Center Of Pressure Differences Research Articles

Countermovement jump and vertical hop demonstrate braking/deceleration and performance alterations after ACL reconstruction with BMA, DBM, and suture tape augmentation

ObjectivesThis study evaluated countermovement jump and Single Leg Jump measures to identify landing measures that best distinguish a novel Anterior Cruciate Ligament reconstruction technique using bone marrow aspirate, demineralized bone matrix, and suture tape augmentation patients from controls. The secondary objective assessed performance differences between operated and non-operated limbs post-reconstruction. The hypothesis was that novel Anterior Cruciate Ligament reconstruction patients at return to sport would not differ from controls during landing and that the operated limb's performance would not differ from the unoperated limb. MethodsThe study included 31 patients with the novel reconstruction technique matched with controls in a 1:10 ratio based on age, sex, weight, and height. Both groups underwent screening and were compared during a Countermovement Jump. Using a Sparta Science Force Platform, each patient's unoperated and operated limbs were also compared for Single Leg Jump post-op (6.5 months). ResultsTest patients showed no difference in center of pressure during landing of both jumps compared to controls (P=0.27) and the uninvolved limb (P=0.26). Test patients exhibited increased braking impulse relative to the uninvolved limb during Single Leg Jump (P<0.001). Deceleration upon landing of Countermovement Jump was also increased compared to controls (P<0.001). Test patients demonstrated slower concentric time during a Countermovement Jump compared to controls (P=0.03) and significantly slower compared to the uninjured leg (P<0.001). Countermovement Jump height was decreased compared to controls (P<0.001). Single-leg jump height was decreased in the injured limb compared to the uninjured limb (P<0.001). ConclusionsTest patients did not show significant differences in landing motion compared to controls or the uninvolved leg. However, power and performance alterations were evident at Return to Sport after reconstruction. Although these results are quite promising, they may be too preliminary to draw definitive conclusions. Double and single-legged assessments should be considered in return-to-sport decision-making.

Are weight shifting and dynamic control strategies different in postmenopausal women with and without type-I osteoporosis?

Tracking postural control processes at dynamic conditions might help develop an appropriate rehabilitation program in osteoporotic women. This study aimed to investigate the differences in center of pressure (COP) control at weight shifting and dynamic tasks between postmenopausal women with and without type-I osteoporosis. Also, we investigated the correlations between bone mineral density (BMD), the activity-specific balance confidence questionnaire (ABC-Q) score, and postural control parameters. A total of 62 volunteer postmenopausal women participated in this study. The participants were classified into non-osteoporotic (NOP, T-score>1, n=35, age=60.04±5.33years) and osteoporotic (OP, T-score<-2.5, n=27, age=61.88±5.34years) groups. The COP sway was recorded using a Kistler force plate during performance-based Limits of Stability (LOS), Curve Tracking (CT), Sit to Stand (STS), and Turn tasks. In addition, the level of balance confidence in daily activities was evaluated by ABC-Q. In the LOS task, COP sway velocity in the anterior direction (P=0.02) and COP maximum excursion in the side-to-side direction (right-side P=0.027 and left-side P=0.044) were significantly lower in the OP than the NOP group. In the CT task, all the quantified parameters, including errors and area, showed significantly lower values in the OP group than the NOP group (P<0.05). In the STS task, the rising index score was significantly higher in the OP group than the NOP group (P=0.014). The two groups had an equal ABC-Q score (P=0.175). The COP sway variables correlated significantly with the lumbar and femoral neck T-score (P<0.05). BMD decline can change weight shifting and dynamic postural control in postmenopausal women.

Comparison of Center of Pressure and Kinematic Differences in Grand Plié With and Without the Barre.

