers had more plasma testosterone than guards (p < 0.05). All groups a similar relative VO2max. CONCLUSION: Center position was associated to lower adiposity and higher jumping performance than playing as guards. All playing positions induced a similar effect on aerobic power.

Los efectos de jugar al baloncesto sobre las concentraciones basales de testosterona y cortisol, así como su asociación a la composición corporal y el rendimiento físico aún están por determinarse. Objetivo: el principal objetivo de este estudio fue determinar los efectos de la posición de juego sobre la condición física, el porcentaje de grasa coporal y el perfil hormonal en jugadores de baloncesto profesionales (BP). Metodología: la capacidad de salto (SJ, CMJ y ABK), la velocidad en 30 m y el VO2max en tapiz rodante se midió en 12 varones BP (24,1 años) pertenecientes a la primera división de la liga de España (ACB). El porcentaje de grasa corporal se determinó a partir de la antropometría, y las concentraciones de hemoglobina, glucosa, testosterona y cortisol se midieron a partir de muestras de sangre en ayunas. Los baloncestistas se dividieron en tres grupos en función de las posiciones de juego: bases (GU), aleros (FW) y pivots (CE). Resultados: GU tuvo mayor porcentaje de grasa corporal (% GC) que CE (p < 0,05). CE desarrolló mayor impulso positivo mecánico que GU en todos los tipos de saltos (p < 0,05) y logró mayor potencia instantánea máxima que GU y FW en el SJ y ABK (p < 0,05). Los pivots tenían más testosterona plasmática que los bases (p < 0,05). Todos los grupos mostraron similar VO2 máx. Conclusión: la posición de pivots fue asociada a una menor adiposidad y a una mayor capacidad de salto en comparación con los bases. Todas las posiciones de juego indujeron un efecto similar sobre la potencia aeróbica.

Physical fitness, adiposity and testosterone concentrations are associated to playing position in professional basketballers / Condición física, adiposidad y concentraciones de testosterona están asociadas a la posición de juego en baloncestistas profesionales

The effects of basketball on basal concentrations of testosterone and cortisol and its associations to body composition and physical performance remain to be determined. Aim: the main aim of this study was to determine the effects of playing position on physical fitness, percentage of body fat and hormonal profile in professional basketball players (BP). Method: jump performance (SJ, CMJ and ABK), 30 m running speed and treadmill VO2 max tests were conducted in 12 male BP (24.1 years) from the first division league of Spain (ACB). The percentage of body fat was determined from anthropometry, and hemoglobin, glucose, testosterone and cortisol concentrations were measured from fasting blood samples. BP were divided into 3 groups depending on playing positions: guards (GU), forwards (FW) and centers (CE) (n = 4 in each group). Results: GU had greater percentage of body fat (%BF) than CE (p< 0.05). CE developed greater positive mechanical impulse than GU in all jump types (p < 0.05) and achieved higher maximal instantaneous power than GU and FW in the SJ and ABK (p< 0.05). Centers had more plasma testosterone than guards (p< 0.05). All groups a similar relative VO2 max. Conclusion: center position was associated to lower adiposity and higher jumping performance than playing as guards. All playing positions induced a similar effect on aerobic power (AU)

Los efectos de jugar al baloncesto sobre las concentraciones basales de testosterona y cortisol, así como su asociación a la composición corporal y el rendimiento físico aún están por determinarse. Objetivo: el principal objetivo de este estudio fue determinar los efectos de la posición de juego sobre la condición física, el porcentaje de grasa coporal y el perfil hormonal en jugadores de baloncesto profesionales (BP). Metodología: la capacidad de salto (SJ, CMJ y ABK), la velocidad en 30 m y el VO2max en tapiz rodante se midió en 12 varones BP (24,1 años) pertenecientes a la primera división de la liga de España (ACB). El porcentaje de grasa corporal se determinó a partir de la antropometría, y las concentraciones de hemoglobina, glucosa, testosterona y cortisol se midieron a partir de muestras de sangre en ayunas. Los baloncestistas se dividieron en tres grupos en función de las posiciones de juego: bases (GU), aleros (FW) y pivots (CE). Resultados: GU tuvo mayor porcentaje de grasa corporal (% GC) que CE (p< 0,05). CE desarrolló mayor impulso positivo mecánico que GU en todos los tipos de saltos (p < 0,05) y logró mayor potencia instantánea máxima que GU y FW en el SJ y ABK (p< 0,05). Los pivots tenían más testosterona plasmática que los bases (p < 0,05). Todos los grupos mostraron similar VO2 máx. Conclusión: la posición de pivots fue asociada a una menor adiposidad y a una mayor capacidad de salto en comparación con los bases. Todas las posiciones de juego indujeron un efecto similar sobre la potencia aeróbica (AU)

