Adolescents' Flexibility Can Affect Motor Competence: The Pathway from Health Related Physical Fitness to Motor Competence.

Motor competence has been shown to predict health-related physical fitness (HRPF) components in youth, but there is indeterminate evidence for the reverse path. Even less is known about the specific relationship between motor competence and flexibility. Our aims in this study were to analyze the relationship between flexibility and motor competence among adolescents; and, secondarily, to examine the relationships between motor competence and other HRPF components (body composition and musculoskeletal fitness). We conducted a longitudinal study (14-months follow-up) with two measurement points of 128 participants (55.5% girls; 45% boys) aged 12-13 years at baseline. We assessed HRPF components at the first time point and determined motor competence at the second time point. We assessed HRPF in terms of body composition (body fat percentage), musculoskeletal fitness (sit-up test), and flexibility (sit and reach). We determined motor competence using the Körperkoordinationstest für Kinder (KTK). We employed multivariate analyses of variance (MANOVA) to examine the effect of HRPF on motor competence through three models, in which each HRPF component was considered an independent variable. Sex, age, physical activity, and body mass index (BMI) z-scores were considered confounders. In our crude models all HRPF components significantly affected motor competence. In adjusted models, flexibility (p = .002) and body composition (p < .001) significantly affected motor competence. Overall, these results supported the assumptions that HRPF components are related to motor competence in adolescence, and that flexibility can affect motor competence in young people.

Association of handgrip strength with anthropometry of a Brazilian healthy adolescent sample.

The importance of dynamometric and anthropometric information for industry is known; however, few studies have investigated the relationship between anthropometry and handgrip strength (HGS) in adolescents. The aim of the present study was to investigate the association of anthropometric variables with the level of HGS production in adolescents. Participants were 541 adolescents aged 12-16 years from a public school in the city of Rio de Janeiro. The behavior of the following variables was examined: the ability to generate HGS, age, total body mass, height and hand dimensions (hand width, hand span, hand length). The results showed an increase in the ability to generate HGS in adolescence and a significant difference between the genders from 13 years old, where boys generated higher HGS values. Correlations between HGS and total body mass and the hand width stood out in both genders, indicating a greater association.

Exploring the Importance of Motor Competence for Behavioral and Health Outcomes in Youth.

In this study, we investigated the relationship between motor competence (MC) and behavioral and health outcomes in youth through its relationship to physical activity (PA) and body composition (in terms of body fat). To date, it is unclear whether these variables reciprocally influence each other over time. We assessed whether and how MC, PA and body composition influence each other across adolescence. In a longitudinal study with 14 months of follow-up, we recruited 166 adolescents aged 12-13 years. We recorded participants' self-reported PA and body fat percentage and assessed their MC using the Körperkoordinationstest für Kinder (KTK). We used linear mixed models and mediation analyses with crude and adjusted (age, sex, time point) models to examine associations among the selected variables across time. MC showed a bidirectional relationship with both PA (p < .001) and body fat (p < .001) in both crude and adjusted models. In addition, MC was a potential mediator (Sobel test = -3.18, p < .001) in the relation between body fat (as predictor) and PA (as outcome) in crude models, but no mediating effect was found in adjusted models. Thus, this study provided longitudinal evidence that MC and PA, as well as MC and body composition, can reciprocally influence each other across adolescence. We recommend the development of MC as a crucial strategy to increase PA engagement and to prevent obesity in youth.

Do Adolescents with Low Motor Competence Have Increased Risk for Overweight and Obesity?

Background: Adolescence is an important time for establishing behavioral patterns which favorably affect health, including weight status. Yet, the prevalence of adolescent overweight/obesity is high, and it is unknown whether low levels of motor competence are a risk factor. The purpose of this study was to assess whether adolescents with low motor competence are at increased risk of overweight/obesity. Methods: A total of 142 adolescents (47.2% boys) aged 12-14 years were recruited from Rio de Janeiro, Brazil. Motor competence level was assessed using the Körperkoordinationtest fur kinder (KTK) and classified in two categories: "low" and "adequate." BMI measures were used to classify weight status as "healthy" or "overweight/obese." The correlation between motor competence level and BMI was tested. A binary logistic regression model was executed adjusting for potential confounders (age, sex, and stature). Results: Motor competence was moderately associated with BMI (r = -0.573, p < 0.001). Nearly four in five adolescents with low motor competence were overweight/obese. Further, adolescents with low motor competence had a risk six times higher of being overweight/obese (odds ratio = 6.832, p < 0.001, 95% confidence interval = 2.477-18.845). Conclusions: This study showed that a low level of motor competence is linked to the odds of being overweight/obese in adolescents. This is a concern given the high prevalence of low motor competence in youth worldwide. However, our cross-sectional design does not allow the determination of causal mechanisms. Regardless, we reinforce the recommendation that young people should establish behavioral patterns favorable to adolescent health, including adequate levels of motor competence.

