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Objective: The primary aim of this study was to investigate the immediate and delayed effects of kinesiotape (KT) on postural control and patient-reported outcome measures under challenging conditions in individuals with anterior cruciate ligament reconstructions. Methods: Thirty-two anterior cruciate ligament-reconstructed patients for whom 6 months had passed since their operation were randomly assigned to either the KT (n = 16, aged 21.8 [5.5] y) or the placebo KT (n = 16, aged 24.0 [5.1] y) groups. Initially, both groups stood barefoot on a force platform while performing postural tasks in 4 randomized conditions (eyes open, eyes closed, cognitive task, and foam). Before the experiment, patients would bring the 4 conditions, which were written on folded papers, one by one, and in this way, the order of conditions for the examiners was determined. The patients' evaluations were conducted immediately and 48 hours after KT application. Postural control measures, with area and displacement of the center of pressure (CoP) in anterior--posterior and medial--lateral directions, and mean total velocity displacement of CoP (MVELO CoP) served as dependent variables. In addition, the International Knee Documentation Committee score was measured pretreatment and 48 hours posttreatment. Results: Significant group-by-time interactions were observed for displacement of COP in medial--lateral direction (P = .002) and MVELO CoP (P = .034). MVELO CoP significantly decreased (mean difference = 0.60, P = .009) immediately after KT application compared with preapplication measures. In the placebo group, a statistically significant decrease in MVELO CoP (mean difference = 0.869, P = .001) was observed at 48 hours post-KT compared with preapplication values. International Knee Documentation Committee scores significantly improved at 48 hours post-KT application in both groups (P < .05). Conclusions: Though observed at different time points, both KT (immediately after the intervention) and placebo KT (48 h after the intervention) were found to improve postural control measures. It appears that the changes in postural control may be more related to proprioceptive enhancement due to KT rather than the specific KT pattern. [ABSTRACT FROM AUTHOR]

Multiple sclerosis is a neurodegenerative disease that causes balance deficits, even in early stages. Evidence suggests that people with multiple sclerosis (PwMS) rely more on vision to maintain balance, and challenging balance with optical flow perturbations may be a practical screening for balance deficits. Whether these perturbations affect standing balance in PwMS is unknown. Therefore, the purpose of this study was to examine how optical flow perturbations affect standing balance in PwMS. We hypothesized that perturbations would cause higher variability in PwMS compared with matched controls during standing and that standing balance would be more susceptible to anterior–posterior (A–P) perturbations than medial–lateral (M–L) perturbations. Thirteen PwMS and 13 controls stood under 3 conditions: unperturbed, M–L perturbation, and A–P perturbations. A–P perturbations caused significantly higher A–P trunk sway variability in PwMS than controls, although both groups had similar center-of-pressure variability. Both perturbations increased variability in A–P trunk sway and center of pressure. Trunk variability data supported the hypothesis that PwMS were more susceptible to optical flow perturbations than controls. However, the hypothesis that A–P perturbations would affect balance more than M–L perturbations was partially supported. These results suggest potential for optical flow perturbations to identify balance deficits in PwMS. [ABSTRACT FROM AUTHOR]

Active video games (AVG) have been used as training tools and are known to ameliorate balance performance in children with Developmental Coordination Disorder (DCD). Our aim was to evaluate balance using clinical tests and by measuring body sway using a force plate with a mixed design of vision (eyes open/eyes closed), surface (rigid/soft). and support (stance/semitandem) before, and after, training and 4 months later (follow-up). Thirty-six DCD children and 40 typically developing children participated in the study, of which 50 children (26 DCD; 24 typically developing) were retested after 4 months. Balance improved on the clinical measures after the training, which was independent of type of AVG (Wii-Fit and Xbox Kinect) used, and this effect was still present after 4 months. The AVG training did not influence general sway behavior, but only sway in the eyes-open condition. corresponding with task demands of the training and indicating a training-specific effect. Overall, DCD children and typically developing children responded comparably to the AVG training, thereby maintaining the gap in performance between the two groups. The changes iii postural sway are interpreted as a sign of more confidence and less freezing of the joints, enabling greater flexibility of movements and balance strategies as supported by the improved performance on balance tests in the DCD children. This is the first study that showed long-term effects of AVG training on balance performance. However. these follow-up results should be interpreted with caution given that 35% of the children were lost in follow-up. [ABSTRACT FROM AUTHOR]

Background: Understanding postural control in low back pain (LBP) subgroups can help develop targeted interventions to improve postural control. The studies on this topic are limited. Therefore, the primary purpose of this study was to compare the postural control of LBP subgroups with healthy individuals during overhead load lifting and lowering. Methods: In this cross-sectional study, the participants were 52 with LBP and 20 healthy. The LBP patients were classified based on the O'Sullivan classification system into 21 flexion patterns and 31 active extension patterns. The participants lifted the box from their waists to their overheads and lowered it to their waists. Changes in postural control parameters were measured with a force plate system. Results: The results of the analysis of variance showed that during load lifting, the mediolateral phase plane (p =.044) and the mean total velocity (p =.029) had significant differences between flexion patterns and healthy. Also, the load-lowering results showed that active extension patterns, compared with healthy, had significant differences in the anteroposterior–mediolateral phase plane (p =.042). The patients showed less postural sway than the healthy. Conclusions: The results in this work highlight the importance of identifying the homogenous subgroups in LBP and support the classification of heterogeneous LBP. Different subgroups exhibit different postural control behaviors. These behaviors can be due to the loading of various tissues during different tasks. [ABSTRACT FROM AUTHOR]

A force plate is mainly used in biomechanics; it aims to measure the ground reaction force in a persons walking or standing position. In this study, a large-area force mat of the piezoresistance sensing type was developed, and a deep-learning-based weight measurement calibration method was applied to solve the problem in which measurements are not normalized because of physical limitations in hardware and signal processing. The test set was composed of the values measured at each point by weight and the value of the center of the pressure variable, and the measured value was predicted using a deep neural network (DNN) regression model. The calibration verification results show that the average weight errors range from a minimum of 0.06% to a maximum of 3.334%. This is simpler than the previous method, which directly measures the ratio of the resistance value to the measured weight of each sensor and derives an equation.

