Resting metabolic rate is increased in hypertensive patients with overweight or obesity: Potential mechanisms.

The purpose of this investigation was to determine whether differences in body composition, pharmacological treatment, and physical activity explain the increased resting metabolic rate (RMR) and impaired insulin sensitivity in hypertension. Resting blood pressure, RMR (indirect calorimetry), body composition (dual-energy X-ray absorptiometry), physical activity (accelerometry), maximal oxygen uptake (VO2 max) (ergospirometry), and insulin sensitivity (Matsuda index) were measured in 174 patients (88 men and 86 women; 20-68 years) with overweight or obesity. Hypertension (HTA) was present in 51 men (58%) and 42 women (49%) (p = .29). RMR was 6.9% higher in hypertensives than normotensives (1777 ± 386 and 1663 ± 383 kcal d-1 , p = .044). The double product (systolic blood pressure × heart rate) was 18% higher in hypertensive than normotensive patients (p < .001). The observed differences in absolute RMR were non-significant after adjusting for total lean mass and total fat mass (estimated means: 1702 kcal d-1 , CI: 1656-1750; and 1660 kcal d-1 , CI: 1611-1710 kcal d-1 , for the hypertensive and normotensive groups, respectively, p = .19, HTA × sex interaction p = .37). Lean mass, the double product, and age were the variables with the higher predictive value of RMR in hypertensive patients. Insulin sensitivity was lower in hypertensive than in normotensive patients, but these differences disappeared after accounting for physical activity and VO2max . In summary, hypertension is associated with increased RMR and reduced insulin sensitivity. The increased RMR is explained by an elevated myocardial oxygen consumption due to an increased resting double product, combined with differences in body composition between hypertensive and normotensive subjects.

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.

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.

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.

ANDROGEN RECEPTOR CAG AND GGN REPEAT POLYMORPHISMS AND BONE MASS IN BOYS AND GIRLS.

INTRODUCTION: the human androgen receptor (AR) gene possesses two trinucleotide polymorphic repeats, (CAG and GGN) that affect the amount of AR protein translated. In this study, we genotyped these polymorphic tracts in a representative sample of Caucasian children (Tanner ≤ 5), 152 boys (11.5 } 2.6 yrs) and 116 girls (10.1 } 3.2 yrs) from Spain and investigated their association with bone mass. METHODS: the length of CAG and GGN repeats was determined by PCR and fragment analysis. Body composition was assessed by dual energy x-ray absorptiometry (DXA). Individuals were grouped as CAG short (CAGS) if harboring repeat lengths of ≤ 21 and CAG long (CAGL) if CAG > 21. Moreover, subjects were grouped as GGN short (GGNS) if harboring repeat lengths of ≤ 23 and GGN long (GGNL) if GGN > 23. RESULTS: in boys, significant differences in height, body mass, whole body bone mineral density (BMD) and content (BMC), upper extremities BMC, lower extremities BMC, femoral neck BMD, Ward's triangle BMC and BMD and lumbar spine BMD were observed between CAGS and CAGL groups (P < 0.05). Thus, upper extremities BMD differed between GGNS and GGNL groups. After adjusting for confounding variables, only upper extremities BMD between GGNS and GGNL groups remained significant (P < 0.05). No differences were observed in girls in any measured site in relation to either CAG or GGN polymorphisms length. CONCLUSIONS: our results support the hypothesis that longer alleles of the AR CAG and GGN polymorphisms are associated with increased bone mass in prepubertal boys.

