Center Of Pressure Excursion Research Articles

Effects of pain exacerbation on postural control in women with patellofemoral pain during single leg squat: a cross-sectional study

BackgroundThe center of pressure (COP) excursion parameters are recognized as risk factors for the etiology and development of patellofemoral pain (PFP). The purpose of the present study measures the effect of pain exacerbation on COP excursion, and the correlation between pain intensity and COP excursion in women with PFP during single leg squat (SLS).MethodsSixty patients with PFP participated in this cross-sectional study. The outcome measures were included pain intensity and COP excursion which evaluated in pre and post pain exacerbation during SLS. The COP parameters were evaluated during single leg squat in 60° of knee flexion. A paired t-test and MANOVA was used to compare pain intensity and COP excursion between the two conditions, respectively. Furthermore, A Pearson’s correlation matrix was used to examine the relationship between pain intensity with COP excursion.ResultsStatistical analysis showed that pain intensity (t = − 16.655, p < 0.001) and COP excursion (Wilks’ Lambda = 0.225, p < 0.001) with medium effect size increased after PFJ loading. In addition, an excellent positive correlation was observed between increased in pain intensity and COP excursion (P < 0.001, r > 0.80).ConclusionAfter PFJ loading, women with PFP presented increases in the pain intensity, COP excursions, and sway velocity. In addition, there was an association between the increase in pain intensity and COP excursions. Clinicians aiming to improve postural control of patients with PFP could use kinesio taping as a short-term intervention and balance training to improvements in postural control at medium and long-term. Furthermore, emphasizing psychological factors to reducing kinesiophobia can be useful to restoring proper movement pattern, reducing pain and improving symptoms.

Short-term effects of kinesiology taping on static and dynamic balance in healthy subjects.

As a therapeutic tool, kinesiology taping (KT) has become increasingly popular for musculoskeletal injuries utilized by physiotherapists. KT has been found to have effects on facilitating muscle strength by generating a concentric pull on the fascia. However, little is known about KT in the improvement of dynamic and static balance. This study aims to explore whether KT on the quadriceps muscle has any immediate effects on static and dynamic balance. Twenty-seven healthy individuals (13 males and 14 females, aged 22 to 29) were recruited in a crossover study with two conditions: KT and no taping. KT was applied to the quadriceps muscle for the taping group, with the control receiving no taping. Pre- and post-test measurements were taken to give an indication of the effect of the tape on balance performance. Center of Pressure Excursion (COPE) and Time to Stabilization (TTS) when landing from a hop test and Y Balance test combined score (YBTCS) were used to assess a stabilizing balance activity and a dynamic balance. The pre- and post-intervention were collected, with differences explored using repeated measures ANOVA with time and condition (tape) factor analysis. We found a significant improvement (p ≤ 0.05) with a moderate to large effect size in YBTCS between KT and no taping, indicating enhanced balance performance in the KT group. However, no significant difference (p ≥ 0.05) with small to moderate effect size was found in COPE or TTS between the two conditions during landing tests, suggesting similar balance capabilities in these specific measures. The use of KT shows no significant immediate effect on static balance in healthy individuals when applied to the quadriceps muscles; however, it demonstrates a positive immediate effect on dynamic balance.

Comparison between six-week exergaming, conventional balance and no exercise training program on older adults’ balance and gait speed

Abstract We evaluated differences between a six-week exergame-training and a conventional balance training program on the balance and gait speed of older adults’ (&gt;65 years). Forty-two healthy participants were recruited from independent living and community centers and randomized to one of three groups: exergaming balance training (EBT), conventional balance training (CBT), or control (no training). The participants completed two balance measurements (Fullerton Advanced Balance Scale (FAB) and center of pressure (COP) excursion), and gait speed at pre, post-intervention, and after a three-week follow-up. Both EBT and CBT groups improved their scores on the FAB, COP displacement, and gait speed post-intervention (p&lt;0.05) and these changes were maintained and did not return to pre-training values after three weeks of detraining. The control group scores for FAB and gait velocity values declined (p&lt;0.001) but not COP excursions during the study. This six-week exergame training program improved balance control and gait speed in community-dwelling seniors in a similar fashion to conventional training. Participants’ physical abilities scores improved and were maintained following three weeks of detraining. Exergame-based training therefore may be considered as an intervention that can address balance control and gait speed in older adults. As well improved scores can be maintained with transient or sporadic activity.

