ABSTRACT
Introduction: Cadence and step length are important biomechanical variables of walking and running but they are not typically monitored by the treadmills. This study explains a novel non-invasive method to estimate the step length of walking and running to maximize the professional skills and scientific capabilities of Physiotherapists and Exercise professionals. Methodology: Seventeen individuals (10 men and 7 women) who have been undergoing supervised fitness training programs were selected for the biomechanical analysis of the relationship between cadence and step length of walking and running on the treadmill in the speeds ranging from 5 Km/h to 15 Km/h for men and 5 Km/h to 12 Km/h for women. Results: Exercisers displayed wide range of step length strategies to manage the walking and running speeds opted for the experiment. Additionally, when the same exercisers were allowed to exhibit their maximum running speed in the outdoor environment, a statistically significant difference was found because all of them faced psychological constraints to explore or sustain their fastest running ability on the treadmill. Conclusion: Assessment of cadence and step lengths of the patients and exercisers looks indispensable. Visual counting method to calculate the cadence can be easily acquired through practice, usually accompanied by the development of the skill to compute the step lengths using mathematical formulae. The same method can be used to ascertain if the individuals are adapting symmetrical or asymmetrical step lengths by just separately counting the number of steps produced by each lower extremity for a specific time length (30 seconds or 60 seconds). Experts should continue exploring such feasible, non-invasive and inexpensive diagnostic procedures.
ABSTRACT
Pre-exercises interventions are frequently implemented in order to maximize athletic performance. In this sense, the aim of this study was to evaluated the effect of three distinct pre-exercise interventions on acute neuromuscular performance in recreational soccer players: 1) parallel squat; 2) static stretching; and 3) ballistic stretching. After all interventions, participants performed a flexibility evaluation (sit-and-reach-test), followed by a squat jump, a counter-movement jump and a 30 meter-sprint test. A one-way analysis of variance revealed: a) a significant decrease in jumping performance was induced by both Stretching conditions when compared to the parallel squat intervention; b) a significant increase in lower limb flexibility after both stretching interventions when compared to parallel squat. In conclusion, it is suggested that a pre-exercise intervention comprised of stretching exercises acutely increase flexibility, while may interfere in jump performance in recreational athletes...(AU)
Intervenções pré-exercício são frequentemente adotadas para maximizar o desempenho atlético. Nesse sentido, o objetivo deste estudo foi avaliar o efeito de três diferentes intervenções pré- exercício sobre o desempenho neuromuscular de jogadores de futebol amadores: 1) agachamento paralelo, 2) alongamento estático e 3) alongamento balístico. Após as intervenções, os participantes realizaram a avaliação de flexibilidade (teste de sentar e alcançar) e, em seguida, o salto com agachamento, o salto com contramovimento e o teste de velocidade de 30 metros. Os resultados da ANOVA one-way revelaram: a) redução significante no desempenho do salto para ambas às condições de alongamento quando comparadas ao agachamento paralelo e b) aumento significante da flexibilidade dos membros inferiores após ambas às intervenções de alongamento em comparação ao achamento paralelo. Em conclusão, sugere-se que as intervenções pré-exercício compostas de exercícios de alongamento aumentam agudamente a flexibilidade, paralelamente, podendo prejudicar o desempenho de saltos de atletas amadores...(AU)
Subject(s)
Humans , Male , Adult , Exercise , Muscle Stretching Exercises , Running , SoccerABSTRACT
The purpose of this study was to clarify the effects of lower limb muscle mass growth on sprinting ability in children aged 3 to 8 years. The subjects were 514 unimpaired children (266 boys and 248 girls). We measured their lower limb muscle thickness (anterior thigh: MTa, posterior thigh: MTp, and calf: MTC) and 25 meter sprinting time. Muscle thickness was measured using a B-mode ultrasound diagnostic imaging unit. From the 25 meter sprint, we measured the following characteristics in relation to sprinting ability: results, maximum velocity, stride and pitch. The results revealed that sprinting ability significantly correlated with MTp and MTC in both boys and girls. This suggests that, in addition to morphological development, lower limb muscle mass growth contributes to an increase in stride (m/step) and affects sprinting ability during the period from infancy to early childhood. However, no relationship was seen between sprinting ability and anthropometric characteristics (body height and mass) or lower limb muscle thickness among 8-year-old boys. It is possible that lower limb muscle quality and power as well as improvement in elements such as sprinting movement have a stronger influence on sprinting ability than morphological elements such as physique and muscle mass in boys around that age. In contrast, a significant relationship was seen between lower limb muscle thickness and sprinting ability in girls of all age groups, suggesting that, unlike boys, innate lower limb muscle mass influences sprinting ability for girls.