The purpose of this study was to determine what differences exist when performing grand plié with and without the barre. Differences in center of pressure (COP) sway, trunk kinematics, and lower extremity kinematics were used in this analysis for both first (P1) and fifth positions (P5). It was hypothesized that use of the barre would result in decreased COP sway, but increased asymmetries in trunk and lower extremity kinematics would be seen compared with the same movements performed without the barre in both positions. Sixteen collegiate dancers (1 male, 15 female) performed three trials of grand plié in P1 and P5 (right leg crossed in front) with or without the barre, for a total of 12 trials. For the barre condition (BC), participants demonstrated less time to complete grand plié, slightly less depth in grand plié, and decreased anterior-posterior (AP) sway compared to the without barre condition (WBC). The BC condition showed increased peak left trunk rotation, right knee flexion, decreased right and left peak hip flexion, and increased right hip abduction in both P1 and P5. Comparing P1 to P5, there was decreased AP sway, decreased peak left trunk rotation, decreased peak right and left hip flexion, increased left hip abduction, and decreased right knee flexion in both BC and WBC conditions. For the BC, there was increased right hip abduction in P1 compared to P5. Our results indicate that while use of the barre provides proprioceptive information, which helps dancers to control balance and learn a motor control strategy, grand plié should also be taught without the barre to challenge the dancer's balance control with different movement patterns in space.

Sport-related Concussions Have A More Conservative Stepping Pattern During Instrumented Tandem Gait Performance

Tandem gait has emerged as a dynamic and clinically viable test of dynamic motor control following sport-related concussion (SRC). A myriad of tools are available to objectively assess gait kinematics. One piece of equipment, the Tekscan Strideway, uses individual load cells on a series of connected force platform tiles to quantify gait. No data exists that examines the performance of SRC using this device. PURPOSE: The purpose of this study was to evaluate the differences in center of pressure (CoP) performance during single-task (ST) and dual-task (DT) tandem gait within 24-48 hours post-SRC. METHODS: 18 Division I [SRC (age: 19 ± 1.00 yr. Male=7, Female=11)] and 18 nearly matched controls [CON (age: 19.88 ± 1.05 yr. Male=7, Female=11)] completed the vestibular ocular motor screening test (VOMS) and 3 trials of ST and 1 trial of DT (serial 7s) using the Tekscan Strideway (30Hz, Boston, MA). The raw CoP trajectory for the best tandem gait trial of each condition (fastest overall) was exported and further analyzed using a custom MATLAB code. All turns during the tandem gait trials were removed and each straight path walking was composed together. The raw CoP data in the AP and ML directions were smoothed using empirical mode decomposition and then excursion and velocity data were calculated. T-tests compared the time to complete ST and DT while two multivariate ANOVAs compared CoP in the AP and ML directions. RESULTS: SRC took significantly longer to complete the ST trial (p=.006; SRC=14.2±4.4s, CON=10.8±2.1s) but not the DT trial (p=.279). The SRC group had a larger VOMS near-point convergence (NPC) (p=.007; SRC=9.5±5.5cm, CON=5.2±2.9cm) and a higher VOMS change score (p<.001; SRC=19.7±6.4, CON=0±0). A significant omnibus effect was noted in AP direction (p=.015) but not in the ML direction (p=.996) for the tandem gait CoP data. Follow-up comparisons noted that in the AP direction during ST, SRC had slower CoP excursion (p=.003; SRC=1.6±0.2cm, CON=1.9±0.4cm) and lower CoP velocity (p=.004; SRC=54.2±7.7cm/s, CON=66.1±14.2cm/s) but no differences during DT. CONCLUSIONS: These results suggest that during instrumented ST tandem gait, SRC have a more conservative and slower heel-to-toe stepping pattern.

Center of pressure excursion and muscle activation during gait initiation in individuals with and without chronic ankle instability

The aim of the current study was to determine differences in center of pressure (COP)excursion and muscle activation during gait initiation (GI) in those with and without chronic ankle instability (CAI). Thirty-four participants, 17 per group, volunteered to participate. Participants were asked to stand barefoot on a force plate before initiating gait upon hearing an auditory cue. Reaction time, anticipatory postural adjustment phase time, as well as normalized peak COP excursion during the anticipatory postural adjustment phase was calculated. Response time of Soleus and Tibialis Anterior muscles were concurrently recorded via electromyography. The results demonstrate a longer reaction time and shorter anticipatory postural adjustment phase time in the CAI group (p < 0.05). No significant between group differences in peak normalized COP excursion were noted (p > 0.05). Muscle onset patterns differed between groups as those with CAI demonstrated earlier Soleus activation compared to the control group (p < 0.05). The results suggest that those with CAI have an altered GI motor control strategy as evidenced by reduced or absent Soleus muscle inhibition during APA phase of GI relative to controls. The APA phase is controlled by the secondary motor area, therefore, the presence of motor control alterations in CAI patients may be due to a supra-spinal alterations.

