Academic journal article Journal of Physical Education and Sport

Myoelectrical Properties of Lower Limbs, in Soccer Players Compared to Different Fall Height and Use of Additional Weight in a Sledge Machine

Academic journal article Journal of Physical Education and Sport

Myoelectrical Properties of Lower Limbs, in Soccer Players Compared to Different Fall Height and Use of Additional Weight in a Sledge Machine

Article excerpt

Introduction

The stretch-shortening cycle (SSC) is an efficient muscular activation type characterized by stretching of the target muscle (eccentric phase) prior to a subsequent shortening in the concentric phase. When compared with concentric actions without preceding stretch, muscular force and power of the SSC is enhanced (Cavagna, G.A., Saibene, F.P. & Margaria, R. 1965; Gregor, R.J., Roy, R.R., Whiting, W.C., Lovely, R.G., Hodgson, J.A. & Edgerton, V.R. 1988). Comparisons of the force-velocity curves in constant velocity and in natural locomotion conditions have shown that muscular output can be enhanced by a stretch-shortening cycle (SSC) muscle function. This has been shown in different experimental set-ups (Gregor, et al., 1988,; Stevens E.D 1993, Komi P.V. 2000). The force- velocity curve of a muscle is distinct from torque- angular velocity curve that has often been used in human studies to describe the mechanical output of the muscles. Those studies have also shown enhancement of joint torque in the concentric phase of SSC type exercise (Bobbert, M.F., Gerritsen, K.G., Litjens, M.C. & Van Soest, A.J. 1996).

Literature suggests that in addition to myo-electrical potentiation (Bosco, C., Viitasalo J.T., Komi, P.V., & Luthanen, P. 1982), the enhanced force and power output in SSC exercise may arise from a stretch-induced force enhancement phenomenon observed in the contractile level (Ettema, G.J.C., Huijing, P.A. & De Haan, A. 1992, Stevens E.D. 1993), or from effective tendon stretch and recoil. During locomotion in vivo, the interaction between the length of contractile and non-contractile tissues depends on the patterns of neural activity that are highly variable between tasks. Constantly changing muscle length, velocity and force make it difficult to attribute the potential enhancement to any specific factor. In spite of these difficulties, our aim was to examine the contribution of the contractile and the elastic components to the potentiation of the muscle-tendon output using in vivo tendon force and fascicle length measuring techniques in human subjects. Force-velocity relationships were compared between maximal knee joint extension exercises and the data recorded during natural movement both at the level of vastus lateralis (VL) muscle fascicle and at the level of the entire muscle- tendon unit (MTU). The data during natural movements, consisting counter movement jumps (CMJ) and drop jumps (DJ) on a sledge apparatus, has been partially reported earlier (Finni, T., Ikegawa, S., Lepola, V. & Komi, P.V.. 2001).

A reliable way to assess the vertical jump (drop jumps and counter movement jumps) in cases where it is not possible to perform the simple form, or to prevent injury or because of the high level of difficulty, is to use a ramp construction sledge machine (SLM), where subjects can execute jumping repeat in a seated position, ensuring the stability and balance of the body, including the joints of the hip, knee and ankle, and to achieve a safe jump without risk of injury. It also facilitates the determination of the height of fall, setting the angle required for the execution of the jump, and putting extra weight. There are several reports in the literature concerning investigations which studied the ability and jump muscle function in relation to the drop height and the use of additional weight (Gissis, I., Grezios, A. Goehner, U., & Dickuth H.H., 2003; Gissis, I., Grezios, A., Goehner, U., Dickuth, H.H., & Papadopoulos Ch., 2004), through various situations jumps where you will find the use of construction ramp. The purpose of this study was to examine the effect of the fall of extra weight for selected parameters for the reactive capability in the sledge apparatus built for the purpose.

In the literature also we can see that these structures were used to facilitate the procedures, when the drop height was large enough, (Galindo, A., Barthèlemy, J., Ishikawa, M. …

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