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In orthopedic patients, the formation of the motor skill of rapid and precise reproduction of an effort by the anterolateral muscles of the shin of the elongated extremity was significantly decelerated as compared to the intact one when tested at 5-50% of the maximum muscular force of the intact extremity. A correlation was observed between the tracking square error, which is an index of precision of instrumental motor reactions, and the dynamic activation indices (the ratios between the electromyogram integrals and the force momentum impulse), which characterize energy expenses, and was assumed to reflect specific optimization of sensorimotor reactions at different power loadings. Both with the elongated and the intact extremities, the interactive search for and fixation of the optimal motor program was most effective in a certain range of muscular loading. The results can serve as a basis for choosing specific rehabilitation programs for orthopedic patients.

We suggested the scale of intra-operative pyramidal disorders severity that is satisfactorily correlated with functional surgical outcomes which are reflected in the dynamics of particular and integral characteristics of voluntary and evoked bioelectrical activity of the lower limb muscles. This fact makes possible to use safely the above-mentioned protocol for IONM, to predict postoperative motor disorders and to formulate reasonably the recommendations for postoperative management.

Relatively few theoretical and applied studies have been carried out using spectrum analysis of electromyograms (EMGs) in comparison with electroencephalograms. The essence of the method is measurement of frequency and energy response characteristics of the relevant forms of bioelectrical activity: spectral density of power G ( ω ) (power spectrum), effective band (width) of the spectrum, maximum G ( ω ) and the corresponding frequency, and mean and square mean G ( ω ) per unit frequency [1]. The most widespread method of calculating G ( ω ) is fast Fourier transform of a fragment of a bioelectrical activity record stored in the memory of a digital EMG system with numerical and/or graphic presentation of the final result. A special emphasis is made on the role of morphological, functional, and biophysical factors (fatigue; testing muscular effort; type of muscular contraction; sizes of muscles, muscular fibers, and motor units; type and size of electrodes; methods of recording the bioelectrical activity; etc.) that influence the values and reproducibility of EMG spectral characteristics [2-10].Some authors have reported specific features of EMG power spectra of various muscles, which, in their opinion, must be allowed for in diagnosis of neuromuscular diseases [11,12].Our purpose was to clarify the features of spectral characteristics of the surface EMG of different muscles of upper and lower limbs as dependent on the degree of cortical influences on segmental motoneuron pools. METHODSWe examined ten healthy subjects (five men and five women) at an age of 21-28 ( 24.0 ± 2.1 ) years and 19 patients at an age of 11-30 ( 20.4 ± 1.4 ) years. The patients were tested during follow-up at the Laboratory of Movement Physiology and Neurophysiology (Ilizarov Research Center for Restorative Traumatology and Orthopedics) 4.9 ± 1.3 years after surgical correction of asymmetry in the length of the lower limbs after Ilizarov (congenital anomaly, 12 patients; consequence of hematogenous osteomyelitis, 6; of osteoarticular tuberculosis, 1). Their limbs were lengthened by 5-12 ( 7.3 ± 0.6 ) cm in the thigh and 3-10 ( 5.3 ± 0.6 ) cm in the shin. The thigh was lengthened in nine patients, the shin in six, and both the thigh and shin in four. The examination employed a BASIS-2381 bioelectrical activity analyzer (O.T.E. Biomedica, Italy). The following muscles were examined in the healthy subjects: m. deltoideus (the middle portion), m. biceps br. ( c.l. ), m. triceps br. ( c.l. ), m. extensor dig., m. flexor carpi rad. , m. gluteus max., m. rectus fem., m. biceps fem., m. tibialis ant., m. gastrocnemius ( c.l. ), m. extensor dig. br. , m. flexor dig. brev. , m. thenar , and m. hypothenar (on the left and right). In the patients, we examined the muscles of the lengthened segments of the leg ( m. rectus fem. and m. biceps fem. in the thigh; m. tibialis ant. and m. gastrocnemius c.l. in the shin). Surface bioelectrical activity of the tested muscles was recorded bipolarly (electrode length, 8 mm; interelectrode distance, 10 mm) with ...

The effect of the force load on the coordination structure of human spatial movements has been dem onstrated by a series of studies on the ergonomic pro file. For example, Semenov [1] and Chekirda [2] observed an improvement of sensorimotor perfor mance in subjects with a moderately loaded arm. Farfel' [3] and Komarov [4] assumed that large force loads (more than 50% of the maximum muscle force) decreased the movement precision. Lyubomirskii [5] demonstrated a dependence of the strength and preci sion of hits with a hammer on the weight of the ham mer head in 11 to 14 year old schoolchildren (the precision was the lowest for the lightest and the heavi est hammers). These data indicate that a moderate load improves the coordination of movements per formed under the conditions of auxotonic muscle contractions. Lyubomirskii [5] assumes that these relationships are also true for precision movements performed in modes close to isometric. The effect of the changes in the structural and functional character istics of muscles on the coordination structure of pre cision movements in a different range of force loads also remains an open question.The objectives of this study were to estimate the asymmetries of the integrated parameters of visuomo tor tracking with the use of isometric control organs in patients in different periods after surgical elimination of a difference between the lengths of the lower extremities and to test the hypothesis that there is a range of isometric loads where subjects organize vol untary control of muscle tension with the maximum precision and minimum specific energy expenditure. METHODSTwenty three patients aged 15-35 years (6 men and 17 women) with shortening of a leg of different eti ologies were subjected to integrated examination using dynamometric, visuomotor tracking, kinesthesiomet ric, and global and local electromyographic methods. The sample was distributed with respect to the etiology of the shortening of the extremity as follows: conse quences of tuberculosis of bones and joints, 11; osteo myelitis, 3; congenital malformations, 9. The Ilizarov distraction apparatus was used to lengthen the lower leg by 4-17 (8.6 ± 0.7) cm, which corresponded to 13-68 (28.7 ± 3.2)% of the initial length of the seg ment. The mean rate of distraction varied from 0.8 to 2.2 (1.2 ± 0.1) mm/day; the durations of distraction and fixation were 44-178 (76 ± 8) and 53-237 (101 ± 10) days, respectively. After removal of the Ilizarov apparatus, immobilization with a plaster dressing was used in 17 cases; the duration of immobilization was 15-117 (50 ± 5) days. Eight subjects were examined once; 15 subjects, twice; 20 examinations were per formed within 296 to 430 (330 ± 29) days and 18 exam inations, within 616 to 870 (747 ± 59) days after the removal of the Ilizarov apparatus or the plaster dress Abstract-Data confirming the hypothesis that there is a range of isometric loads where subjects organize voluntary control of muscle tension with the maximum precision and minimum specific energy expenditure are p...

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Comparative evaluation of functional lower limb muscle status depending on gonarthrosis severity and technique of surgical intervention was performed using the results of stimulation electromyography (M-responses). Data obtained showed that the changes of evoked bioelectrical activity in lower limb muscles depend to a great degree on the initial status (gonarthrosis grade) than on the technique of surgical intervention.

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