Kinematics and physiological parameters in maximal swimming tests in age-group swimmers / Cinemática y parámetros fisiológicos en pruebas de natación máxima en nadadores de grupos de edad

Objective: The aim of this study was compared and correlate kinematics and physiological parameters in four maximal swimming tests of two groups of young swimmers.Methods: Twelve swimmers, separated in two groups by age (percentile > 50th (n = 6): 15.4 ± 1.11 years old as group 1, and < 50th (n = 6): 12.1 ± 0.83 as group 2) performed four tests during two different sessions. . They performed front crawl trials at maximum intensity: 50 and 200 meters on first day and 100 and 400 m meters on second day. Anthropometric characteristics were measured. Stroke rate, stroke length, stroke index, swimming speed and critical speed were obtained by video analysis. Moreover, were measured the blood lactate concentration, heart rate and rate of perceived exertion.Results: There are no differences at anthropometric characteristics. We found difference between group 1 and group 2. Better results for performance, swimming speed, stroke length and stroke index in group 1. Swimming speed and stroke index show strong correlation in all tests for group 1 and in 50 and 100 meters for group 2. To measure the swimmer profile is essential to verify the benefits that the training program is or is not providing.Conclusion: The parameters evaluated seem related to age and capacities of the swimmers.(AU)

Electromyographical and Physiological Correlation in Patient with Heart Disease

Abstract Background: Walking is an economic activity, the more efficient the mechanical contribution, the less metabolic energy is necessary to keep walking. Patients with chronic heart failure and heart transplant present peripheral musculoskeletal disorders, dyspnea, and fatigue in their activities. Objective: In this scenario, the present study sought to verify the correlations between metabolic and electromyographic variables in chronic heart failure, heart transplant patients, and healthy controls. Methods: Regression and correlation between cost of transport and electromyographic cost, as well as correlation between oxygen consumption and muscle coactivation in patients and controls at five different walking speeds have been performed, with alpha = 0.05. Results: Strong correlation values (r controls: 0.99; chronic heart failure: 0.92; heart transplant: 0.88) indicate a linear relationship between the cost of transport and electromyographic cost. Oxygen consumption was significantly correlated to muscle activation in all groups. Conclusion: These results suggested that dynamic muscle coactivation was an important factor, especially for CHF and HT. These data support the idea that peripheral muscle limitations play an important role in people with CHF and HT. These findings indicate a strong relation between metabolic and electromyographic variables. For chronic heart failure and heart transplant patients, it can help to explain some difficulties in daily activities and aid in physical rehabilitation.

Medidas angulares de la columna vertebral de adultos mayores activos y sedentarios / Spine angular measurements from active and sedentary elderly people

Se considera que la actividad física regulada y sistematizada conlleva beneficios para la salud en diferentes ámbitos para el adulto mayor, ya sean: composición corporal, sistema cardiovascular, nivel metabólico y endócrino, fuerza muscular, huesos, articulaciones y flexibilidad. OBJETIVO: Evaluar y comparar los ángulos de la columna entre dos grupos de adultos mayores: activos y sedentarios, utilizando el método de flexicurva. MÉTODOS: Para este estudio participaron 30 adultos mayores, de los cuales se dividieron en dos grupos: 15 activos y 15 sedentarios (no presentaron diferencias cuanto a características antropométricas), entre 65 y 74 años. Para medir los ángulos de la columna vertebral (cervical, torácica y lumbar) se utiliza la flexicurva y el software Biomec Flex V.3.0. RESULTADOS: Se obtuvo como resultado una diferencia significativa entre grupos en la medida de la columna cervical, donde solo los adultos mayores activos presentan medidas dentro de los parámetros normales, y los sedentarios presentaron hiperlordosis cervical. Las medidas de la columna lumbar presentaron valores de rectificación de la curvatura para ambos grupos (de acuerdo con los valores de referencia de la literatura). CONCLUSIÓN: La curvatura de la columna cervical se mostró afectada en adultos mayores sedentarios del presente estudio, en comparación la curvatura de la columna de los adultos mayores activos. Además la rectificación de la curvatura de la columna lumbar y los cambios debido a esta postura deben ser considerados en la planificación de ejercicio físico en esta población

Regulated and systematized physical activity is considered to have health benefits in different areas for the older adult, like: body composition, cardiovascular system, metabolic and endocrine level, muscle strength, bones, joints and flexibility. Purpose. Evaluate and compare the spinal angles between two groups of elderly people: active and sedentary, using the flexicurve method. METHODS: Participated 30 elderly people, of which they were divided into two groups: 15 active and 15 sedentary (they did not present differences for anthropometric characteristics), between 65 and 74 years old. To measure the angles of the vertebral column (cervical, thoracic and lumbar) the flexicurve and the Biomec Flex software V.3.0 are used. RESULTS: Significant difference was obtained between groups in the measurement of the cervical spine, where only active older adults presented measurements within normal parameters, and sedentary older adults presented cervical hyperlordosis. The lumbar spine measurements presented curvature rectification values ​​for both groups (according to the reference values ​​of the literature). CONCLUSION: The curvature of the cervical spine was affected in sedentary older adults in the present study, compared to the curvature of the spine in active older adults. Furthermore, the rectification of the curvature of the lumbar spine and the changes due to this posture should be considered in the planning of physical exercise in this population

Effect of walking speed in heart failure patients and heart transplant patients.

