Background:Evidence on correlates relies on subjective metrics and fails to include correlates across all levels of the ecologic model.We determined which correlates best predict sensor-based physical activity(PA),sed...Background:Evidence on correlates relies on subjective metrics and fails to include correlates across all levels of the ecologic model.We determined which correlates best predict sensor-based physical activity(PA),sedentary time(ST),and self-reported cell phone screen time(CST)in a large sample of youth,while considering a multiplicity of correlates.Methods:Using sensor-based accelerometry,we assessed the PA and ST of 2179 youths.A χ^2 automatic interaction detection algorithm was used to hierarchize the correlates associated with too much ST(>50th percentile),insufficient moderate-to-vigorous PA(MVPA)(<60 min/day),and prolonged CST(≥2 h/day).Results:Among youth 10-14 years old,the correlates for being inactive consisted of being a girl,not having sport facilities in the neighborhood,and not perceiving the neighborhood as a safe place,whereas in the youth 15-18 years old,the correlate for being inactive was not performing sports(9.7%chance of being active).The correlates for predicting high ST in the younger group was not performing sports(55.8%chance for high ST),and in the older group,the correlates were not owning a pet,perceiving the neighborhood as safe,and having inactive parents(63.7%chance for high ST).In the younger group,the greatest chances of having high CST were among those who were in the last elementary school years,who were girls,and who did not have friends in the neighborhood(73.1%chance for high CST),whereas in the older group,the greatest chance for having high CST was among those who were girls and had a TV in the bedroom(74.3%chance for high CST).Conclusion:To counteract ST and boost MVPA among youths,a specific focus on girls,the promotion of sport participation and facilities,neighborhood safety,and involvement of family must be prioritized.展开更多
Background: Motor competence and health-related fitness are important components for the development and maintenance of a healthy lifestyle in children. This study examined cross-cultural performances on motor compete...Background: Motor competence and health-related fitness are important components for the development and maintenance of a healthy lifestyle in children. This study examined cross-cultural performances on motor competence and health-related fitness between Portuguese and U.S.children.Methods: Portuguese(n = 508; 10.14 § 2.13 years, mean § SD) and U.S.(n = 710; 9.48 § 1.62 years) children performed tests of cardiorespiratory fitness(Progressive Aerobic Cardiovascular Endurance Run), upper body strength(handgrip), locomotor skill performance(standing long jump), and object projection skill performance(throwing and kicking). Portuguese and U.S. children were divided into 2 age groups(6à9 and 10à13 years) for data analysis purposes. A twoàfactor oneàway analysis of covariance(ANOVA) was conducted with the Progressive Aerobic Cardiovascular Endurance Run, handgrip, standing long jump scores, kicking, and throwing speed(km/h) as dependent variables.Results: Results indicated that Portuguese children, irrespective of sex, presented better performances in locomotor and cardiorespiratory performance(standing long jump and Progressive Aerobic Cardiovascular Endurance Run) than U.S. children in both age bands. U.S. children outperformed Portuguese children during throwing and handgrip tests. Kicking tests presented gender differences: Portuguese boys and U.S. girls outperformed their internationally matched counterparts.Conclusion: Cultural differences in physical education curricula and sports participation may impact differences in motor competence and fitness development in these countries.展开更多
Background:Recently,Mullen et al.(2011)presented an 8-item version of the Physical Activity Enjoyment Scale(PACES)that provides a valid instrument for assessing enjoyment in physical activity.The present paper investi...Background:Recently,Mullen et al.