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A growing interest in constitutional thinness has been observed in the last decades, but the publications however cover various fields of study and report equivocal results. The present work systematically reviewed any clinical trials enrolling participants with constitutional thinness and bibliographic researches were performed between December 2018 and June 2020. From a total of 1 212 records initially identified, 402 records were removed as duplicates, 381 articles were excluded based on titles or abstracts and 390 references were excluded against eligibility criteria. Thirty-nine articles were finally included in the systematic review. The results showed that constitutionally thin people seem to be underweight but not underfat and present a fat-free mass as blunted as anorexic patients, despite being a little less underweight. The meta-analysis confirmed that constitutionally thin people present normal energy intake and revealed a trend toward a higher resting metabolic rate to fat-free mass ratio which suggests a highly metabolic fat-free mass. Contrary to patients with anorexia nervosa, constitutionally thin people present normal levels of insulin-like growth factor 1, estradiol, growth hormone, follicle-stimulating hormone, and luteinizing hormone. An intermediate level of leptin between anorexic and control participants was however observed in constitutional thinness. While all the studies reported normal free triiodothyronine and cortisol levels in constitutionally thin individuals, a higher fasting free triiodothyronine level (p = 0.033) and a lower 24 h mean cortisol level (p = 0.005) were observed for the first time. Present results give robust evidence that constitutionally thin people present an atypical phenotype highly different from anorexia nervosa. [ABSTRACT FROM AUTHOR]

Constitutional thinness is defined as a state of severe underweight with a body mass index similar to anorectic patients (BMI < 17.5 kg/m2), in the absence of any eating disorders or other obvious disruptive factors impacting energy balance. The analysis of body composition is essential as a first approach to characterize constitutional thinness and might help identify new discriminating differences between constitutional thinness and anorexia nervosa. A meta-analytical approach was performed to compare body composition of constitutionally thin, anorectic, and normal-weight subjects from all available studies found in the literature. The statistical analysis was carried out on large sample sizes: n = 205 females with constitutional thinness, n = 228 normal-weight control females, and n = 258 females with anorexia nervosa. Despite being as underweight as anorectic patients, constitutionally thin participants paradoxically presented higher percentages of fat mass than anorectic patients (18.9% vs. 11.4%, respectively; SMD [95% CI]: 1.62 [1.16; 2.08]), even found in the normal healthy ranges. Constitutionally thin people, however, display as low fat-free mass as anorectic patients. These observations question the use of high-fat diets in this population and bring new insights for nutrition and/or training strategies directed toward muscle mass gain. The present results give new elements to further distinguish constitutional thinness from anorexia nervosa and reinforce the need to better investigate the atypical phenotype of constitutional thinness. [ABSTRACT FROM AUTHOR]

Capillary network of skeletal muscle has a crucial role in oxygen supply and is strongly associated with the phenotype and metabolic profile of muscle fibers. Abundant literature has explored capillarization of skeletal muscle in different populations and in response to different interventions. Capillary and fiber type identification techniques have considerably evolved over the last decades, but to the best of our knowledge, no validated immunohistochemical method has yet been developed to simultaneously identify capillaries (using CD31), the three different muscle fiber types, and basal lamina. Nine human muscle biopsies of vastus lateralis were stained using 5 different methods to test: the reliability of different CD31 antibodies for capillary identification, the reliability between single-section or serial-section methods, and the intra-experimenter reproducibility in visual detection of capillaries. High reliability for the different antibodies directed against capillaries was observed for capillary contacts (CC) measurements (intra-class correlations (ICC) [ICC95%] of 0.89 [0.72; 0.96] for type I fibers, 0.93 [0.81; 0.97] for type IIA fibers, 0.88 [0.71; 0.96] for type IIX fibers, 0.95 [0.86; 0.98] for all fiber types) as well as a high level of similarity between single and serial sections methods. A strong similarity in capillary analysis between the different methods was obtained for each sample measurements. Analysis of Lin's concordance correlation coefficients and Bland and Altman's graphics showed a strong intra-experimenter reproducibility. This article proposes two time- and tissue-sparing immunohistochemical methods to accurately assess a complete fiber typing (type I, IIA, and IIX) along with muscle capillarization on a single muscle section. [ABSTRACT FROM AUTHOR]