Introducción: el gen humano del receptor de androgenos (AR) posee dos repeticiones polimorficas de trinucleotidos (CAG y GGN) que afectan a la cantidad de proteina AR traducida. En este estudio, genotipamos esos tractos polimorficos en una muestra representativa de ninos caucasicos espanoles (Tanner ≤ 5), compuesta por 152 ninos (11.5 } 2.6 anos) y 116 ninas (10.1 } 3.2 anos) e investigamos su asociacion con la masa osea. Métodos: la longitud de las repeticiones CAG y GGN se determino mediante PCR y analisis de fragmentos. La composicion corporal se midio mediante absorciometria dual de rayos X (DXA). Los participantes fueron agrupados como CAG cortos (CAGS) si poseian una longitud de repeticiones ≤ 21 y CAG largos si esta era > 21. Ademas, los participantes se agruparon como GGN cortos (GGNS) si poseian una longitud de repeticiones ≤ 23 y GGN largos (GGNL) si esta era > 23. Resultados: en los ninos se encontraron diferencias en talla, peso corporal, densidad mineral osea (BMD) y contenido mineral oseo (BMC) del cuerpo entero, BMC de las extremidades superiores e inferiores, BMD del cuello del femur, BMC y BMD del triangulo de Ward's y BMD de la espina lumbar entre los grupos CAGS y CAGL (P < 0,05). Ademas, el BMD de las extremidades superiores fue significativamente diferente entre los grupos GGNS y GGNL. Tras ajustar por variables confusoras, la unica diferencia que se mantuvo significativa fue la del BMD en las extremidades superiores entre los grupos GGNS y GGNL (P < 0,05). No se observaron diferencias entre los grupos CAG y GGN y la masa osea en las ninas. Conclusiones: nuestros resultados apoyan la hipotesis de que los alelos largos de los polimorfismos CAG y GGN del AR estan asociados con una mayor masa osea en ninos prepuberes.

Androgen receptor CAG and GGN repeat polymorphisms and bone mass in boys and girls / Polimorfismos CAG y GGN del gen del receptor de andrógenos y masa ósea en niños y niñas

Introduction: the human androgen receptor (AR) gene possesses two trinucleotide polymorphic repeats, (CAG and GGN) that affect the amount of AR protein translated. In this study, we genotyped these polymorphic tracts in a representative sample of Caucasian children (Tanner ≤5), 152 boys (11.5±2.6 yrs) and 116 girls (10.1±3.2 yrs) from Spain and investigated their association with bone mass. Methods: the length of CAG and GGN repeats was determined by PCR and fragment analysis. Body composition was assessed by dual energy x-ray absorptiometry (DXA). Individuals were grouped as CAG short (CAGS) if harboring repeat lengths of ≤21 and CAG long (CAGL) if CAG >21. Moreover, subjects were grouped as GGN short (GGNS) if harboring repeat lengths of ≤23 and GGN long (GGNL) if GGN >23. Results: in boys, significant differences in height, body mass, whole body bone mineral density (BMD) and content (BMC), upper extremities BMC, lower extremities BMC, femoral neck BMD, Ward’s triangle BMC and BMD and lumbar spine BMD were observed between CAGS and CAGL groups (P<0.05). Thus, upper extremities BMD differed between GGNS and GGNL groups. After adjusting for confounding variables, only upper extremities BMD between GGNS and GGNL groups remained significant (P<0.05). No differences were observed in girls in any measured site in relation to either CAG or GGN polymorphisms length. Conclusions: our results support the hypothesis that longer alleles of the AR CAG and GGN polymorphisms are associated with increased bone mass in prepubertal boys (AU)

Introducción: el gen humano del receptor de andrógenos (AR) posee dos repeticiones polimórficas de trinucleótidos (CAG y GGN) que afectan a la cantidad de proteína AR traducida. En este estudio, genotipamos esos tractos polimórficos en una muestra representativa de niños caucásicos españoles (Tanner ≤5), compuesta por 152 niños (11.5±2.6 años) y 116 niñas (10.1±3.2 años) e investigamos su asociación con la masa ósea. Métodos: la longitud de las repeticiones CAG y GGN se determinó mediante PCR y análisis de fragmentos. La composición corporal se midió mediante absorciometría dual de rayos X (DXA). Los participantes fueron agrupados como CAG cortos (CAGS) si poseían una longitud de repeticiones ≤21 y CAG largos si esta era >21. Además, los participantes se agruparon como GGN cortos (GGNS) si poseían una longitud de repeticiones ≤23 y GGN largos (GGNL) si esta era >23. Resultados: en los niños se encontraron diferencias en talla, peso corporal, densidad mineral ósea (BMD) y contenido mineral óseo (BMC) del cuerpo entero, BMC de las extremidades superiores e inferiores, BMD del cuello del fémur, BMC y BMD del triángulo de Ward’s y BMD de la espina lumbar entre los grupos CAGS y CAGL (P<0,05). Además, el BMD de las extremidades superiores fue significativamente diferente entre los grupos GGNS y GGNL. Tras ajustar por variables confusoras, la única diferencia que se mantuvo significativa fue la del BMD en las extremidades superiores entre los grupos GGNS y GGNL (P<0,05). No se observaron diferencias entre los grupos CAG y GGN y la masa ósea en las niñas. Conclusiones: nuestros resultados apoyan la hipótesis de que los alelos largos de los polimorfismos CAG y GGN del AR están asociados con una mayor masa ósea en niños prepúberes (AU)

