Download MOTION ANALYSIS: ONE VERSUS TWO STRIDE ANALYSES

THE NEUROMUSCULAR CHANGES IN ATHLETES AFTER THE ACL
RECONSTRUCTION
Mario Kasović, Branka R. Matković and Mladen Mejovšek
Faculty of Kinesiology, University of Zagreb, Croatia
KEY WORDS: alpine skiing, ACL injury, sEMG, surgery techniques
INTRODUCTION: The study considered two presently most commonly applied
reconstruction techniques using grafts of either muscles semitendinosus and gracillis (STG)
or medial third of the patellar ligament (PAT). The aim of the research was to establish
whether there are any qualitative neuromuscular changes and departures from healthy
movement pattern shown in the surface electromyographic signal and to what extend such
changes and deviations differ in terms of the applied surgery technique two years after ACL
reconstruction. The results of this research could be useful in the alpine ski training because
it is well known that the knees in this sport are the most loaded and prone to injury.
METHOD: The subjects were divided into three homogenous groups. The first group (P,
n=10) consisted of injured athletes who were treated by PAT technique. The second group
(S, n=10) comprised injured athletes treated by STG technique. The third group, control
group included fully healthy athletes (C, n=10). Signal sample are measured original surface
electromyographic signals of the four dominant knee muscles (m. rectus femoris, m. vastus
medialis, m. vastus lateralis and m. biceps femoris) measured whilst executing the motor
task of single leg vertical jump. The following variables were defined for the description of
obtained signal envelopes: the initial moment of muscle activation (tstart), the moment of the
end of muscle activation (tend), the moment when the maximum amplitude of
electromyographic signal is reached (tmax) and duration of activation expressed in the
percentage of the duration of the observed jump section (tdur).
RESULTS and DISCUSSION: The values of Kruskal-Wallis (.0166, p=.05) and MannWhitney (.015152, p=.05/3=.016) tests indicate a statistically significant delay of the
maximum amplitude in the S group. In the flight phase the same group is reaching the
maximum amplitude significantly sooner. Also, the values of Kruskal-Wallis (.0433, p=.05)
and Mann-Whitney (.025974, p=.05) tests indicate a statistically significantly sooner
occurrence of the maximum amplitude than in the P group. Our results show the existence of
particularly statistically significant differences between observed surgical techniques that led
to the change of the neuromuscular pathway during simple and controlled knee movements
even two years after ACL reconstruction in athletes who have returned to active training.
These disturbances of muscle coordination in the knee joint could be tied to function and
location from which the autotransplant is taken and not to transplant quality itself.
CONCLUSION: Results indicate neuromuscular changes as long as two years after ACL
reconstruction, when the respective rehabilitation was completed and athletes resumed a full
training load. This may result in an increased risk of repeated knee injury, including potential
permanent consequences. This study may primarily be useful for professional alpine skiers
and their coaches, who could then plan, programme and adequately adjust their training
process, thereby improving knee function in the best possible way, which in turn would
maintain and extend the skiers respective sports careers. In practical terms this means that
we can determine the optimal load level, at the ski slope or in the gym, which could result
with positive changes in the skiers neuromuscular system without risk of injury.
REFERENCES
Kasović, M., Mejovšek. M., Matković, B., Janković, S. & Tudor, A. (2010). Electromyographic analysis
of the knee using fixed activation threshold after anterior cruciate ligament reconstruction. International
Orthopaedics. Published oneline, http://www.springerlink.com