(2011)presented an 8-item version of the Physical Activity Enjoyment Scale(PACES)that provides a valid instrument for assessing enjoyment in physical activity.The present paper investigated the psychometric properties of a Portuguese adaptation of PACES.Methods:After a process of back-to-back translation into Portuguese,395 members of fitness centers who ranged in age from 18 to 66 years(31.11§8.90,mean§SD)completed the translated version of the PACES.On average,participants had 3.2 years of experience in fitness group classes and practiced for approximately 3.3 times per week.Results:An initial exploratory factor analysis(n=139)revealed a unidimensional structure with factor loadings ranging from 0.79 to 0.89.Results also showed acceptable internal consistency.A confirmatory factor analysis in an independent sample(n=256)provided additional support for the unidimensional structure of the questionnaire.In addition,moderate positive correlations between enjoyment and intrinsic and identified regulation,and moderate negative correlations between enjoyment and external and amotivation,demonstrate the convergent validity of the instrument.Finally,measurement invariance between 2 independent samples was also found.Conclusion:The 8-item Portuguese version of PACES is a valid and reliable instrument for measuring enjoyment of physical activity in Portuguese adult fitness exercisers,and it is therefore suitable to use as a measure of affect in exercise adherence interventions studies.展开更多
Bone is known to have a natural function to heal itself.However,if the bone damage is beyond a critical degree,intervention such as bone grafting may be imperative.In this work,the fabrication of a novel bone scaffold...Bone is known to have a natural function to heal itself.However,if the bone damage is beyond a critical degree,intervention such as bone grafting may be imperative.In this work,the fabrication of a novel bone scaffold composed of natural bone components and polycaprolactone(PCL)using 3D printing is put forward.α1,3-galactosyltransferase deficient pigs were used as the donor source of a xenograft.Decellularized porcine bone(DCB)with attenuated immunogenicity was used as the natural component of the scaffold with the aim to promote bone regeneration.The 3D printed DCB-PCL scaffolds combined essential advantages such as uniformity of the interconnected macropores and high porosity and enhanced compressive strength.The biological properties of the DCB-PCL scaffolds were evaluated by studying cell adhesion,viability,alkaline phosphatase activity and osteogenic gene expression of human bone marrow-derived mesenchymal stem cells.The in vitro results demonstrated that the DCB-PCL scaffolds exhibit an enhanced performance in promoting bone differentiation,which is correlated to the DCB content.Furthermore,critical-sized cranial rat defects were used to assess the effect of DCB-PCL scaffolds on bone regeneration in vivo.The results confirm that in comparison with PCL scaffolds,the DCB-PCL scaffolds can significantly improve new bone formation in cranial defects.Thus,the proposed 3D printed DCB-PCL scaffolds emerge as a promising regeneration alternative in the clinical treatment of large bone defects.展开更多
AIM: To study the therapeutic effect of three tubeguides with electrical conductivity associated to mesenchymal stem cells(MSCs) on neuro-muscular regeneration after neurotmesis.METHODS: Rats with 10-mm gap nerve inju...AIM: To study the therapeutic effect of three tubeguides with electrical conductivity associated to mesenchymal stem cells(MSCs) on neuro-muscular regeneration after neurotmesis.METHODS: Rats with 10-mm gap nerve injury were tested using polyvinyl alcohol(PVA), PVA-carbon nanotubes(CNTs) and MSCs, and PVA-polypyrrole(PPy). The regenerated nerves and tibialis anterior muscles were processed for stereological studies after 20 wk. The functional recovery was assessed serially for gait biomechanical analysis, by extensor postural thrust, sciatic functional index and static sciatic functionalindex(SSI), and by withdrawal reflex latency(WRL). In vitro studies included cytocompatibility, flow cytometry, reverse transcriptase polymerase chain reaction and karyotype analysis of the MSCs. Histopathology of lung, liver, kidneys, and regional lymph nodes ensured the biomaterials biocompatibility. RESULTS: SSI remained negative throughout and independently from treatment. Differences between treted groups in the severity of changes in WRL existed, showing a faster regeneration for PVA-CNTs-MSCs(P < 0.05). At toe-off, less acute ankle joint angles were seen for PVA-CNTs-MSCs group(P = 0.051) suggesting improved ankle muscles function during the push off phase of the gait cycle. In PVA-PPy and PVA-CNTs groups, there was a 25% and 42% increase of average fiber area and a 13% and 21% increase of the "minimal Feret's diameter" respectively. Stereological analysis disclosed a significantly(P < 0.05) increased myelin thickness(M), ratio myelin thickness/axon diameter(M/d) and ratio axon diameter/fiber diameter(d/D; g-ratio) in PVA-CNT-MSCs group(P < 0.05). CONCLUSION: Results revealed that treatment with MSCs and PVA-CNTs tube-guides induced better nerve fiber regeneration. Functional and kinematics analysis revealed positive synergistic effects brought by MSCs and PVA-CNTs. The PVA-CNTs and PVA-PPy are promising scaffolds with electric conductive properties, bio- and cytocompatible that might prevent the secondary neurogenic muscular atrophy by improving the reestablishment of the neuro-muscular junction.展开更多