BACKGROUND: Chronic heart failure patients present higher cost of transport and some changes in pattern of walking, but the same aspects have not yet been investigated in heart transplant patients. METHODS: The aim of this study was to investigate both metabolic and mechanicals parameters, at five different walking speeds on treadmill, in chronic heart failure and heart transplant patients. Twelve chronic heart failure patients, twelve healthy controls and five heart transplant patients participated in the study. Tridimensional kinematics data and oxygen uptake were collected simultaneously. FINDINGS: In both experimental groups the self-selected walking speed was lower than in controls, and lower than the expected optimal walking speed. At that speed all groups showed the best ventilatory efficiency. On contrary, chronic heart failure and heart transplant patients reached the minimum cost of transport and the maximum recovery at greater speeds than the self-selected walking speed. Their mechanical efficiency was lower than in controls, while their metabolic cost and mechanical work were on average larger. INTERPRETATION: We conclude that actions, like a physical training, that could increase the self-selected walking speed in these patients, could also increase their economy and optimize the mechanical parameters of walking. We propose a rehabilitation index, based on the theoretical optimal walking speed, to measure the improvements during a physical rehabilitation therapy. These results have an important clinical relevance and can help to improve the quality of life of heart failure and transplant patients.

Electromyography and economy of walking in chronic heart failure and heart transplant patients.

Background Patients with chronic heart failure frequently report intolerance to exercise and present with changes in walk pattern, but information about heart transplant patients is lacking. Alterations of the gait pattern are related to interaction changes between the metabolism, neurological system and the mechanical demands of the locomotor task. The aim of this study was to investigate the electromyographic cost, coactivation and cost of transport of walking of chronic heart failure and heart transplant patients. Design This research was of an exploratory, cross-sectional design. Methods Twelve chronic heart failure patients, twelve healthy controls and five heart transplant patients participated in the study. Electromyographic data and oxygen uptake were collected simultaneously at five walking speeds. Results In the experimental groups, the electromyographic cost, percentage of coactivation in the leg and cost of transport were higher than in controls. The electromyographic cost was in line with the cost of transport. The minimum electromyographic cost matched with the self-selected walking speed in controls, while in chronic heart failure and heart transplant patients, it was reached at speeds higher than the self-selected walking speed. Conclusion The largest postural isometric activation and antagonist activation resulted in the highest metabolic demand. These findings are of great clinical relevance because they support the concept that interventions in order to improve the muscle performance in these patients can increase the self-selected walking speed and therefore the metabolic economy of walking.

Avaliação da Força de Atrito em máquina de musculação durante exercícios de extensão de joelho / Evaluation in Resistance training machines during knee extension exercises

Durante exercícios realizados em máquinas de musculação, a força de atrito (FA) entre seus componentes mecânicos pode influenciar na magnitude da sobrecarga oferecida pela máquina para o praticante do exercício. No entanto, pouco se sabe sobre como medir esse atrito e qual seu real efeito. Assim, os objetivos deste estudo foram (i) descrever uma técnica para medição da FA em máquinas de musculação, e (ii) exemplificar a técnica quantificando a FA de uma máquina de musculação durante exercício em diferentes velocidades e cargas. Foram utilizados diagramas de corpo livre, equações da mecânica clássica além da medição dos ângulos articulares com eletrogoniômetro, e da força aplicada ao cabo de aço com célula de carga, para estimar a força de atrito. Para testar a metodologia, um indivíduo realizou repetições do exercício variando cargas e velocidade de execução. As cargas avaliadas foram 3kg, 6 kg e 9 kg; e as velocidades foram 30º/s, 60º/se 120º/s. A FA, expressa em percentual da carga, mostrou-se crescente com o incremento de velocidade e decrescente com o aumento da carga. Resultados em torno 40% obtidos para a menor carga e maior velocidade sugerem que a força de atrito deve ser um fator levado em consideração na escolha e manutenção de equipamentos de musculação.

During exercises performed in weight training machines, the friction force (FF) between its mechanical components can influence the magnitude of the overload offered by the machine on force of the exercise. However, little is known about how to measure this friction and what its real effect. Thus the objectives of this study were (i) describe a technique for measuring FF in weight training machines, and (ii) exemplify the technique, by quantifying the FF of the weight training machine at different exercise speeds and loads. For this, a subject performed repetitions of the exercise in different loads and speeds. The loads evaluated were 3 kg, 6 kg and 9 kg; and the speeds were 30°/s, 60°/s and 120°/s. The FF, normalized by selected load, increased significantly with the increasing of the speed and decreased with increasing of the load. Results for friction force around 40% found for highest speed and lowest load show that take the FF in count it's an important factor to consider during muscle equipment choice and maintaining.