Balance Performance across the Lifespan Assessed by the Leonardo Mechanograph®: A Cross-Sectional Study.

Reference values of sway parameters have not been published for the Leonardo mechanograph® so far. The aim of this cross-sectional study was to determine normative values on postural control measured by the force plate Leonardo Mechanograph® and to analyze the influence of age and sex on balance performance. A set of standardized standing positions with eyes opened (Romberg, semi-tandem, tandem, unipedal standing) was carried out. Analysis of covariance (ANCOVA) was used to detect age-and sex-related differences in center of pressure (COP) parameters (path length, velocity, elliptical area, anterior-posterior, and medio-lateral directions). Measurements were available for 570 subjects aged 20–86 years. Statistical analysis showed a high effect of age group on postural control (partial n2 between 0.1 and 0.4) with a U-shaped dependency between postural control and age for all area- and path-related COP parameters, with the largest sway in the youngest (aged 20–40) and the oldest age group (aged 60–86). For velocity of COP, a linear deterioration with increasing age was found. Medio-lateral components of COP are likely to indicate the extent of postural control. Significant sex differences were not clearly supported by current findings. Age- and sex-related normative values are a useful resource for diagnostic, research, and training.

Postural deviations in individuals with chronic obstructive pulmonary disease (COPD)

ABSTRACTRATIONALE: While upper back pain in chronic obstructive pulmonary disease (COPD) suggests that postural dysfunction is a potential cause, the extent of postural deviation in COPD is unknown.OBJECTIVE: This study compared postural measurements in people with COPD to healthy controls and explored the relationship between posture deviations and pain in COPD.METHODS: Participants with COPD and age, gender, BMI and comorbidity-matched healthy controls. Participants underwent a postural geometric measurement in upright standing. 3-D motion analysis generated the coordinates of skeletal structures from anatomical landmarks. Participants with COPD completed questionnaires related to pain. Postural stability measures of center of pressure in the anteroposterior (A/P) and mediolateral (M/L) directions, spinal alignment, thoracic kyphosis, scapula and sternal orientation were completed.RESULTS: Twenty-one participants with COPD and 21 matched controls completed the study. The method of postural stability and alignment demonstrated excellent reliability in both groups (all ICC > 0.75). Those with COPD had a trend towards a greater center of pressure M/L sway compared to controls (mean 4.3 cm vs 2.9 cm), with no difference in center of pressure A/P sway. Thoracic kyphosis was greater in COPD (51.8° vs 39.1°, p = 0.001), but there was no difference in spinal alignment (p > 0.05). Those with COPD had an increase in left (p = 0.003) and right (p = 0.002) scapula protraction. Increased thoracic kyphosis and altered scapula position were unrelated to back pain in COPD (all p > 0.05).CONCLUSIONS: Postural deviations are evident in COPD, but the small number of those with pain limited analysis of the association between postural deviations and pain.

Balance and mobility training with or without concurrent cognitive training does not improve posture, but improves reaction time in healthy older adults

Background and aimsThe purpose was to determine whether balance and mobility training (BMT) or balance and mobility plus cognitive training (BMT+C) would reduce postural sway and reaction time (RT) and maintain these improvements after a 12-week follow-up in healthy older adults. MethodsParticipants were allocated to the BMT (n=15; age: 70.2±3.2), BMT+C (n=14; age:68.7±5.5), or control group (n=13; age: 66.7±4.2). The BMT group trained one-on-one, 3×/wk for 12 weeks on a balance obstacle course. The BMT+C group trained one-on-one, 3×/week for 12 weeks on a balance obstacle course while completing cognitive tasks. Participants stood on a force plate for 30s in feet-apart (FA) and semi-tandem (ST) positions while completing simple RT and choice RT tasks at baseline, at the 12-week post-training, and at the 12-week follow-up. Participants were instructed to stand as still as possible while verbally responding as fast as possible to the auditory cues. ResultsNo group differences in center of pressure (COP) Area, COP Velocity, or Sample Entropy of the COP displacement were shown after the training or 12-week follow-up, but the BMT and BMT+C showed faster RT after training and maintained these improvements at the 12-week follow-up compared to the control group. No differences in postural sway or RT emerged between the BMT and BMT+C groups. ConclusionBoth training groups improved RT after the interventions and sustained these improvements over 12 weeks, but showed no reductions in postural sway. Multi-task balance training likely results in reduced attention demand.