How Important is Motor Competence for Healthy Weight Status across Adolescence?

Background: Although evidence supports that motor competence is negatively associated with adiposity levels in children, less is known about how motor competence and weight status relate in adolescence. Adolescence is a critical period to study this relationship because the associations between these elements are expected to strengthen over developmental time. The aim of this study was to analyze the relationship between motor competence and weight status across adolescence. Methods: A longitudinal study (2-year follow-up) was conducted with 122 participants (59.8% girls) aged 12-13 years at baseline. They were assessed annually at three time points. Body fatness, motor competence, physical activity, and musculoskeletal fitness levels were determined through skinfold thickness, Körperkoordinationstest für Kinder (KTK), Physical Activity Questionnaire for Older Children (PAQ-C), and sit-up tests. Generalized Estimating Equation (GEE) models were conducted adjusting for potential confounders (age, gender, anthropometry, physical activity, and fitness). Results: Motor competence and body fat showed moderate-to-high negative correlations (r = -0.65 to -0.69, p < 0.001) across time. Furthermore, motor competence significantly predicted body fat over time (B = -0.05, p = 0.05), even after adjusting for potential confounders. Conclusions: There is a lot of emphasis in the literature on increasing physical activity to maintain a healthy weight status or to prevent unhealthy weight gain, but this study has highlighted the role of motor competence on these aspects across the critical period of adolescence. Therefore, it seems plausible to recommend initiatives that foster the development of motor competence in early adolescence with the aim to prevent obesity.

Gait analysis with videogrammetry can differentiate healthy elderly, mild cognitive impairment, and Alzheimer's disease: A cross-sectional study.

Gait parameters have been investigated as an additional tool for differential diagnosis in neurocognitive disorders, especially among healthy elderly (HE), those with mild cognitive impairment (MCI), and Alzheimer's disease (AD) patients. A videogrammetry system could be used as a low-cost and clinically practical equipment to capture and analyze gait in older adults. The aim of this study was to select the better gait parameter to differentiate these groups among different motor test conditions with videogrammetry analyses. Different motor conditions were used in three specific assessments: 10-meter walk test (10mWT), timed up and go test (TUGT), and treadmill walk test (TWT). These tasks were compared among HE (n=17), MCI (n=23), and AD (n=23) groups. One-way ANOVA, Kruskal-Wallis, and Bonferroni post-hoc tests were used to compare variables among groups. Then, an effect size (ES) and a linear regression analysis were calculated. The gait parameters showed significant differences among groups in all conditions, but not in TWT. Controlled by confounding variables, the gait velocity in 10mWT at usual speed, and TUGT in dual-task condition, predicts 39% and 53% of the difference among diagnoses, respectively. Finally, these results suggest that a low-cost and practical video analysis could be able to differentiate HE, those with MCI, and AD patients in clinical assessments.

Stages of mild cognitive impairment and Alzheimer's disease can be differentiated by declines in timed up and go test: A systematic review and meta-analysis.

Motor dysfunction increases in the moderate and severe stages of dementia. However, there is still no consensus on changes in mobility during its early stages. This meta-analysis aimed to measure the level of single-task functional mobility in older subjects with mild cognitive impairment (MCI) and/or Alzheimer's disease (AD). In a search of the PubMed, ISI Web of Knowledge, and Scopus databases, 2728 articles were identified. At the end of the selection, a total of 18 studies were included in the meta-analysis. Functional mobility was investigated using the timed up and go (TUG) test in all studies. When compared to healthy elderly (HE) adults, the following mean differences (MD) in seconds were found for the investigated subgroups: no amnestic MCI (MD = 0.26; CI95% = -0.77, 1.29), amnestic MCI (MD = 0.86; CI95% = -0.02, 1.73), very mild AD (MD = 1.32; CI95% = 0.63, 2.02), mild AD (MD = 2.43; CI95% = 1.84, 3.01), mild-moderate AD (MD = 3.01; CI95% = 2.47, 3.55), and mild-severe AD (MD = 4.51; CI95% = 1.14, 7.88); for the groups, the following MD were found: MCI (MD = 0.97; CI95% = 0.51, 1.44) and AD (MD = 2.66; CI95% = 2.16, 3.15). These results suggest a transition period in motor capacity between healthy aging and dementia, wherein functional mobility analysis in a single-task (TUG) can contribute to the diagnosis and staging of predementia states and AD.

