Abstract This study is based on the numerical simulation of the mechanical response of yttrium-stabilized zirconia ceramic (3Y-TZP) dental implants as a function of their intrinsic geometry and masticatory loads. Samples (n=20) of 3Y-TZP ceramics were compacted, sintered at 1500 °C - 2h, and characterized by relative density, X-Ray diffraction (XRD), and scanning electron microscopy (SEM). The elastic parameters (modulus of elasticity and Poisson ratio), used in the numerical simulations, were measured by the Impulse Excitation Technique, and the bending strength was obtained using piston-on-three-balls testing. An authorial implant design and, comparatively, commercial implant CAD models were used in this study as an initial geometry of dental implant in a typical adult mandible anatomy. From CAD and CAE techniques, finite element models were generated for all implant geometries. Loading cases were considered based on different intensities (100N to 500N) and orientation angles (45° or 90°) to reproduce the human masticatory efforts. The numerical predictions were compared with finite element simulations of gold-standard titanium-based implants. The investigated 3Y-TZP sintered ceramics presented high densification (> 99%), with a microstructure formed by submicron equiaxed tetragonal zirconia grains. The 3Y-TZP average bending strength obtained from piston-on-three-balls testing is 1192 ± 99 MPa. For both dental implant geometries, the zirconia implants showed average strength of less than 550 MPa, which, in turn, is independent of the masticatory load value or orientation angle. All finite element predictions are 50% inferior to the corresponding measured flexural strength values and preliminarily enable the 3Y-TZP ceramics for dental implant applications without fracture risk.

In this work, mixtures of ceramic powders containing Al2O3 with different amounts of Y2O3 (1%, 3%, 5% and 10wt.%) along their cross-section were fabricated to obtain multilayer composites based on Al2O3 with different levels of Y3Al5O12 (YAG) as reinforcement. Monolithic cylindrical multilayer Al2O3 blocks were compacted and subsequentially, sintered at 1610°C for 4h. Phase stability, microstructural aspects, and physical and mechanical properties of the specimens were acquired by relative density, X-ray diffraction, scanning electron microscopy, Vickers hardness, fracture toughness, Young’s modulus and biaxial flexural strength measurements. The results indicated that monolithic alumina specimens exhibited relative density of 98%, with average hardness of 1203 ±83 HV, fracture toughness of 2.1 ±0.8 MPa.m1/2 and flexural strength of 187 ±64 MPa. Progressive incorporation of Y2O3 into the chemical composition of the specimens led to formation of the YAG phase by solid state reaction during sintering, which reduced hardness and increased densification, fracture toughness and flexural strength, with average values of HV=1023 ±28 HV, KIC=3.5 ±0.3 MPa.m1/2, σf=273 ±58 MPa and 14% Y3Al5O12 for the specimens with 10wt.% Y2O3. This improvement is probably associated with toughness mechanisms, such as crack deflection and residual thermal stresses between the phases present in the composites.

This work investigated the effect of a composite of tetragonal zirconia with alumina-reinforced Ceria (ATZ) previously synthesized, on the properties of alumina-based ceramics (Al2O3). Monolithic alumina powder and Al2O3 powder mixtures containing 5, 10, 15 and 20 wt.% of Ce-TZP/Al2O3 were processed by high energy milling, compacted and then sintered at 1600 °C - 2 h. Sintered pure alumina and composites were characterized by relative density, scanning electron microscopy, X-ray diffraction and surface roughness. Then, the elastic modulus, the Vickers hardness, the fracture toughness and the 4-point flexural strength were evaluated. The results indicated an increase in relative density as a function of the addition of ATZ, with values between 94.3 ± 0.8% and 98.9 ± 0.7%. The observed microstructure after sintering showed tetragonal ZrO2 grains with average sizes of 0.6 μm well dispersed in the Al2O3 matrix, which presents average grain sizes of around 1.5 μm. The crystalline phases identified in the composites were ZrO2-tetragonal and Al2O3 hexagonal. The addition of the composite (ATZ) in the alumina matrix generates a gradual reduction in the elastic modulus (398 ± 15 GPa ~366 ± 34 GPa) and in the hardness (20.5 ± 1 GPa ~17.3 ± 0.7 GPa) of the sintered ceramics. On the other hand, the addition of this same composite (ATZ) in the alumina matrix considerably increases the materials fracture toughness, reaching values of approximately 6.7 ± 0.9 MPa.m1/2. The same trend was observed in the flexural strength results which ranged from 258 MPa (5wt.% Ce-TZP/Al2O3) to 316 MPa (20wt.% Ce,Y-TZP/Al2O3). The Ce-TZP reinforcement acts as a toughening agent of the Al2O3 matrix due to the coupled mechanisms of toughening by zirconia phase transformation, residual stresses due to the difference in thermal expansion of the crystalline phases and differences in microstructural morphologies.