A comparison of the effects of mediolateral surface and foot placement perturbations on balance control and response strategies during walking

BackgroundBalance perturbation studies during walking have improved our understanding of balance control in various destabilizing conditions. However, it is unknown to what extent balance recovery strategies can be generalized across different types of mediolateral balance perturbations. Research questionDo similar mediolateral perturbations (foot placement versus surface translation) have similar effects on balance control and corresponding balance response strategies? MethodsKinetic and kinematic data were previously collected during two separate studies, each with 15 young, healthy participants walking on an instrumented treadmill. In both studies, medial and lateral balance perturbations were applied at 80% of the gait cycle either by a treadmill surface translation or a pneumatic force applied to the swing foot. Differences in balance control (frontal plane whole body angular momentum) and balance response strategies (hip abduction moment, ankle inversion moment, center of pressure excursion and frontal plane trunk moment) between perturbed and unperturbed gait cycles were evaluated using statistical parametric mapping. ResultsBalance disruptions after foot placement perturbations were larger and sustained longer compared to surface translations. Changes in joint moment responses were also larger for the foot placement perturbations compared to the surface translation perturbations. Lateral hip, ankle, and trunk strategies were used to maintain balance after medial foot placement perturbations, while a trunk strategy was primarily used after surface translations. SignificanceSurface and foot placement perturbations influence balance control and corresponding response strategies differently. These results can help inform the development of perturbation-based balance training interventions aimed at reducing fall risk in clinical populations.

Postural stability of adults with down syndrome – differences between women and men

ObjectiveThis study aimed to analyse differences in postural stability (PS) between adults with Down syndrome (DS) and adults without DS of the same age and to compare the PS between men and women with DS.MethodsTwenty-six individuals with DS (mean age 38.4 ± 8.7 yrs.) and 26 individuals without DS (mean age 38.8 ± 9.2 yrs.) participated in the study. Postural stability was measured using a pressure sensing platform MobileMat 3140 (Tekscan) in these modifications of the bipedal stance: a. wide base of support with the eyes open (WO); b. wide base of support with the eyes closed (WC); c. narrow base of support with the eyes open (NO). Six parameters of PS were compared in the statistical analysis: centre of pressure (COP) path length, COP excursion front-back, COP excursion left-right, COP velocity average, time to boundary (TTB) front-back, and TTB left-right.ResultsMost PS variables (COP path length, COP excursion left-right, COP velocity average, TTB front-back) indicate significantly lower PS of adults with DS than that of the reference group (p < 0.05). Some PS variables (COP path length and COP velocity average in WC, COP excursion front-back and COP excursion left-right in NO) showed differences between men and women in more demanding conditions, indicating lower PS in men with DS.

The relationship between cervical spine range of motion and postural sway in mechanical neck pain: A cross-sectional study.

Impairments in postural sway have been identified in people with mechanical neck pain. The influence of cervical spine range of motion (ROM) on postural sway is unclear in mechanical neck pain (MNP). This study investigated the relationship between cervical spine range of motion (ROM) and postural sway in MNP. The cervical ROM was measured using the Cervical Range of Motion (CROM) device. Standing postural sway characterised by mean centre of pressure (COP) measurements in the anterior posterior (AP) and medio-lateral direction with eyes closed and feet together condition was recorded on a posturography platform. Pearson product moment correlation coefficient was used to identify the relationship between cervical ROM and postural sway. Seventy-two MNP individuals (Mean age: ) of either sex (Male: ) were recruited. Overall, no statistically significant correlations were identified between cervical spine ROM in sagittal and frontal plane and postural sway (r values ranging from 0.00 to ; p-values ). However, a weak negative correlation was present between the cervical rotation and AP (r-; p-) and mediolateral (r-; p-) COP excursion. The cervical spine ROM was found to have a weak relationship with postural sway in individuals with MNP. This suggests the investigation of other mechanisms especially muscle tension which might be responsible for altered postural sway in MNP.