Kinematic analysis of subtalar eversion during gait in women with fibromyalgia.

OBJECTIVE: To analyse the subtalar eversion range of motion during walking in women with fibromyalgia. METHOD: Twenty women diagnosed with fibromyalgia were directed to walk barefoot at comfortable and self-paced speed on a 7m walkway. Subtalar eversion range of motion was measured using the difference between the maximum and minimum values of subtalar eversion in stance phase. A range of motion between 4°-6° was considered as reference values for subtalar eversion during gait. Descriptive statistics were performed. RESULTS: In both right and left lower limb analysis of subtalar eversion range of motion, five women showed joint hypomobility, and twelve showed hypermobility. Only one patient performed unaltered subtalar eversion range of motion in both lower limbs. Both joints expressed high variability, and there were no significant differences between the right and left sides. CONCLUSIONS: The findings suggest that biomechanical function of the subtalar joint eversion during the loading response phase of gait in women with fibromyalgia, by excessive rigidity or complacency joint, tends to be impaired. This finding suggests that the indication of walking as an auxiliary strategy in the treatment of women with fibromyalgia should be preceded by thorough examination of the mechanical conditions of the subtalar joint of the patient.

Do Girls with Excess Adiposity Perform Poorer Motor Skills than Leaner Peers?

The main aim of this study was to analyze the joint association of body fat percentage and physical activity levels on motor coordination scores in girls with different adiposity status. Sixty-eight school-aged children between 12 and 14 years participated in the study. Skinfold thickness was measured and the Körperkoordinationstest für Kinder test was administered. Participants completed a self-reporting questionnaire on physical activity. Children's adiposity status was attributed in according to age-specific cutoff points of a Brazilian database. Analysis of Variance was used to compare motor coordination scores among groups with different status of adiposity and physical activity. Girls with appropriate body fat percentage performed higher motor coordination scores than girls with excess adiposity, regardless of their physical activity levels (p < 0.05). Additionally, within groups with the same adiposity status, no differences were found in motor coordination scores (p > 0.05). Adiposity status was predominant over physical activity status when joint associations of body fat percentage and physical activity levels on motor coordination scores were analyzed in girls. In addition to metabolic and cardiovascular issues, the acquisition and/or maintenance of appropriate body fat levels in female students should be focused in physical education classes due to its association with motor skills performance.

Análise da relação entre níveis de coordenação motora, aptidão física e desempenho acad~emico em crianças: implicações para a educação física na escola / Analysis of the relationship among levels of motor coordination, physical fitness, and academic achievement in children: implications for physical education in the school / Análisis de la relación entre los niveles de coordinación motora, habilidad física y rendimiento académico en niños: implicaciones para la educación física en la escuela

O objetivo do estudo foi analisar a relação entre os níveis de coordenação motora, força/resistência muscular e desempenho acadêmico em crianças. A amostra foi composta por 119 escolares com idade entre 12 e 14 anos sem registros de distúrbios de aprendizagem. Os níveis de coordenação, força/resistência muscular e desempenho acadêmico foram estimados utilizando-se, respectivamente, os testes KTK, sit-up e exames governamentais. Os resultados indicaram que os níveis de força/resistência muscular podem influenciar as associações entre coordenação e desempenho acadêmico, assim como os níveis de coordenação podem influenciar as associações entre força/resistência e desempenho acadêmico. As tendências de associações positivas entre as variáveis analisadas sugerem que a prática de atividades físicas nas escolas não deve ser preterida em detrimento do alcance de metas no desempenho acadêmico.

