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EN
The aim of this study was to compare the activity of upper limb muscles during hand rim wheelchair propulsion and lever wheelchair propulsion at two different velocity levels. Methods: Twenty male volunteers with physical impairments participated in this study. Their task was to push a lever wheelchair and a hand rim wheelchair on a mechanical wheelchair treadmill for 4 minutes at a speed of 3.5 km/h and 4.5 km/h in a flat race setting (conditions of moving over flat terrain). During these trials, activity of eight muscles of upper limbs were examined using surface electromyography. Results: The range of motion in the elbow joint was significantly higher in lever wheelchair propulsion (59.8 ± 2.43°) than in hand rim wheelchair propulsion (43.9 ± 0.26°). Such values of kinematics resulted in a different activity of muscles. All the muscles were more active during lever wheelchair propulsion at both velocity levels. The only exceptions were extensor and flexor carpi muscles which were more active during hand rim wheelchair propulsion due to the specificity of a grip. In turn, the examined change in the velocity (by 1 km/h) while moving over flat terrain also caused a different EMG timing of muscle activation depending on the type of propulsion. Conclusions: Lever wheelchair propulsion seems to be a good alternative to hand rim wheelchair propulsion owing to a different movement technique and a different EMG timing of muscle activity. Therefore, we believe that lever wheelchair propulsion should serve as supplement to traditional propulsion.
EN
The information about the workload on individual muscles in the course of a specific physical activity is essential for targeted prevention, early diagnosis and suitable therapy concerning their overloading and injury. The aim of this study is to evaluate temperature changes in particular skin areas in the course of front crawl swimming, caused by muscle work. Methods: Thermograms were taken of 13 students of Defense University immediately and 15 minutes after swimming 1,000 m focused on 20 regions of the skin over the selected agonists and synergists in upper extremities and body. FLUKE TiR infrared hand camera was used. Results: The results indicated the significant increase in the relative temperatures in the areas of agonists of swimmers’ movement – triceps brachii: from 0.952 to 0.997 of normalized units (nu) on the right and from 0.955 to 0.986 nu on the left. At the same time, the temperature of the muscles participating in lifting the arms above the water surface and stretching them forward – deltoids – increased as well (rear part: from 1.002 to 1.015 nu on the right and from 1.002 to 1.014 nu on the left, sides: from 1.008 to 1.023 nu on the right and from 1.011 to 1.023 nu on the left). Conclusions: In conclusion, the order of the other agonists is as follows: biceps brachii, pectoralis major muscle, and latissimus dorsi. This study provides the options for objective assessment of workload on specific muscles or muscle groups during front crawl swimming.
EN
Stair climbing under backpack load condition is a challenging task. Understanding muscle activation patterns of lower limb during stair climbing with load furthers our understanding of the factors involved in joint pathology and the effects of treatment. At the same time, stair climbing under backpack load requires adjustments of muscle activations and increases joint moment compared to level walking, which with muscle activation patterns are altered as a result of using an assistive technology, such as a wearable exoskeleton leg for human walking power augmentation. Therefore, the aim of this study was to analyze lower limb muscles during stair climbing under different backpack load. Nine healthy volunteers ascended a four-step staircase at different backpack load (0 kg, 10 kg, 20 kg, 30 kg). Electromyographic (EMG) signals were recorded from four lower limb muscles (gastrocnemius, tibialis anterior, hamstring, rectus femoris). The results showed that muscle activation amplitudes of lower limb increase with increasing load during stair climbing, the maximum RMS of gastrocnemius are greater than tibialis anterior, hamstring and rectus femoris whether stair climbing or level walking under the same load condition. However, the maximum RMS of hamstring are smaller than gastrocnemius, tibialis anterior and rectus femoris. The study of muscle activation under different backpack load during stair climbing can be used to design biomechanism and explore intelligent control based on EMG for a wearable exoskeleton leg for human walking power augmentation.
EN
This study examined the electromyographic amplitude–force relationships for 5 (age = 19.20 ± 0.45 yrs) aerobically-trained, 5 (age = 25 ± 4.53 yrs) resistance-trained, and 5 (age = 21.20 ± 2.17 yrs) sedentary individuals. Participants performed an isometric trapezoidal muscle action at 60% maximal voluntary contraction of the leg extensors that included linearly increasing, steady force, and linearly decreasing muscle actions. Electromyography was recorded from the vastus lateralis. The b (slopes) and a (y-intercepts) terms were calculated from the natural log-transformed electromyographic amplitude–force relationships (linearly increasing and decreasing segments) for each participant. An average of the electromyographic amplitude was calculated for the entire steady force segment. The b terms for the resistance-trained (1.384 ± 0.261) were greater than the aerobically-trained (0.886 ± 0.130, P = 0.003) and sedentary (0.955 ± 0.105, P = 0.008) participants during the linearly increasing segment, whereas, there were no differences in b terms among training statuses for the linearly decreasing segment. The b terms for the resistance-trained were greater (P = 0.019) during the linearly increasing segment than decreasing segment (1.186 ± 0.181), however, the b terms for the aerobically-trained were lower (P = 0.017) during the linearly increasing than decreasing segment (1.054 ± 0.176). The a terms from the log-transformed electromyographic amplitude–force relationships and electromyographic amplitude during the steady force segment were not different among training statuses (P = 0.187, P = 0.910). The linearity of the electromyographic amplitude patterns of response (b terms) recording during increasing and decreasing muscle actions may provide insight on motor unit control strategy differences as a result of exercise training status and muscle action, however, the a terms of these patterns and electromyographic amplitude during a steady force contraction did not distinguish among training statuses.