Abnormalities in myocardial and vascular function have been reported in the metabolic syndrome (MetS), but whether these alterations are related remains poorly documented. Our aim was accordingly to investigate interrelationships between macro- and microcirculatory vasoreactivity and left ventricular (LV) myocardial function in MetS patients. Eighty-eight MetS individuals and 44 age- and gender-matched healthy controls were enrolled. LV global longitudinal strain (GLS) was measured using Vector Velocity Imaging. Endothelial-dependent and independent reactivity in macro- and microcirculatory territories was established using flow-mediated dilation and nitrate-mediated dilation of the brachial artery and cutaneous blood flow measured with laser Doppler flowmetry in response to iontophoresis of acetylcholine and sodium nitroprusside, respectively. Carotid intima-media thickness (cIMT) was measured according to the Mannheim consensus. Compared to controls, MetS patients presented with reduced GLS (p < 0.001) increased cIMT and impaired (p < 0.001) endothelial and smooth muscle function of the brachial artery and the forearm skin microcirculation. Highly significant relationships (p < 0.01) were noticed between GLS and vascular outcomes. In addition, cIMT (β = 0.21, p = 0.024) and microcirculatory endothelium-dependent reactivity (β = − 0.20, p = 0.035) were identified as independent predictors of GLS. In MetS, abnormalities in myocardial function and endothelial as well as smooth muscle function of small and large arteries co-exist and are closely associated. This study supports a role for microvascular dysfunction in the pathogenesis of LV myocardial dysfunction. [ABSTRACT FROM AUTHOR]

Given the rise in pediatric obesity, clarifications on the relationship between obesity and bone health and on the impact of structured intervention on this relationship are needed. This systematic review and meta-analysis investigated the effect of obesity on bone health and assessed the effect of structured intervention in children and adolescents with obesity. Medline complete, OVID, CINAHL, EMBASE and PubMed databases were searched for studies on obesity and bone health variables up to September 2016, then an update occurred in March 2016. Search items included obesity, childhood, dual energy X-ray absorptiometry and peripheral quantitative computed tomography. Twenty-three studies (14 cross-sectional and nine longitudinal) matched the inclusion criteria. Results from the meta-analysis (cross-sectional studies) confirmed that children and adolescents with obesity have higher bone content and density than their normal weight peers. Results from longitudinal studies remain inconclusive as only 50% of the included studies reported a positive effect of a structured intervention program on bone health. As such, the meta-analysis reported that structured intervention did not influence bone markers despite having beneficial effects on general health in youth with obesity. [ABSTRACT FROM AUTHOR]

The rising prevalence of overweight and obesity among pediatric populations has become a major global concern. The objective of this review is to demonstrate potential interactions between the products released by fat tissue and the hormonal production of bone tissue in obese children and adolescents. Advancing the understanding of the complex interactions between adipocyte and osteocyte activities may contribute to the mechanistic understanding of the body's responses to weight loss during adolescence. This knowledge could also reveal any side effects encountered with these interventions. Currently, the concept of bone-adiposity crosstalk has not been fully elucidated, and the mechanisms remain controversial. Understanding the local interactions between the released products by fat tissue and hormones produced in bone tissue requires further investigations. [ABSTRACT FROM AUTHOR]