This study aimed to analyze the relationships among motor coordination, physical fitness, and academic achievement among children. The sample consisted of 119 students aged between 12 and 14 years old without medical certificate of learning disabilities. Motor coordination, physical fitness, and academic achievement were estimated through KTK, sit-up, and governmental tests respectively. Results suggest that muscular strength/endurance may influence the associations between coordination and academic achievement, as well as the coordination levels may influence the associations between muscular strength/endurance and academic achievement. The trends of positive associations among these variables suggest that engagement in physical activity should not be discouraged due to goals in academic achievement.

El objetivo de estudio fue analizar la relación entre los niveles de coordinación motora, fuerza/resistencia muscular y rendimiento académico en niños. La muestra se estuvo compuesta por 119 alumnos con edades comprendidas entre 12 y 14 años y sin registros de trastornos de aprendizaje. Los niveles de coordinación, fuerza/resistencia muscular y rendimiento académico fueron estimados usándose, respectivamente, KTK, sit-up, y las pruebas gubernamentales. Los resultados sugieren que los resultados de fuerza/resistencia muscular pueden influenciar las asociaciones entre coordinación y rendimiento académico, así como los niveles de la coordinación y desempeño pueden influenciar las asociaciones entre fuerza/resistencia y rendimiento académico. Las tendencias de las asociaciones positivas entre las variables sugieren que la práctica de actividades físicas en las escuelas no debe ser restringida en detrimiento del logro de los objetivos en el rendimiento académico.

Associations between motor coordination and BMI in normal weight and overweight/obese adolescents

INTRODUCTION: While evidence suggests that the levels of motor coordination and body mass index (BMI) are negatively correlated, little is known about the influence of levels of physical activity on associations between these variables among adolescents OBJECTIVE: To analyse the relationships between levels of motor coordination and BMI in normal weight and overweight/obese adolescents, controlling for physical activity levels METHODS: Fifty-six students (50% overweight/obese adolescents), aged 12-14 years old, participated in this study. The Physical Activity Questionnaire for Older Children and the Körperkoordinationstest für Kinder were used in order to assess the levels of physical activity and motor coordination, respectively. Bivariate and partial correlations were used to analyse the interrelationships among motor coordination, BMI and physical activity. The analysis of covariance test was used in order to compare the levels of motor coordination between normal weight and overweight/obeses adolescents, considering the physical activity level as a covariate RESULTS: Weak to moderate negative correlations (p < 0.05) were found between motor coordination and BMI in the sample as a whole, normal weight and overweight/obese groups. However, when controlled for physical activity levels. no significant correlation was observed in the normal weight group. Further, overweight/obese adolescents showed lower levels of motor coordination than their normal weight peers CONCLUSION: Physical activity levels influence the association between levels of motor coordination and BMI in normal weight adolescents, but not in their overweight/obese peers

INTRODUÇÃO: Enquanto evidências sugerem que níveis de coordenação motora e de índice de massa corporal (IMC) estão negativamente correlacionados, pouco se sabe sobre a influência dos níveis de atividade física na associação entre essas variáveis em adolescentes OBJETIVO: Analisar as associações entre os níveis de coordenação motora e o IMC em adolescentes com peso saudável e com sobrepeso/obesos, controlando pelos níveis de atividade física MÉTODO: Cinquenta e seis escolares (50% adolescentes com sobrepeso/obesos), entre 12 e 14 anos, participaram do estudo. Os instrumentos Physical Activity Questionnaire for Older Children e o Körperkoordinationstest für Kinder foram usados para avaliar os níveis de atividade física e de coordenação motora, respectivamente. Correlações bivariadas e parciais foram usadas para analisar o inter-relacionamento entre os níveis de coordenação motora, IMC e atividade física. O teste de Análise de Covariância foi utilizado para comparar os níveis de coordenação entre adolescentes com peso saudável e com sobrepeso/obesos, considerando o nível de atividade física como covariável RESULTADOS: Foram encontradas correlações significativamente negativas (p < 0,05), de fraca a moderada, entre IMC e níveis de coordenação no grupo como um todo, nos grupos com peso saudável e com sobrepeso/obesos. No entanto, quando controladas pelos níveis de atividade física, não foram observadas correlações significativas no grupo com peso saudável. Ademais, adolescentes com sobrepeso/obesos apresentaram menores níveis de coordenação motora que adolescentes com peso saudável CONCLUSÃO: Os níveis de atividade física influenciam a associação entre os níveis de coordenação motora e IMC em adolescentes com peso saudável, mas não em adolescentes com sobrepeso/obesos