An explorative investigation of functional differences in plantar center of pressure of four foot types using sample entropy method

In the study of biomechanics of different foot types, temporal or spatial parameters derived from plantar pressure are often used. However, there is no comparative study of complexity and regularity of the center of pressure (CoP) during the stance phase among pes valgus, pes cavus, hallux valgus and normal foot. We aim to analyze whether CoP sample entropy characteristics differ among these four foot types. In our experiment participated 40 subjects with normal feet, 40 with pes cavus, 19 with pes valgus and 36 with hallux valgus. A Footscan® system was used to collect CoP data. We used sample entropy to quantify several parameters of the investigated four foot types. These are the displacement in medial–lateral (M/L) and anterior–posterior (A/P) directions, as well as the vertical ground reaction force of CoP during the stance phase. To fully examine the potential of the sample entropy method for quantification of CoP components, we provide results for two cases: calculating the sample entropy of normalized CoP components, as well as calculating it using the raw data of CoP components. We also explored what are the optimal values of parameters m (the matching length) and r (the tolerance range) when calculating the sample entropy of CoP data obtained during the stance phases. According to statistical results, some factors significantly influenced the sample entropy of CoP components. The sample entropies of non-normalized A/P values for the left foot, as well as for the right foot, were different between the normal foot and pes valgus, and between the normal foot and hallux valgus. The sample entropy of normalized M/L displacement of the right foot was different between the normal foot and pes cavus. The measured variable for A/P and M/L displacements could serve for the study of foot function.

The Effects of Balance Training on Stability and Proprioception Scores of the Ankle in College Students

Objective: The purpose of this study was to determine if stability and proprioception scores improved on college-aged students using a slack line device. Methods: One group of 20 participants aged 18-23 from a Midwestern university performed a pre-test/post-test on a computerized posturography plate to determine Center of Pressure (CoP) and Limit of Stability (LoS) scores. Participants performed three 20-30 minute sessions per week of balance and proprioceptive training using a Balance Bow for a period of four weeks. Data were analyzed (SPSS 21.0) using a dependent t-test to determine if any changes occurred between pre- and post-test scores after four weeks. Results: The analyses found no significance difference in Center of Pressure (CoP), normal stability eyes open (NSEO), normal stability eyes closed (NSEC), perturbed stability eyes open (PSEO), perturbed stability eyes closed (PSEC), or LoS forward (F), backward (B), or right (R) scores in college-aged participants. A significant difference was found in LoS left (L) and a notable trend towards significance was found in LoS R results. Conclusion: With the exception of LoS L stability scores, it was concluded that 12 sessions of 20-30 minutes, utilizing a slack line device, over a four week training period did not significantly improve stability and proprioceptive scores of the ankle in college-aged participants. Keywords: Proprioception, Limit of Stability (LoS), Center of Pressure (CoP), slack line device

Center of pressure trajectory differences between shod and barefoot running

This study examined differences in center of pressure (COP) trajectories between shod and barefoot running. Ten habitually shod runners ran continuous laps under both shod and barefoot conditions. The COP trajectory was calculated in the global coordinate system but then transformed to the anatomic coordinate system of the foot. The anterior–posterior and medio-lateral positions and excursions of the COP, as well as the most medial location and percent stand at which it occurred were examined. Additionally, external eversion moments and ground reaction forces were assessed. Compared to the shod condition, in the barefoot condition the COP was located more anteriorly early in stance and the COP was located significantly more medially at most time points across stance. There were no differences in external eversion moments during early stance or peak ground reaction forces between conditions. Future studies on mechanical or epidemiological differences between shod and barefoot running may find the COP trajectory an informative parameter to examine.