Background: Although chronic low back pain (LBP) is a complex condition often associated with altered motor control and compensatory postural adjustments, existing literature provides inconsistent reports on the underlying control mechanisms for maintaining balance. Purpose: This study aimed to compare differences in sway distances between the center of pressure (COP) and the center of gravity (COG), while considering limb dominance, in adults with and without LBP. Methods: There were 26 subjects with LBP and 39 control subjects who performed three repeated unilateral standing tasks on a force platform. Outcome measures included the sway distances between COP and COG in the anteroposterior (AP) and mediolateral (ML) directions, as well as the results of the fall efficacy scale (FES). Results: A significant group interaction was demonstrated on limb dominance and direction for the sway distance (F = 5.46, p = 0.02). Specifically, the third trial in the ML direction while standing on the dominant limb indicated a significant difference in COP-COG sway distance (t = -2.30, p = 0.01). When FES scores were used as a covariate, a significant three-way interaction (dominance x direction x trial) was found (F = 4.06, p = 0.04). Conclusion: Although no significant group interaction was observed for dominance, direction, and trial, the LBP group demonstrated an ability to leverage fall efficacy following repeated trials to reduce ML balance deficits. Clinicians should consider neuromuscular control and limb dominance when developing fall efficacy strategies for postural adaptations in adults with LBP. [ABSTRACT FROM AUTHOR]

Objectives: Chronic ankle instability (CAI) is characterized by persistent neuromechanical impairments following an initial lateral ankle sprain. Ankle joint mobilization and plantar massage have improved the range of motion and static postural control in those with CAI. This study aimed to determine the impact of two-week joint mobilization and plantar massage interventions on gait kinematics and kinetics in individuals with CAI. Methods: A single-blind randomized trial was conducted with 60 participants with CAI, randomized into three groups: joint mobilization (n = 20), plantar massage (n = 20), and control (n = 20). The two treatment groups received six 5-min sessions manual therapy over a 2-week, while the control group received no intervention. Gait biomechanics were assessed on an instrumented treadmill before and after the intervention using 3D kinematics and kinetics analysis. Analyses compared biomechanical outcomes from each treatment group to the control group individually using a 1-dimensional statistical parametric mapping. The alpha level was set at p < 0.05. Results: Eighteen participants per group were part of the final analysis. No significant main or interactions effects were found for ankle sagittal or frontal plane positions following either intervention (p > 0.05 for all comparisons). COP location relative to the lateral border of the foot also did not change (p > 0.05). Conclusion: The findings suggest that two-week joint mobilization and plantar massage interventions do not significantly alter gait biomechanics in individuals with CAI. These results support the need for gait-specific interventions to modify biomechanics in this population. [ABSTRACT FROM AUTHOR]

BackgroundObjectiveCase DescriptionOutcomesConclusionBody lateropulsion (BL) is a phenomenon in which the body involuntarily falls to one side; however, its detailed postural control characteristics remain unclear.This case report aimed to measure the surface electromyography (EMG) of the lower limbs while standing in a patient with severe BL on the affected side due to pontine infarction and to investigate the characteristics of postural control.We evaluated a patient with severe BL due to pontine infarction at two-time points, 6 and 20 days after onset, to assess static standing balance under open and closed eye conditions and measure the center of pressure (COP) and lower extremity EMG during these tasks.There were minimal changes in COP position and total locus length during the eyes closed condition compared to the eyes open condition. However, the head and trunk to the non-BL side of the tilt and bilateral medial hamstring muscle activity tended to be higher when the eyes were closed. At the final evaluation, head and trunk tilt and EMG changes were reduced during the eyes-closed condition compared to the eyes-open condition. The initial postural response was considered to reflect a compensatory postural strategy for BL, characterized by the body involuntarily tilting to one side.The change in posture over time may indicate a reduction in the compensatory postural response as the condition improves. In this case, characteristic postural findings were identified through EMG measurements, suggesting the possibility of future studies involving multiple cases. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate center of pressure (CoP) changes in unilateral sports and examine how these changes affect the athlete's feet, ankles, knees or posture. The study sample consisted of 40 professional male players (age: 19.4 ± 2.08 years; height: 165.78 ± 4.92 cm; weight: 59.04 ± 4.02 kg; BMI: 21.57 ± 2.22; foot size: 40.9 ± 1.6), divided by type of sport into group H—handball (n: 20) and group F—football (n: 20). To evaluate the monitored parameters, we used the instrumental diagnostic techniques: 3D laser footscan, baropodometric platform FreeStep and 2D Videography. We found no significant differences between the groups in the loading of the right and left foot (F: 8.3 ± 4.22; H: 7.7 ± 6.1) (p = 0.410). We found a significant difference in the load on the front and back of the left (p = 0.0079) and right foot (p = 0.0210) depending on the type of sport performed. Maximum and mean values of CoP (g/cm2) showed statistically significant differences depending on the sport performed (p < 0.0001). The shift in CoP (mm) from the norm depending on the sport performed was confirmed in the latero-lateral direction (p = 0.003), but not in the antero-posterior direction (p = 0.320). We found a difference in the angulation of the knees and heels depending on the sport played. Handball players showed higher knee varosity/valgosity (p = 0.015) and heel values than football players (p = 0.002). The handball players also confirmed a worse postural load and initial forward posture. The one-sided sports, handball and football, showed negative effects on the athlete's movement system. These changes were more pronounced in handball players. Proper training programs should be applied in athletes' daily routine to improve the negative effects of unilateral sports. [ABSTRACT FROM AUTHOR]

