Adaptive autoregressive model for the analysis of center of pressure in healthy subjects during quiet standing

The characteristics of postural sway were assessed in quiet standing under three different postural task conditions in 14 patients with nonspecific chronic low back pain and 12 healthy subjects using linear and nonlinear center of pressure parameters. The linear parameters consisted of area, the mean total velocity, sway amplitude, the SD of velocity, and the phase plane portrait. The nonlinear parameters included the Lyapunov exponent, sample entropy, and the correlation dimension. The results showed that the amount of postural sway was higher in the patients with low back pain compared with the healthy subjects. Assessing the nonlinear parameters of the center of pressure showed a lower sample entropy and a higher correlation dimension in the patients with low back pain compared with the healthy subjects. The results of this study demonstrate the greater regularity and higher dimensionality of the center of pressure fluctuations in patients with nonspecific chronic low back pain, which suggests that these patients adopt different postural control strategies to maintain an upright stance.

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The Effects of Uni- and Bilateral Fatigue on Postural and Power Tasks

Journal of Applied Biomechanics ◽

10.1123/jab.29.1.44 ◽

2013 ◽

Vol 29 (1) ◽

pp. 44-48 ◽

Cited By ~ 7

Author(s):

Paulo H. Marchetti ◽

Maria I.V. Orselli ◽

Marcos Duarte

Keyword(s):

Lower Limb ◽

Healthy Subjects ◽

Postural Sway ◽

Center Of Pressure ◽

Lower Limbs ◽

Quiet Standing ◽

Ground Reaction Forces ◽

Before And After ◽

Reaction Forces ◽

The Mean

The aim of this study was to investigate the effects of unilateral and bilateral fatigue on both postural and power bipedal tasks. Ten healthy subjects performed two tasks: bipedal quiet standing and a maximal bipedal counter-movement jumping before and after unilateral (with either the dominant or nondominant lower limb) and bilateral (with both lower limbs) fatigue. We employed two force plates (one under each lower limb) to measure the ground reaction forces and center of pressure produced by subjects during the tasks. To quantify the postural sway during quiet standing, we calculated the resultant center of pressure (COP) speed and COP area of sway, as well as the mean weight distribution between lower limbs. To quantify the performance during the countermovement jumping, we calculated the jump height and the peak force of each lower limb. We observed that both unilateral and bilateral fatigue affected the performance of maximal voluntary jumping and standing tasks and that the effects of unilateral and bilateral fatigue were stronger in the dominant limb than in the nondominant limb during bipedal tasks. We conclude that unilateral neuromuscular fatigue affects both postural and power tasks negatively.

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The influence of thermoplastic thoraco lumbo sacral orthoses on standing balance in subjects with idiopathic scoliosis

Prosthetics and Orthotics International ◽

10.1177/0309364615589466 ◽

2015 ◽

Vol 40 (4) ◽

pp. 460-466 ◽

Cited By ~ 1

Author(s):

Minoo Khanal ◽

Mokhtar Arazpour ◽

Mahmood Bahramizadeh ◽

Mohammad Samadian ◽

Stephen W Hutchins ◽

...

Keyword(s):

Idiopathic Scoliosis ◽

Healthy Subjects ◽

Center Of Pressure ◽

Center Of Gravity ◽

Quiet Standing ◽

Balance Performance ◽

Lateral Direction ◽

Test Conditions ◽

Postural Changes

Background: Idiopathic scoliosis patients have postural equilibrium problems. Objective: The objective of this study was to assess postural control in subjects with idiopathic scoliosis following a 4-month intervention in an unbraced position. Study design: Quasi-experimental. Methods: Eight healthy girls and eight girls with idiopathic scoliosis took part. A Kistler force platform was used with a frequency of 100 Hz for recording data. The center of pressure was recorded in different positions out of brace for scoliosis and healthy subjects. Test conditions were single limb and double limb stance, with eyes open and closed, and foam and rigid surfaces. Results: The data reflected a weak balance of idiopathic scoliosis subjects compared to healthy subjects. After 1 and 4 months of wearing the brace, center of pressure and center of gravity sway increased in the majority of the tests, although there were no significant differences in any of the test conditions (p > 0.05). While the center of pressure sway in medio-lateral direction decreased after 4 months of wearing a brace, in other variables center of pressure and center of gravity sway increased. Conclusion: Idiopathic scoliosis patients have weak balance in comparison to healthy subjects. In addition, following a period of 4 months of wearing a brace, balance parameters in the scoliosis subjects did not improve. The results show that we need more follow-up of orthoses wearing in idiopathic scoliosis subjects and suggest more studies at least 1-year follow-up to identify the efficiency of brace wear on balance. Clinical relevance Scoliosis can alter postural stability and balance performance during quiet standing. Spinal deformity can alter a subject’s ability to compensate for postural changes and cause gait deviations. This study investigated balance differences between the healthy and idiopathic scoliosis patients and the results of thoraco lumbo sacral orthosis brace wear. It might provide some new insight into the conservative treatment of idiopathic scoliosis patients for clinicians and researchers.