ABSTRACT
Objetivou-se neste estudo verificar, em corredores mirins, o comportamento cinemático em provas de 50 e 100m rasos e a concentração de lactato sangüíneo ao final destas. A cinemática refere-se à análise da curva de velocidade e de algumas variáveis analisadas ao final destas provas. Fizeram parte deste estudo 14 indivíduos, sendo 7 do gênero masculino (12,35 ± 0,83 anos) e 7 femininos (12,61 ± 0,70 anos). Para obtenção da curva de velocidade foi utilizado o método panning. As demais variáveis cinemáticas foram obtidas por meio de videografia bidimensional, utilizando-se uma câmera de vídeo do sistema Peak Motus, operando à 180 Hz. Uma amostra de sangue foi coletada do lóbulo da orelha para analisar a concentração de lactato. Os resultados mostraram que o pico de velocidade é alcançado em ambas aos 40m, porém correspondendo aos 80% da prova nos 50m rasos e apenas aos 40% nos 100m. As alterações significativas observadas na cinemática entre as duas corridas foram: aumento do tempo da fase de suporte nos sujeitos masculinos, redução da freqüência da passada nos sujeitos femininos e da velocidade média final em todos os sujeitos ao final dos 100m em comparação ao final dos 50m. As maiores concentrações de lactato foram encontradas nos 100m. Conclui-se que houve maior comprometimento da performance nos 100m rasos, em função de alterações de algumas variáveis cinemáticas e das maiores perdas de velocidade. Além disso, apesar da concentração de lactato ser superior ao final desta prova, os valores são considerados baixos, indicando a fraca capacidade anaeróbia destes indivíduos.
The purpose of this study was to verify the kinematic behavior of young runners during 50 and 100m sprints and their blood lactate concentration at the end of these sprints. Kinematic analysis was performed on the speed curve and some variables analyzed at the end of these runs. Fourteen individuals took part in this study, being 7 males (12.35 ± 0.83 years) and 7 females (12.61 ± 0.70 years). The speed curve was constructed using the panning method. The remaining kinematic variables were measured using two-dimensional videography with a Peak Motus video camera operating at 180 Hz. Blood samples were taken from the runners earlobes in order to assay lactate concentration. The results demonstrate that at both distances top speed is reached at 40m. This, however, corresponds to 80% of the distance of the 50m sprint, but just 40% of the 100m run. The significant differences in kinematic variables observed between the two sprints were: increased duration of the support phase in the males, decreased stride frequency among the females and lower average speed at the end of 100m in comparison to 50m, in all individuals. The highest blood lactate concentrations were observed after the 100m run. It was concluded that there was greater loss of performance during 100m, based on the differences between some kinematic variables and the major loss of speed. Moreover, despite lactate concentration being higher after this run, the values were still considered low, indicating a lack of anaerobic capacity in these individuals.
ABSTRACT
Sprinting speed is the final result of sprinting movement. Though sprint runners always try to sprint as rapidly as possible, their speed changes with time. Such changes in speed are caused mainly by physical movement in the support phase of sprinting, because sprint runners encounter deceleration force and generate acceleration force in only this phase. Especially, the support leg has an immediate effect on the sprinting speed.<BR>The purpose of this study was twofold : (a) to determine whether functions of the support leg segments change with changes in sprinting speed and the sprinting situation, and (b) to investigate the characteristics of changes in the functions of the support leg segments.<BR>Ten male sprint runners (age 20.7±1.2 yr, height 1.72±0.06m, body mass 63.3±4.7 kg) participated in the study. Subjects performed three sprints from starting blocks, and were instructed to execute exhaustive sprint runs. Their movement patterns were analyzed for five support phases : (S1) at 77.4±3.1% of maximum sprinting speed (MSS) during the acceleration period, (S2) at 95.4±1.9% of MSS during the acceleration period, (S3) at MSS, (S4) at 94.1±1.4% of MSS during the deceleration period, and (S5) at 90.8±2.2% of MSS during the deceleration period. These phases were designed to allow comparison of movement patterns in different situations with equal sprinting speeds. The linear dynamics approach was adopted to determine the direct effects of segmental movement on the sprinting speed. This is based on the theory that the velocity of a segmental center of mass (SCM) is the vector sum of the velocity of the adjacent lower joint and the relative velocity of the SCM with respect to the adjacent lower joint.<BR>The force acting on each segment of the support leg created a stereotypical pattern in spite of differences in sprinting speed and the sprinting situation. However, the support time and the magnitude of the force acting on the shank and the foot changed with the sprinting speed. The sprinting speed was closely related to impulses acting on the shank and the foot. In contrast, the magnitude of the force acting on the thigh remained unchanged. The impulse acting on the thigh was not related to the sprinting speed, but there was a close relationship between impulses acting on the thigh and the shank, and the foot.<BR>In conclusion, (1) The performance of the function of the thigh remains unchanged in spite of differences in sprinting speed and the sprinting situation. The thigh always works to attain its task, which is to sprint as rapidly as possible ; (2) The functions of the shank and the foot have a direct influence on changes in sprinting speed. These changes are caused by changes in the magnitude of the forces acting on the shank and the foot, and the support time ; (3) While the function of the thigh does not affect the sprinting speed directly, it affects the functions of the shank and the foot. The function of the thigh thus has an indirect influence on sprinting speed ; (4) The thigh and the foot work to compensate for decreases in the performance of the shank during the deceleration period.
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The principal cause of avulsion fracture of anterior superior iliac spine is sudden powerful contraction of sartorius muscle in strenuous sporting activities. The condition usually occurs in young people in whom the apophysis has still not firmly united to the ilium. We presented the three cases of avulsion fracture of anterior superior iliac spine which occurred during sprinting in Physical Fitness Test.