אימונים OLYMPIC-WEIGHT LIFTING TRAINING CAUSES DIFFERENT KNEE MUSCLE - CO ACTIVATION ADAPTATI

[Mike Bikov]

J Strength Cond Res. 2011 Oct 12. [Epub ahead of print]
OLYMPIC-WEIGHT LIFTING TRAINING CAUSES DIFFERENT KNEE MUSCLE - CO ACTIVATION ADAPTATIONS COMPARED WITH TRADITIONAL WEIGHT TRAINING.
Arabatzi F, Kellis E.
Source

Laboratory of Neuromechanics, Department of Physical Education and Sport Science, Aristotle University of Thessaloniki at Serres, Greece.
Abstract

The purpose of this study was to compare the effects of an Olympic-weight lifting (OL), and traditional weight (TW) training program on muscle- co-activation around the knee joint during vertical jump tests. Twenty six males were assigned randomly to 3 groups: the OL (n=9), the TW (n=9) and Control (C) groups (n=8). The experimental groups trained 3 days a week for eight weeks. Electromyographic (EMG) activity from rectus femoris (RF) and Biceps Femoris (BF), sagital kinematics, vertical stiffness, maximum height and power were collected during squat (SJ), counter movement (CMJ) and drop (DJ), jumping before and after training. Knee muscle co-activation (CI) index was calculated for different phases of each jump by dividing the antagonist EMG activity by the agonist. Analysis of variance showed that the CI recorded during the pre-activation and eccentric phases of all jumps increased in both trainings groups. The OL group showed a higher stiffness and jump height adaptation than the TW group (P <0.05). Further, the OL showed a decrease or maintenance of the CI recorded during propulsion phase of the CMJ and DJs which is in contrast to the increase in the CI observed after TW training (P < 0.05). The results indicated that the altered muscle activation patterns about the knee, coupled with changes of leg stiffness differ between the two programs. The OL program improves jump performance via a constant CI while the TW training caused an increased CI, probably to enhance joint stability.​

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