This work investigated the effect of adding ceria-stabilized tetragonal zirconia (Ce-TZP) on the fatigue behavior of alumina-based ceramic composites. Alumina powder (control group) and mixtures containing 5 wt.% (group A) and 20 wt.% (group B) of a commercial m-ZrO2/Al2O3/CeO2 powder mixture were milled/homogenized, compacted, sintered at 1600°C-2h, and submitted to hydrothermal degradation. The samples were characterized by relative density, microstructure, crystalline phases, and static mechanical properties. The cyclic fatigue strength was determined using the modified staircase method in 4-point bending tests. The results indicate that adding the m-ZrO2/Al2O3/CeO2 powder mixture to the Al2O3-matrix increases the tetragonal-ZrO2 grains (Ce-TZP) content, presenting 2.9 wt.% of Ce-TZP and 11.9 wt.% of Ce-TZP for group A and group B, respectively. Furthermore, the addition of Ce-TZP improves densification (98.5% → 99.1%) with a slight reduction in hardness and modulus of elasticity and a significant KIC increase of the composite (KIC = 6.7 MPa.m1/2, group B) when compared to monolithic alumina (KIC=2.4 MPa.m1/2). The fatigue strength limit of the control group was around 100 MPa, while the composites (groups A and B) presented the values of 279 MPa and 239 MPa, respectively. The results indicated that the incorporation of Ce-TZP significantly improves the fracture toughness of alumina-based ceramics. On the other hand, regarding the fatigue behavior, there was an increase in fatigue resistance in group A, resulting from the benefits of the t→m Ce-TZP grains transformation, which occurs during cyclic loading, producing a zone shielding that involves the tip of the crack, slowing its growth. The increase in the amount of Ce-TZP (group B) leads to an increase in the internal residual stresses between the phases due to anisotropy and difference in the thermal expansion coefficients, which accelerates the phase transformation and formation of microcracks at grain boundaries, reducing the fatigue strength of composites of group B.

The influence of Fe2O3 additions on the microstructure, mechanical properties and translucence of zirconia with 3 mol-% or 5 mol-% Y2O3 was evaluated. Samples were pressed with different thickness and sintered at 1475, 1500, 1550 and 1600°C for 2 h. Density, phases, microstructure, roughness, strength and translucency were analyzed. All samples showed densification greater than 99%. After sintering at 1600°C, the phase analysis revealed only tetragonal ZrO2 in samples with 3% Y2O3, while in samples with 5% Y2O3 the cubic ZrO2 phase was identified. Significant increase in the grain size was noted, when increasing the Y2O3 content from 3% to 5% from 0.8 µm to 2.3 µm for sintered samples at 1600°C. The strength was affected with Y2O3 content and no relevant influence of the Fe2O3 on density, microstructure or mechanical properties. Visible reflectance spectroscopy analyses, related to the CIELab scale, indicate variation in the contrast ratio as function of thickness of samples and coloring agent Fe2O3 content.