Postural Asymmetries in Response to Holding Evenly and Unevenly Distributed Loads During Self-Selected Stance

ABSTRACT The authors examined postural asymmetries during quiet stance and while holding evenly or unevenly distributed loads. Right-hand dominant subjects preferentially loaded their right lower limb when holding no load or a load evenly distributed in both hands, but no differences in center of pressure (CoP) were observed between the left and right limbs. However, longer CoP displacement was observed under the preferentially loaded limb, which may reflect a functional asymmetry that allows quick movement of one limb in response to a potential perturbation. When a load was held only in the nondominant hand, sample entropy decreased in the left (loaded) limb but increased in the right (unloaded) limb, suggesting the unloaded foot compensated for a loss of control flexibility in the loaded foot.

Altered postural sway in patients suffering from non-specific neck pain and whiplash associated disorder - A systematic review of the literature

Study designSystematic literature review.ObjectivesTo assess differences in center of pressure (COP) measures in patients suffering from non-specific neck pain (NSNP) or whiplash-associated disorder (WAD) compared to healthy controls and any relationship between changes in postural sway and the presence of pain, its intensity, previous pain duration and the perceived level of disability.Summary of Background dataOver the past 20 years, the center of pressure (COP) has been commonly used as an index of postural stability in standing. While several studies investigated COP excursions in neck pain and WAD patients and compared these to healthy individuals, no comprehensive analysis of the reported differences in postural sway pattern exists.Search methodsSix online databases were systematically searched followed by a manual search of the retrieved papers.Selection CriteriaPapers comparing COP measures derived from bipedal static task conditions on a force plate of people with NSNP and WAD to those of healthy controls.Data collection and analysisTwo reviewers independently screened titles and abstracts for relevance. Screening for final inclusion, data extraction and quality assessment were carried out with a third reviewer to reconcile differences.ResultsTen papers met the inclusion criteria. Heterogeneity in study designs prevented pooling of the data and no direct comparison of data across the studies was possible. Instead, a qualitative data analysis was conducted. There was broad consensus that patients with either type of neck pain have increased COP excursions compared to healthy individuals, a difference that was more pronounced in people with WAD. An increased sway in antero-posterior direction was observed in both groups.ConclusionsPatients with neck pain (due to either NSNP or WAD) exhibit greater postural instability than healthy controls, signified by greater COP excursions irrespective of the COP parameter chosen. Further, the decreased postural stability in people with neck pain appears to be associated with the presence of pain and correlates with the extent of proprioceptive impairment, but appears unrelated to pain duration.

Is balance different in women with and without stress urinary incontinence?

This study investigated whether there are differences in center of pressure (COP) displacement, trunk motion, and trunk muscle activity in women with and without stress urinary incontinence (SUI) during static balance tasks when the bladder is empty and moderately full. Subjects stood on a force plate during six static balance conditions: eyes open, eyes closed, standing on foam with eyes open, standing on foam with eyes closed, tandem stance, and standing on a short base. Electromyographic activity (EMG) of the pelvic floor (PF), abdominal, and erector spinae muscles were recorded using surface electrodes. Motion of the lumbar spine, pelvis, and hips was measured with four inclinometers. Trials were performed with the bladder empty, and when the subject reported a sensation of moderate bladder fullness after drinking 250-1,000 ml of water. Women with SUI had greater COP displacement (range and root mean square), and increased trunk muscle EMG during static balance tests compared to continent women. When tasks were performed with the bladder moderately full, COP displacement and abdominal muscle EMG were increased in both groups. This study demonstrates that women with SUI have decreased balance ability compared to continent women. Increased activity of the PF and trunk muscles in women with SUI may impair balance as a result of a reduced contribution of trunk movement to postural correction or compromised proprioceptive acuity. As compromised balance has been linked to falls risk, further research into balance deficits and falls prevalence in this population is warranted.

Body sway characteristics during static upright posture in young children

This study aimed to determine gender and age differences in center of pressure (COP) during static upright posture in young children and to clarify their body sway characteristics. Subjects were 59 boys and 60 girls (3–6 years of age). Four body sway factors (sway velocity, anterior-posterior sway, medial-lateral sway, and high frequency sway) were used to assess characteristics of COP sway. Subjects' height and body weight did not differ significantly with gender and significantly increased with age. Sway velocity and anterior-posterior sway factors differed significantly with age and gender. For both boys and girls, the factors were larger in 3- and 4-year-old children and larger in boys than in girls at 3 and 4 years of age. In conclusion, sway velocity and anterior-posterior sway of young children change with growth and approach that of adults at 6 years of age. There is no gender difference in the physiques of young children, but boys tend to have greater body sway (faster and larger in the sagittal plane). The changes of sway characteristics in young children with growth may be largely influenced by development of the nervous system rather than by physique.