Evaluation of stability of the subjects with toe in gait due to increase in femoral head anteversion angle during quiet standing

Background: Toe in gait may be due to metatarsus adductus, increase in tibia torsion and femoral anteversion. It is controversial that it influences on standing stability or not. Therefore, the aim of this study was to evaluate the effects of toe in gait, due to increase in femoral head anteversion, on standing stability. Method: 11 subjects with toe in gait due to increase in femoral head anteversion were recruited in this study. There was also a control group matched with the toe in gait group. A Kistler force plate was used to evaluate stability of the subjects during quiet standing based on center of pressure (COP) sways. Results: The mean values of center of pressure (COP) excursion in anteroposterior direction was 14.41±4.66 and 23.41± 8.17 mm in normal and those with toe in gait, respectively (p-value &lt;0.05). The difference between COP excursion in mediolateral direction in both group was not significant (p-value=0.085). There was a significant difference between velocity and path length of COP in both planes between the groups (p-value&lt;0.05). Conclusion: Based on the results of this study, the subjects with toe in gait due to increase in femoral head anteversion are more unstable in quiet standing than normal subjects.

Practice walking on a treadmill-mounted balance beam modifies beam walking sacral movement and alters performance in other balance tasks.

The goals of this study were to determine if a single 30-minute session of practice walking on a treadmill mounted balance beam: 1) altered sacral marker movement kinematics during beam walking, and 2) affected measures of balance during treadmill walking and standing balance. Two groups of young, healthy human subjects practiced walking on a treadmill mounted balance beam for thirty minutes. One group trained with intermittent visual occlusions and the other group trained with unperturbed vision. We hypothesized that the subjects would show changes in sacrum movement kinematics after training and that there would be group differences due to larger improvements in beam walking performance by the visual occlusions group. We also investigated if there was any balance transfer from training on the beam to treadmill walking (margin of stability) and to standing static balance (center of pressure excursion). We found significant differences in sacral marker maximal velocity after training for both groups, but no significant differences between the two groups from training. There was limited evidence of balance transfer from beam-walking practice to gait margin of stability for treadmill walking and for single leg standing balance, but not for tandem stance balance. The number of step-offs while walking on a narrow beam had the largest change with training (partial η2 = 0.7), in accord with task specificity. Other balance metrics indicative of transfer had lower effect sizes (partial η2<0.5). Given the limited transfer across balance training tasks, future work should examine how intermittent visual occlusions during multi-task training improve real world functional outcomes.

The relationship of multifidus and gastrocnemius muscle thickness with postural stability in patients with ankylosing spondylitis.

This study aimed to investigate potential changes in the thickness of the multifidus and gastrocnemius muscles and to demonstrate the association of muscle thickness with postural stability in ankylosing spondylitis (AS) patients. The cross-sectional observational study enrolled 32 AS patients (23 males, 9 females; mean age: 39.4±7.2 years; range, 18 to 65 years) diagnosed according to the modified New York criteria and 32 healthy controls (22 males, 10 females; mean age: 36.6±7.5 years; range, 18 to 65 years) between April 2017 and October 2018. Plantar center of pressure (CoP) excursions were recorded using a pressure platform to evaluate postural stability. The thickness of the lumbar multifidus and gastrocnemius muscles was measured using ultrasound. Patients with AS showed reduced muscle thickness at the multifidus (p<0.05) muscle and medial gastrocnemius (p=0.002) and lateral gastrocnemius (p=0.002) muscles compared to controls. Increased CoP excursions were observed only in the anteroposterior direction in the double-leg (standard) stance with the eyes closed (p=0.003) and in both anteroposterior and mediolateral directions in tandem and single-leg stances (all p<0.05). Center of pressure excursions in standard stance with the eyes closed were negatively correlated with all muscle thickness values (all p<0.05). In the single-leg stance, CoP excursions were negatively correlated with muscle thickness of medial gastrocnemius (p=0.008) and lateral G (p=0.016) muscles. Early planning of exercise programs taking muscle loss into account can help improve balance and thereby prevent falls and fractures in AS patients.

The effect of six week virtual reality training on the improvement of functional balance in women with type-I osteoporosis: A preliminary study.