Background: A core component of older adult health care assessment includes identifying fall risk, which also includes identifying those with subtle balance deficits. Objective: To compare body displacement of the Center of Pressure (CoP) and time held during the balance test. Also, to examine whether balance tests at baseline can predict falls after 6 months. Methods: A longitudinal study with 153 community-dwelling older adults, between 60–89 years old. Anteroposterior (AP) and mediolateral (ML) amplitude and velocity CoP displacements were assessed in four upright positions using a force platform: double-leg, semi-tandem, tandem, and single-leg stances, with a maximum duration of 30 s each. Adjusted repeated measures ANOVA were used to compare the differences among the balance positions. Comparisons between males and females were also conducted. Logistic regression adjusted for confounders was performed to verify whether upright balance tests can predict future falls. Results: As the base of support narrows, body sway increases. A decrease in stance time was observed across the balance stages, i.e., double-leg/semi-tandem versus tandem versus single-leg stances. The mean duration held in the single-leg stance was 14.8 s and for tandem was 22.2 s. Similar stance durations were observed for double-leg and semi-tandem stances. Males were able to maintain balance positions longer than females even with greater CoP displacement. ML amplitude of CoP displacement and the time held during tandem and single-leg positions were able to predict falls after 6 months (p < 0.05). Conclusion: In clinical practice in which only stance time is recorded, it is possible to interchangeably use the double-leg or semi-tandem stance. To identify early signs of imbalance, we suggest setting a time limit for the balance test equal to or greater than 23 s, as 10 s appear to be insufficient to detect subtle balance deficits. The time maintenance on tandem and single-leg positions was able to predict future falls. [ABSTRACT FROM AUTHOR]

Background: Patients with adolescent idiopathic scoliosis (AIS) has been reported to exhibit impaired postural stability. Posterior correction and fusion using four-dimensional (4D) anatomical spinal reconstruction techniques may improve postural stability to correct the spine for optimal anatomical alignment. This prospective study aimed to determine the effect of posterior correction and fusion using a 4D anatomical spinal reconstruction technique on postural stability in the eye-open and eye-closed standing position in patients with thoracic AIS. Methods: Thirty-three patients with AIS, excluding those with Lenke type 5C AIS, participated in the study. The mean and standard deviation of the minimum values of the time-to-boundary (TTB) were determined. All patients were asked to perform the quiet standing position under the eye-open and eye-closed condition on a force plate preoperatively and at 1 week and 2 years postoperatively. The TTB value was calculated from the velocity and distance to the foot boundary of the acquired center-of-pressure data. Results: Under the eye-closed condition, the mean and standard deviation of the minimum TTB were significantly higher at 2 years postoperatively than preoperatively and at 1 week postoperatively. The mean and standard deviation of the minimum TTB values were significantly lower at 1 week postoperatively than preoperatively. Conclusions: The results of this study suggest that surgery using the 4D anatomical spinal reconstruction technique reduces postural stability immediately after surgery; however, it improves postural stability at 2 years compared to the preoperative values. [ABSTRACT FROM AUTHOR]

Background and Aims: Gait initiation (GI) in individuals with chronic ankle instability (CAI) has shown differences in the center of pressure (COP) and muscular measures compared to healthy controls. Some studies reported that these alterations appeared when GI was with the affected leg, while others indicated that they occurred when GI was with the non‐affected leg. This systematic review aimed to understand kinetic and muscular differences between individuals with CAI, healthy controls, and the affected and non‐affected legs of individuals with CAI. Methods: PubMed, Science Direct, Web of Science, Google Scholar, and Scopus databases (1990–2023) were searched using the Population, Exposure, Comparator, and Outcome measure. The PRISMA guidelines were followed. The outcome measures were the peak and rate of COP displacement in the medial‐lateral and anterior‐posterior directions, and resultant plane during phases 1, 2, and 3 of COP trace during GI and the duration of each phase. The other measures included the onset time of the tibialis anterior and soleus muscle activity between individuals with CAI, healthy controls, and the affected and non‐affected legs of the individuals with CAI. The studies' quality assessment was conducted based on the Strengthening the Reporting of Observational Studies in Epidemiology checklist. Results: Five studies were included in the final evaluation. The results of included studies showed, individuals with CAI spent less time during phases 1 and 2, as well as a shorter peak of COP displacement in the lateral direction during phase 1 compared to healthy controls, regardless of whether the GI was with the affected or non‐affected leg. Conclusion: Individuals with CAI have probably adopted a strategy involving adjusting the peak of COP displacement to manage internal sway while in a single‐leg stance. Overall, there was no comprehensive conclusion about differences between the two legs in individuals with CAI. [ABSTRACT FROM AUTHOR]

