Yazar "Begovic, Haris" seçeneğine göre listele

Listeleniyor 1 - 3 / 3
  • Küçük Resim Yok
    Yayın
    Effects of Transverse Friction Massage on the Electromechanical Delay Components and Fractal Dimension of Surface Electromyography in Quadriceps Muscles
    (Mdpi, 2023) Özturk, Necla; Begovic, Haris; Demir, Pınar; Can, Filiz; Yagcioğlu, Suha
    The purpose of this study was to assess the effects of transverse friction massage (TFM) on the electromechanical delay components and complexity of the surface electromechanical activity in the rectus femoris (RF) and vastus medialis (VM) muscles and to identify possible mechanisms behind TFM-induced alterations in the dynamics of RF and VM activity. Seven female and five male healthy subjects participated in this study. The subjects generated five maximal voluntary isometric contractions (MVICs) consecutively before and after TFM. Meanwhile, electromyography (EMG), mechanomyography (MMG), and force were recorded. The onset times of the recorded signals were detected offline by setting the threshold to three times the SD of the baseline. The delays between EMG and MMG (At(EMG-MMG)), MMG and force (At(MMG-Force)), and EMG and force (At(EMG-Force)) were computed from the detected onsets. The fractal dimension (FD) of the EMG time series was computed using the correlation dimension method. TFM increased At(MMG-Force) and At(EMG-Force) significantly in the RF but decreased At(EMG-MMG) and increased At(MMG-Force) in the VM. TFM decreased the FD in the RF and increased it in the VM. The results imply that TFM decreased the stiffness of both the RF and VM and decreased the duration of the electrochemical processes in the VM. It is proposed that the decrease in EMG complexity in the RF may be associated with the decreased stiffness of the RF, and the increase in EMG complexity in the VM may be associated with the decreased electrochemical processes in this muscle. It is also suggested that the opposite changes in EMG complexity in the RF and VM can be used as a discriminating parameter to search for the effects of an intervention in the quadriceps muscles. The present study also demonstrates how to discriminate the nonlinear dynamics of a complex muscle system from a noisy time series.
  • Küçük Resim Yok
    Yayın
    Passive stretching-induced changes detected during voluntary muscle contractions
    (TAYLOR & FRANCIS INC, 2020) Begovic, Haris; Can, Filiz; Yagcioglu, Suha; Ozturk, Necla
    Stretching exercises are known for reduction of musculoskeletal stiffness and elongation of electromechanical delay (EMD). However, computing a change in stiffness by means of time delays, detected between onset of electromyographic (EMG), mechanomyographic (MMG) and force signals, can reveal changes in subcomponents (Delta tEMG-MMG and Delta tMMG-FORCE) of EMD after stretching. In our study, the effect of stretching was investigated while quadriceps femoris (QF) muscle performed isometric contractions. The EMG, MMG, and Force signals were recorded from rectus femoris (RF) and vastus medialis (VM) during five voluntarily isometric contractions at 15 degrees, 30 degrees, and 45 degrees of knee flexion angle, while the leg was positioned on a custom-made device. Subjects in both intervention and control groups underwent same recording procedure before and after stretching. No difference between the baseline repeated contractions (before stretching) was ensured by ANOVA for repeated measures while a difference between PRE and POST was analyzed and concluded based on the effect size results. The EMD did not change; however, subcomponents (Delta tEMG-MMG and Delta tMMG-FORCE) showed differences within RF and VM muscles after stretching. The 30 degrees knee flexion angle appears to be a position where isometric contraction intensity needs to be carefully monitored during rehabilitation period.
  • Küçük Resim Yok
    Yayın
    Rectus Femoris and Vastus Medialis Muscles Exhibit Different Dynamics in Processing of Isometric Voluntary Contractions: A Fractal Analysis Study
    (Ieee, 2019) Özturk, Necla; Begovic, Haris; Demir, Pınar; Yagcioğlu, Suha; Can, Filiz
    The purpose of this study is to obtain distinguishing features of the surface EMG (sEMG) generated by the rectus femoris (RF) and vastus medialis (VM) under maximum voluntary contractions by using the fractal analyses method and compare their dynamic behavior. 15 healthy subjects were requested to produce 5 consecutive maximum voluntary isometric contractions of quadriceps muscle, each lasting 5 seconds with a resting period of 10 seconds between contractions at a knee flexion angle of 15o. Force produced by quadriceps muscles and sEMG from RF and VM were recorded. Correlation dimension and root mean square (rms) values of stationary part of each sEMG were computed. Two-way ANOVA analysis for repeated measures reveled that the mean of the correlation dimension was 1.388 +/- 0.004 for RF and 1.376 +/- 0.007 for VM. There was a significant main effect for muscle (p = 0.027) whereas there was not a significant effect for time (p = 0.918). The means of the rms of the sEMG signals from RF and VM were not significantly different. It was concluded that the processes in producing sEMG in RF are more complex than that in VM and the correlation dimension can be used as a distinguishing feature of RF and VM.