The purpose of this study was to further develop the constant power model of a previous study and to provide the final solution of Hill’s force-velocity equation. Forearm and whole arm rotations of three different su...The purpose of this study was to further develop the constant power model of a previous study and to provide the final solution of Hill’s force-velocity equation. Forearm and whole arm rotations of three different subjects were performed downwards (elbow and shoulder extension) and upwards (elbow and shoulder flexion) with maximum velocity. These arm rotations were recorded with a special camera system and the theoretically derived model of constant maximum power was fitted to the experimentally measured data. The moment of inertia of the arm sectors was calculated using immersion technique for determining accurate values of friction coefficients of elbow and whole arm rotations. The experiments of the present study verified the conclusions of a previous study in which theoretically derived equation with constant maximum power was in agreement with experimentally measured results. The results of the present study were compared with the mechanics of Hill’s model and a further development of Hill’s force-velocity relationship was derived: Hill’s model was transformed into a constant maximum power model consisting of three different components of power. It was concluded that there are three different states of motion: 1) the state of low speed, maximal acceleration without external load which applies to the hypothesis of constant moment;2) the state of high speed, maximal power without external load which applies to the hypothesis of constant power and 3) the state of maximal power with external load which applies to Hill’s equation. This is a new approach to Hill’s equation.展开更多
Modeling the force-velocity dependence of a muscle-tendon unit has been one of the most interesting objectives in the field of muscle mechanics. The so-called Hill’s equation [1,2] is widely used to describe the forc...Modeling the force-velocity dependence of a muscle-tendon unit has been one of the most interesting objectives in the field of muscle mechanics. The so-called Hill’s equation [1,2] is widely used to describe the force-velocity relationship of muscle fibers. Hill’s equation was based on the laboratory measurements of muscle fibers and its application to the practical measurements in muscle mechanics has been problematic. Therefore, the purpose of this study was to develop a new explicit calculation method to determine the force-velocity relationship, and test its function in experimental measurements. The model was based on the motion analysis of arm movements. Experiments on forearm rotations and whole arm rotations were performed downwards and upwards at maximum velocity. According to the present theory the movement proceeds as follows: start of motion, movement proceeds at constant maximum rotational moment (Hypothesis 1), movement proceeds at constant maximum power (Hypothesis 2), and stopping of motion. Theoretically derived equation, in which the motion proceeds at constant maximum power, fitted well the experimentally measured results. The constant maximum rotational moment hypothesis did not seem to fit the measured results and therefore a new equation which would better fit the measured results is needed for this hypothesis.展开更多
Purpose Neuromotor exercise,which stimulates motor fitness components(balance,agility,coordination),has been less investigated than other forms of exercise such as resistance or aerobic training to counteract the age-...Purpose Neuromotor exercise,which stimulates motor fitness components(balance,agility,coordination),has been less investigated than other forms of exercise such as resistance or aerobic training to counteract the age-related impairment in mobility.The aim of the study was to verify whether neuromotor exercise was as effective as resistance training in improving mobility and related fitness components in healthy older women.Methods Thirty-five women(mean age 69.6±3.2 years)were assigned to a neuromotor(NMT)or a progressive resistance training(PRT)group,both exercising 1 h,twice weekly for 12 weeks.The NMT group exercised static and dynamic balance,agility,speed,reaction time and coordination,while the PRT performed prevalently machine based,strengthening exercises.All participants were tested before and after the intervention for walking speed under different conditions,chair rise time,cardiorespiratory fitness,muscular strength and power.A 2×2 MANOVA and subsequent ANOVAs were performed to ascertain the effects of the two trainings.Results Similar improvements were observed for mobility(P=0.000, η^(2)_(p)=0.73)and for fitness(P=0.000, η^(2)_(p)=0.96)in both groups.Conclusions The present results suggest that in healthy older women improvements in mobility may be obtained through both strength and neuromotor exercise.The present results contribute to further our knowledge on the effects of neuromotor exercise for older people and add relevant information on exercise interventions targeting mobility in the elderly.展开更多
文摘The purpose of this study was to further develop the constant power model of a previous study and to provide the final solution of Hill’s force-velocity equation. Forearm and whole arm rotations of three different subjects were performed downwards (elbow and shoulder extension) and upwards (elbow and shoulder flexion) with maximum velocity. These arm rotations were recorded with a special camera system and the theoretically derived model of constant maximum power was fitted to the experimentally measured data. The moment of inertia of the arm sectors was calculated using immersion technique for determining accurate values of friction coefficients of elbow and whole arm rotations. The experiments of the present study verified the conclusions of a previous study in which theoretically derived equation with constant maximum power was in agreement with experimentally measured results. The results of the present study were compared with the mechanics of Hill’s model and a further development of Hill’s force-velocity relationship was derived: Hill’s model was transformed into a constant maximum power model consisting of three different components of power. It was concluded that there are three different states of motion: 1) the state of low speed, maximal acceleration without external load which applies to the hypothesis of constant moment;2) the state of high speed, maximal power without external load which applies to the hypothesis of constant power and 3) the state of maximal power with external load which applies to Hill’s equation. This is a new approach to Hill’s equation.
文摘Modeling the force-velocity dependence of a muscle-tendon unit has been one of the most interesting objectives in the field of muscle mechanics. The so-called Hill’s equation [1,2] is widely used to describe the force-velocity relationship of muscle fibers. Hill’s equation was based on the laboratory measurements of muscle fibers and its application to the practical measurements in muscle mechanics has been problematic. Therefore, the purpose of this study was to develop a new explicit calculation method to determine the force-velocity relationship, and test its function in experimental measurements. The model was based on the motion analysis of arm movements. Experiments on forearm rotations and whole arm rotations were performed downwards and upwards at maximum velocity. According to the present theory the movement proceeds as follows: start of motion, movement proceeds at constant maximum rotational moment (Hypothesis 1), movement proceeds at constant maximum power (Hypothesis 2), and stopping of motion. Theoretically derived equation, in which the motion proceeds at constant maximum power, fitted well the experimentally measured results. The constant maximum rotational moment hypothesis did not seem to fit the measured results and therefore a new equation which would better fit the measured results is needed for this hypothesis.
文摘Purpose Neuromotor exercise,which stimulates motor fitness components(balance,agility,coordination),has been less investigated than other forms of exercise such as resistance or aerobic training to counteract the age-related impairment in mobility.The aim of the study was to verify whether neuromotor exercise was as effective as resistance training in improving mobility and related fitness components in healthy older women.Methods Thirty-five women(mean age 69.6±3.2 years)were assigned to a neuromotor(NMT)or a progressive resistance training(PRT)group,both exercising 1 h,twice weekly for 12 weeks.The NMT group exercised static and dynamic balance,agility,speed,reaction time and coordination,while the PRT performed prevalently machine based,strengthening exercises.All participants were tested before and after the intervention for walking speed under different conditions,chair rise time,cardiorespiratory fitness,muscular strength and power.A 2×2 MANOVA and subsequent ANOVAs were performed to ascertain the effects of the two trainings.Results Similar improvements were observed for mobility(P=0.000, η^(2)_(p)=0.73)and for fitness(P=0.000, η^(2)_(p)=0.96)in both groups.Conclusions The present results suggest that in healthy older women improvements in mobility may be obtained through both strength and neuromotor exercise.The present results contribute to further our knowledge on the effects of neuromotor exercise for older people and add relevant information on exercise interventions targeting mobility in the elderly.
