The Effect of Increasing Volume of Exercise on Activation Pattern of Vastus Medialis and Lateralis and its Correlation With Anterior Knee Pain in Karate Elites.
BACKGROUND
The effects of exercise volume on the pattern of muscle activity is one of the most important factors in training management and injury risk reduction. In the lower limb, the quadriceps muscle which plays a determining role in performing the stance and other karate techniques could be injured in intensive exercise and may induce anterior knee pain in athletes.


OBJECTIVE
The aim of this study was to determine the relationship between training volume and muscle activity of vastus medialis and vastus lateralis and its association with anterior knee pain in karate elites.


METHODS
Male and female athletes from national junior and cadet karate team (14 to 18 years) were invited to participate in the study at the beginning and the end of the training camps. Studies involved measurement of electromyographic muscle activity of vastus medialis and vastus lateralis in both lower extremities with surface electromyography device and assessment of movement by electrogoniometery. Muscle activity was recorded in three tests of dachi, walking up and walking down stairs. Simultaneously, anterior knee pain was evaluated using visual analogue scale and anterior knee pain scale questionnaire.


RESULTS
Eight athletes of a total number of 23 reported increased ratings of pain in their right knees. No differences in muscle activity were observed in tests of Dachi and stairs between the groups with and without pain. Comparing Dachi task pattern at the beginning and end of training camps, there was no significant difference in pattern of biomechanical movement; however, reducing the amount of muscle activity in early and late phases of tasks was observed in electromyographic assessment.


CONCLUSIONS
The results showed that performing the same task after a six-week training period, less muscle activity was required in all phases in two groups of tasks, including karate-specific movement (dachi) and activities of daily living (up or down stairs).
Rasoul Akram Medical Complex, Iran University of Medical Sciences, Tehran, IR Iran; Sports Medicine Research Center, Tehran University of Medical Sciences, Tehran, IR Iran.
Afsaneh
A
Safar Cherati
Rasoul Akram Medical Complex, Iran University of Medical Sciences, Tehran, IR Iran; Sports Medicine Research Center, Tehran University of Medical Sciences, Tehran, IR Iran.
Sara
S
Lotfian
Rehabilitation Research Center, Department of Physical Therapy, Faculty of Rehabilitation Science, Iran University of Medical Sciences, Tehran, IR Iran.
Aliashraf
A
Jamshidi
Biomechanics Lab, Rehabilitation Research Center, Department of Rehabilitation, Department of Rehabilitation Basic Sciences, Iran University of Medical Sciences, Tehran, IR Iran.
Mohammad Ali
MA
Sanjari
Rasoul Akram Medical Complex, Iran University of Medical Sciences, Tehran, IR Iran.
Mohammad
M
Razi
Exercise Volume; Karate; Vastus Lateralus; Vastus Medialis