Differences In Neuromuscular Activity Of Knee Flexors And Extensors Muscle During Concentric And Eccentric Isokinetic Contraction In Active And Non Active People With Medal Retardation

Introduction
Previous studies reported that people with mental retardation (M.R.) exert lower strength than untrained adults with
normal IQ, in either absolute or relative terms, while there are not enough researches investigate the electromyographic
activation (EMG) of those people.
Aim of the present study was to examine the maximal isokinetic (concentric & eccentric) torque as the
electromyographic activity of agonistic knee muscles during extension and flexion of knee articulation in people with
Mental Retardation (M.R.).

Methods
A total of twenty-four (N=24) people participated voluntary in the study, 8 people (N=8) in each of the tree groups. The
first group member from people with normal IQ (control group), the second group from trained adults with MR(MRE)
and the third adults with MR who exercised occasionally.
Cybex Norm (CYBEX Division of Lumex, Ronkonkoma, N.Y.) isokinetic dynamometer was used to measure and
estimate the maximal isokinetic torque of muscle knee extensor and flexor muscle. The maximal isokinetic contraction
performed from the sit position (angle thigh-pelvis=110°). Each of the examinant performed three isokinetic concentric
contractions in three different angle velocities (60ο, 120ο, 240ο) whereas for the eccentric contraction they performed
only one angle velocity (60ο). EMG activity of vastus lateralis, vastus medialis and biceps femoris were also reported.
Two minute interval was given between of the two trial. The antagonist activity was calculate as a percentage of the
activity of the same muscle group when acting as agonist at the same angular velocity and muscle action. Analyses of
variance of repeated measurements (ΑΝΟVA) was used for the statistical processing of the results, the significally level
was determined 0,05 (p<0,05).

Results
From the results of the current study we conclude that individuals with normal IQ can exert higher torque out put and
lower antagonist activity in all selected velocities and mode actions in relations to both of the two MR group.
Additionally the MRE group showed higher torque out put and lower antagonist activity in all selected velocities and
mode actions in relations to the MR group

Discussion / Conclusions
The findings of the present result indicate that the systematic exercise increase the performance of the MR group. These
reasons probably have neuronal explanation and the antagonist activity partially explain the reported adaptations

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