This preliminary study aimed to investigate the effects of exergames in a virtual reality environment to improve functional balance during goal-directed functional tasks in postmenopausal women with osteoporosis. Twelve volunteer postmenopausal women with osteoporosis were randomly assigned to virtual reality (VRT, n = 6) and conventional multimodal (CMT, n = 6) training groups. The exercise was performed for 6weeks, 3days weekly, and 18 sessions. Using a force platform, functional balance assessments were made through four dynamic tasks, including performance-based limits of stability (LOS), curve tracking (CT), sit-to-stand (STS), and turning before and after 18 sessions of treatment. Each task's time-dependent center of pressure (COP) variables was separately calculated via Kistler-Mars software. The COP variables of LOS and CT tasks were significantly improved after 6weeks of CMT and VRT (P ≤ 0.05). In the VRT group, the rising index (P < 0.00), COP sway velocity in STS, and Turn sway were significantly reduced (P < 0.05). Following the VRT, the mean difference of forwarding maximum COP excursion increased (P = 0.03), and errors in CT (P = 0.03) significantly decreased. The VRT and CMT improved the COP sway parameters during weight-shifting tasks. The VRT was more effective than CMT in increasing the ability to control weight-shifting and dynamic functional tasks in postmenopausal women with osteoporosis. This approach in training has suitable potential to provide convenient error feedback learning.

Postural balance strategies during landing at the moment of return-to-sports after anterior cruciate ligament reconstruction

Most athletes that return to sport (RTS) after Anterior Cruciate Ligament (ACL) injury undergo reconstruction (ACLR) to restore their knee stability. The major concern for RTS is for the patient to be able to perform challenging dynamic tasks whilst adequately stabilizing the knee joint and maintaining their postural balance. Nevertheless, the interaction between knee protective mechanisms (such as knee unloading and knee stabilisation) and postural balance strategies has not yet been comprehensively analyzed. Thus, the aim of this study was to investigate landing balance strategies in ACLR athletes at time of RTS. Twenty-one athletes with a unilateral ACLR were tested at the time of RTS while performing a single leg hop for distance on both limbs. Three balance mechanisms that influence the GRF during the landing phase (foot placement, center of pressure (CoP) excursion, counter-rotation of segments) were investigated and compared between the ACL injured and uninjured limb. Interactions between knee protective mechanisms and postural balance strategies were tested using a statistical parametric mapping regression analysis. Results show that CoP excursions in the injured limb increased, as well as ankle joint moment contribution to anterior-posterior (A-P) GRF. Besides, patients presenting reduced knee joint contribution to A-P GRF had to compensate with higher hip joint contribution in order to maintain postural balance. In conclusion, ACLR athletes who at RTS still protect their reconstructed knee are forced to employ compensatory postural balance strategies. Therefore, there is a persistent trade-off between knee protection and postural balance at the moment of RTS.

Tandem Gait Center Of Pressure Following Sport-related Concussion

Tandem gait is becoming a widely used sideline tool to evaluate dynamic postural control following sport-related concussion (SRC). Little to no research has evaluated tandem gait center of pressure (COP) following SRC compared to the traditional temporal characteristics. PURPOSE: Compare the differences from baseline to acute SRC post-injury using temporal and COP metrics in tandem gait. METHODS: 8 NCAA Division 1 athletes (age = 20 ± 1 years) performed tandem gait prior to their competitive season (PRE) and within 24-48 hours post-injury (POST) using an instrumented walkway (30 Hz, Tekscan Strideway, Tekscan Inc., South Boston, MA). The head team physician independently verified and diagnosed the SRC. During tandem gait, student-athletes were instructed to walk 3-meters, turning en pointe, and returning to the start position walking heel-to-toe as fast as possible. Three randomized trials of single-task (ST) and dual-task (DT) were completed and the raw center of force from the Strideway was exported and further analyzed. COP excursion in the mediolateral (ML) and mean velocity in the anteroposterior (AP and ML directions were calculated using a custom MATLAB code along with time to completion were evaluated during the entire trial. Multiple RM ANOVAs compare the baseline to post-injury tandem gait. RESULTS: There were no significant differences for ST ML excursion (PRE = 2.78 ± 0.47, POST = 3.61 ± 1.9; p = 0.25), for ST ML velocity (PRE = 16.57 ± 4.38, POST = 22.83 ± 17.68; p = 0.30), for ST AP velocity (PRE = 82.15 ± 16.12, POST = 107.82 ± 64.29; p = 0.196), and for ST time (PRE = 9.9 ± 1.81, POST = 11.82 ± 3.45; p = 0.62). CONCLUSION: The results indicate there are no significant differences between PRE and POST SRC. Although the data does not show any significant difference between times, SRC does generally slow an individual’s velocity thus suggesting a causal relationship exists.