Assessment of resistance torque and resultant muscular force during Pilates hip extension exercise and its implications to prescription and progression.

BACKGROUND: The understanding of the external mechanics of Pilates exercises and the biomechanics of the joints may guide the prescription of rehabilitation exercises. OBJECTIVES: To evaluate the resistance torque (Γ(R)) during hip extension (HE) exercises performed on the Pilates Cadillac. To perform a biomechanic analysis of the Γ(R) and the weighted mean moment arm (WMMA) in order to calculate the resultant muscle force (FM(R)) of the hip extensors and flexors. To present a mechanical criteria for progression of HE exercise on the Pilates Cadillac. METHODS: Fourteen participants performed HE exercises on the Cadillac in four randomly assigned situations - using two springs (blue and red), which were attached in two positions (high and low). Angular positions were measured using an electrogoniometer. In order to calculate Γ(R), the muscle torque (Γ(M)) and FM(R), free-body diagrams and movement equations were used. The WMMA of the hip extensors and flexors were estimated from the literature. RESULTS: The Γ(R) and FM(R) presented a similar behavior during all situations; however, the maximum Γ(R) values did not occur at the same joint position as the FM(R) maximum values. The WMMA of the hip flexors presented an increased- decreased behavior with greatest values around 55º of flexion, while the hip extensors presented a similar behavior with greatest values around 25º of flexion. CONCLUSION: Biomechanic analysis of HE exercises and the evaluation of mechanical features in relation to the hip joint may be used as an objective criteria for the prescription and progression of HE exercise in Pilates.

Análise do torque de resistência e da força muscular resultante durante exercício de extensão de quadril no Pilates e suas implicações na prescrição e progressão / Assessment of resistance torque and resultant muscular force during Pilates hip extension exercise and its implications to prescription and progression

CONTEXTUALIZAÇÃO: A análise da mecânica externa dos exercícios de Pilates e da biomecânica das articulações pode subsidiar a prescrição de exercícios na reabilitação. OBJETIVOS: Avaliar o comportamento do torque de resistência (ΓR) do exercício de extensão de quadril (EQ) realizado no Cadillac; realizar uma análise biomecânica a partir do comportamento do ΓR e das distâncias perpendiculares médias ponderadas (DPMPs) para estimar a força muscular resultante (FM R) dos extensores e flexores e propor critérios mecânicos para progressão do exercício de EQ realizado no Cadillac. MÉTODOS: Catorze praticantes de Pilates realizaram EQ no aparelho Cadillac em quatro situações em ordem aleatorizada - usando duas molas (vermelha e azul) fixadas em duas posições (alta e baixa). As posições angulares foram coletadas por meio de eletrogoniometria. Para o cálculo do ΓR, torque muscular (ΓM) e da FM R foram usados diagramas de corpo livre e equações de movimento. Os valores de DPMP dos músculos flexores e extensores do quadril foram quantificados usando dados da literatura. RESULTADOS: O ΓR e a FM R apresentaram comportamentos semelhantes em todas as situações, entretanto os valores máximos de ΓR não ocorrem na mesma posição articular que a FM R máxima. A DPMP dos flexores de quadril apresentou um comportamento crescente-decrescente, com máximo próximo aos 55º de flexão, enquanto os extensores de quadril apresentaram comportamento semelhante, com máximo próximo aos 25º de flexão. CONCLUSÃO: A análise biomecânica do exercício e a avaliação das características mecânicas associadas à articulação do quadril podem ser usadas como critérios objetivos de prescrição e progressão do exercício de EQ no Pilates.

BACKGROUND: The understanding of the external mechanics of Pilates exercises and the biomechanics of the joints may guide the prescription of rehabilitation exercises. OBJECTIVES: To evaluate the resistance torque (ΓR) during hip extension (HE) exercises performed on the Pilates Cadillac. To perform a biomechanic analysis of the ΓR and the weighted mean moment arm (WMMA) in order to calculate the resultant muscle force (FM R) of the hip extensors and flexors. To present a mechanical criteria for progression of HE exercise on the Pilates Cadillac. METHODS: Fourteen participants performed HE exercises on the Cadillac in four randomly assigned situations - using two springs (blue and red), which were attached in two positions (high and low). Angular positions were measured using an electrogoniometer. In order to calculate ΓR, the muscle torque (ΓM) and FM R, free-body diagrams and movement equations were used. The WMMA of the hip extensors and flexors were estimated from the literature. RESULTS: The ΓR and FM R presented a similar behavior during all situations; however, the maximum ΓR values did not occur at the same joint position as the FM R maximum values. The WMMA of the hip flexors presented an increased- decreased behavior with greatest values around 55º of flexion, while the hip extensors presented a similar behavior with greatest values around 25º of flexion. CONCLUSION: Biomechanic analysis of HE exercises and the evaluation of mechanical features in relation to the hip joint may be used as an objective criteria for the prescription and progression of HE exercise in Pilates.