The planning and execution of the adequate welding procedure for the superduplex stainless steel (SAF 2507 SDSS) in multiple passes is a complex technological task since thermal cycling may cause the precipitation of harmful phases, such as the sigma (σ) and chi (χ) phases. For this reason, technical standards limit the maximum interpass temperature (T.I.) in an extremely conservative manner at 100 °C. In order to investigate a possibly wider temperature range for this procedure, SAF 2507-SDSS tubes were subjected to autogenous Tungsten Inert Gas (TIG) welding with interpass temperatures ranging from 150°C to 400°C. The different welding zones were characterized by microscopy, Vickers microhardness, and polarization corrosion tests. The results indicated that in the Fusion Zone (FZ), columnar grains of ferrite were formed surrounded by allotriomorphic austenite (AA), besides intragranular austenite (AI) and Widmanstätten austenite (AW). The heat-affected zone (HAZ) had a lower ferrite content and was composed of equiaxed grains of ferrite, also surrounded by AA, besides AI and AW. Hardnesses varied between HV272 and HV293, regardless of the region or the interpass temperature used. Furthermore, the corrosion resistance has not been significantly affected by the interpass temperatures between 150 °C and 400°C.

Abstract The aim of this work was to analyze the properties and shear bond strength (SBS) of lithium disilicate to resin cement before and after etching the glass-ceramic surfaces. Lithium-metasilicate samples were heat treated and characterized by Scanning Electron Microscopy, X-ray diffraction and roughness measurement. For the analysis of the shear bonding strength (SBS) of lithium disilicate to dental resin cement, three groups (n = 12) of Li2Si2O5 were prepared: 1°)without treatment (NT); 2°)surface etching with hydrofluoric acid(HF), followed by silane agent and adhesive treatment; 3°) surface treatment with a self-etching ceramic primer (SECP). After the heat-treatment, the samples had Li2Si2O5 crystalline phase dispersed in a residual amorphous phase. Roughness of the NT and SECP samples was smaller that of the HF samples. Samples without surface treatment (NT) had the lowest SBS (5.5MPa). HF(24.2MPa) and SECP(24.8MPa) samples has similar SBS. Weibull statistics showed that HF-samples are more reliable than NT and SECP. The SBS was significantly increased by either HF etching and SECP surface treatment. While the chemical characteristics of the surface submitted to SECP treatment are considered to be responsible for the SBS increase, the main adhesion mechanism after HF etching is the increase in surface roughness.

Abstract Ti-6Al-4V and TiAl-based alloys are widely used for fabricating the implantable orthopedic devices and automotive components, respectively. Ti6Si2B-based alloys are attractive for use in orthopedic components because their higher hardness, superior biocompatibility and corrosion resistance in simulated body fluid than Ti and Ti-6Al-4V alloy. Limited information on Ti6Si2B stability in Co-dopped 67Ti-22Si-11B alloys are available in literature. This work presents the effect of cobalt doping and milling time on microstructure and Vickers microhardness of 65Ti-2Co-22Si-11B and 61Ti-6Co-22Si-11B (at-%) alloys produced by spark plasma sintering at 1100 oC for 12min using 20MPa. Samples were characterized by X ray diffraction, scanning electron microscopy, energy dispersive spectrometry, laser particle size analysis, and Vickers microhardness. Sintered alloys with 2 and 6at-%Co indicated the major presence of Ti6Si2B and Ti5Si3 dissolving up to 2.7 and 4.2 at-%Co, respectively, besides the minor precipitates of CoTi2 (4.4-16.7at-%Si) and CoTi (4.6-4.7at-%Si). Vickers microhardness of the sintered 65Ti-2Co-22Si-11B and 61Ti-6Co-22Si-11B alloys were in the range of 950-1050 and 1050-1150HV, respectively. Although the increase from 2 to 6at-%Co has reduced the Ti6Si2B stability, the Co-rich phases increased their hardness values up to 1150HV (11.3GPa), which are superior than those of commercial Ti alloys used for joint orthopedic components and automotive rotating parts.