Vertical ground reaction force oscillation during standing on hard and compliant surfaces: The "postural rhythm".

When a person stands upright quietly, the position of the Centre of Mass (CoM), the vertical force acting on the ground and the geometrical configuration of body segments is accurately controlled around to the direction of gravity by multiple feedback mechanisms and by integrative brain centres that coordinate multi-joint movements. This is not always easy and the postural muscles continuously produce appropriate torques, recorded as ground reaction force by a force platform. We studied 23 young adults during a 90 s period, standing at ease on a hard (Solid) and on a compliant support (Foam) with eyes open (EO) and with eyes closed (EC), focusing on the vertical component of the ground reaction force (VGRF). Analysis of VGRF time series gave the amplitude of their rhythmic oscillations (the root mean square, RMS) and of their frequency spectrum. Sway Area and Path Length of the Centre of Pressure (CoP) were also calculated. VGRF RMS (as well as CoP sway measures) increased in the order EO Solid ≈ EC Solid < EO Foam < EC Foam. The VGRF frequency spectra featured prevailing frequencies around 4–5 Hz under all tested conditions, slightly higher on Solid than Foam support. Around that value, the VGRF frequencies varied in a larger range on hard than on compliant support. Sway Area and Path Length were inversely related to the prevailing VGRF frequency. Vision compared to no-vision decreased Sway Area and Path Length and VGRF RMS on Foam support. However, no significant effect of vision was found on VGRF mean frequency for either base of support condition. A description of the VGRF, at the interface between balance control mechanisms and sway of the CoP, can contribute information on how upright balance is maintained. Analysis of the frequency pattern of VGRF oscillations and its role in the maintenance of upright stance should complement the traditional measures of CoP excursions in the horizontal plane.

Standing Posture in Motor and Cognitive Dual-Tasks during Smartphone Use: Linear and Nonlinear Analysis of Postural Control.

Analysis of the center of pressure (CoP) during cognitive or motor dual-tasking is widely used to characterize postural control. Most studies use traditional measures of CoP to quantify postural control, but given its complexity, nonlinear analysis of CoP is of growing interest in the area. This study aims to analyze CoP behavior in healthy young adults during standing posture performance while simultaneously performing motor or cognitive tasks on a smartphone, using linear and nonlinear analysis of CoP. Thirty-six healthy participants (23.08 ± 3.92 years) were found eligible for this study. They performed a single task (ST), cognitive dual-task (cog-DT), and motor dual-task (mot-DT). The total excursion of CoP, displacement of CoP in the anterior-posterior and medial-lateral directions, mean total velocity of CoP, and mean anterior-posterior and medial-lateral velocities of CoP were measured with a force plate. Approximate entropy (ApEn) of the anterior-posterior (ApEn-AP) and medial-lateral (ApEn-ML) displacement of CoP were also calculated. The results showed that dual-task costs for the total excursion, displacement in the anterior-posterior direction, mean total velocity, and mean anterior-posterior velocity of CoP were greater during the cog-DT than the mot-DT (p < 0.05). In the nonlinear analysis of the CoP, there was no difference (p > 0.05) between the cog-DT and mot-DT for ApEn values of the anterior-posterior and medial-lateral time series of the CoP. Both linear and nonlinear analyses showed differences between the cog-DT and ST (p < 0.05), revealing a decline in postural control during the cog-DT compared with the ST. In conclusion, performing a cog-DT causes sway impairments and lower postural control efficacy compared with motor single and dual-tasks. Furthermore, both linear and nonlinear analyses were able to distinguish between conditions.