Estudo de associação entre os níveis de coordenação motora, adiposidade e atividade física de crianças em idade escolar / Associations among motor coordination, body fatness, and physical activity levels in middle school children

Há um crescente conjunto de evidências que têm indicado associações significativas entre os níveis de coordenação motora e outros atributos relacionados à saúde, tais como os níveis de adiposidade corporal e atividade física. Entretanto, as associações entre os níveis de coordenação motora, adiposidade e atividade física têm sido analisadas de forma bivariada, sem considerar a influência recíproca que essas variáveis exercem entre si, o que pode ser a causa da produção de dados enviesados. Assim sendo, o objetivo geral do presente estudo foi analisar o inter-relacionamento entre os níveis de coordenação motora, adiposidade e atividade física de crianças entre 12 e 14 anos de idade. Cento e dezenove participantes (51 meninos e 68 meninas) foram recrutados. O questionário Physical Activity Questionnaire for Older Children, o teste de coordenação motora Kõrperkoordinationstest für Kinder e um plicômetro clínico foram utilizados para estimar, respectivamente, os níveis de atividade física, coordenação motora e adiposidade corporal dos participantes. Coeficientes de Correlação de Pearson foram usados para examinar as associações bivariadas entre níveis de atividade física e coordenação motora e entre níveis de adiposidade corporal e coordenação motora. Correlações parciais foram usadas para analisar as associações entre os níveis de atividade física e coordenação motora, controlando pelos níveis de adiposidade corporal, e entre os níveis de adiposidade corporal e coordenação motora, controlando pelos níveis de atividade física. O teste de Análise de Covariância Multivariada (MANCOVA) foi utilizado para testar diferenças entre os grupos formados de acordo com o status de adiposidade e atividade física com o intuito de examinar a influência combinada dessas variáveis sobre os níveis de coordenação motora...

There is a growing scope of evidences which has indicated significant associations between motor coordination scores and some health-related attributes, such as levels of adiposity and physical activity. However, the inter-relationships among motor coordination, body fat percentage, and physical activity levels have been examined through bivariate analyses, without considering reciprocal influences these variables exert themselves, which might be the cause of biased results. Therefore, the main aim of this study was to analyze the inter-relationships among motor coordination, body fat percentage, and physical activity levels in children between 12 and 14 years old. One hundred and nineteen children (51 boys and 68 girls) were recruited. The Physical Activity Questionnaire for Older Children, the Kõrperkoordinationstest für Kinder, and an clinical caliper were used in order to asses, respectively, levels of physical activity, motor coordination, and body fatness. Pearson correlations were used in order to assess the bivariate associations between levels of physical activity and motor coordination as well between body fat percentage and motor coordination. Partial correlations were used to analyze the associations between levels of physical activity and motor coordination, controlling for body fat percentage, as well between body fat percentage and motor coordination, controlling for physical activity levels. Multivariate Analysis of Covariance (MANCOVA) was used to test differences among groups formed in according to status of body fatness and physical activity in order to examine the combined influence these variables on motor coordination scores. In general, our results indicated that associations of motor coordination scores with bodt fat percentage and physical activity levels can be altered in according to covariates included into analyses in boys, but not in girls...

Influence of a preventive training program on lower limb kinematics and vertical jump height of male volleyball athletes.

OBJECTIVE: To examine the influence of a preventative training program (PTP) on sagittal plane kinematics during different landing tasks and vertical jump height (VJH) in males. DESIGN: Six weeks prospective exercise intervention. PARTICIPANTS: Fifteen male volleyball athletes (13 ± 0.7 years, 1.70 ± 0.12 m, 60 ± 12 kg). INTERVENTIONS: PTP consisting of plyometric, balance and core stability exercises three times per week for six weeks. Bilateral vertical jumps with double leg (DL) and single leg (SL) landings were performed to measure the effects of training. MAIN OUTCOME MEASUREMENTS: Kinematics of the knee and hip before and after training and VJH attained during both tasks after training. The hypothesis was that the PTP would produce improvements in VJH, but would not generate great changes in biomechanical behavior. RESULTS: The only change identified for the SL was the longest duration of landing, which represents the time spent from initial ground contact to maximum knee flexion, after training, while increased angular displacement of the knee was observed during DL. The training did not significantly alter the VJH in either the SL (difference: 2.7 cm) or the DL conditions (difference: 3.5 cm). CONCLUSIONS: Despite the PTP's effectiveness in inducing some changes in kinematics, the changes were specific for each task, which highlights the importance of the specificity and individuality in selecting prevention injury exercises. Despite the absence of significant increases in the VJH, the absolute differences after training showed increases corroborating with the findings of statistically powerful studies that compared the results with control groups. The results suggest that short-term PTPs in low risk young male volleyball athletes may enhance performance and induce changes in some kinematic parameters.

