ABSTRACT
Purpose: In approaching full trunk flexion [75%-80% of full flexion], myoelectric activity of lumbar erector spinae muscles is reduced or silenced; this response is known as flexion-relaxation phenomenon [FRP]. FRP is a shift in load sharing and spinal stabilization from active structures [erector spinae muscles] to passive ligamentous and articular structures. Static lumbar flexion under constant displacement or load, within the physiological range, elicits creep in lumbar viscoelastic tissues. During a short static lumbar flexion, significant changes are elicited in the muscular activity pattern of the FRP. Laxity in the passive tissues of the spine during prolonged spinal flexion disturbs the spinal stability. This study investigated the effects of Kinesio taping [KT] before and after periods of the static lumbar flexion on the timing of FRP for the erector spinae muscles
Methods: The research was conducted on 22 healthy female college students. The surface electromyographic silence and onset of the erector spinae muscle activities were measured in two states; before the static lumbar flexion and 10 minutes after the static lumbar flexion in two conditions [with and without KT]
Results: The results indicate that KT causes erector spinae muscles relaxation earlier in the flexion and later reactivated in the extension. In other words, KT increased flexion relaxation time in erector spinae muscles [P<0.05]. The results also indicate that 10 minutes static lumbar flexion will produce relaxation of the erector spinae muscles later during the forward bending activity and earlier reactivation during the extension [P<0.05]. Application of KT cannot compensate the effects of 10 minutes static flexion at the onset and the silence of flexion relaxation and over again creep causes FRP occurs later
Conclusion: According to the effects of KT before the creep in reducing the duration of the muscles activity, kinesio tape may be used in reducing muscle spasms and duration of erector spinae muscles activity. It may also improve FRP in the back and the people who are predisposed to the back pain and FRP has not seen in them. Therefore, the need for research on these subjects and other factors, such as the electrical activity of muscles is essential. Although the application of KT cannot substitute the effects of 10 minutes static flexion on the onset and the silence of flexion relaxation, it could be used for protection and reduction of using strained viscoelastic structures
ABSTRACT
Due to the frequent use of surface electromyography as a tool for the study of muscle function, to accurately compare electromyographic data from different muscles and different subjects, it is necessary to normalize the integrated data obtained from each muscle. The most common normalization technique is the use of maximum voluntary isometric contraction [MVIC] of a predetermined isometric movement as the reference electromyographic signal. The purpose of this study was to determine the Reproducibility of maximum voluntary isometric contraction of shoulder muscles in Empty Can position test and the correlation between force and MVIC of shoulder muscles. The electromyographic activity of these four muscles [anterior and middle deltoid, upper and lower trapezius] was examined in 20 healthy subjects [10 men and 10 women with 31.25 +/- 8.92 age]. Muscle force was determined by dynamometer. Each test repeated 3 times. Results showed that same day test retest reliability coefficients were significant [ICC>95%], but separate day test retest reliability coefficients were not significant. Maximum muscle force did not relate to any of muscles MVIC amplitude. Reproducibility results may be due to electrode placement, emotional and physical condition of subjects and the large range of motion of shoulder and compensatory movements of shoulder and trunk