Lack of exercise of "moderate to vigorous" intensity in people with low levels of physical activity is a major discriminant for sociodemographic factors and morbidity.

INTRODUCTION: The aim is to examine the differences between participation at low and zero moderate to vigorous physical activity (MVPA) in relation to their trends and associations with known socio-demographic and health factors. We hypothesised that the number of people at zero MVPA level could be rising despite a parallel increase in the population meeting the recommended MVPA level. We also hypothesised that graded associations of sociodemographic and health factors exist across MVPA levels. METHODS: Two independent population-based samples (n = 4320 [2004] and n = 2176 [1997]), were recruited with a stratified and random sampling procedure and interviewed at home by professional interviewers. The MVPA was assessed by validated questionnaire. The participants were classified into three MVPA levels: zero, low and recommended MVPA. The trend of each MVPA level was analysed with the standardized prevalence ratios. Correlates of low and zero MVPA levels were examined using multinomial logistic regression. RESULTS: The population at zero and recommended MVPA levels rose between 1997-2004 by 12% (95% CI, 5-20%) and 7% (95% CI,-4-19%) respectively, while the population at low MVPA level decreased. At zero MVPA level, associative patterns were observed with sociodemographic and health factors which were different when compared to the population at low MVPA level. CONCLUSIONS: Despite the slight increase of population meeting the recommended MVPA level, a higher trend of increase was observed at zero MVPA level. Both recommended and low MPVA levels increased their participation by absorbing participants from the low MVPA level. The sociodemographic profile of those with low MVPA was more similar to the population at recommended MVPA than at zero MVPA level. Methodological implications about the combination of light and moderate-intensity PA could be derived. The prevention of decline in actual low MVPA could change the trend of increase in the population at zero MVPA level, particularly among young adults.

Consumo de alcohol en Canarias: tendencia y factores sociodemográficos asociados más importantes (1997-2009) / Consumption of alcohol in Canary Islands: trends and the most important sociodemographic factors associated (1997-2009)

Objetivo: Caracterización del patrón de consumo de alcohol en el período (1997-2009) así como las asociaciones con los factores sociodemográficos asociados más importantes. Métodos: Estudio epidemiologico observacional, con tres muestras independientes, representativas de la población residente, no institucionalizada, de Canarias (>=16 años) de los años 1997 (n=2.176), 2004 (n=4,320) y 2009 (n=4,560), total (n=11,056), selecionados mediante muestreo polietápico y estratificado por islas y comarcas. El consumo de alcohol se agrupó en no bebedores, consumo habitual y consumo excesivo. En el análisis de tendencias se calculó la prevalencia del consumo de alto riesgo y no bebedores en las tres cohortes. Se utilizó la regresión logística multinomial con sus odds ratio correspondientes (OR), su intervalo de confianza (95% IC) y significación (p) para valorar las asociaciones entre los diferentes niveles de consuo como variables independiente y la variables sociodemográficas seleccionadas. Resultados: La prevalencia del consumo de alto riesgo ha aumentado en Canarias disminuyendo los no bebedores sobre todo en la mujer (40%). El consumo de alto riesgo se incrementa con la edad y el cosnumo habitual en todos los grupos de edad, sobre todo en los jóvenes (16-30). El mayor riesgo de ser bebedor de alto riesgo son los hombres, (OR): 9,47; fumadores (OR); 3,96; y os que tienen de peor salud(OR): 2,29. Conclusiones: La prevalencia del consumo de alcohol se ha incrementado en ambos sexos y el consumo excesivo con la edad, presentando un mayor riesgo en hombres, fumadores, y los que tienen peor autopercepción de la salud (AU)

