In the literature, it is well established that subjects are able to jump higher in a countermovement (CMJ) than squat (SJ). The purpose of this study was estimate relative contribution time available for force development and storage reutilization elastic energy enhancement performance CMJ compared with SJ. Six male volleyball players performed Kinematics, kinetics, muscle electrical activity (EMG) from six muscles lower extremity were monitored. It found even when body position at start...

In the literature, drop jumping is advocated as an effective exercise for athletes who prepare themselves explosive activities. When executing jumps, different techniques can be used. this study, influence of technique on biomechanics investigated. Ten subjects executed jumps from a height 20 cm and counter-movement jumps. For execution two were adopted. The first technique, referred to bounce jump, required reverse downward velocity into upward one soon possible after landing. second them...

This target article addresses the role of storage and reutilization elastic energy in stretch-shortening cycles. It is argued that for discrete movements such as vertical jump, does not explain work enhancement due to prestretch. seems occur because prestretch allows muscles develop a high level active state force before starting shorten. For cyclic which cycles repetitively, some authors have claimed enhances mechanical efficiency. In current it demonstrated this claim often based on...

In this study the effects of systematic manipulations control and muscle strength on vertical jump height were investigated. Forward dynamic simulations squat jumps performed with a model human musculoskeletal system. Model input was STIM(t), stimulation six lower extremity muscles as function time; output body motion. The incorporated all features system test subjects considered salient for jumping, initial configuration set equal to that subjects. First, optimal STIM(t) found standard...

BOBBERT, M. F., P. A. HUIJING, and G. J. VAN INGEN SCHENAU. Drop jumping. II. The influence of dropping height on the biomechanics drop Med. Sci. Sports Exerc., Vol. 19, No. 4, pp. 339–346, 1987. In literature, athletes preparing for explosive activities are recommended to include jumping in their training programs. For execution jumps, different techniques heights can be used. This study was designed investigate performance bounce jumps jumps. Six subjects executed from 20 cm (designated...

Purpose: To investigate whether the difference in jump height between countermovement jumps (CMJ) and squat (SJ) could be explained by a active state during propulsion. Methods: Simulations were performed with model of human musculoskeletal system comprising four body segments six muscles. The model's only input was STIM, stimulation muscles, which switched “off” or “on.” After switching “on,” STIM increased to its maximum at fixed rate change (dSTIM/dt). For various values dSTIM/dt, switch...

Ten well-trained male volleyball players performed one-legged and two-legged vertical countermovement jumps. Ground reaction forces, cinematographic data,and electromyographic data were recorded. Jumping height in jumps was 58.5% of that reached Mean net torques hip ankle joints higher Net power output the joint extremely high This explained by a level activation both heads m. gastrocnemius jump. A also found vastus medialis. These differences between unilateral bilateral performance complex...

Better running economy (i.e. a lower rate of energy consumption at given speed) is correlated with superior distance performance. There substantial variation in economy, even among elite runners. This might be due to the storage and reutilization elastic tendons. Using simple musculoskeletal model, it was predicted that amount stored tendon during movement depends more critically on moment arm than mechanical properties tendon, increasing as gets smaller. Assuming link between overall...

Force-velocity relationships reported in the literature for functional tasks involving a combination of joint rotations tend to be quasi-linear. The purpose this study was explain why they are not hyperbolic, like Hill's relationship. For purpose, leg press task simulated with musculoskeletal model human leg, which had stimulation knee extensor muscles as only independent input. In ankles moved linearly, away from hips, against an imposed external force that reduced over contractions 95 5%...

ABSTRACT The purposes of this study were to determine the dependence human squat jump performance on compliance series elastic elements (SEEs) triceps surae (consisting soleus and gastrocnemius) explain dependence. Vertical jumps simulated using an optimal control model musculo-skeletal system. Maximum height was found for several values SEE strain at maximum isometric force (ε0). When ε0 increased from 1 10 %, by 8 cm. This partly due a higher work output contractile (CEs) muscles,...

Length changes of the muscle-tendon complex (MTC) during activity are in part result length active muscle fibres, contractile component (CC), and also stretch elastic structures [series-elastic (SEC)]. We used a force platform kinematic measurements to determine human calf walking, running squat jumping. The force-length relation SEC was determined dynamometer experiments on same four subjects. CC calculated as total minus dependent SEC. measured relations between or velocity were compared...