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Prediction of global ionospheric VTEC maps using an adaptive autoregressive model

Earth Planets and Space ◽

10.1186/s40623-017-0762-8 ◽

2018 ◽

Vol 70 (1) ◽

Cited By ~ 8

Author(s):

Cheng Wang ◽

Shaoming Xin ◽

Xiaolu Liu ◽

Chuang Shi ◽

Lei Fan

Keyword(s):

Autoregressive Model ◽

Adaptive Autoregressive Model

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Baropodometric technology used to analyze types of weight-bearing during hemiparetic upright position

Fisioterapia em Movimento ◽

10.1590/s0103-51502012000300014 ◽

2012 ◽

Vol 25 (3) ◽

pp. 583-594 ◽

Cited By ~ 7

Author(s):

Lidiane Teles de Menezes ◽

Paulo Henrique Ferreira de Araujo Barbosa ◽

Abraão Souza Costa ◽

Anderson Castro Mundim ◽

Gabrielly Craveiro Ramos ◽

...

Keyword(s):

Healthy Subjects ◽

Center Of Pressure ◽

Weight Bearing ◽

Upright Position ◽

The Other ◽

Control Group ◽

Gender And Age ◽

Coordination System ◽

Support Area ◽

Arch Index

INTRODUCTION: Although baropodometric analysis has been published since the 1990s, only now it is found a considerable number of studies showing different uses in the rehabilitation. OBJECTIVE: To amplify the use of this technology, this research aimed to analyze baropodometric records during upright position of subjects with hemiparesis, describing a way to define weight-bearing profiles in this population. METHOD: 20 healthy subjects were matched by gender and age with 12 subjects with chronic spastic hemiparesis. This control group was formed to establish the limits of symmetry during weight-bearing distribution in the hemiparesis group. Next, hemiparesis group was submitted to procedures to measure baropodometric records used to provide variables related to the weight-bearing distribution, the arch index and the displacements in the center of pressure (CoP). Data were used to compare differences among kinds of weight-bearing distribution (symmetric, asymmetric toward non-paretic or paretic foot) and coordination system for CoP displacements. RESULTS: Hemiparesis group was compounded by eight symmetrics, eight asymmetrics toward non-paretic foot and four asymmetric toward paretic foot. Significant differences in the weight-bearing distributions between non-predominantly and predominantly used foot did not promote differences in the other baropodometric records (peak and mean of pressure, and support area). Mainly in the asymmetry toward non-paretic foot it was observed significant modifications of the baropodometric records. CONCLUSION: Baropodometric technology can be used to analyze weight-bearing distribution during upright position of subjects with hemiparesis, detecting different kinds of weight-bearing profiles useful to therapeutic programs and researches involving subjects with this disability.

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Assessment of Static Plantar Pressure, Stabilometry, Vitamin D and Bone Mineral Density in Female Adolescents with Moderate Idiopathic Scoliosis

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph17062167 ◽

2020 ◽

Vol 17 (6) ◽

pp. 2167

Author(s):

Liliana Cațan ◽

Simona Cerbu ◽

Elena Amaricai ◽

Oana Suciu ◽

Delia Ioana Horhat ◽

...

Keyword(s):