Deterministic center of pressure patterns characterize postural instability in Parkinson’s disease

Static posturographic recordings were obtained from six Parkinson's patients and six age-matched, healthy control participants. The availability of vision and visuo-spatial cognitive load were manipulated. Postural sway patterns were analyzed using recurrence quantification analysis (RQA), which revealed differences in center of pressure (COP) dynamics between Parkinson's and control participants. AP COP trajectories for the Parkinson's group were not only significantly more variable than for the control group, but also exhibited distinct patterns of temporal dynamics. The visual manipulation did not differentially affect the two groups. No cognitive load effects were found. The results are generally consistent with the hypothesis that pathological physiological systems exhibit a tendency for less flexible, more deterministic dynamic patterns.

Postural adjustments to voluntary head motions during standing are modified following stroke

Objective. To compare postural adjustments to voluntary head motions during standing between stroke and healthy subjects. Design. Quasi-experimental design involving two groups: stroke patients ( n=8) and age-matched healthy controls ( n=5). Background. Massive sensory stimulation from the visual, vestibular and neck proprioceptive systems is conveyed during a voluntary head motion. It remains to be investigated how stroke patients integrate this sensory information and generate appropriate postural adjustments to maintain standing balance. Methods. Eight stroke patients and five healthy age-matched subjects performed fast head motions (up, down, right, left, or none) in random sequence during standing. Body kinematics in 3-D, horizontal displacement of the center of pressure and the body center of mass, as well as bilateral vertical ground reaction forces and activation of tibialis anterior, medial gastrocnemius, vastus lateralis and semitendinosus muscles, were acquired and analyzed. Results. Stroke patients moved their heads at lower velocities while maintaining similar range of motion as compared to healthy subjects. Stroke patients showed larger difference in center of pressure and center of mass excursions and larger root-mean-square values for center of pressure and center of mass displacement and velocity during all directions of head motions. Stroke patients presented disrupted loading patterns to avoid weight bearing of the paretic limb, in contrast to the typical and direction-specific loading patterns observed in healthy subjects during head motions. Conclusions. Stroke patients manifest altered postural adjustments to voluntary head motions during standing. It suggests that sensorimotor integration processes for stance and balance are impaired by a stroke. Relevance Head motions are expected to produce little displacement in body center of mass, as the mass of the head is relatively small as compared to the rest of the body. However, the complex information channeled from vestibular, visual and neck proprioceptive afferents must be processed by the central nervous system in relation to the motor commands, such that head motions can be executed smoothly and rapidly while maintaining standing balance. The altered postural adjustments to head motions observed in stroke patients suggest an underlying impairment in sensorimotor integration.

Measurement of Stern Flow Field of a Ship in Oblique Towing Motion

In this paper, we describe on the results of our investigation on a stern flow field of a ship in oblique towing motion. The purpose of this investigation is to get basic data necessary and available for developing, improving and verifying an estimation method of hydrodynamic forces acting on a ship in manoeuvring motion.We used three VLCC model ships. They have almost same principal dimensions but different stern shapes. One ship has a V shaped stern, another ship has an U shaped stern, and the other ship has a medium shape stern between the V and the U shaped stern.Kinds of experiments that we did are measurement of flow field by 5 hole Pitot tube, observation of flow field by tuft and measurement of hydrodynamic forces acting on a model ship. By these experiments, we investigated characteristics of flow field around a ship in oblique towing motion, and discussed relation among stern shape, flow field and hydrodynamic forces.There is no big difference qualitatively among stern flow field of these three model ships in oblique towing motion, characteristics of which are represented by two groups of separating vortices. However, there are clear differences in strength, concentration and range of distribution of wake and vorticity among three model ships.Concerning to hydrodynamic forces acting on a model ship in oblique towing motion, there is little difference in magnitude itself of hydrodynamic forces, but there is a clear difference in center of pressure that has a serious effect on a ship manoeuvrability.These results will be useful data for framing a flow model, developing, improving and verification of estimation method of flow field and hydrodynamic forces, and for examination of ship stern shape.