Sports training characterized by impacts or weight-bearing activity is well known to induce osteogenic effects on the skeleton. Less is known about the potential effects on bone strength and geometry, especially in female adolescent athletes. The aim of this study was to investigate hip geometry in adolescent soccer players and swimmers compared to normal values that stemmed from a control group. This study included 26 swimmers (SWIM; 15.9 ± 2 years) and 32 soccer players (SOC; 16.2 ± 0.7 years), matched in body height and weight. A group of 15 age-matched controls served for the calculation of hip parameter Z-scores. Body composition and bone mineral density (BMD) were assessed by dual-energy X-ray absorptiometry (DXA). DXA scans were analyzed at the femoral neck by the hip structure analysis (HSA) program to calculate the cross-sectional area (CSA), cortical dimensions (inner endocortical diameter, ED; outer width and thickness, ACT), the centroid (CMP), cross-sectional moment of inertia (CSMI), section modulus (Z), and buckling ratio (BR) at the narrow neck (NN), intertrochanteric (IT), and femoral shaft (FS) sites. Specific BMDs were significantly higher in soccer players compared with swimmers. At all bone sites, every parameter reflecting strength (CSMI, Z, BR) favored soccer players. In contrast, swimmers had hip structural analysis (HSA) Z-scores below the normal values of the controls, thus denoting weaker bone in swimmers. In conclusion, this study suggests an influence of training practice not only on BMD values but also on bone geometry parameters. Sports with high impacts are likely to improve bone strength and bone geometry. Moreover, this study does not support the argument that female swimmers can be considered sedentary subjects regarding bone characteristics. [ABSTRACT FROM AUTHOR]

We attempted to clarify whether rugby was able to enhance bone mineral density (BMD) and content (BMC) of weight-bearing bones by modifying bone remodelling in relation to physical fitness in male rugby players compared to controls. 22 male international rugby players aged 20-31 years (forwards, n = 12 and backs, n = 10) were compared to 14 age-matched controls of the same ethnic origin aged 21-33 years. BMD and BMC were measured by DEXA and bone metabolism was evaluated by specific makers. Physical fitness level was analysed in parallel. Both forwards and backs exhibited significantly higher BMD (+15%, +6%, respectively) and BMC (+36%, +18%, respectively) for whole body and all examined sites, regions and segments than controls, with more pronounced difference at forwards. The difference between both groups of rugby players and controls noted for BMD became more pronounced for BMC (+52% for lower limbs). BMD and BMC values were higher in forwards than backs at total body (+9, +16%) and at stressed sites such as spine (+12%, +13%), pelvis (+10%, +11%), upper (+17% for BMC) and lower limbs (+9%, +18%). Athletes, especially forwards, presented higher concentrations of OC and CTX resulting in positive values of the uncoupling index. Total body lean mass as well as muscular strength strongly correlated with total and stressed regional sites such as spine, pelvis, and lower limbs BMD and BMC (r = 0.59, p < 0.01 to r = 0.84, p < 0.001). Similarly, OC, but not CTX, is highly correlated with the same regional and total BMD and BMC (r = 0.67 to r = 0.81, p < 0.001). Rugby participation is associated with improved physical fitness, enhanced axial and appendicular bone mass and increased bone turnover in adult athletes. Moreover, the positive bone adaptation of these athletes may be related to an increase of bone remodelling rate in favour of bone formation, especially in forwards. [ABSTRACT FROM AUTHOR]

The aim of this study was to determine the relative importance of lean mass (LM) and fat mass (FM) on bone mineral density (BMD) in a group of adolescent girls and boys. A total of 65 adolescent boys and 35 adolescent girls participated in this study. Whole body (WB) and lumbar spine (L1-L4) BMD were measured by dual-energy X-ray absorptiometry (DXA). Body composition was assessed using the same technique. In boys, LM was strongly related to WBBMD (r = 0.68; p < 0.001) and to L1-L4 BMD (r = 0.61; p < 0.001), whereas FM was not positively related to BMD and was negatively associated with WB bone mineral apparent density (WBBMAD). In girls, both LM and FM were positively related to WBBMD (r = 0.41; p < 0.05 and r = 0.49; p < 0.01, respectively), whereas only FM was correlated to L1-L4 BMD (r = 0.33; p < 0.05). Finally, in a multiple regression analysis, FM was found to be a better positive determinant of WBBMD than LM in girls, whereas in boys, FM was found to be a negative determinant of WBBMD and L1-L4 BMD. This study suggests that LM is a strong determinant of WBBMD and L1-L4 BMD in boys, and that FM is a stronger determinant of WBBMD than LM in girls. [ABSTRACT FROM AUTHOR]