Vitamin D ◽

Idiopathic Scoliosis ◽

Bone Mineral ◽

Vitamin D3 ◽

Plantar Pressure ◽

Healthy Subjects ◽

Center Of Pressure ◽

Female Adolescents ◽

Z Score ◽

Mineral Density

(1) Background: Adolescent idiopathic scoliosis (AIS) can be associated with vitamin D deficiency and osteopenia. Plantar pressure and stabilometry offer important information about posture. The objectives of our study were to compare static plantar pressure and stabilometric parameters, serum 25-OH-vitamin D3 and calcium levels, and bone mineral densitometry expressed as z-score in patients with moderate AIS and healthy subjects. (2) Methods: 32 female adolescents (idiopathic S shaped moderate scoliosis, main lumbar curve) and 32 gender and age-matched controls performed: static plantar pressure, stabilometry, serum 25-OH-vitamin D3 and calcium levels, and dual X-ray absorptiometry scans of the spine. (3) Results: In scoliosis patients, significant differences were recorded between right and left foot for total foot, first and fifth metatarsal, and heel loadings. Stabilometry showed a poorer postural control when compared to healthy subjects (p < 0.001). Patients had significantly lower vitamin D, calcium levels, and z-scores. Lumbar Cobb angle was significantly correlated with the z-score (r = −0.39, p = 0.02), with right foot fifth metatarsal load (r = −0.35, p = 0.04), center of pressure CoPx (r = −0.42, p = 0.01), CoP displacement (r = 0.35, p = 0.04) and 90% confidence ellipse area (r = −0.38, p = 0.03). (4) Conclusions: In our study including female adolescents with idiopathic S shaped moderate scoliosis, plantar pressure and stabilometric parameters were influenced by the main scoliotic curve.

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Surface height effects on postural control: A hypothesis for a stiffness strategy for stance*

Journal of Vestibular Research ◽

10.3233/ves-1999-9405 ◽

1999 ◽

Vol 9 (4) ◽

pp. 277-286 ◽

Cited By ~ 8

Author(s):

Mark G. Carpenter ◽

James S. Frank ◽

Cathy P. Silcher

Keyword(s):

Postural Control ◽

Center Of Pressure ◽

High Surface ◽

Quiet Standing ◽

Vestibular Input ◽

Mean Power ◽

Mean Power Frequency ◽

Balance Confidence ◽

Eyes Closed ◽

Ankle Stiffness

One possible factor influencing the control of upright stance is the perceived threat to one's personal safety, i.e. balance confidence. We explored this factor by examining the control of stationary stance when standing on an elevated platform under various conditions of reduced visual and vestibular inputs. Twenty-eight adults (14 male and 14 female, mean age = 23.5 years) participated in the experiment. Postural control was examined by recording the amplitude variability (RMS) and mean power frequency (MPF) of center of pressure excursions (COP) over a 2-minute interval while participants stood in a normal stance on a low (0.19 m) and a high (0.81 m) platform with toes positioned either at or away from the edge of the platform. Vision was manipulated through eyes open and eyes closed trials. Vestibular input was reduced by tilting the head into extension [1]. Anterior-posterior RMS and MPF of COP were significantly influenced by an interaction between surface height and vision. When vision was available, a significant decrease in RMS was observed during quiet standing on a high surface compared to a low surface independent of step restriction. When vision was available MPF increased when subjects were raised from a low to a high surface. The mean position of the COP was significantly influenced by an interaction between height and step restriction. Differences in RMS and MPF responses to height manipulation were observed between genders in eyes closed conditions. Vestibular input influenced postural control at both low and high levels with significant increases in RMS when vestibular input was reduced. The reciprocal changes observed in RMS and MPF suggest modifications to postural control through changes in ankle stiffness. Vision appears to play a role in increasing ankle stiffness when balance confidence is compromised.

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Effect of Eye-Object Distance on Body Sway during Galvanic Vestibular Stimulation

Brain Sciences ◽

10.3390/brainsci8110191 ◽

2018 ◽

Vol 8 (11) ◽

pp. 191 ◽

Cited By ~ 1

Author(s):

Osamu Aoki ◽

Yoshitaka Otani ◽

Shinichiro Morishita

Keyword(s):

Healthy Subjects ◽

Center Of Pressure ◽

Force Plate ◽

Distance Effect ◽

Vestibular Stimulation ◽

Galvanic Vestibular Stimulation ◽

Body Sway ◽

Mean Square ◽

Visual Condition ◽

Object Distance

Gazing at objects at a near distance (small eye-object distance) can reduce body sway. However, whether body sway is regulated by movement in the mediolateral or anteroposterior direction remains unclear. Galvanic vestibular stimulation (GVS) can induce body tilting in the mediolateral or anteroposterior direction. This study examined the directionality of the eye-object distance effect, using body-tilting GVS manipulations. Ten healthy subjects (aged 21.1 ± 0.3 years) stood on a force plate covered with a piece of foamed rubber and either closed their eyes or gazed at a marker located 0.5 m, 1.0 m, or 1.5 m in front of them. The GVS polarities were set to evoke rightward, forward, and backward body tilts. To compare the effects of eye-object distance in the mediolateral and anteroposterior directions, the root mean square (RMS) of the center of pressure (COP) without GVS was subtracted from the COP RMS during GVS. For swaying in the mediolateral direction, significant visual condition-related differences were found during rightward and forward GVS (p < 0.05). Thus, reductions in mediolateral body sway are more evident for smaller eye-object distances during rightward GVS. It would be appropriate to use body-tilting GVS to detect the directionality of the eye-object distance effect.