Objective: charracterization of the pattern of alcohol consumption in the period (1997-2009) and the characteristics of the most important sociodemographic factors associated. Method: Observational epidemiological study, including three independent samples, representative of the resident population, not institutionalized in Canarias (>= 16 years), years 1997 (n=2,176), 2004 (n=4,320) and 2009 (n=4,560), total (n=11,056), samples selected by multi stage sampling and stratified by island and region. Alcohol consumption was grouped into non drinkers, regular consumption and oversconsumption. Intrend analysis the prevalence of high-risk and non-drinkers was calculated in the three cohorts. Multinomial logistic regression with corresponding odds ratio (OR), confidence interval (95% IC) and significance (p) was used to assess associations between different levels of consumption as the independent variable, and selected sociodemographic variables. Results: The prevalence of high risk has increased in Canary Islands while non drinkers decrease especially in women (40%). High risk consumption increases with age and habitual consumption in all age groups, especially young people (16-30). The greater risk of high-risk drinking are men (OR): 9.47; smoking (OR): 3.96, and those with poorer health (OR): 2.29. Conclusions: The prevalence of alcohol consumption has increased in both sexes and excesive consumption with age, presenting and increased risk in men, smokers, and poorer self-rated health (AU)

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.

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.

Adiposity and age explain most of the association between physical activity and fitness in physically active men.

BACKGROUND: To determine if there is an association between physical activity assessed by the short version of the International Physical Activity Questionnaire (IPAQ) and cardiorespiratory and muscular fitness. METHODOLOGY/PRINCIPAL FINDINGS: One hundred and eighty-two young males (age range: 20-55 years) completed the short form of the IPAQ to assess physical activity. Body composition (dual-energy X-Ray absorptiometry), muscular fitness (static and dynamic muscle force and power, vertical jump height, running speed [30 m sprint], anaerobic capacity [300 m running test]) and cardiorespiratory fitness (estimated VO(2)max: 20 m shuttle run test) were also determined in all subjects. Activity-related energy expenditure of moderate and vigorous intensity (EEPA(moderate) and EEPA(vigorous), respectively) was inversely associated with indices of adiposity (r = -0.21 to -0.37, P<0.05). Cardiorespiratory fitness (VO(2)max) was positively associated with LogEEPA(moderate) (r = 0.26, P<0.05) and LogEEPA(vigorous) (r = 0.27). However, no association between VO(2)max with LogEEPA(moderate), LogEPPA(vigorous) and LogEEPA(total) was observed after adjusting for the percentage of body fat. Multiple stepwise regression analysis to predict VO(2)max from LogEEPA(walking), LogEEPA(moderate), LogEEPA(vigorous), LogEEPA(total), age and percentage of body fat (%fat) showed that the %fat alone explained 62% of the variance in VO(2)max and that the age added another 10%, while the other variables did not add predictive value to the model [VO(2)max  = 129.6-(25.1× Log %fat) - (34.0× Log age); SEE: 4.3 ml.kg(-1). min(-1); R(2) = 0.72 (P<0.05)]. No positive association between muscular fitness-related variables and physical activity was observed, even after adjusting for body fat or body fat and age. CONCLUSIONS/SIGNIFICANCE: Adiposity and age are the strongest predictors of VO(2)max in healthy men. The energy expended in moderate and vigorous physical activities is inversely associated with adiposity. Muscular fitness does not appear to be associated with physical activity as assessed by the IPAQ.

Osteocalcin as a negative regulator of serum leptin concentration in humans: insight from triathlon competitions.