The aim of the study was to determine the influence of obesity on bone status in prepubertal children. This study included 20 obese prepubertal children (10.7 +/- 1.2 years old) and 23 maturation-matched controls (10.9 +/- 1.1 years old). Bone mineral area, bone mineral content (BMC), bone mineral density (BMD), and calculation of bone mineral apparent density (BMAD) at the whole body and lumbar spine (L1-L4) and body composition (lean mass and fat mass) were assessed by DXA. Broadband ultrasound attenuation (BUA) and speed of sound (SOS) at the calcaneus were measured with a BUA imaging device. Expressed as crude values, DXA measurements of BMD at all bone sites and BUA (69.30 versus 59.63 dB/MHz, P < 0.01) were higher in obese children. After adjustment for body weight and lean mass, obese children displayed lower values of whole-body BMD (0.88 versus 0.96 g/cm2, P < 0.05) and BMC (1190.98 versus 1510.24 g, P < 0.01) in comparison to controls. When results were adjusted for fat mass, there was no statistical difference between obese and control children for DXA and ultrasound results. Moreover, whole-body BMAD was lower (0.086 versus 0.099 g/cm3, P < 0.0001), whereas lumbar spine BMAD was greater (0.117 versus 0.100 g/cm3, P < 0.001) in obese children. Thus, it was observed that, in obese children, cortical and trabecular bone displayed different adaptation patterns to their higher body weight. Cortical bone seems to enhance both size and BMC and trabecular bone to enhance BMC. Finally, considering total body weight and lean mass of obese children, these skeletal responses were not sufficient to compensate for the excess load on the whole body. [ABSTRACT FROM AUTHOR]

Mechanical loading during growth magnifies the normal increase in bone diameter occurring in long bone shafts, but the response to loading in long bone ends remains unclear. The aim of the study was to investigate the effects of tennis playing during growth at the distal radius, comparing the bone response at trabecular and cortical skeletal sites. The influence of training duration was examined by studying bone response in short-term (children) and long-term (young adults) perspectives. Bone area, bone mineral content (BMC), and bone mineral density (BMD) of the radius were measured by DXA in 28 young (11.6 +/- 1.4 years old) and 47 adult tennis players (22.3 +/- 2.7 years old), and 70 age-matched controls (12 children, 58 adults) at three sites: the ultradistal region (trabecular), the mid-distal region, and the third-distal region (cortical). At the ultradistal radius, young and adult tennis players displayed similar side-to-side differences, the asymmetry in BMC reaching 16.3% and 13.8%, respectively (P < 0.0001). At the mid- and third-distal radius, the asymmetry was much greater in adults than in children (P < 0.0001) for all the bone parameters (mid-distal radius, +6.6% versus +15.6%; third-distal radius, +6.9% versus +13.3%, for BMC). Epiphyseal bone enduring longitudinal growth showed a great capacity to respond to mechanical loading in children. Prolonging tennis playing into adulthood was associated with further increase in bone mineralization at diaphyseal skeletal sites. These findings illustrate the benefits of practicing impact-loading sports during growth and maintaining physical activity into adulthood to enhance bone mass accrual and prevent fractures later in life. [ABSTRACT FROM AUTHOR]

The effect of intensive exercise training on urinary androgen and cortisol excretions in prepubertal girls of various ages was tested in competitive premenarchal gymnasts (n=56) and in age-matched controls (n=53). Both sexual maturation and bone age were assessed. Urinary excretions of androstenedione, dehydroepiandrosterone sulphate (DHEA-S), testosterone and cortisol were determined by radioimmunoassay procedures. The gymnasts were taller [mean (SD) 138.3 (9.0) cm vs 144.7 (8.3) cm; P<0.001] and lighter [32.0 (6.9) kg vs 36.7 (8.2) kg; P<0.001], and had a lower percentage of fat mass [16.8 (2.2)% vs 22.5 (6.6)%; P<0.0001] than the controls. There was no difference between groups in urinary testosterone, cortisol and DHEA-S levels, while androstenedione levels were significantly lower in gymnasts than in controls [mean (SEM) 187.10 (18.00) nmol/24 h vs 256.50 (15.00) nmol/24 h; P<0.01). There was no difference in the regression slopes between the two groups for all hormonal values. In conclusion, these results suggest that during the prepubertal period, intensive training alters only urinary androstenedione concentrations in girls. [ABSTRACT FROM AUTHOR]

