BJMB
Brazilian Journal of Motor Behavior
Research Article
!
Ávila de Oliveira et al.
2019
VOL.13
N.5
144 of 154
Feasibility of evaluating effects of muscle fatigue on postural stability and muscular
activation of the supporting leg in soccer power kicking
JÚLIA A. OLIVEIRA
1
| CAROLINE R. DE SOUZA
1
| CARLA D. P. RINALDIN
2
| DANIEL B. COELHO
1,3
| LUIS A. TEIXEIRA
1
|
1
Human Motor Systems Laboratory, School of Physical Education and Sport, University of São Paulo, SP, Brazil.
2
Graduate Program on Health Technology, Pontifical Catholic University of Paraná, PR, Brazil.
3
Biomedical Engineering, Federal University of ABC, São Bernardo do Campo, SP, Brazil.
Correspondence to: Júlia Ávila de Oliveira, Av. Prof. Mello Moraes, 65. Cidade Universitária, USP, São Paulo, SP. BRAZIL. 05508-030
email: julia.avila@usp.br
https://doi.org/10.20338/bjmb.v13i5.146
HIGHLIGHTS
• Effect of muscular fatigue on dynamic
balance and muscular activation in a kick task.
• Muscular fatigue failed to lead to functional
changes in a specific soccer task.
• Neuromuscular adaptations allow for
maintenance of balance stability while kicking.
ABBREVIATIONS
APAs anticipatory postural adjustments
CoP center of pressure
EMG electromyographic
MG medial gastrocnemius
PL peroneus longus
SD self-declared
SOL soleus
TA tibial anterior
PUBLICATION DATA
Received 15 10 2019
Accepted 30 11 2019
Published 01 12 2019
BACKGROUND: Muscle fatigue accumulated during a soccer game can be a critical element to athletic
performance.
AIM: The aim of this study was to analyze the feasibility of evaluating the effect of local fatigue on balance and
muscular activation of the support leg in soccer players when performing power kicks.
METHOD: Six soccer players were evaluated in the kicking task, supported on a force platform. The ball was
stabilized on a base beside the force platform by two elastic strings attached to fixed points on the floor. The
variables analyzed were: CoP displacement amplitude; activation magnitude of the soleus (SOL), medial
gastrocnemius (MG), tibial anterior (TA), and peroneus longus muscles (PL) for three intervals: 200 ms prior to
foot-ball contact, and between 30-60 ms and 80-135 ms after foot-ball contact; co-contraction between the MG-
TA and PL-TA muscles; and peak velocity of the kicking leg. Muscular fatigue was induced by means of
repeated oscillations of the kicking leg until exhaustion.
RESULTS: Results indicated that fatigue failed to affect either velocity of the kicking leg or postural stability while
kicking. Electromyographic analysis revealed that induced fatigue decreased activation of the medial
gastrocnemius muscle and increased activation of the soleus muscle following foot-ball contact.
CONCLUSION: These results demonstrate the feasibility of analyzing the effect of local fatigue on dynamic
balance and muscular activation in the performance of a power kick.
KEYWORDS: Fatigue| Postural Control| Muscular Activation| Soccer
INTRODUCTION
Postural stability has been shown to be determinant in soccer player performance
1
.
Postural instability is one of the intrinsic factors that may lead to increased risk of injury
2
.
Ankle sprains have been cited as one of the most common musculoskeletal injuries among
athletes who rely on sudden stops and changes of direction, like in a soccer game
3
. More
specifically, an epidemiological study on soccer injuries showed that 17% of injuries are
lateral ankle sprains
4
. Among ankle injuries in soccer players, 48% occur at the end of
each half of the match
5
. It has been speculated that alteration in muscle responses caused
by local fatigue may explain the increase in lower limb injuries among athletes
3,6,7
. The
fatigue process induces exaggerated joint stiffness and delayed automatic postural
responses by reducing spinal reflexes
8-10
, compromising motor control performance in
reactive postural responses to perturbation
9,11-13
. When an individual is exposed to
stressful tasks, motoneurons become less sensitive to synaptic entry, degrading
proprioceptive afferent feedback from the muscle spindles, and efferent information
BJMB! ! ! ! ! ! ! ! Research Article!
Brazilian(Journal(of(Motor(Behavior!
Ávila de Oliveira et al.
2019
VOL.13
N.5
145 of 154
becomes insufficient, compromising muscle contraction latency in several tasks
14
. As the
literature has shown that the postural control of soccer athletes is preferably regulated by
proprioceptive pathways, which are impaired by fatigue, it is possible to assume that
delayed and decreased postural muscle recruitment may lead to a higher incidence of
ankle injury in this condition.
Some studies have evaluated whether soccer-induced fatigue alters postural
control, and may be a potential cause of the high incidence of ankle injuries in players
7,15-17
.
However, results are controversial. In addition to using different protocols for fatigue
induction, these studies used different mechanisms to measure postural stability, with
scarce concomitant assessment of balance related to muscle activation parameters and
postural control strategies. The effect of fatigue on postural control is influenced by the
parameters of muscle location, decreased muscle strength, exercise intensity and duration,
muscle action, and number of affected muscles
11
. Different compensatory postural
strategies are used to reduce the perturbation of postural control caused by general or
local muscle fatigue
11-13
, but no studies were identified in the reviewed literature evaluating
the influence of the activity of different ankle stabilizer muscles and compensatory
strategies on postural control after fatigue induction in soccer players.
Controlled studies about the effect of fatigue on the postural control of soccer
athletes are still lacking in the literature. It would be of interest to adjust a fatigue-induction
protocol to resemble the demands of the game, or induce postural perturbations that alter
neuromuscular control to analyze the effects. It is also necessary to choose postural tests
that resemble the movements used in the sport modality. In addition, postural control
should be evaluated in conjunction with muscular activation to better understand the
effects of fatigue on postural control and the possible use of compensatory strategies. The
aim of the present study was to analyze the feasibility of evaluating the effect of muscle
fatigue of the supporting leg in soccer players on postural stability and activation of the
stabilizing muscles of the ankle in the task of kicking a ball, with similar mechanical
requirements as in a real game situation.
METHODS
Participants
Six male university soccer and/or futsal athletes, right-footed for kicking (self-
declared), age range 19-27 years (M = 22.00, SD = 2.68), participated voluntarily in this
study. As inclusion criteria, participants were required to have had no ankle sprain in the
supporting leg in the previous six months, have participated in regular training in the
previous four years, with at least three training sessions per week, and regular
participation in competitive soccer games. Participants signed an informed consent in
accordance with procedures approved by the local research ethics committee.
Task and equipment
The task was performed on a force platform (BTS, P6000, Italy),during which
participants were tested while performing a power kick of a soccer ball (Figure 1). The kick
was made with the upper face of the right foot, with the purpose of striking the ball with
maximum power towards a rectangular target (100 cm x 60 cm), placed on the ground 2 m
in front of the ball position. The ball was stabilized on a base arranged beside the force