ABSTRACT New techniques for manufacturing of biomaterials using additive/substrate manufacturing such as melting laser sintering (SLM) or CAD/CAM milling use micrometric metal powders to build custom parts. CoCrMo alloys are commonly used as biomaterials due to biocompatibility, high corrosion resistance and good mechanical properties. In this work, Cr-Co-based powder was obtained by mechanical alloying of Cr-Co-Mo-W alloy, using different Ball/Powder-Ratios (BPR) and thermal treatments. The powders were deagglomerated and characterized by X-ray diffraction (XRD) and Scanning electron microscopy (SEM). Based on SEM micrographs, the particle size analysis was used to compare the particles spheroidizing degree, using Feret’s diameter. The XRD patterns shown Co(solid-solution) as crystalline phase. The results of particles size indicates a decrease of Feret’s diameter in BPR (Ball/Powder-Ratio) from 4:1 to 6:1 understanding that from this ratio there is no significant decrease of this relation but there is an average size increase with losses in morphological aspect. The comparison between atomized powders and powder developed in this work indicates that atomized products present relation close to one which indicates there is uniformity in the particles spherical shape. Comparing ground powders from 6:1 ratio (before and after thermal treatment) there is a considerable decrease of Feret’s diameter being it decreased from 1.75 to 1.4, an increase of about 46% in particles spheroidizing.

Abstract In this work, CoCrMo-base alloys specimens were produced by additive manufacturing using selective laser melting (SLM) as well as CAD/CAM milling. For SLM specimens, spherical particles were laser processed at 1320°C under argon atmosphere and submitted to thermal stress relieving at 750°C–45min. Specimens from CoCrMo blocks were milled by CAD/CAM machining and sintered at 1300°C–60min. The materials from both techniques were characterized by relative density, dilatometry, SEM/BSE, OM and XRD analysis. The mechanical properties were determined by Vickers hardness and tensile tests. The specimens from both techniques exhibited single phase γCo (FCC) and CTE of 14 x10-6 °C-1. Relative density of 95.4%/ 85.6%, hardness values near 400HV/ 350HV and UTS of 905MPa/ 780MPa were measured for SLM and CAD/CAM specimens, respectively. Higher relative density is the main factor for increased mechanical properties of SLM specimens. On the other hand, both SLM and CAD/CAM specimens present properties in accordance with ISO-22674 recommendations, compatible with dental applications such as bridges containing four or more elements as well as fully dense pontics.

Resumo: O objetivo deste trabalho foi avaliar os atributos agronômicos e a eficiência produtiva de forragem e grãos de milho em um sistema de integração lavoura-pecuária-floresta (ILPF), com consorciação de eucalipto, milho e cultivares de Urochloa, durante três safras. O delineamento experimental utilizado foi o inteiramente casualizado, em parcelas 2x5x3 sub-subdivididas, com quatro repetições. As parcelas consistiram de cultivo de milho entre renques de eucalipto (ILPF) e a pleno sol; as subparcelas, das forrageiras U. brizantha 'Marandu', U. brizantha 'Xaraés', U. brizantha 'Piatã', U. ruziziensis e U. decumbens 'Basilisk'; e as sub-subparcelas, das safras 2011/2012, 2012/2013 e 2013/2014. Não houve efeito do eucalipto nas produtividades de forragem e grãos de milho consorciado com as forrageiras em 2011/2012. A eficiência produtiva de forragem e grãos teve redução de25 e 48%, respectivamente, em 2012/2013 (eucalipto com 12 meses). Também houve redução de 56% na produtividade de grãos em 2013/2014 (eucalipto com 24 meses), em relação ao cultivo a pleno sol. No ano de implantação do sistema ILPF, a eficiência produtiva de forragem e grãos de milho não é afetada pelo eucalipto, mas é reduzida com o desenvolvimento das árvores nas safras subsequentes.

Abstract: The objective of this work was to evaluate the agronomic attributes and production efficiency of corn silage and grains in an integrated crop-livestock-forestry (ICLF) system, with intercropping of eucalyptus, corn, and Urochloa cultivars during three crop years. The experimental design was completely randomized, in 2x5x3 split-split plots with four replicates. The plots consisted of corn cropped between eucalyptus rows (ICLF) and in full sun; the subplots, of the forage grasses U. brizantha 'Marandu', U. brizantha 'Xaraés', U. brizantha 'Piatã', U. ruziziensis, and U. decumbens 'Basilisk'; and the split-split plots, of the 2011/2012, 2012/2013, and 2013/2014 crop years. There was no effect of eucalyptus on the silage and grain yields of corn when intercropped with forages in 2011/2012. The production efficiency of silage and grains decreased by 25 and 48%, respectively, in 2012/2013 (12-month-old eucalyptus). There was also a 56% reduction in grain yield in 2013/2014 (24-month-old eucalyptus), compared with full sun. In the year the ICLF system is established, the production efficiency of corn silage and grains is not affected by eucalyptus, but decreases with the development of the trees in the subsequent crop years.