Quantitative analysis is increasingly being used in team sports to better understand performance in these stylized,delineated,complex social systems.Here,the authors provide a first step toward understanding the patte...Quantitative analysis is increasingly being used in team sports to better understand performance in these stylized,delineated,complex social systems.Here,the authors provide a first step toward understanding the pattern-forming dynamics that emerge from collective offensive and defensive behavior in team sports.The authors propose a novel method of analysis that captures how teams occupy sub-areas of the field as the ball changes location.The authors use this method to analyze a game of association football(soccer) based upon a hypothesis that local player numerical dominance is key to defensive stability and offensive opportunity.The authors find that the teams consistently allocated more players than their opponents in sub-areas of play closer to their own goal.This is consistent with a predominantly defensive strategy intended to prevent yielding even a single goal.The authors also find differences between the two teams' strategies:while both adopted the same distribution of defensive,midfield,and attacking players(a 4:3:3 system of play),one team was significantly more effective in maintaining both defensive and offensive numerical dominance for defensive stability and offensive opportunity.That team indeed won the match with an advantage of one goal(2 to 1) but the analysis shows the advantage in play was more pervasive than the single goal victory would indicate.The proposed focus on the local dynamics of team collective behavior is distinct from the traditional focus on individual player capability.It supports a broader view in which specific player abilities contribute within the context of the dynamics of multiplayer team coordination and coaching strategy.By applying this complex system analysis to association football,the authors can understand how players' and teams' strategies result in successful and unsuccessful relationships between teammates and opponents in the area of play.展开更多
基金conducted at the Interdisciplinary Center of the Study of Human Performance (CIPER),I&D 472 (UID/DTP/00447/2019)supported by the Portuguese Foundation for Science and Technology+1 种基金the Portuguese Ministry of Science.PBJ is supported by the Portuguese Foundation for Science and Technology (SFRH/BPD/115977/2016)supported by a grant from Comite Olimpico de Portugal (doctoral scholarship-COP)
文摘Background:Evidence on correlates relies on subjective metrics and fails to include correlates across all levels of the ecologic model.We determined which correlates best predict sensor-based physical activity(PA),sedentary time(ST),and self-reported cell phone screen time(CST)in a large sample of youth,while considering a multiplicity of correlates.Methods:Using sensor-based accelerometry,we assessed the PA and ST of 2179 youths.A χ^2 automatic interaction detection algorithm was used to hierarchize the correlates associated with too much ST(>50th percentile),insufficient moderate-to-vigorous PA(MVPA)(<60 min/day),and prolonged CST(≥2 h/day).Results:Among youth 10-14 years old,the correlates for being inactive consisted of being a girl,not having sport facilities in the neighborhood,and not perceiving the neighborhood as a safe place,whereas in the youth 15-18 years old,the correlate for being inactive was not performing sports(9.7%chance of being active).The correlates for predicting high ST in the younger group was not performing sports(55.8%chance for high ST),and in the older group,the correlates were not owning a pet,perceiving the neighborhood as safe,and having inactive parents(63.7%chance for high ST).In the younger group,the greatest chances of having high CST were among those who were in the last elementary school years,who were girls,and who did not have friends in the neighborhood(73.1%chance for high CST),whereas in the older group,the greatest chance for having high CST was among those who were girls and had a TV in the bedroom(74.3%chance for high CST).Conclusion:To counteract ST and boost MVPA among youths,a specific focus on girls,the promotion of sport participation and facilities,neighborhood safety,and involvement of family must be prioritized.