Ativação muscular do quadril e do joelho em duas aterrissagens realizadas por atletas do sexo masculino / Activation of hip and knee muscles during two landing tasks performed by male volleyball athletes

OBJETIVO: Comparar a atividade muscular antes e após o contato com o solo entre as aterrissagens unilateral (AU) e bilateral (AB) em atletas do sexo masculino. PARTICIPANTES: Quinze atletas masculinos de voleibol sem sinais e sintomas de lesões nas extremidades inferiores (13 ± 1 ano, 1,70 ± 0,12m, 60 ± 12kg). MENSURAÇÕES:Os participantes realizaram dois saltos verticais, aterrissando unilateralmente e bilateralmente. A atividade mioelétrica do reto femoral (RF), bíceps femoral (BF), adutores de quadril (AQ) e a relação BF/RF foram comparados entre as duas aterrissagens e entre as fases caracterizadas por 100ms antes (PRE) e 100ms após (POS) o contato com o solo. RESULTADOS: Em ambas as aterrissagens, a ativação do RF foi maior na fase POS em relação à PRE. Na comparação entre as aterrissagens dentro da mesma fase não encontramos diferenças estatísticas. Apesar de o BF não ter apresentado diferenças entre as fases PRE e POS em cada aterrissagem, sua ativação foi maior na AU. Os AQ apresentaram maior ativação na fase POS durante a AU, no entanto não houve diferenças quando comparadas as duas aterrissagens. A relação BF/RF apresentou valores maiores em ambas as aterrissagens na fase PRE. No entanto, não encontramos diferenças entre as aterrissagens. CONCLUSÃO: Os resultados sugerem que cada músculo apresenta um papel diferente durante a fase de aterrissagem em homens. Enquanto que o RF possui como principal função a frenagem da articulação do joelho e do movimento descendente, caracterizada pelo aumento da ativação na fase pós-contato, o BF parece atenuar a tensão articular do joelho em atividades de maior impacto, mantendo-se mais ativo durante todo o ciclo da AU. Já a maior ativação dos AQ após o contato com solo na AU evidencia a importância da região lombo-pélvica na estabilização pélvica em situações de grande instabilidade. Estudos futuros são necessários para determinar os efeitos da ativação muscular apresentada na imposição de cargas mecânicas potencialmente lesivas no joelho em atletas do sexo masculino.

OBJECTIVE: To compare the myoelectric activity before and after ground contact between single leg (SL) and double leg (DL) landings in male athletes. PARTICIPANTS: Fifteen male volleyball athletes without signs and symptoms of lesions in the lower extremities, with a minimum of three years experience in the sport (13 ± 1 years, 1.70 ± 0.12 m, 60 ± 12 kg). MEASUREMENTS: Participants performed two vertical jumps, landing unilaterally and bilaterally. The myoelectric activity of the rectus femoris (RF), biceps femoris (BF), hip adductors (HA) and the BF/RF ratio were compared between the two landings and between the phases characterized by 100ms before (PRE) and after 100 ms (POST) ground contact using ANOVA two-way test with post hoc test of Bonferroni (á = 5 percent). RESULTS: In both landings activation of RF was higher in the POST in relation to the PRE (p <0.0001). Comparing the landings in the same phase statistical differences (p = 0.2212) were not found. Although the BF did not present significant differences between the PRE and POST in each landing (p = 0.2321), its activation was higher in SL (p = 0.0051). The HA showed greater activation in the POST during the SL (p = 0.0013), however there were no differences when comparing the two landings (p = 0.9233). The BF/RF ratio was higher in both landings during PRE (p = 0.0012). Nevertheless, no differences between the landings (p = 0.7037) were found. CONCLUSION: The results suggest that each muscle has a different role during landing tasks in men. While RF has the main function to decelerate the knee and the downward movement, characterized by increased activation in the POST, BF seems to attenuate the loads on the knee in activities of higher impact, staying more active throughout the cycle in the SL. The increased activation of HA after ground contact in the SL highlights the importance of core region in stabilizing the pelvis in situations of great instability. Further studies are needed to determine the effects of muscle activation at the imposition of mechanical load on the knee that are potentially harmful to male athletes.