The hypertrophy of the lateral abdominal wall and quadratus lumborum is sport-specific: an MRI segmental study in professional tennis and soccer players.

The aim was to determine the volume and degree of asymmetry of quadratus lumborum (QL), obliques, and transversus abdominis; the last two considered conjointly (OT), in tennis and soccer players. The volume of QL and OT was determined using magnetic resonance imaging in professional tennis and soccer players, and in non-active controls (n = 8, 14, and 6, respectively). In tennis players the hypertrophy of OT was limited to proximal segments (cephalic segments), while in soccer players it was similar along longitudinal axis. In tennis players the hypertrophy was asymmetric (18% greater volume in the non-dominant than in the dominant OT, p = 0.001), while in soccer players and controls both sides had similar volumes (p > 0.05). In controls, the non-dominant QL was 15% greater than that of the dominant (p = 0.049). Tennis and soccer players had similar volumes in both sides of QL. Tennis alters the dominant-to-non-dominant balance in the muscle volume of the lateral abdominal wall. In tennis the hypertrophy is limited to proximal segments and is greater in the non-dominant side. Soccer, however, is associated to a symmetric hypertrophy of the lateral abdominal wall. Tennis and soccer elicit an asymmetric hypertrophy of QL.

Contribution of individual and environmental factors to physical activity level among Spanish adults.

BACKGROUND: Lack of physical activity (PA) is a major risk for chronic disease and obesity. The main aims of the present study were to identify individual and environmental factors independently associated with PA and examine the relative contribution of these factors to PA level in Spanish adults. METHODOLOGY/PRINCIPAL FINDINGS: A population-based cross-sectional sample of 3,000 adults (18-75 years old) from Gran Canaria (Spain) was selected using a multistage stratified random sampling method. The participants were interviewed at home using a validated questionnaire to assess PA as well as individual and environmental factors. The data were analyzed using bivariate and multivariate logistic regression. One demographic variable (education), two cognitive (self-efficacy and perceived barriers), and one social environmental (organized format) were independently associated with PA in both genders. Odds ratios ranged between 1.76-2.07 in men and 1.35-2.50 in women (both p<0.05). Individual and environmental factors explained about one-third of the variance in PA level. CONCLUSIONS/SIGNIFICANCE: Self-efficacy and perceived barriers were the most significant factors to meet an adequate level of PA. The risk of insufficient PA was twofold greater in men with primary or lesser studies and who are employed. In women, living in rural environments increased the risk of insufficient PA. The promotion of organized PA may be an efficient way to increase the level of PA in the general population. Improvement in the access to sport facilities and places for PA is a prerequisite that may be insufficient and should be combined with strategies to improve self-efficacy and overcome perceived barriers in adulthood.

Muscle hypertrophy in prepubescent tennis players: a segmentation MRI study.