基金supported by grants from the National Institutes of Health (1R15HD071514-01A1 and R21HD05562101A2)the National Association for Sport and Physical Education Research Grant Program
文摘Background: Motor competence and health-related fitness are important components for the development and maintenance of a healthy lifestyle in children. This study examined cross-cultural performances on motor competence and health-related fitness between Portuguese and U.S.children.Methods: Portuguese(n = 508; 10.14 § 2.13 years, mean § SD) and U.S.(n = 710; 9.48 § 1.62 years) children performed tests of cardiorespiratory fitness(Progressive Aerobic Cardiovascular Endurance Run), upper body strength(handgrip), locomotor skill performance(standing long jump), and object projection skill performance(throwing and kicking). Portuguese and U.S. children were divided into 2 age groups(6à9 and 10à13 years) for data analysis purposes. A twoàfactor oneàway analysis of covariance(ANOVA) was conducted with the Progressive Aerobic Cardiovascular Endurance Run, handgrip, standing long jump scores, kicking, and throwing speed(km/h) as dependent variables.Results: Results indicated that Portuguese children, irrespective of sex, presented better performances in locomotor and cardiorespiratory performance(standing long jump and Progressive Aerobic Cardiovascular Endurance Run) than U.S. children in both age bands. U.S. children outperformed Portuguese children during throwing and handgrip tests. Kicking tests presented gender differences: Portuguese boys and U.S. girls outperformed their internationally matched counterparts.Conclusion: Cultural differences in physical education curricula and sports participation may impact differences in motor competence and fitness development in these countries.
文摘Background:Recently,Mullen et al.(2011)presented an 8-item version of the Physical Activity Enjoyment Scale(PACES)that provides a valid instrument for assessing enjoyment in physical activity.The present paper investigated the psychometric properties of a Portuguese adaptation of PACES.Methods:After a process of back-to-back translation into Portuguese,395 members of fitness centers who ranged in age from 18 to 66 years(31.11§8.90,mean§SD)completed the translated version of the PACES.On average,participants had 3.2 years of experience in fitness group classes and practiced for approximately 3.3 times per week.Results:An initial exploratory factor analysis(n=139)revealed a unidimensional structure with factor loadings ranging from 0.79 to 0.89.Results also showed acceptable internal consistency.A confirmatory factor analysis in an independent sample(n=256)provided additional support for the unidimensional structure of the questionnaire.In addition,moderate positive correlations between enjoyment and intrinsic and identified regulation,and moderate negative correlations between enjoyment and external and amotivation,demonstrate the convergent validity of the instrument.Finally,measurement invariance between 2 independent samples was also found.Conclusion:The 8-item Portuguese version of PACES is a valid and reliable instrument for measuring enjoyment of physical activity in Portuguese adult fitness exercisers,and it is therefore suitable to use as a measure of affect in exercise adherence interventions studies.
基金the financial support from National Natural Science Foundation of China(81601626)Zhejiang Provincial Natural Science of Foundation of China(Y20C070010)+1 种基金start-up funding from Wenzhou Institute,University of Chinese Academy of Sciences(WIUCASQD2019002)Singapore MOE Tier 1 Grant RG46/18.
文摘Bone is known to have a natural function to heal itself.However,if the bone damage is beyond a critical degree,intervention such as bone grafting may be imperative.In this work,the fabrication of a novel bone scaffold composed of natural bone components and polycaprolactone(PCL)using 3D printing is put forward.α1,3-galactosyltransferase deficient pigs were used as the donor source of a xenograft.Decellularized porcine bone(DCB)with attenuated immunogenicity was used as the natural component of the scaffold with the aim to promote bone regeneration.The 3D printed DCB-PCL scaffolds combined essential advantages such as uniformity of the interconnected macropores and high porosity and enhanced compressive strength.The biological properties of the DCB-PCL scaffolds were evaluated by studying cell adhesion,viability,alkaline phosphatase activity and osteogenic gene expression of human bone marrow-derived mesenchymal stem cells.The in vitro results demonstrated that the DCB-PCL scaffolds exhibit an enhanced performance in promoting bone differentiation,which is correlated to the DCB content.Furthermore,critical-sized cranial rat defects were used to assess the effect of DCB-PCL scaffolds on bone regeneration in vivo.The results confirm that in comparison with PCL scaffolds,the DCB-PCL scaffolds can significantly improve new bone formation in cranial defects.Thus,the proposed 3D printed DCB-PCL scaffolds emerge as a promising regeneration alternative in the clinical treatment of large bone defects.