Gait ability on center of pressure excursion using a pressure-sensitive mat in the elderly with ischemic stroke: a case–control study with propensity score matching

Background: Center of pressure (COP) is a useful measure for dynamic balance, which directly represents the ability of weight shift and control of the foot, however, there is no study analyzing COP during whole stance phase in the elderly with acute stroke.Methods: A total of 30 acute ischemic stroke patients (mean age±standard deviation [SD], 75.0±5.6 years; 11 females) and 30 propensity score matched controls (mean age±SD, 72.8±5.9 years; 17 females) using age, sex, and Korean version of Mini-Mental State Examination score were finally included. Participants performed barefoot walking trials on a pressure-sensitive mat until 20 footfalls in each limb were corrected. To evaluate gait function based on COP, mean and coefficient of variance as variability were calculated for 3 types of variables as followings: (1) durations of sub-phases in stance phase, (2) mean locations and displacement ranges of COP, and (3) velocities.Results: Significant difference was observed in many of both mean and variability variables. Especially, stroke patients had an increased duration, posterior location of COP, wide range of mediolateral and anteroposterior displacement range, and slow velocity in foot flat phase belonging to the double limb stance. In variability variables, stroke patients had significantly larger variabilities of COP velocities in all sub-phases except in foot flat phase and late propulsive phase were stood out.Conclusions: The elderly with acute ischemic stroke had inefficiency during double limb stance and reduced functional balance in single limb stance in both sides, implying impaired gait ability on COP excursion in these patients.

Relationship between physical activity level and sleep quality with postural control and hemodynamic response in the prefrontal cortex during dual-task performance

Understanding the cortical activation and postural control behavior during dual-task (DT) has been an object of study. However, despite the multiple benefits of exercise and good sleep quality, less is known about the correlation between physical activity (PA) and sleep quality (SQ) on postural control and brain activation under dual-task performance. This study aimed to analyze the correlation between PA level and SQ with postural control performance and hemodynamic response in the prefrontal cortex during the DT performance in young adults. Thirty-four healthy young adults (mean age ± SD = 22.91 ± 3.90 years) participated in this study, and they performed a single-task and cognitive and motor DT using their smartphones. Postural control was assessed using a force plate to record the center of pressure (CoP) data (total excursion of CoP (TOTEX CoP), displacements of the CoP in anterior-posterior (CoP-AP) and medial-lateral (CoP-ML) directions, mean total velocity displacement of CoP (MVELO CoP), mean displacement velocity of CoP in anterior-posterior (MVELO CoP-AP) and medial-lateral (MVELO CoP-ML) directions, amplitude of CoP in anterior-posterior (A-AP) and medial-lateral (A-ML) directions, and 95% confidence ellipse sway area (CEA)). The hemodynamic response was measured by the oxyhemoglobin and deoxyhemoglobin concentrations using the functional near-infrared spectroscopy. The Pittsburg Sleep Quality Index and International Physical Activity Questionnaire-Short Form questionnaires assessed SQ and level of PA, respectively. Results indicated a positive correlation between SQ and cognitive DT cost for CoP-ML (rs = 0.422, p = 0.013), MVELO CoP-ML (rs = 0.422, p = 0.013) and A-ML (rs = 0.579, p < 0.001). There were no significant relations between the other outcomes (p > 0.05). In conclusion, poor sleep quality was associated with a worse postural control performance in CoP-ML, MVELO CoP-ML and A-ML parameters under cognitive dual-task conditions. The differences found in the postural control and hemodynamic response during dual-task performance do not correlate with physical activity level.

Balance Relationships Between the Multi-Directional Reach Test and Upper Body Dressing

Abstract Date Presented 04/01/2022 The Multi-Directional Reach Test’s (MDRT’s) limits of stability when reaching to the right (i.e., cm) statistically correlated with shirt dressing time (doff time rs = -.320, p = .023; total dressing time rs = -.340, p = .016). Center of pressure excursion during the MDRT and shirt dressing were very strongly correlated anteroposteriorly and mediolaterally (rs = .923-.991, p &amp;lt; .001). Time-based dressing tasks may be a robust indicator of balance for OT use but require further investigation. Primary Author and Speaker: Carol Getz Rice Additional Authors and Speakers: Kayla Michaels, Urvi Patel, Cassandra Stahl

Static and local dynamic stability of subjects with knee joint osteoarthritis.