Diferenças na cinemática entre dois tipos de aterrissagens em atletas de voleibol masculinos / Difference in kinematical behavior between two landing tasks in male volleyball athletes

As lesões no ligamento cruzado anterior (LCA) são frequentes no âmbito esportivo. O estudo dos mecanismos de lesão demonstrou que a maioria das lesões é oriunda tanto de aterrissagens unilaterais quanto bilaterais. Apesar de estudos terem demonstrado diferenças no comportamento cinemático de membros inferiores entre homens e mulheres, não há evidências de como homens se comportam em diferentes condutas. O objetivo neste estudo foi comparar a cinemática angular e temporal dos membros inferiores, manifestaem aterrissagens de saltos com propulsão bilateral, realizadas sobre um e dois membros inferiores. Aterrissagens unilaterais e bilaterais no plano frontal e sagital de quinze atletas masculinos de voleibol foram registradas e processadas por meio de técnicas videogramétricas. Os resultados indicam que, na aterrissagem unilateral, os atletas apresentaram menor flexão do quadril e joelho, assim como maior valgismo do joelho, quando comparada coma aterrissagem bilateral. A diferença no tempo de aterrissagem entre as duas condutas não foi estatisticamente significante. Em conclusão, os resultados deste estudo apóiam a premissa de que a cinemática dos membros inferiores se altera em função da configuração da conduta motora realizada em homens. Estudos futuros são necessários para explorar o impacto das diferenças cinemáticas encontradas na tensão ligamentar e relacioná-las comos mecanismos de lesões no LCA em homens.

Anterior cruciate ligament (ACL) injuries are common in sports. Studies investigating injury mechanisms have demonstrated that most injuries arise from landing tasks. Despite the demonstration of differences between male and female kinematics, there are no studies showing how males behave during different landing tasks. The objective of this study was to compare theangular and temporal kinematics of the lower limbs between two different landing tasks. Double leg and single leg landings were recorded in the frontal and sagittal plane in 15 male volleyball athletes by videogrammetry. Reduced hip and knee flexion and increased knee valgus were observed in the single leg landing task compared to the double leg landing task. No significantdifference in landing time was observed between the two tasks. In conclusion, the results support the premise that lower limb kinematics change according to the task performed. Further studies are necessary to explore the impact of these kinematic differences on knee loading and to relatethem to ACL injury mechanisms in men.

Influence of hip external rotation on hip adductor and rectus femoris myoelectric activity during a dynamic parallel squat.

This study sought to compare the myoelectric activity of the hip adductors (HAs) and rectus femoris (RF) when the hip was in a neutral position or externally rotated by 30° or 50° (H0, H30, and H50, respectively) during a parallel squat. Ten healthy subjects performed 10 repetitions of squats in each of the 3 hip positions and the myoelectric activities of the HAs and RF were recorded. The signal was then divided into categories representing concentric (C) and eccentric (E) contractions in the following ranges of motion: 0-30° (C1 and E1), 30-60° (C2 and E2), and 60-90° (C3 and E3) of knee flexion. From those signals, an root mean square (RMS) value for each range of motion in each hip position was obtained. All values were normalized to those obtained during maximum voluntary isometric contraction. We found that HAs showed a significant increase in myoelectric activity during C3 and E3 in the H30 and H50 positions, as compared with H0. Meanwhile, RF activity did not significantly differ between hip positions. Both muscles showed higher activation during 60-90° (C3 and E3) of knee flexion, as compared with 0-30° (C1 and E1) and 30-60° (C2 and E2). The results suggest that if the aim is to increase HA activity despite the low percentage of muscle activation, squats should be performed with 30° of external rotation and at least 90° of knee flexion.