Osteocalcin is a hormone produced by osteoblasts which acts as a negative regulator of fat mass, protecting against diet induced obesity and insulin resistance in rodents. To determine if an acute increase in osteocalcin concentration is associated with opposed changes in circulating leptin levels and insulin resistance we studied 15 middle and long distance male triathletes, (age 32.1 ± 6.9 years), before and 48 h after an Olympic (OT) or an Ironman (IT) triathlon competition. Muscle power, anaerobic capacity, body composition (dual-energy X-ray absorptiometry), and serum concentrations of testosterone, dihydrotestosterone, osteocalcin, leptin, glucose, insulin and insulin resistance (HOMA) were determined pre- and post-race. Pre- and 48 h post-race total and regional lean body mass was not altered, but fat mass was similarly increased (~250 g) 48 h after the competitions. This elicited an increase in plasma leptin of 33% after the IT while it remained unchanged after the OT, likely due to a 25% increase in plasma osteocalcin which occurred only after the OT (all p < 0.05). Post-race HOMA remained unchanged in OT and IT. Performance was normalized 48 h after the competitions, with the exception of a slightly lower jumping capacity after the IT. Serum testosterone concentration tended to decrease by 10% after the IT whilst dihydrotestosterone was reduced by 24% after the IT. In conclusion, an acute increase in serum osteocalcin concentration blunts the expected increase of serum leptin concentration that should occur with fat mass gain. This study provides evidence for osteocalcin as a negative regulator of serum leptin in humans.

Bone and lean mass inter-arm asymmetries in young male tennis players depend on training frequency.

Professional tennis players (TP) have marked inter-arm asymmetry in bone mass (BMC) and density (BMD). To determine if this asymmetry is influenced by training frequency and volume, we studied 24 young tennis players (mean age 10.6 years, Tanner 1-2), 17 physically active control boys (CG) and ten male professional tennis players. Young TP were divided into two groups depending on the number of training days per week (TP5: 5 days/week, n = 10; TP2: 2 days/week, n = 14). In young TP, the dominant arm (DA) compared to the non-dominant arm (NDA) had greater lean mass (TP5, 13.3 +/- 2.0% and TP2, 8.3 +/- 1.3%), BMC (TP5, 22.4 +/- 4.1% and TP2, 12.1 +/- 2.2%), bone area (TP5, 15.6 +/- 3.3% and TP2, 7.9 +/- 2.2%) and BMD (TP5, 4.6 +/- 1.5% and TP2, 3.8 +/- 0.6%). Inter-arm asymmetry in lean mass, BMC and bone area was greater in TP5 than TP2, being related to the number of weekly hours devoted to tennis (r = 0.45-52, P < 0.05). No significant differences in lumbar spine or femoral neck BMC or BMD were observed between TP5, TP2 and CG. In professional TP, the DA had 18, 32, 11 and 15% greater lean mass, BMC, bone area and BMD than the NDA. Thus, TP5 had 69% of the inter-arm asymmetry in BMC observed in professional TP and a similar inter-arm asymmetry in bone area, although this comparison may not be generalisable. Young tennis players have increased BMC, bone area and lean mass in dominant arm, which magnitude depends on the number of weekly hours devoted to tennis.

High femoral bone mineral density accretion in prepubertal soccer players.

PURPOSE: To determine the effect of physical activity on bone mineral accrual during growth in prepuberal boys. METHODS: Seventeen soccer players and 11 matched (physically active) control boys (Tanner 1-2, at the start of the study) were followed over a 3-yr period. Bone mineral content (BMC) and a real density (BMD) was measured by dual-energy x-ray absorptiometry. The maximal positive mechanical impulse (CJipos) and height jumped (Hj) during countermovement vertical jumps were assessed with a plate force. Additionally, 30-m running speed test (T30), 300-m run test (AC), and 20-m shuttle run test (MAP) were performed. RESULTS: The soccer players attained better results in MAP and AC than the controls (P < 0.05). At the end of the follow-up, the controls increased their percentage of body fat in 11 units (P < 0.05) whereas it remained unchanged in the soccer players. Lean body mass increased with growth but more in the soccer players than in the controls (P < 0.05). The soccer players exhibited greater BMC in the legs and greater BMD in all bone-loaded regions at the end of the study (P < 0.05). During these 3 yr, the soccer players gained twice as much femoral neck and intertrochanteric BMC than the control group (P < 0.05) and increased their femoral neck BMD by 10% and their mean hip BMD by a third more than the control group (both P < 0.05). Multiple regression analysis showed that the improvement in T30 and CJipos has predictive value for the enhancement of bone mass in growing boys. CONCLUSION: Long-term soccer participation, starting at a prepubertal age, results in greater improvement of physical fitness, greater acquisition of bone mass and a lower accumulation of body fat.