Introduction: In traffic rule, green/blue means go, and red means stop. It has been shown that this prior knowledge about traffic signal colors can affect reaction times (RTs). For example, RTs are longer when responding to a red “Go” signal and withholding the response to a blue “No-go” signal (Red Go/Blue No-go task) than when responding to a blue “Go” signal and withholding the response to a red “No-go” signal (Blue Go/Red No-go task), when responses are provided by button press. However, it remains unknown whether this holds in different actions. The aim of this study was to investigate the effect of prior knowledge of color on gait initiation in a Go/No-go task. Methods: Seventeen participants performed Green Go/Red No-go and Red Go/Green No-go tasks, in which they stepped forward from a force plate in response to a green or red signal and withhold the response to red or green signal, respectively. We recorded the center of pressure (COP) and electromyogram (EMG) from the bilateral tibialis anterior muscles during gait initiation. Results: The onset of COP movement and toe-off time as well as COP displacements did not differ between the Go/No-go tasks. The EMG onset for the stance leg was delayed in the Red Go/Green No-go than Green Go/Red No-go task. Discussion: These findings suggest that the conflict between prior knowledge of color related to traffic rule and the meaning of the stimulus color affects muscle activity but not COP characteristics during gait initiation, highlighting two distinct motor control mechanisms, where the initial phase is influenced by cognitive load while the subsequent phase remains unaffected. This dissociation suggests that the later phase of gait initiation relies on robust spinal loops and central pattern generators, which are less influenced by cognitive factors such as prior knowledge. [ABSTRACT FROM AUTHOR]

Background: This study examines the effect of two types of custom-made foot orthoses (CFOs) in patients with structural hallux limitus (SHL). Methods: In this quasi-experimental, repeated measures study, 24 participants with SHL were sampled. Two CFOs—cut-out CFO and anterior stabilizer element (AFSE) CFO—were compared using minimalist SAGURO neoprene shoes: no foot orthoses (FO), cut-out CFO, and AFSE CFO. Plantar pressures and center of pressure (CoP) displacement were measured using a Podoprint® platform. Results: Both CFOs shifted the CoP medially during midstance (p < 0.001 with AFSE CFO and p = 0.0036 with cut-out CFO). The AFSE CFO showed a more anterior CoP in midstance, while the cut-out CFO affected anterior CoP in midstance and pre-swing. The AFSE CFO significantly increased pressure in the second toe, lesser metatarsal heads (MTH), midfoot, and rearfoot. In contrast, the cut-out CFO decreased pressure in the second MTH and lesser toe regions, increasing pressure in the midfoot and heel. Both CFOs lowered the hallux/first MTH ratio compared to shod without CFO. Conclusions: The cut-out CFO led to medial and anterior CoP displacement, reducing lateral foot and hallux pressure while transferring loads to the first MTH. The AFSE CFO caused a similar shift by increasing loads on the first MTH. [ABSTRACT FROM AUTHOR]

AbstractAdopting a postural configuration may be regarded as preparation for the performance of an upcoming movement. However, it is unclear how different postural configurations affect motor performance. The aim of the current study was to examine how body posture – sitting versus standing – influences fast and accurate planar point-to-point hand movements. Twenty-three healthy adults performed a “Go/No-go” paradigm while doing repetitive point-to-point movements. Arousal levels, which may change due to the change in posture, were independently manipulated by using a sham threat of electrical stimulation. Upper limb kinematics, center of pressure displacement, and galvanic skin responses were recorded in four test conditions: sitting and standing with and without arousal manipulation. Descriptive performance measures were computed and analyzed using multiple analyses of variance. A difference in arousal level was observed in the two conditions with the arousal manipulation, but no difference in arousal level was found between sitting and standing. Center of pressure displacement onset was found to be earlier in the two standing conditions compared to those in sitting. No difference was found in upper limb performance between the two postures, nor due to the arousal manipulation. We concluded that under the tested conditions, body posture does not appear to affect upper limb performance. [ABSTRACT FROM AUTHOR]

Chronic heart failure (CHF) is a complex clinical syndrome, associated with frailty, higher fall rates, and frequent hospitalizations. Heart Failure (HF) and preserved ejection fraction (HFpEF) is defined as a condition where a patient with HF have a diagnosis of left ventricular ejection fraction (LVEF) of ≥ 50%. The risk of HFpEF increases with age and is related to higher non-cardiovascular mortality. The aim of this study was to evaluate static balance and examine the effect of task difficulty on the discriminating power of balance control between patients with HFpEF (Patients with HFpEF) and their healthy controls. Moreover, the associations between static balance parameters, balance confidence, falls, lean muscle mass, and strength were assessed. Seventy two patients with HFpEF (mean age: 66.0 ± 11.6 years) and seventy two age- and gender-matched healthy individuals (mean age: 65.3 ± 9.5 years) participated in this study. Participants underwent a 30 s bilateral stance (BS) test and a 20 s Tandem-Romberg stance (TRS) on a force platform, evaluating the Range and Standard Deviation of Center of Pressure (COP) displacement parameters in both axes. Balance confidence was evaluated by the Activities-Specific Balance Confidence (ABC) Scale, and the number of falls during the last year was recorded. Lower limb strength was measured using an isokinetic dynamometer, isometric leg strength, and a Sit-to-Stand test. Bioelectrical impedance analysis was conducted to assess lean fat mass, lean fat mass index, and lean%. Patients with HFpEF presented with lower static balance in BS and TRS compared to healthy controls (p < 0.05), lower balance confidence by 21.5% (p < 0.05), and a higher incidence of falls by 72.9% (p < 0.05). BS was a better descriptor of the between-group difference. Furthermore, static balance, assessed in controlled lab conditions, was found to have little if no relationship to falls, strength, lean muscle mass, and balance confidence. Although no correlation was noted between the static balance parameters and falls, the fall rate was related to balance confidence, age, muscle strength, and lean fat. [ABSTRACT FROM AUTHOR]