基金Supported by System of Incentives for Research and Technological development of QREN in the scope of project n°38853/2013-DEXGELERATION:"Solucoes avancadas de regeneracao ossea com base em hidrogeis de dextrin"the European Community FEDER fund through ON2-O Novo Norte-North Portugal Regional Operational Program 2007-2013+4 种基金Project n°34128-BEPIM II:"Microdispositivos biomédicos com capacidade osteointegrativa porμPIM"funded by Ad Ithe program COMPETE-Programa Operacional Factores de Competitividade,projects Pest-OE/AGR/UI0211/2011PTDC/CVT/103081/2008CDRsp’s Strategic Project-UI-4044-2011-2012(Pest-OE/EME/UI4044/2011)funding from FCT
文摘AIM: To study the therapeutic effect of three tubeguides with electrical conductivity associated to mesenchymal stem cells(MSCs) on neuro-muscular regeneration after neurotmesis.METHODS: Rats with 10-mm gap nerve injury were tested using polyvinyl alcohol(PVA), PVA-carbon nanotubes(CNTs) and MSCs, and PVA-polypyrrole(PPy). The regenerated nerves and tibialis anterior muscles were processed for stereological studies after 20 wk. The functional recovery was assessed serially for gait biomechanical analysis, by extensor postural thrust, sciatic functional index and static sciatic functionalindex(SSI), and by withdrawal reflex latency(WRL). In vitro studies included cytocompatibility, flow cytometry, reverse transcriptase polymerase chain reaction and karyotype analysis of the MSCs. Histopathology of lung, liver, kidneys, and regional lymph nodes ensured the biomaterials biocompatibility. RESULTS: SSI remained negative throughout and independently from treatment. Differences between treted groups in the severity of changes in WRL existed, showing a faster regeneration for PVA-CNTs-MSCs(P < 0.05). At toe-off, less acute ankle joint angles were seen for PVA-CNTs-MSCs group(P = 0.051) suggesting improved ankle muscles function during the push off phase of the gait cycle. In PVA-PPy and PVA-CNTs groups, there was a 25% and 42% increase of average fiber area and a 13% and 21% increase of the "minimal Feret's diameter" respectively. Stereological analysis disclosed a significantly(P < 0.05) increased myelin thickness(M), ratio myelin thickness/axon diameter(M/d) and ratio axon diameter/fiber diameter(d/D; g-ratio) in PVA-CNT-MSCs group(P < 0.05). CONCLUSION: Results revealed that treatment with MSCs and PVA-CNTs tube-guides induced better nerve fiber regeneration. Functional and kinematics analysis revealed positive synergistic effects brought by MSCs and PVA-CNTs. The PVA-CNTs and PVA-PPy are promising scaffolds with electric conductive properties, bio- and cytocompatible that might prevent the secondary neurogenic muscular atrophy by improving the reestablishment of the neuro-muscular junction.
基金supported by the Portuguese Foundation for Science and Technology(SFRH/BD/43251/2008)
文摘Quantitative analysis is increasingly being used in team sports to better understand performance in these stylized,delineated,complex social systems.Here,the authors provide a first step toward understanding the pattern-forming dynamics that emerge from collective offensive and defensive behavior in team sports.The authors propose a novel method of analysis that captures how teams occupy sub-areas of the field as the ball changes location.The authors use this method to analyze a game of association football(soccer) based upon a hypothesis that local player numerical dominance is key to defensive stability and offensive opportunity.The authors find that the teams consistently allocated more players than their opponents in sub-areas of play closer to their own goal.This is consistent with a predominantly defensive strategy intended to prevent yielding even a single goal.The authors also find differences between the two teams' strategies:while both adopted the same distribution of defensive,midfield,and attacking players(a 4:3:3 system of play),one team was significantly more effective in maintaining both defensive and offensive numerical dominance for defensive stability and offensive opportunity.That team indeed won the match with an advantage of one goal(2 to 1) but the analysis shows the advantage in play was more pervasive than the single goal victory would indicate.The proposed focus on the local dynamics of team collective behavior is distinct from the traditional focus on individual player capability.It supports a broader view in which specific player abilities contribute within the context of the dynamics of multiplayer team coordination and coaching strategy.By applying this complex system analysis to association football,the authors can understand how players' and teams' strategies result in successful and unsuccessful relationships between teammates and opponents in the area of play.