To solve chipping of veneer porcelain in zirconia dental prosthesis it has been studied different cooling rates in firing schedules to control residual stresses generated by differences in thermal properties between the ceramics. However, cooling rates may affect the porcelain, irrespectively of interaction with zirconia. This study analyzed the effect of cooling rate on the three-point flexural strength (FS), residual stress, Vickers hardness (VH) and V-notch fracture toughness (SEVNB) on a feldspathic porcelain (Vita VM9) indicated for covering zirconia. Bar-shaped specimens were sintered according manufacturer's schedule firing and cooled at different rates (slow, normal or fast). Specimens were tested for FS (n=30), VH (n=15) and SEVNB tests (n=15). Weibull analysis were performed from FS values to measure reliability and probability of failure (PF). One-way ANOVA was significant for VH (p<0.001), and Tukey's test showed that slow cooling led to higher values. There was no significant difference for FS (p=0.654) and SEVNB (p=0.734). Fast cooling led to the lowest PF, but cooling rate factor was not significant for Weibull modulus. All cooling group showed residual tensile stress (MPa): Slow = 34.81; Normal = 27.04; Fast = 18,98. It was concluded that cooling rate produce minor changes in the porcelain properties.

Resumo O objetivo deste estudo foi verificar o perfil somatotípico e a composição corporal de atletas da seleção brasileira de futebol de 5. Participaram 23 atletas do sexo masculino. Todos foram submetidos à avaliação antropométrica e em seguida foram feitos os cálculos de índice de massa corporal (IMC), percentual de gordura corporal (%GC), somatório de pregas cutâneas (Σ9DC) e somatotipo. Observou-se que apenas os goleiros apresentaram diferença significativa (p ≤ 0,05) nas variáveis de IMC, %GC e Σ9DC em relação às outras posições. Os goleiros apresentaram perfil endomorfo-mesomorfo, os fixos mesomorfo-equilibrado e os alas e pivôs, endo-mesomorfo. Concluímos que os goleiros apresentam diferença significativa de %GC quando comparados com as outras posições e apresentaram diferenças somatotipológicas significativas em relação às outras posições. O mesmo foi observado na posição fixo quando comparados com os pivôs.

Abstract The aim of this study was to determine the profiles somatotype and body composition of athletes of Brazilian 5-a-side football team. This study involved 23 male athletes. Were all submitted to anthropometric measurements and then were carried the calculations of body mass index (BMI), body fat percentage (BF%), Skinfolds sum (Σ9DC) and somatotype. It was observed that goalkeepers differ significantly (p ≤ 0.05) in body mass, BF% and Σ9DC for other positions. The goalkeepers showed profile endomorph-mesomorph, the defender mesomorph- balanced, while the winger and pivot, endo-mesomorph. Concluded that the goalkeepers were significant differences in BF% when compared to other positions and showed significant differences in somatotype compared to other positions, the same was observed in defenders when compared with pivots.

Resumen El objetivo del estudio fue determinar los perfiles somatotípicos y la composición corporal de los atletas de la selección brasileña de fútbol 5. Participaron en el estudio 23 atletas masculinos. Todos pasaron mediciones antropométricas y después se realizaron los cálculos del índice de masa corporal (IMC), porcentaje de grasa corporal (%GC), la suma de pliegues cutáneos (Σ9DC) y somatotipo. Los porteros difieren (p ≤ 0,05) en la MC, %BF y Σ9DC con relación a otras posiciones. Los porteros mostraron perfil mesomorfo-endomorfo, los defensas mostraron un perfil mesomorfo-equilibrado y laterales y pivotes, endomorfo-mesomorfo. Llegamos a la conclusión de que en los porteros se encontraron diferencias significativas en el %GC en comparación con otras posiciones y mostraron diferencias significativas en el somatotipo de otras posiciones. Lo mismo se observó en una posición fija en comparación con los pivotes.