Migraine is a neurological disease that affects proportionally more women. It has been documented that migraineurs often experience balance disturbances. To evaluate the balance between migraineur patients (MG) and healthy volunteers classified as control group (CG). A cross-sectional study. Seventy-four women were evaluated: 37 MG and 37 CG. The evaluation of the center of pressure (COP) variables was carried out using a balance platform in three postures, bipodal eyes closed (BEC), right monopodal with eyes open (RMEO), and left monopodal with eyes open (LMEO). Self-report questionnaires (dizziness handicap inventory (DHI), fall risk efficacy scale (FES I), the functional impact scale (HIT 6) and the timed up and go test (TUG test) were used. The U-Mann Whitney test was used to verify differences in the COP between MG and CG. The Kruskal-Wallis one-way ANOVA was used to analyze the differences between migraine groups (MGs) with postures, self-report questionnaires, and TUG test. A p < 0.05 was considered statistically significant. No statistically significant changes were found in the balance variables, except the medial-lateral excursion variable in the BEC (p < 0.02) and LMEO (p = 0.04) postures. No significant differences were found between the MGs with HIT 6 (p = 0.48) or FES I (p = 0.49). Significant differences were found between the MGs with DHI (p = 0.003). The TUG test showed statistically significant changes between groups (p < 0.01). The women with migraine in this sample did not show differences in postural balance, however, dizziness and functional differences are shown compared to healthy women. [ABSTRACT FROM AUTHOR]

Simple Summary: The reliability of a modified Posturomed balance platform was assessed for static and dynamic posturographic measurements in healthy dogs at two different time points. Static posturographic measurements appeared reliable, while results indicated a slight to moderate training effect for two of the three tested center of pressure parameters during both dynamic conditions. Further studies are needed to investigate Posturomed-based balance analysis in dogs with neurologic and orthopedic diseases. Reliable, standardized balance tests for dogs are not available yet. The purpose of this study was to investigate the reliability of static and dynamic posturography in healthy dogs. Healthy dogs (n = 20) were positioned with four paws longitudinally and with the forepaws only transversely on a modified pressure-sensitive balance platform (Posturomed-FDM-JS, Zebris, Isny, Germany). Three static and dynamic posturographic trials were recorded (recording duration: 20 s) and repeated after 7–14 days. Center of pressure (COP) parameters COP-path-length (PL; mm), 95% COP-confidence-ellipse-area (CEA; mm2), and COP-average-velocity (AV; mm/s) were calculated for the first steady-state 5 s intervals of each trial. The reliability of COP parameters was assessed with robust linear mixed effects models with nested random effects of patient and trial. The training effect was analyzed using Cohen's d. For static posturography, PL, CEA, and AV did not differ significantly between time points; CEA had the highest reliability (p = 0.92). For dynamic posturography, AV and PL differed significantly between time points (AV: p ≤ 0.043; PL: p ≤ 0.045). Slight training effects were observed for transverse positioning (Cohen's d: PL 0.65; AV 0.267) and moderate training effects for longitudinal positioning (Cohen's d: PL: 0.772; AV: 0.783). This study showed that static posturography on a modified Posturomed-balance platform was reliable in healthy dogs but indicated training effects during dynamic posturography. [ABSTRACT FROM AUTHOR]

Abstract Background A core component of older adult health care assessment includes identifying fall risk, which also includes identifying those with subtle balance deficits. Objective To compare body displacement of the Center of Pressure (CoP) and time held during the balance test. Also, to examine whether balance tests at baseline can predict falls after 6 months. Methods A longitudinal study with 153 community-dwelling older adults, between 60–89 years old. Anteroposterior (AP) and mediolateral (ML) amplitude and velocity CoP displacements were assessed in four upright positions using a force platform: double-leg, semi-tandem, tandem, and single-leg stances, with a maximum duration of 30 s each. Adjusted repeated measures ANOVA were used to compare the differences among the balance positions. Comparisons between males and females were also conducted. Logistic regression adjusted for confounders was performed to verify whether upright balance tests can predict future falls. Results As the base of support narrows, body sway increases. A decrease in stance time was observed across the balance stages, i.e., double-leg/semi-tandem versus tandem versus single-leg stances. The mean duration held in the single-leg stance was 14.8 s and for tandem was 22.2 s. Similar stance durations were observed for double-leg and semi-tandem stances. Males were able to maintain balance positions longer than females even with greater CoP displacement. ML amplitude of CoP displacement and the time held during tandem and single-leg positions were able to predict falls after 6 months (p