EN
Purpose: The aim of this study is to investigate the drop jump performance of male patients who underwent ACLR and a control group using combined data acquisition system. Methods: A total of 28 male subjects aged 20 to 26 were studied: 22 did not show and were not diagnosed with any knee joint dysfunction (the control group) and six men who underwent ACLR of the left limb (group of patients). The control group was age, height and body mass matched. A data acquisition setup consisting of three independent modules including force platforms, position analysis system and electromyography was used. Subjects were jumping down from 0.1, 0.2, and 0.3 m step heights. The acquired signals were used to determine the ground reaction force, muscular activity, mass centre position, velocity and acceleration. Results: Statistically significant differences were found between the groups (t-test, p < 0.05) in the maximum vertical ground reaction force in the left limb for 0.2 and 0.3 m step heights. Differences in the muscle activity between the groups were found to be statistically significant (t-test, p < 0.05) before the jump, during the landing phase, and after the jump for selected muscle groups and step heights. Conclusion: Combing the three independent measurement systems provided new information on drop jump biomechanics. The distribution of loads in different muscles was not uniform across the groups. Patients allocated more energy to control their motion and seemed to protect their operated limb by shifting the bodyweight to the healthy limb.
EN
The goal of this review was to summarise the scientific findings of research conducted on the triceps brachii muscle using surface electromyography. To achieve this goal, we searched through several articles available from the online databases ScienceDirect and SpringerLink published in the English language between January 2008 and June 2012. We specifically searched for the phrases ‘‘EMG’’ and ‘‘triceps brachii’’ in the title, abstract, keywords or methods sections. From a total of 569 articles we identified 77 potentially relevant studies where 42 studies have been examined triceps brachii muscle activity using surface electromyography that applied in the field of rehabilitation, physiological exercise, sports, and prosthesis control. Among the 42 articles found, 16 studies have been examined triceps brachii muscle activity in rehabilitation, 13 for physiological exercise, 9 for sports, and 4 for prosthesis control in this literature review. We therefore believe that the information contained in this review will greatly assist and guide the progress of studies that use surface electromyography to measure triceps brachii muscle activity in the context of rehabilitation, physiological exercise, sports, and prosthesis control.
EN
The aim of the study was to estimate the influence of trunk inclination on muscle activity during sitting on forward inclined seats without backrest. The group consisting of thirteen healthy women was examined. Based on anthropometrical data two types of sitting position were adopted with two different angles between thighs and trunk: 120 and 135 degrees. Bioelectrical activity of five muscles was recorded. There was observed statistical influence of the trunk inclination on erector spinae, gastrocnemius lat. and tibialis anterior ( p < 0.05). Especially, the inclination of seat pan influenced tibialis anterior activity (10%), although EMG measured during sitting did not exceed 20% of MVC.
8
Content available remote Symmetry of muscle activity during abdominal exercises
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.
PL
W pracy analizowano możliwość oceny aktywności mięśni na podstawie pomiaru zmian temperatury bezpośrednio nad powierzchnią pracujących mięśni. Przedstawiono wyniki pomiaru zmian temperatury na powierzchni skóry nad grupą mięśni zginających przedramię po ćwiczeniach czynnych z oporem, wykonywanych asymetrycznie. Określono optymalne warunki rejestracji termograficznej zmian temperatury skóry nad mięśniem dwugłowym ramienia oraz zależność tych zmian od intensywności ćwiczeń.
EN
The aim of this work was to analyse the possibility of evaluating muscular activity on the basis of temperature changes measured directly over the surface of working muscles. Temperature changes on the skin surface over the group of muscles responsible for flexing the forearm after active exercises with resistance carried out asymmetrically, were measured. The following parameters were determined: optimal conditions for thermal recording of the temperature changes of the skin's surface over the biceps muscle of forearm and the influence of the exercises intensity on temperature distribution.
10
Content available remote Finger curvature movement recognition interface technique using SEMG signals
EN
Purpose: Until recently, keyboard has been used as the primary input method for machinery operation system. But in recent years, numerous methods related to direct input interface have been developed. One of them is to measure the surface electric potential that generates on the skin surface during muscle contraction. Based of this fact, hand finger operation can also be recognized with the help of the surface muscle electric potential. The purpose of this study is to identify the hand finger operation using surface electromyogram (SEMG) during crookedness state of the finger. Design/methodology/approach: Two electrodes (Ag-AgCl electrode) were sticked randomly on the forearm muscles and the intensity of EMG signals at different muscles were measured for each crooked finger. Then depending on the intensity of the obtained electric potentials, a position was located and considered to have participated most actively during the crookedness state of that finger. Thus five locations on the forearm muscles were identified for five different fingers. Moreover, four different types of crookedness states were considered for each finger. Findings: In this experimental study, the electric current that generates on the skin during muscle activity was measured for different hand finger operations. As a result, it is found that there is a specified position related the maximum intensity of EMG signals for each finger. Practical implications: This paper cleared that the amount of crookedness of each finger can also be recognized with the help of surface EMG. It could be used as a machine interface technology in the field of welfare equipments, robot hand operation, virtual reality, etc. Originality/value: The objective of this research project was to develop the method of recognizing the hand finger operation and their crookedness states from surface electromyogram (SEMG).
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