RESUMO As florestas ciliares e de galeria localizadas no “arco do desmatamento”, vêm sofrendo degradação acelerada e, com a implantação do novo Código Florestal Brasileiro (Lei nº 12.651 de 2012), essas poderão ser reduzidas ainda mais. Diante desse fato, novos estudos acerca da produção de mudas para recuperação de áreas degradadas devem ser realizados com espécies nativas do domínio Amazônico e também do Cerrado. Por conseguinte, o objetivo do presente trabalho foi verificar em quais níveis de sombreamento, mudas de Calophyllum brasiliense, espécie típica de ambientes úmidos, apresentam os valores mais adequados de crescimento e eficiência de uso interno de nutrientes, visando a recomposição de áreas perturbadas. O estudo foi desenvolvido em viveiro florestal da UNEMAT de Nova Xavantina-MT. Avaliamos o crescimento das mudas em diâmetro, altura, número de folhas, produção de massa seca aérea e radicular, Índice de Qualidade de Dickson (DQI) e a Eficiência no Uso Interno de Nutrientes (EIUN) em casas de vegetação a 0 (pleno sol), 30, 50, 70 e 90% de sombreamento. De forma geral, os melhores resultados foram obtidos nos sombreamentos a 50 e 70%. Ecologicamente, a espécie responde melhor tanto em condições de clareira (50% de sombreamento) quanto em condições de dossel ou fechamento de clareira (70%). Nossos resultados demonstraram que as condições ideais para a produção de mudas desta espécie e maior EIUN, podem ser obtidas em condições de viveiro com 70% de sombreamento.

ABSTRACT Riparian and gallery forests located at the “arc of deforestation” have been undergoing fast degradation. With the implementation of the new Brazilian Forest Code (Law 12,651 of 2012), these can be reduced further. Thus, new studies on seedling production for ecological restoration should be carried out using native species from the Amazon and Cerrado. The objective of the present study was to assess under which shading levels the seedlings of Calophyllum brasiliense, a tree species typical of humid environments, show the highest values of growth and nutrient use efficiency, aiming at using these seedlings for restoration. The study was carried out in a plant nursery of the State University of Mato Grosso in Nova Xavantina, Brazil. We assessed seedling growth in diameter, height, number of leaves, production of shoot and root dry mass, Dickson quality index (DQI), and efficiency in the internal use of nutrients (EIUN) in greenhouses at 0 (full sunlight), 30, 50, 70, and 90% shading. The treatments at 50 and 70% shading showed the best results. Ecologically, the species responds well under both gap conditions (50% shading) and canopy or closing gap conditions (70% shading). Our results showed that the ideal conditions to produce seedlings of this species with high EIUN are obtained in greenhouses with 70% shading.

RESUMO Introdução: Nas últimas décadas, a incidência de obesidade na população pediátrica vem aumentando, juntamente com a inatividade física. A obesidade e a inatividade física são componentes predisponentes para o agravo dos fatores de risco metabólico, sendo de fundamental importância seu tratamento visando melhora da saúde dos jovens. Objetivo: Verificar o efeito de 12 semanas de uma intervenção focada na atividade física sobre os fatores de risco metabólico em crianças obesas. Métodos: A amostra final foi composta por 19 escolares com idade entre oito e 10 anos (10 no grupo pedômetro e nove no grupo controle). A atividade física foi mensurada e orientada por meio do pedômetro Yamax(r) sw 700 (Tóquio, Honchu, Japão). Para comparações intra e entre grupos foi aplicado a ANOVA two way para medidas repetidas com significância estipulada em p < 0,05. Resultados: O número de passos aumentou significativamente somente no grupo pedômetro após as 12 semanas de intervenção (pré 9729,7 ± 2539,8 vs. pós 13151,6 ± 3581,7). Foi observado aumento significativo do peso corporal, da estatura e do IMC no grupo controle. No grupo pedômetro, observou-se aumento significativo apenas na estatura. Com relação aos fatores de risco metabólicos, não foi encontrada mudança significativa no grupo controle, enquanto no grupo pedômetro foi observada diminuição significante nos valores de insulina (pré 12,21 ± 8,53 vs. pós 7,26 ± 4,70 µUI/ml) e HOMA IR (pré 2,76 ± 1,93 vs. pós 1,49 ± 0,93). Conclusão: A presente intervenção com atividade física a partir do estabelecimento de metas utilizando pedômetros reduziu significativamente as concentrações de insulina e o índice de homeostase (HOMA IR) em crianças obesas, independentemente da perda de peso.