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Characteristics of Functional Stability in Young Adolescent Female Artistic Gymnasts

Journal of Human Kinetics ◽

10.2478/hukin-2021-0051 ◽

2021 ◽

Vol 77 (1) ◽

pp. 51-59

Author(s):

Agnieszka Opala-Berdzik ◽

Magdalena Głowacka ◽

Kajetan J. Słomka

Keyword(s):

Postural Control ◽

Center Of Pressure ◽

National Level ◽

Stability Limit ◽

Young Adolescent ◽

Quiet Standing ◽

Adolescent Female ◽

Functional Stability ◽

Postural Control System ◽

Stability Limits

Abstract The aim of this study was to determine whether young adolescent female artistic gymnasts demonstrate better functional stability than age- and sex-matched non-athletes. Different characteristics of the gymnasts’ postural control were expected to be observed. Twenty-two 10- to 13-year-old healthy females (ten national-level artistic gymnasts and twelve non-athletes) participated in the study. To assess their forward functional stability, the 30-s limit of stability test was performed on a force plate. The test consisted of three phases: quiet standing, transition to maximal forward leaning, and standing in the maximal forward leaning position. Between-group comparisons of the directional subcomponents of the root mean squares and mean velocities of the center of pressure and rambling-trembling displacements in two phases (quiet standing and standing in maximal leaning) were conducted. Moreover, anterior stability limits were compared. During standing in maximal forward leaning, there were no differences in the center of pressure and rambling measures between gymnasts and non-athletes (p > 0.05). The values of trembling measures in both anterior-posterior and medial-lateral directions were significantly lower in gymnasts (p < 0.05). Both groups presented similar values for anterior stability limits (p > 0.05). The comparisons of rambling components may suggest a similar supraspinal control of standing in the maximal leaning position between gymnasts and healthy non-athletes. However, decreased trembling in gymnasts may indicate reduced noise in their postural control system possibly due to superior control processes at the spinal level. The anterior stability limit was not influenced by gymnastics training in female adolescents.

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Differences in Balance Function Between Cancer Survivors and Healthy Subjects: A Pilot Study

Integrative Cancer Therapies ◽

10.1177/1534735418790387 ◽

2018 ◽

Vol 17 (4) ◽

pp. 1144-1149 ◽

Cited By ~ 6

Author(s):

Shinichiro Morishita ◽

Yuta Mitobe ◽

Atsuhiro Tsubaki ◽

Osamu Aoki ◽

Jack B. Fu ◽

...

Keyword(s):

Muscle Strength ◽

Cancer Survivors ◽

Healthy Subjects ◽

Center Of Pressure ◽

Healthy Adults ◽

Body Sway ◽

Balance Function ◽

Adult Cancer Survivors ◽

Eyes Open ◽

The Mean

Older adults who have survived cancer experience significantly more falls compared with healthy adults. Adult cancer survivors may also have a lower balance function than healthy adults. We examined muscle strength and balance function among 19 cancer survivors and 14 healthy subjects. The mean age of the cancer survivors was 51.5 ± 11.2 years; 6 men and 13 women. Cancer diagnoses included breast cancer, retroperitoneal sarcoma, acute leukemia, lung cancer, colorectal cancer, thyroid cancer, Ewing’s sarcoma, and tongue cancer. The mean age of healthy subjects was 47.4 ± 14 years; 3 men, 11 women. Muscle strength was assessed using hand grip and knee extensor strength tests. Balance function was evaluated using the Timed Up and Go (TUG) test, and body sway was tested using a force platform. No significant differences were found with respect to right and left grip strength or right and left knee extension strength between the 2 groups. A significantly higher TUG time was observed in cancer survivors than in healthy subjects ( P < .05). With eyes open, the area of the center of pressure was significantly larger in cancer survivors than in healthy subjects ( P < .05). Similarly, the length per area was significantly lower both with eyes open and closed for cancer survivors than for healthy subjects ( P < .05). TUG was significantly correlated with muscle strength in both groups ( P < .05). However, no body sway parameters were related to muscle strength in either group. Cancer survivors had lower balance function that might not have been related to muscle strength. Cancer survivors should be evaluated for balance function as there is a potential for impairment. The findings of this study will be relevant for planning the prevention of falls for cancer survivors.

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