The aim of the present study was to analyse the effect of 1 year of intensive swimming training on lung volumes, airway resistance and on the flow-volume relationship in prepubertal girls. Five girls [9.3 (0.5) years old] performing vigorous swimming training for 12 h a week were compared with a control group of 11 girls [9.3 (0.5) years old] who participated in various sport activities for 2 h per week. Static lung volumes, maximal expiratory flows (MEF) at 75, 50 and 25% of vital capacity, 1-s forced expiratory volume (FEV1.0) and airway resistance ( Raw) were measured by means of conventional body plethysmograph techniques. Prior to the training period there were no significant differences between the two groups for any of the parameters studied. Moreover, for both groups, all parameters were within the normal range for children of the corresponding age. After 1 year of training, vital capacity (VC), total lung capacity (TLC) and functional residual capacity (FRC) were larger ( P<0.05) in the girl swimmers than in the control group, while physical development in terms of height and weight was similar. FEV1.0 ( P<0.01), MEF25, MEF50 ( P<0.05) and MEF75 as well as the ratio MEF50 / TLC ( P<0.05) had increased in the girl swimmers but were unchanged in the control group. Raw tended to be lower in the girl swimmers and higher in the control group. The results indicate that intensive swimming training prepuberty enhances static and dynamic lung volumes and improves the conductive properties of both the large and the small airways. As to the causative mechanism, it can be speculated that at prepuberty intensive swimming training promotes isotropic lung growth by harmonizing the development of the airways and of alveolar lung spaces. [ABSTRACT FROM AUTHOR]

Summary: We identified the determinants of 12-month changes of areal bone mineral density (aBMD), hip geometry and trabecular bone score (TBS) in adolescent male athletes. Changes in region-specific lean mass and the type of sport are the most consistent determinants in this population.Purpose: This study aims to identify the determinants of 12-month changes of areal bone mineral density (aBMD), hip geometry and trabecular bone score (TBS) in adolescent male athletes.Methods: The sample was 104 adolescent males aged 12-14 years at baseline that were followed over 12 months: 39 swimmers, 37 footballers (or soccer players) and 28 cyclists. Dual-energy X-ray absorptiometry measured aBMD at the whole body, lumbar spine and dual hip. Hip geometry estimates at the femoral neck were measured using hip structural analysis. Lumbar spine texture was measured by TBS.Results: Multivariate regression models significantly explained 38-60% of the variance in the aBMD changes, 36-62% in the hip geometry estimates changes and 45% in the TBS changes. Δregion-specific lean mass was the most consistent predictor of changes in aBMD outcomes (β = 0.591 to 0.696), followed by cycling participation (β = − 0.233 to − 0.262), swimming participation (β = − 0.315 to − 0.336) and ΔMVPA (β = 0.165). Cycling participation was the most consistent predictor of changes in hip geometry estimates (β = − 0.174 to − 0.268), followed by Δregion-specific lean mass (β = 0.587) and Δcardiorespiratory fitness (β = 0.253). Finally, cycling and swimming participation (β = − 0.347 to − 0.453), Δregion-specific lean mass (β = 0.848) and Δstature (β = 0.720) were predictors of change in TBS.Conclusions: Changes in region-specific lean mass and the type of sport are the most consistent determinants of 12-month changes in aBMD, hip geometry estimates and TBS in adolescent male athletes.Trial registration: ISRCTN17982776 [ABSTRACT FROM AUTHOR]