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Constitutional thinness is defined as a state of severe underweight with a body mass index similar to anorectic patients (BMI < 17.5 kg/m.sup.2), 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., Author(s): Mélina Bailly [sup.1] [sup.2] , Audrey Boscaro [sup.1] , Bruno Pereira [sup.3] , Daniel Courteix [sup.1] , Natacha Germain [sup.2] [sup.4] , Bogdan Galusca [sup.2] [sup.4] , Yves Boirie [...]

The relationship between inflammatory markers and bone turnover in adults is well known, and a negative association between cardiorespiratory fitness (CRF) and inflammatory markers has also been described. Hence, we tested whether the association between CRF and bone turnover markers is mediated by inflammatory markers in adults with metabolic syndrome. A total of 81 adults (58.5 ± 5.0 years, 62.7% women) were included in the analysis. CRF was measured by the 6-min walking test. Serum interleukin (IL)-1β, IL-6, IL-10, tumor necrosis factor alpha, high-sensitivity c-reactive protein (hsCRP) and vascular endothelial growth factor, collagen type I cross-linked C-telopeptide, procollagen type I N-terminal propeptide (P1NP), and total osteocalcin were assessed using a sensitive ELISA kit. Body composition was assessed by dual-energy X-ray absorptiometry. Partial correlation was used to test the relationship between CRF, inflammatory markers, and bone turnover markers, controlling for sex, lean mass, and fat mass. Boot-strapped mediation procedures were performed, and indirect effects with confidence intervals not including zero were interpreted as statistically significant. CRF was positively correlated with P1NP levels (r =.228, p =.044) and osteocalcin levels (r =.296, p =.009). Furthermore, CRF was positively correlated with IL-1β levels (r =.340, p =.002) and negatively correlated with hsCRP levels (r = −.335, p =.003), whereas IL-1β levels were positively correlated with P1NP levels (r =.245, p =.030), and hsCRP levels were negatively correlated with P1NP levels (r = −.319, p =.004). Finally, the association between CRF and P1NP levels was totally mediated by hsCRP (percentage of mediation = 39.9). Therefore, CRF benefits on bone formation could be dependent on hsCRP concentrations in this population. [ABSTRACT FROM AUTHOR]

Introduction: Since adolescents with obesity are prone to bone fragility during weight loss, the aim was to compare the impact of high-intensity interval training (HIIT) versus moderate-intensity continuous training (MICT) on bone density, geometry, and strength. Methods: Sixty-one adolescents were randomly assigned to 2 cycling trainings (HIIT and MICT) and a control (CTR, without training) group. Anthropometry, dual-energy X-ray absorptiometry with hip structural analysis and the trabecular bone score (TBS) were assessed before and after the 16-week intervention. Results: Body mass index (BMI) and fat mass (FM) percentage decreased at T1 versus T0 in both training groups (p < 0.001 for HIIT, p = 0.01 for MICT), though to a larger extent in HIIT (p < 0.05). Total body bone mineral density (BMD) and bone mineral content (BMC) increased in both training groups (p < 0.001), but to a greater extent in HIIT for BMC (p < 0.05). Lumbar spine BMD and BMC increased in both training groups (p < 0.001 for HIIT, p < 0.01 for MICT), with a time × group interaction between HIIT and CTR (p < 0.05) only. TBS increased in both training groups (p < 0.01 for HIIT, p < 0.05 for MICT). Hip BMD and BMC increased in both HIIT (p < 0.001 and p < 0.01) and MICT (p < 0.01 and p < 0.05). At the narrow neck (NN), endocortical diameter, width (p < 0.01), cross-sectional moment of inertia, and section modulus (Z) (p < 0.05) increased only in the HIIT group, such as BMD and Z (p < 0.05) at the intertrochanteric region (IT) and average cortical thickness (p < 0.001) and width (p < 0.05) at the femoral shaft. At the NN and IT, the buckling ratio decreased only in the HIIT group (p < 0.05), predicting higher resistance to fracture. Conclusions: In addition to inducing greater BMI and FM percentage decreases in comparison to MICT, HIIT improves multisite bone density, geometry, and strength, which heighten the justification for HIIT as part of weight loss interventions in adolescents with obesity. [ABSTRACT FROM AUTHOR]