Patients with knee osteoarthritis and varus knee deformity have impaired postural balance, resulting in decreased walking performance and an increased risk of falls. This study aimed to investigate the early changes in the postural balance following inverted V-shaped high tibial osteotomy (HTO). Fifteen patients with medial knee osteoarthritis were recruited. Postural balance was assessed using the center-of-pressure (COP) data during single-leg standing before and 6 weeks after inverted V-shaped HTO. The maximum range, mean velocity, and area of COP movements in the anteroposterior and mediolateral directions were analyzed. Preoperative and postoperative visual analog scale for knee pain was assessed. The maximum range of COP in the mediolateral direction decreased (P =.017), whereas the mean velocity of COP in the anteroposterior direction increased 6 weeks postoperatively (P =.011). The visual analog scale score for knee pain significantly improved at 6 weeks postoperatively (P =.006). Valgus correction with inverted V-shaped HTO resulted in improved postural balance in the mediolateral direction and good short-term clinical outcomes early following surgery. Early rehabilitation after inverted V-shaped HTO should focus on postural balance in the anteroposterior direction. [ABSTRACT FROM AUTHOR]

Abstract Background Gait event detection is crucial for assessment, evaluation and provision of biofeedback during rehabilitation of walking. Existing online gait event detection algorithms mostly rely on add-on sensors, limiting their practicality. Instrumented treadmills offer a promising alternative by utilizing the Center of Pressure (CoP) signal for real-time gait event detection. However, current methods have limitations, particularly in detecting cross-step events during perturbed walking conditions. Methods We present and validate a CoP-based algorithm to detect gait events and cross-steps in real-time, which combines thresholding and logic techniques. The algorithm was evaluated on CoP datasets from healthy participants (age range 21–61 years), stroke survivors (age range 20–67 years), and people with unilateral transtibial amputation (age range 28–63 years) that underwent perturbation-based balance assessments, encompassing different walking speeds. Detected gait events from a simulated real-time processing operation were compared to offline identified counterparts in order to present related temporal absolute mean errors (AME) and success rate. Results The proposed algorithm demonstrated high accuracy in detecting gait events during native gait, as well as cross-step events during perturbed walking conditions. It successfully recognized the majority of cross-steps, with a detection success rate of 94%. However, some misclassifications or missed events occurred, mainly due to the complexity of cross-step events. AME for heel strikes (HS) during native gait and cross-step events averaged at 78 ms and 64 ms respectively, while toe off (TO) AME were 126 ms and 111 ms respectively. A statistically significant difference in the algorithm's success rate score in detecting gait events during cross-step intervals was observed across various walking speeds in a sample of 12 healthy participants, while there was no significant difference among groups. Conclusion The proposed algorithm represents an advancement in gait event detection on instrumented treadmills. By leveraging the CoP signal, it successfully identifies gait events and cross-steps in the simulated real-time processing operation, providing valuable insights into human locomotion. The algorithm's ability to accommodate diverse CoP patterns enhance its applicability to a wide range of individuals and gait characteristics. The algorithm's performance was consistent across different populations, suggesting its potential for diverse clinical and research settings, particularly in the domains of gait analysis and rehabilitation practices.

Objective To assess postural stability, specifically center of body sway during single-leg standing balance, among individuals with and without forward head posture (FHP) during smartphone use. Methods The research recruited 53 healthy smartphone users, aged 18–25, and categorized them into FHP group comprising 26 subjects and the normal (control) group with 27 subjects. Participants were assigned the task of maintaining balance while engaged in smartphone typing during single-leg standing. The experiment involved four specific conditions according to neck posture and stable of surface. The study meticulously quantified body center of pressure (COP) sway amplitudes using the Nintendo Wii Balance Board. Results The research revealed that individuals with FHP exhibited significantly greater body sway compared to the control group when using smartphones. Notably, distinct variations were observed in path length sway, anteroposterior (AP), and mediolateral (ML) sway amplitude, particularly evident when maintaining flexed neck positions on a soft surface while engaged with smartphones. Conclusion These findings strongly suggest that individuals with FHP encounter deteriorated postural stability during smartphone use, particularly in challenging head positions.

Abstract Background The 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). Methods Sixty 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. Results Statistical analysis showed that pain intensity (t = − 16.655, p 0.80). Conclusion After 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.

In the quotidian, people perform voluntary whole-body movements requiring dynamic body balance. However, the literature is scarce of dynamic balance evaluations employing standardized voluntary movements. In this investigation, we aimed to analyze the sensitivity of balance evaluation between gymnasts and athletes from other sports in the performance of balance tasks. Participants were evaluated in upright quiet standing and the performance of cyclic dynamic tasks of hip flexion-extension and squat-lift movements. Movements were individually standardized in amplitude, while the rhythm was externally paced at the frequency of 0.5 Hz. Tasks were performed on a force plate, with dynamic balance measured through the center of pressure displacement. Results showed that in quiet standing and the dynamic hip flexion-extension task, no significant differences were found between the groups. Conversely, results for the squat-lift task revealed a better balance of the gymnasts over controls, as indicated by the reduced amplitude and velocity of the center of pressure displacement during the task execution. The superior balance performance of gymnasts in the squat-lift task was also observed when vision was suppressed. These findings suggest the employed squat-lift task protocol is a potentially sensitive procedure for the evaluation of voluntary dynamic balance.