Stability is defined as the ability to control the amplitude and velocity of center of gravity (CoG) changes during quiet standing, and to decrease the risk of falling during walking. Few studies exist which examine the local dynamic stability of those with knee joint osteoarthritis (OA). Nevertheless, it is debatable whether the stability of OA subjects differs from that of normal subjects or not. The aim of this study was to evaluate the static and local dynamic stability of the subjects with knee OA in comparison to normal subjects. Fifteen OA subjects and 15 healthy subjects with matching age, weight, and gender participated in this study. A Qualysis motion analysis system incorporating a Kistler force plate was used to record data during quiet standing and when walking on a treadmill. Static stability was evaluated based on center of pressure (COP) sways excursion, path length and velocity in mediolateral and anteroposterior axes. Local dynamic stability was evaluated by the use of short Lyapunov exponent when subjects walk on treadmill. A two-sample test-test was used for the final analysis (α = 0.05). Mean values of the COP excursion in mediolateral and anteroposterior directions, and the velocity of COP in both mediolateral and anteroposterior directions, differed significantly between healthy and OA subjects (p < 0.05). Local dynamic stability of OA subjects appeared to be reduced compared to healthy subjects, especially when ambulating at higher walking speeds (p-value < 0.05). Study results demonstrated that both static and local dynamic stability decreased in OA subjects. This may be in part due to altered control mechanisms which are required for response to perturbations during standing and walking to ensure stability. As a decrease in local dynamic stability is correlated to an increased risk of falling, it is important that this group should receive appropriate treatment interventions to improve standing and walking stability.

The Effects of a 6-Week Intrinsic Foot Morphology, Kinematics, and Kinetics in Individuals with Pes Planus

CONTEXT: The intrinsic foot muscles are vital in supporting the medial longitudinal arch of the foot. Individuals with pes planus have poor foot morphology, strength, and biomechanics, warranting an intervention. MAIN OUTCOME MEASURES: At pre-intervention, foot posture and arch height were assessed via the Foot Posture Index-6 and the Navicular Drop test, respectively. Cross-sectional area of the abductor hallucis was assessed using ultrasound as an indirect measure of strength. Biomechanical measures, including peak rearfoot eversion, peak tibial internal rotation, peak rearfoot eversion moment, and center of pressure excursion, were collected using 3D-motion capture and an instrumented treadmill. At post-intervention, these morphological and biomechanical measures were repeated. Descriptive statistics were calculated for each dependent variable by group and time. A repeated measures ANOVA was conducted for each dependent variable with the within subjects factor time and between subjects factor group.

Movement patterns of the functional reach test do not reflect physical function in healthy young and older participants.

The relationship of the Functional Reach Test (FRT) value with the Center of Pressure Excursion (COPE) and physical function remains unclear, and would be influenced by different population characteristics and movement patterns used in the FRT. Therefore, we explored the relationship between the FRT value and the COPE and physical function in healthy young and older individuals classified according to movement patterns. In 21 healthy young participants (42 sides) and 20 older participants (40 sides), three-dimensional motion analysis was performed during the FRT and physical function assessments. The participants were assigned to two clusters after performing a motion analysis during the FRT. Kinematic and kinetic parameters during the FRT and physical function assessment results were compared between the clusters for both groups. Correlation analysis was performed to investigate the relationships of the FRT value with COPE and physical function parameters in each cluster, in young and older individuals separately. The results showed that the hip strategies could be divided into two groups according to the degree of use (Small Hip Strategy, SHS Group; Large Hip Strategy, LHS Group). In the older SHS group, the FRT values were significantly correlated with the COPE (r = 0.75), toe grip strength (r = 0.62), and the five-times sit-to-stand test time (r = -0.52). In the older LHS group and in both groups of young individuals, there were no significant correlations of the FRT value with any parameters. The FRT value reflects the COPE and physical function only in older individuals using the SHS. This could explain previous discrepant results. As there is no simple relationship between the FRT value and physical function, it is important to include movement strategy assessment when using the FRT in clinical evaluations.