Affiliations: [a] School of Physical Education and Sports, Anadolu
University, Eskisehir, Turkey | [b] School of Medicine, Biophysics Department, Hacettepe
University, Ankara, Turkey | [c] Research Institute for Sport and Exercise Sciences,
Liverpool John Moores University, Liverpool, UK
Note: [] Address for correspondence: Ali Onur Cerrah, Anadolu University,
School of Physical Education and Sports, Iki Eylul Kampusu 26555, Eskisehir,
Turkey. Tel.: +90 222 321 35 50/ 6716; Fax: +90 222 321 35 64; E-mail:
[email protected]/[email protected]
Abstract: The aim of the study was to define activation characteristics of
knee muscles of the kicking leg during the in-step kick and interpret these in
relation to isokinetic strength parameters and ball velocity in professional
(N=14) compared to amateur (N=17)
soccer players. Electromyographic (EMG) recordings were taken from the rectus
femoris (RF), vastus lateralis (VL), vastus medialis (VM), long head of biceps
femoris (BF) and medial gastrocnemius (GAS) as players performed three
successful maximal in-step kicks using a 0° approach
angle with two steps to a stationary ball towards a target. Kicks were also
recorded with high speed video and ball velocity was measured by a radar gun.
Afterward the bilateral concentric isokinetic strength of the knee extensors
and flexors was recorded. Results suggest that during the swing phase, BF
activation occurred significantly earlier, RF showed reduced activation and an
earlier and greater muscle activity occurred in VL and VM in professionals
compared to amateur players. During knee extension, VL and VM showed a markedly
greater magnitude of muscle activity in professionals; during the follow
through, GAS showed reduced activity in professionals. Relationships between
muscle strength and performance (ball speed) were found for amateurs but not
for professionals (r=0.57 to r=0.72, p< 0.05). The findings of this study indicate that the
superior performance of professional players compared to amateurs appears not
to be due to muscle strength factors but rather to subtle differences in
technique, as indicated by EMG data, throughout both the build up and execution
of the kick.