Background: Gait event detection is crucial for assessment, evaluation and provision of biofeedback during rehabilitation of walking. Existing online gait event detection algorithms mostly rely on add-on sensors, limiting their practicality. Instrumented treadmills offer a promising alternative by utilizing the Center of Pressure (CoP) signal for real-time gait event detection. However, current methods have limitations, particularly in detecting cross-step events during perturbed walking conditions. Methods: We present and validate a CoP-based algorithm to detect gait events and cross-steps in real-time, which combines thresholding and logic techniques. The algorithm was evaluated on CoP datasets from healthy participants (age range 21–61 years), stroke survivors (age range 20–67 years), and people with unilateral transtibial amputation (age range 28–63 years) that underwent perturbation-based balance assessments, encompassing different walking speeds. Detected gait events from a simulated real-time processing operation were compared to offline identified counterparts in order to present related temporal absolute mean errors (AME) and success rate. Results: The proposed algorithm demonstrated high accuracy in detecting gait events during native gait, as well as cross-step events during perturbed walking conditions. It successfully recognized the majority of cross-steps, with a detection success rate of 94%. However, some misclassifications or missed events occurred, mainly due to the complexity of cross-step events. AME for heel strikes (HS) during native gait and cross-step events averaged at 78 ms and 64 ms respectively, while toe off (TO) AME were 126 ms and 111 ms respectively. A statistically significant difference in the algorithm's success rate score in detecting gait events during cross-step intervals was observed across various walking speeds in a sample of 12 healthy participants, while there was no significant difference among groups. Conclusion: The proposed algorithm represents an advancement in gait event detection on instrumented treadmills. By leveraging the CoP signal, it successfully identifies gait events and cross-steps in the simulated real-time processing operation, providing valuable insights into human locomotion. The algorithm's ability to accommodate diverse CoP patterns enhance its applicability to a wide range of individuals and gait characteristics. The algorithm's performance was consistent across different populations, suggesting its potential for diverse clinical and research settings, particularly in the domains of gait analysis and rehabilitation practices. [ABSTRACT FROM AUTHOR]

In the quotidian, people perform voluntary whole-body movements requiring dynamic body balance. However, the literature is scarce of dynamic balance evaluations employing standardized voluntary movements. In this investigation, we aimed to analyze the sensitivity of balance evaluation between gymnasts and athletes from other sports in the performance of balance tasks. Participants were evaluated in upright quiet standing and the performance of cyclic dynamic tasks of hip flexion-extension and squat-lift movements. Movements were individually standardized in amplitude, while the rhythm was externally paced at the frequency of 0.5 Hz. Tasks were performed on a force plate, with dynamic balance measured through the center of pressure displacement. Results showed that in quiet standing and the dynamic hip flexion-extension task, no significant differences were found between the groups. Conversely, results for the squat-lift task revealed a better balance of the gymnasts over controls, as indicated by the reduced amplitude and velocity of the center of pressure displacement during the task execution. The superior balance performance of gymnasts in the squat-lift task was also observed when vision was suppressed. These findings suggest the employed squat-lift task protocol is a potentially sensitive procedure for the evaluation of voluntary dynamic balance. [ABSTRACT FROM AUTHOR]

Postural control can be challenged by breathing. What is the effect of an acute increase in respiratory demand on postural control compared to quiet breathing? A systematic review was conducted. Electronic databases were systematically searched until October 18, 2022 on studies reporting changes in center of pressure (CoP) motion related to an acute manipulation of respiratory demand compared to quiet breathing during upright standing in healthy participants and/or participants with a clinical condition. Twenty-one studies in healthy participants showed that voluntary (not metabolic-induced) hyperventilation or inspiratory resistive loading significantly increased CoP motion, while breath-holding decreased CoP motion, compared to quiet breathing (p< 0.05). Manipulating respiratory rate or breathing patterns did not reveal consistent results. Four studies showed that people with low back pain showed similar CoP responses to increasing respiratory demand (p> 0.05), except for breathing at different rates, whereas they showed greater CoP motion during quiet breathing. The extent of postural disturbance depended on the breathing mode and how it was quantified (i.e., CoP coupled with breathing movement or overall CoP measures). Voluntary hyperventilation and inspiratory resistive loading increased postural sway. For voluntary hyperventilation, this could be explained by CoP motion being directly coupled to chest wall movements whereas metabolic-induced hyperventilation did not increase CoP motion or CoP coupling with breathing. Breath-holding decreased postural sway. Patients with low back pain show greater postural sways than pain-free individuals during quiet breathing, although they exhibit similar postural adaptations to respiratory-related challenges as controls. • Studies assessing the effect of breathing demand on postural control were reviewed • Voluntary (not metabolic-induced) hyperventilation increased postural sway • Inspiratory resistive loading increased postural sway • Breath-holding decreased postural sway • Patients with low back pain show similar responses to increasing breathing demand [ABSTRACT FROM AUTHOR]

