Purpose: The work aimed to assess the functioning of the musculoskeletal system within the lumbar spine in relation to everyday postures of sitting and standing. Methods: The comparative analysis was based both on experimental tests and computer simulations performed in the AnyBody Modeling System environment. Input data used to prepare models were based on the information obtained in experimental tests. The test participants were tasked with adopting two postures: 1) standing position and 2) sitting position. Kinematics measurements were performed using the Zebris ultrasonic system. During sitting position, the tests additionally involved the use of a dynamometric platform measuring reaction forces occurring between buttocks and the seat. Results: The comparative analysis included measurements of the trunk inclination angle and the pelvic inclination angle as well as results of computer simulations. The sitting posture is responsible for increased trunk inclination and a change in the position of the pelvis. In terms of the sitting position, it was possible to observe an increase in the loads affecting individual intervertebral joints of the lumbar spine by 155–184% in comparison with the standing posture (100%). Simulations revealed an increased muscle activity of the erector spinae, abdominal internal oblique muscles and abdominal external oblique muscles. Conclusions: Adopting a sitting position increases the loads on the lumbar spine and increases the activity of the erector spinae and abdominal muscles compared to the standing position, which is caused by change in the position of the pelvis and the curvature of the lumbar region.
The aim of the study was to compare the values of selected stability indices registered in the trials in standing with eyes open and without visual control, and in handstand in athletes practicing artistic gymnastics at the highest level of advancement. Methods: The study included 20 athletes practicing artistic gymnastics. The research tool was posturograph CQ-Stab 2P. The results obtained in individual trials were compared using Friedman repeated measures analysis of variance by ranks and then subjected to Dunn post-hoc test with Bonferroni adjustment. Results: Statistically significant differences in the values of stability indices recorded in individual samples were found. Exceptions are the results obtained in the trials with eyes open and without visual control with regard to the size of the surface area delineated by the COP ( p = 0.173) and the frequency of corrective reactions ( p = 0.464), as well as the length of the statokinesiogram path in the mediolateral direction ( p = 0.342), mean velocity of COP movement in the mediolateral direction ( p = 0.246), maximal amplitude of the COP in the mediolateral direction ( p = 0.342) and number of COP displacements in the mediolateral direction ( p = 0.246). Conclusions: In seniors, disabling visual control during free standing as well as adopting a handstand position result in deterioration of the stability indices, which is a resultant of the COP displacement in both directions as well as in the anteroposterior direction. Lack of differences in the values of stability indices in the mediolateral direction suggest that in a free standing position, seniors practicing artistic gymnastics control the movement of the center of foot pressure in the mediolateral direction and eye control is not important for the stability of the body in the frontal plane.
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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.
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Celem pracy było określenie, czy odległość pomiędzy wypadkową siły reakcji podłoża (COP) a osią obrotu stawu skokowo goleniowego w pozycji stojącej jest modyfikowana w zależności od wcześniej wykonanego zadania ruchowego. Analizowano parametry amplitudowe stabliogramu w czterech kolejno następujących po sobie próbach. Zaobserwowano 3 schematy zachowań różniące się dokładnością odtworzenia pozycji wyjściowej. Grupa 1 - badani, którzy powracając do pozycji spoczynkowej minęli punkt wyjściowy. Grupa 2 badani, którzy powracają nic dotarli do punktu wyjściowego. Grupa 3 - badani, którzy powracając dokładnie odwzorowali położenie spoczynkowe.
EN
The aim of work was the answer, is the distance between center of pressure (COP) and axis rotation of ankle in standing position is modify after making physical task. In experiment were analysed amplitude parameters in four tests. It appeared that students with were examined were using 3 different type of behavior. In group 1 (n = 13) after the physical task definitely the distance between center of pressure (COP) and axis rotation of ankle was shorter. In group 2 (n = 6) the distance was longer and in group 3 (n = 8) statistically the distance was precisely the same.
The effect of reach levels, horizontal angles and vertical angles on isometric pull and push strengths of males and females in standing and seated positions was determined. The effect of reach levels on strength varied as a consequence of force direction, working position and gender. Reach level has a significant effect on women's pull strength in the seated position and on push strength in the standing position. The strength value was significantly greater in the extreme reach than in maximum or normal reach. Vertical angle ö had a significant effect on strength consistently in all cases. Strength values increased significantly with the increase of ö angles from 0º to 45º to 90º. The horizontal angle è had a significant influence only on the pull strength of standing and seated men and standing women (not seated woman). The maximum strength was significantly greater at è = 90º.
The isometric pull and push strength profiles of males and females were determined in seated and standing positions in the workspace. The strongest pull strength location was at extreme reach vertically above the shoulder for both males and females. The greatest pull strength of 400 Newtons (N) for males was recorded in the seated and standing positions. Females. pull strengths in the seated and standing positions were 222 and 244 N, respectively. The strongest push strength was always at the maximum reach at the overhead location. Males. maximum push strength was 227 N in the seated position and 251 N in the standing position. Females’ maximum push strength was 96 N in the seated position and 140 N in the standing position. On the average the strength in the standing position was 79% of the seated position. The push strength was 71% of the pull strength and females were 56% as strong as males.
Niniejszy referat zawiera opis parametrów opisujących sylwetkę badanego pacjenta w pozycji stojącej na podstawie obrazów uzyskanych z kamerki internetowej. Rejestracja sylwetki wykonana jest z widokiem z przodu i z tyłu pacjenta. Kamera jest umieszczona w urządzeniu projekcyjno-odbiorczym prążków mory. Wzbogacono w ten sposób możliwości wykorzystania systemu mory nie tylko w diagnostyce ortopedycznej i ortopedii lecz również w ergonomii. Na podstawie analizy obrazów mory i obrazów sylwetki badanych osób na wybranych stanowiskach pracy uzyskano wyniki wspomagające ocenę ergonomiczności tych miejsc pracy
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