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Symmetry of electromechanical delay, peak torque and rate of force development in knee flexors and extensors in female and male subjects

Szpala A., Rutkowska-Kucharska A., Stawiany M.

Acta of Bioengineering and Biomechanics

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2015

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Vol. 17, no. 1

61--68

EN

Purpose: The aim of the study was to evaluate electromechanical delay (EMD), peak torque (PT) and rate of force development (RFD) in selected muscles of right and left lower extremities in groups of female and male subjects. Methods: The study evaluated 9 volunteer female subjects (mean ± SD: age: 21.67 ± 0.87 years; height: 168 ± 7 cm; body mass: 59.44 ± 4.8 kg) and 10 male university students (mean ± SD: age 22 ± 1.25 years; height: 179 ± 6 cm; body mass: 74.3 ± 5.1 kg) from the Faculty of Physical Education. Muscle torques and electromyographic activity were measured for knee flexors and extensors in static conditions, separately for the right and the left lower extremities. During the measurements, the subjects generated the maximum torque as fast as possible. Surface electrodes were placed on the right and left lower extremities on the following muscles: rectus femoris, vastus lateralis (m.VL), vastus medialis and biceps femoris. Results: Symmetry of EMD, RFD and “flexors-extensors” ratio was found in the muscles of the right and left lower extremities (with an exception of m.VL) in the group of male and female subjects. Statistical analysis demonstrated the presence of asymmetry in PT (297.66 vs. 272.05 N⋅m) and relative force in knee extensors in the group of men (3.90 vs. 3.54 N⋅m⋅kg–1). Conclusions: Symmetry of EMD and asymmetry of PT might suggest that the cause of asymmetry of the muscular force is mainly morphological characteristics of the muscle rather than the process of controlling its activity.

2

Electromechanical delay of abdominal muscles is modified by low back pain prevention exercise

Szpala A., Rutkowska-Kucharska A., Drapala J.

Acta of Bioengineering and Biomechanics

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2014

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Vol. 16, no. 3

95--102

EN

The objective of the research was to assess the effect of a 4-week-long training program on selected parameters: electromechanical delay (EMD) and amplitude of electromyographic signal (EMG). Fourteen female students of the University School of Physical Education participated in the study. Torques and surface electromyography were evaluated under static conditions. Surface electrodes were glued to both sides of the rectus abdominis (RA), external oblique (EO), and erector spinae (ES) muscles. The 4-week-long program was aimed at strengthening the abdominal muscles and resulted in increased EMD during maximum torque production by flexors of the trunk, increased amplitudes of the signals of the erector spinae (p = 0.005), and increased EMG amplitude asymmetry of the lower (p = 0.013) and upper part (p = 0.006) of the rectus abdominis muscle. In a training program composed of a large number of repetitions of strength exercises, in which the training person uses their own weight as the load (like in exercises such as curl-ups), the process of recruitment of motor units is similar to that found during fatiguing exercises and plyometric training.

3

Two stage EMG onset detection method

Drapała J., Brzostowski K., Szpala A., Rutkowska-Kucharska A.

Archives of Control Sciences

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2012

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Vol. 22, no. 4

427-440

EN

Detection of the moment when a muscle begins to activate on the basis of EMG signal is important task for a number of biomechanical studies. In order to provide high accuracy of EMG onset detection, we developed novel method, that give results similar to that obtained by an expert. By means of this method, EMG is processed in two stages. The first stage gives rough estimation of EMG onset, whereas the second stage performs local, precise searching. The method was applied to support signal processing in biomechanical study concerning effect of body position on EMG activity and peak muscle torque stabilizing spinal column under static conditions.

4

Asymmetry of electromechanical delay (EMD) and torque in the muscles stabilizing spinal column

Szpala A., Rutkowska-Kucharska A., Drapała J., Brzostowski K., Zawadzki J.

Acta of Bioengineering and Biomechanics

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2010

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Vol. 12, no. 4

11-18

EN

Stabilization of the spinal column is ensured by the activity of trunk flexor and erector muscles, including rectus abdominis (RA) and erector spinae (ES). The goal of this study was to evaluate the symmetry of action potential and electromechanical delay (EMD) in RA and ES during generation of maximal muscle torque. In the present study, the symmetry of EMG activity in the right and left parts of RA and ES was tested under isometric conditions. The subjects (N = 13) were selected from the university population. Electromyographic signals and muscles torques were recorded with the sampling frequency of 1000 Hz. Lack of significant differences in EMD between left and right sides in both muscles studied and lack of correlation between EMD and maximal muscle torque were observed. Analysis aimed at assessing the symmetry of EMG signals amplitude revealed crossed laterality characterized by increased activity in the right side of RA muscle and left side of ES. The proportion of maximal muscle torque in ES to RA in the women examined amounted to 1.7:1.

5

Symmetry of muscle activity during abdominal exercises

Rutkowska-Kucharska A., Szpala A., Pieciuk E.

Acta of Bioengineering and Biomechanics

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2009

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Vol. 11, nr 1

25-30

EN

In this study, the symmetry of EMG activity of right and left parts of rectus abdominis, erector spinae, rectus femoris has been tested during isometric exercises. Subjects (N = 3) were selected from the university population. In each of nine isometric exercises, the position of lower and upper extremities is different in relation to the upper body. Electromyographic signals were recorded from left and right parts of selected muscles at 1000 Hz sampling frequency. Differences in EMG activity between specific exercises for left and right parts of each muscle were tested for significance with a one-way ANOVA. It was concluded that EMG activity of left and right sides of rectus abdominis and rectus femoris does not differ significantly; nevertheless statistically important differences were noticed between left and right sides of erector spine. These findings provide more detailed knowledge and understanding of different forms of abdominal exercises.

6

Foot kinematics in gait of children with cerebral palsy (CP)

Dziuba A., Szpala A.

Acta of Bioengineering and Biomechanics

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2008

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Vol. 10, nr 4

3-6

EN

Cerebral palsy (CP) is a developmental disorder of motor, psychological and emotional functions. Its most typical symptom is a walking disorder. The aim of this study was to analyze children's walking abilities based on basic kinematic parameters. In this research, the analysis of a three-dimensional kinematical movement is used to record the right and left parts of the child's body. The walking skills of two CP children are described. For locomotion analysis, the angular displacements in the right and left knees and ankles and foot distortion in both support and swing phases of the walk were chosen. The kinematic parameters can be helpful in the diagnosis and allow physiotherapists to suggest what exercise program should be develop in order to improve the habit of walking.