ABSTRACT Introduction: In recent decades, the incidence of obesity in children is increasing along with physical inactivity. Obesity and physical inactivity are predisposing components to the worsening of metabolic risk factors and treatment is fundamental aiming at improving the health of young people. Objective: To verify the effect of 12 weeks of an intervention focused on physical activity on metabolic risk factors in obese children. Methods: The final sample consisted of 19 students aged between 8 and 10 years (10 in the pedometer group and nine in the control group). Physical activity was measured and guided by the Yamax(r) sw 700 pedometer (Tokyo, Honshu, Japan). For within and between groups comparisons the two way ANOVA was applied for repeated measures with significance set at p<0.05. Results: The number of steps increased significantly only in the pedometer group after the 12-week intervention (9729.7±2539.8 before vs. 13151.6±3581.7 after). Significant increase was observed in body weight, height, and BMI in the control group. In the pedometer group, it was observed significant increase only in stature. Regarding the metabolic risk factors, there was no significant change found in the control group, while in the pedometer group a significant decrease in insulin levels was observed (12.21±8.53 before vs. 7.26±4.70 µUI/ml after) and HOMA IR (2.76±1.93 before vs. 1.49±0.93 after). Conclusion: This intervention with physical activity from setting goals using pedometers significantly reduced the concentrations of insulin and the homeostasis index (HOMA IR) in obese children regardless of weight loss.

RESUMEN Introducción: En las últimas décadas, la incidencia de la obesidad en los niños es cada vez mayor, junto con la inactividad física. La obesidad y la inactividad física son componentes que predisponen al empeoramiento de los factores de riesgo metabólico, siendo de fundamental importancia el tratamiento destinado a mejorar la salud de los jóvenes. Objetivo: Comprobar el efecto de 12 semanas de una intervención centrada en la actividad física sobre los factores de riesgo metabólico en los niños obesos. Métodos: La muestra final fue de 19 estudiantes de edades comprendidas entre ocho y 10 años (10 en el grupo podómetro y nueve en el grupo de control). La actividad física se midió y fue guiada por el podómetro Yamax(r) sw 700 (Tokio, Honchu, Japón). Para las comparaciones dentro y entre grupos se aplicó la ANOVA de dos vías para medidas repetidas, con una significación establecida en p < 0,05. Resultados: El número de pasos aumentó significativamente sólo en el grupo podómetro después de 12 semanas de intervención (pre 9729,7 ± 2539,8 vs. post 13151,6 ± 3581,7). Se observó un aumento significativo en el peso corporal, la estatura y el IMC en el grupo control. En el grupo podómetro, hubo un aumento significativo sólo en estatura. En cuanto a los factores de riesgo metabólico, no hubo ningún cambio significativo en el grupo control, mientras que en el grupo podómetro se observó disminución significativa de los valores de insulina (pre 12,21 ± 8,53 vs. post 7,26 ± 4,70 µUI/ml) y HOMA IR (pre 2,76 ± 1,93 vs. post 1,49 ± 0,93). Conclusión: Esta intervención con actividad física a partir del establecimiento de metas utilizando podómetros redujo significativamente las concentraciones de insulina y el índice de la homeostasis (HOMA-IR) en niños obesos, independientemente de la pérdida de peso.