Frequency Analyses of Postural Sway during Prolonged (original) (raw)

2014

Selected schools in Slovenia have launched an initiative to replace school chairs with large gymnastics balls (LGBs) in order to improve children’s posture. The rational given was that LGB saffect posture in a way that is beneficial to the body because they mimic the frequencies of body movement during walking. To identify the influence of seating furniture on the frequency of postural sway, the postural dynamics of eight school children were studied. A comparison was made of their posture while they were sitting on a stool and on a LGB, each for 30 minutes. The lumbar lordosis (LL) and pelvicinclination (PI) angles were both studied. They were measured from the sagittal plane with a video measurement system (3 fps). From the time pattern of each angle, calculations were made to determine the frequency spectrum median and distribution of power in frequency spectra at four intervals: 1) 0.01–0.05 s−1, 2) 0.05–0.1 s−1, 3) 0.1–0.33 s−1, and 4) 0.33–0.6 s−1. It was determined that the m...

Comparing static sitting postural sway of healthy young and older adults Comparação da oscilação postural estática na posição sentada entre jovens e idosos saudáveis

2009

Objectives: To describe a new method to analyze the static sitting postural sway and to compare the results of healthy young and older adult subjects. Methods: Thirty-eight healthy subjects took part in the study, including 17 young adults (mean age 23±2.38 years old) and 21 older adults (mean age 67±2.42 years old). The device used to quantify trunk sway was the magnetic field sensor Polhemus ® 3Space Isotrack II. The measurements were taken in the eyes-opened (EO) and eyes-closed (EC) condition with the subjects seated first on a wooden stable surface (SS) then on a foam unstable surface (US) without back or foot support. Each sensory condition was assessed for 90 seconds. The analyzed parameters were: maximum amplitude (Amp), total trajectory (Traj) and mean velocity (Vel) in the sagittal (X) and frontal (Y) planes. Results: In the EO and EC conditions on SS, young adults presented greater postural sway in the X and Y planes on the Traj and Vel parameters. In the US, young adults showed greater Y Traj and Y Vel in the EO and EC conditions, and there was no significant difference between the groups with regard to X Traj and X Vel in the EC condition. The young adults presented greater Amp only in the EOSS condition in the X plane. Conclusions: The young adult subjects presented greater sway in the sitting position than the older adult subjects. In addition, the Polhemus ® device was a useful tool to analyze static sitting postural sway and can be used in future studies that associate static sitting postural sway with the effect of various motor tasks.

Quantitative Analysis of the Limits of Stability in Sitting

Journal of Applied Biomechanics, 2010

This study defines the limits of stability in sitting, and quantitatively assesses two measures of postural control relative to these limits. Young, healthy subjects sat, feet unsupported, on an elevated force plate. The limits of stability were determined by a least square fit of an ellipse to the center of pressure (CoP) excursion during maximal leaning in 8 directions. These were highly symmetrical and centered within the base of support. The ellipses had a mean eccentricity of 0.66 (major axis in the sagittal plane) and covered an area approx. 1/3 of the base of support. The CoP was then monitored over 4 min of quiet sitting, during which the postural sway covered an area <0.05% of the limits of stability and was closely centered within the latter. Finally, targetdirected trunk movements were performed, in 5 directions, at 4 movement speeds and 3 target distances. Increased target distance and movement speed both decreased the margin of stability (distance between the CoP and the limits of stability), as did movement in the frontal plane, reflecting the eccentricity of the limits of stability. These combined findings support the validity of this quantitative method of defining the limits of stability in sitting, for healthy individuals.

Lumbopelvic Kinematics and Trunk Muscle Activity During Sitting on Stable and Unstable Surfaces

Journal of Orthopaedic & Sports Physical Therapy, 2006

A single-group comparative study. Objectives: To compare lumbopelvic kinematics and muscle activation patterns while sitting on stable and unstable surfaces. Background: Unstable surfaces are commonly used during the rehabilitation of certain low back pain disorders. The benefits postulated are increased muscle activity and facilitation of sustainable midrange positions via neuromuscular control. The use of unstable sitting devices in the workplace is controversial, as the postulated increase in muscle activity is thought to lead to a muscle fatigue/pain response. However, little evidence exists for or against the ability of these devices to alleviate or prevent spinal pain.

Comparação da oscilação postural estática na posição sentada entre jovens e idosos saudáveis

Revista Brasileira de Fisioterapia, 2009

A quantitative investigation of lumbar and pelvic postures in standing and sitting: Interrelationships with body position and hip muscle length

International Journal of Industrial Ergonomics, 1992

Lumbar angles, pelvic tilts and hip muscle indices of 25 female and 25 male subjects were measured in standing and in a variety of body positions in order to test hypotheses derived from the model of standing and sitting posture expounded by authors such as and later by Manda! (1991). The model emphasises the interrelationship between the anterior and posterior thigh muscles and the tilt of the pelvis in determining spinal posture in different body positions. The posterior trunk-thigh muscles are held to play a major role in the flattening of the lumbar spine in sitting and the anterior trunk-thigh muscles in accentuating the lumbar curve in standing.

Relevance of adding a triangular dynamic cushion on a traditional chair: A 3D-analysis of seated schoolchildren

Clinical Biomechanics

Background: Low back pain is highly prevalent in the general population and is even reported as early as at primary school. A poor sitting position has been suggested as an etiologic factor. This study analysed, in primary schoolchildren, the influence of a triangular dynamic cushion that aims to help children maintain their physiological lumbar lordosis and to induce movement to reduce the static effect of the sitting position. Methods: Thirty 8-year-old children took part in this study. A 3D analysis combined with electromyography was used to evaluate the biomechanics and the related muscle activation in two sitting positions (with and without a triangular cushion on a horizontal stool) during a 15-minute working task. In addition, the force of the feet on the ground was assessed with a force plate. Findings: The cushion improved the trunk-thighs angle, lumbar lordosis, anterior pelvis tilt, and feet support on the ground (p < 0.0001). In addition, sitting on the cushion appeared to be more dynamic (p < 0.05) and induced a decrease of the lumbar paravertebral muscle activity (p < 0.01). Interpretation: Sitting on a dynamic triangular cushion tends to favour the "ideal" siting position usually described in the literature and to decrease the level of paravertebral muscle recruitment. Seeing that sitting position is a risk factor to develop low back pain, the cushion could be a solution to prevent it.

Cortical activity, kinematics and trunk muscles activity response to pelvis movements during unstable sitting

Technology and Health Care, 2021

BACKGROUND: Balance control is a leading component of human motor activities and its impairment is associated with an increased risk of falling, lower back pain due to impaired motor control mechanism. Prolonged sitting position at workplace is one of the risk factors of reduced postural control and lower back pain. OBJECTIVE: To evaluate theta and alpha waves cortical activity, trunk muscles activity and kinematics in static sitting, dynamic sitting on different platforms: simple wobble board (WB) and wobble board on bearing surface (WBB). METHODS: The kinematics of body segments, electromyography of five trunk muscles, electroencephalography of 32 scalp electrodes were measured during balance tasks in sitting position for 17 subjects with continuous seated position at workplace. RESULTS: Cortical power on WBB1 increase in fronto – central (p< 0.05) region while on WBB2 increase in centro – parietal region (p< 0.05). WBB2 increase more muscles compared with WB2. The amplitude...

Frequency Analyses of Postural Sway during Prolonged (original) (raw)

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