PURPOSE: To asses if tennis at prepubertal age elicits the hypertrophy of dominant arm muscles. METHODS: The volume of the muscles of both arms was determined using magnetic resonance imaging (MRI) in 7 male prepubertal tennis players (TP) and 7 non-active control subjects (CG) (mean age 11.0 ± 0.8 years, Tanner 1-2). RESULTS: TP had 13% greater total muscle volume in the dominant than in the contralateral arm. The magnitude of inter-arm asymmetry was greater in TP than in CG (13 vs 3%, P<0.001). The dominant arm of TP was 16% greater than the dominant arm of CG (P<0.01), whilst non-dominant arms had similar total muscle volumes in both groups (P = 0.25), after accounting for height as covariate. In TP, dominant deltoid (11%), forearm supinator (55%) and forearm flexors (21%) and extensors (25%) were hypertrophied compared to the contralateral arm (P<0.05). In CG, the dominant supinator muscle was bigger than its contralateral homonimous (63%, P<0.05). CONCLUSIONS: Tennis at prepubertal age is associated with marked hypertrophy of the dominant arm, leading to a marked level of asymmetry (+13%), much greater than observed in non-active controls (+3%). Therefore, tennis particpation at prepubertal age is associated with increased muscle volumes in dominant compared to the non-dominant arm, likely due to selectively hypertrophy of the loaded muscles.

Marked effects of Pilates on the abdominal muscles: a longitudinal magnetic resonance imaging study.

PURPOSE: The study's purpose was to analyze the effects of Pilates on the volume of the rectus abdominis (RA), obliques, and transversus abdominis, with the last two considered conjointly (OT). METHODS: The volume of OT and RA were determined using magnetic resonance imaging in nine nonactive healthy women, before and after 36 wk of a standardized Pilates training program (Modern Pilates). RESULTS: The volume of the dominant OT was increased by 8% (P < 0.05) with training, whereas the nondominant OT volume remained unchanged (+2%, P = 0.58). The total volume of RA increased by 21% after Pilates (P < 0.05) because of a similar increase of dominant and nondominant RA volume (21% and 20%, respectively, P < 0.05). Before Pilates, the volume of the OT was 8% greater in the nondominant compared with the dominant side (P < 0.01). This asymmetry was compensated by Pilates training (2%, P = 0.43). No side-to-side asymmetries in RA muscle volumes were observed either before (2%, P = 0.51) or after (1%, P = 0.81) Pilates. CONCLUSIONS: The present study reveals the existence of asymmetries in the muscles of the abdominal wall in nonactive healthy women. Pilates practice twice a week for 9 months elicits hypertrophy of the abdominal wall muscles, particularly of the RA, and eliminates preexisting asymmetries of the OT. Modern Pilates can be recommended as an effective method to reinforce the muscles of the abdominal wall and to compensate preexisting asymmetric developments.

Associations between screen time and physical activity among Spanish adolescents.

BACKGROUND: Excessive time in front of a single or several screens could explain a displacement of physical activity. The present study aimed at determining whether screen-time is associated with a reduced level of moderate to vigorous physical activity (MVPA) in Spanish adolescents living in favorable environmental conditions. METHODOLOGY/PRINCIPAL FINDINGS: A multi-stage stratified random sampling method was used to select 3503 adolescents (12-18 years old) from the school population of Gran Canaria, Spain. MVPA, screen-time in front of television, computer, video game console and portable console was assessed in the classroom by fulfilling a standardized questionnaire. Bivariate and multivariate logistic regression analyses adjusted by a set of social-environmental variables were carried out. Forty-six percent of girls (95% CI±2.3%) and 26% of boys (95% CI±2.1%) did not meet the MVPA recommendations for adolescents. Major gender differences were observed in the time devoted to vigorous PA, video games and the total time spent on screen-based activities. Boys who reported 4 hours•week(-1) or more to total screen-time showed a 64% (OR = 0.61, 95% CI, 0.44-0.86) increased risk of failing to achieve the recommended adolescent MVPA level. Participation in organized physical activities and sports competitions were more strongly associated with MVPA than screen-related behaviors. CONCLUSIONS/SIGNIFICANCE: No single screen-related behavior explained the reduction of MVPA in adolescents. However, the total time accumulated through several screen-related behaviors was negatively associated with MVPA level in boys. This association could be due to lower availability of time for exercise as the time devoted to sedentary screen-time activities increases. Participation in organized physical activities seems to counteract the negative impact of excessive time in front of screens on physical activity.