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FUNCTIONAL MOTOR ASYMMETRY IN THE QUADRICEPS IN SUBJECTS DOING HIGH INTENSITY PHYSICAL EXERCISE

S. N. PIGARE VA, N. A. FUDIN ANOKHIN INSTITUTE OF NORMAL PHYSIOLOGY, MOSCOW, RUSSIA

Objective: the EMG investigation of symmetric dynamic force in the quadriceps of right and left lower limbs in subjects doing high intensity physical exercise.
Materials and Methods: 12 males. Every participant was asked to perform an increasing intensity step-dosed physical load test on the ergocycle till refusal. The intensity on the first load was 60 watts, the load intensity increased 20 watts every step, from 80 watts to 120 watts. The duration of the load on each step was 1 minute. At 140 watts the subject pedaled till refusal. Load testing was performed with a constant speed of pedaling. At all levels we recorded the EMG from straight head of the right thigh quadriceps muscle.
Results: a significant increase in EMG indices and the ratio decrease under high loads of right quadriceps. Under small loads we found high EMG levels in comparison with leading limb muscle, and a significant increase of ratio of the left not leading limb.
Conclusions: it was shown that not leading limb muscle contraction at low load levels involves all functionally active motor units. Further maintenance of muscle force is realized by increased rate of motor neuron impulses of already involved motor units and by compensatory effort of the same muscle of the leading limb. Significant decrease of correlation of number of turns and EMG average amplitude with the growth of its individual parameters at high load levels is a quality informative indicator determining high power characteristics of the quadriceps in young trained persons.
Keywords: 
quadriceps; asymmetry; EMG; average amplitude; turns; ratio; motor units.