An ankle-foot orthosis (AFO) with plantar flexion resistance (PFR) can improve the first rocker function during gait, but the incremental changes in the resistive moment on balance and gait have not been well identified. To investigate the effect of changing the PFR moment of dynamic AFO (DAFO) on measures of the center of pressure (COP) and clinical gait outcomes in individuals with post-stroke hemiparesis. In this randomized repeated measure study of 36 stroke individuals, the customized DAFO using foot drop ankle units set in three PFR situations (low, medium, and high) was evaluated. The balance parameters for COP measures were investigated by HUMAC® Balance & Tilt System. Gait parameters and ankle kinematics were recorded using the 3D motion analysis through force platform and optoelectronic system. The comparison was made using a parametric ANOVA test and the P value was set at 0.05 for statistical significance. Significant differences were observed for COP average velocity (1.30 ± 0.64, 1.10 ± 0.05, and 1.37 ± 0.43), COP path length (43.3 ± 4.6, 33.4 ± 4.3, and 36.3 ± 5.4), walking velocity (11.0 ± 3.1, 13.2 ± 4.4, and 9.9 ± 3.5), and cadence (31.5 ± 2.0, 33.0 ± 3.1, and 29.0 ± 1.6) respectively for low, medium and high PFR settings (P < 0.05). Except for the COP path length and cadence, posthoc multiple comparisons revealed significant differences between low and medium (P < 0.05) and medium and high (P < 0.05) PFR grades. PFR with medium resistance demonstrated near-normal maximal peak ankle dorsiflexion (mean deviation of 8 degrees, P < 0.05). Medium PFR grade should be encouraged since it can enhance balance parameters like path length and average velocity of COP, increase cadence and average velocity during gait, and improve maximal peak ankle dorsiflexion. • Changes in resistive moment of plantar-flexion affects gait and balance in stroke. • The influence of PFR moment on ankle kinematics, gait and balance was examined. • Dynamic AFOs with dorsiflexion assist Klenzak joints allow for adjustable PFR. • Moderate PFR setting may improve the ankle kinematics, gait and balance parameters. • High PFR may increase non-symmetrical ankle dorsiflexion during swing. [ABSTRACT FROM AUTHOR]

A significant challenge in deploying bipedal robots for human-oriented real-world applications is their ability to maintain balance when externally disturbed. Current momentum-based balance control strategies often exhibit inadequate robustness to disturbances due to reliance on simple proportional controllers and imprecise incorporation of desired angular momentum changes. Furthermore, the sequential activation of momentum and posture correction controllers compromises system stability when confronted with consecutive disturbances. This paper proposes and validates a new Variable Power Reaching Law for Sliding Mode Control (SMC) to enhance the regulation of linear momentum against disturbances. The proposed reaching law adjusts dynamically to the system's errors, ensuring fast convergence and minimal chattering. In this paper, we precisely define the desired angular momentum change in relation to the Center of Pressure (CoP), a crucial stability metric, as well as the desired linear momentum and ground reaction forces. The null-space method, which allows for simultaneous task execution by using unused degrees of freedom, is employed to ensure effective balance and upright posture without interference. The posture correction control is projected onto the null-space of momentum control. Simulation results confirm that the proposed control system effectively stabilizes the robot against external disturbances, regulating momentum and restoring upright posture. The nullspace method proves effective in maintaining balance under multiple disturbances by simultaneously controlling momentum and posture. Comparative evaluations show that our approach outperforms traditional momentum-based controls and nonadaptive reaching laws, reducing CoP fluctuations, managing disturbances up to 117 N, and minimizing chattering and steady-state error. These advancements underscore the potential for deploying bipedal robots in dynamic environments. [ABSTRACT FROM AUTHOR]

BACKGROUND: Stability of the support surface and visual input are important factors affecting static balance, but most of the studies on the balance ability of elderly with mild cognitive impairment have focused on the stable hard support surface, and the control of static balance on the unstable support surface under different visual input conditions is not known. OBJECTIVE: To investigate the static balance ability of the elderly with mild cognitive impairment on soft and hard support surfaces under different visual input conditions. METHODS: Twenty-one elderly people with mild cognitive impairment and nineteen elderly people with normal cognition were selected for the study, and the Kistler three-dimensional dynamometer was used to conduct four tests: standing with two feet on hard support surface with eyes open, standing with two feet on soft support surface with eyes open, standing with two feet on hard support surface with eyes closed, standing with two feet on soft support surface with eyes closed, and standing with two feet on soft support surface with eyes closed, and the duration of each test was 30 seconds. The plantar center of pressure data were collected and compared between the two groups under different visual conditions on the soft and hard support surfaces. RESULTS AND CONCLUSION: (1) Under the condition of visual input, the total excursions (soft support surface: P=0.003), the total excursions-medial-lateral sides (soft support surface: P=0.001, hard support surface: P < 0.001) and the 95% confidence ellipse area (soft support surface: P=0.001, hard support surface: P < 0.001) of the center of pressure in the elderly with mild cognitive impairment on the soft and hard support surfaces were significantly higher than those of the elderly with normal cognition. (2) In the absence of visual input, the root mean square distance (P=0.014), the root mean square distance-medial-lateral sides (P=0.014), and the 95% confidence ellipse area (P=0.001) of center of pressure in the elderly with mild cognitive impairment on the soft support surfaces were significantly higher than those of the elderly with normal cognition, but there were no significant differences between the groups on the hard support surface (P > 0.05). (3) These findings confirm that compared with the elderly with normal cognition who could make full use of visual sensory input to maintain body balance on the soft and hard support surfaces, mild cognitive impairment elderly presented a deficit in balance function. In particular, mild cognitive impairment elderly relied more on ankle proprioception to maintain balance when visual interference was present, suggesting that mild cognitive impairment elderly should focus on strengthening ankle proprioceptive training. [ABSTRACT FROM AUTHOR]

Postural imbalance is a leading cause of injury in older adults. Our study investigated the effectiveness of virtual reality (VR)-based interventions on balance ability in this population. Here, we examined 21 older, healthy adults (75.8 ± 5.2 years old). Participants performed 6 weeks of balance training, twice per week for 30 min; the experimental group donned an Oculus VR headset during the training while control participants did not. To assess balance ability, a force platform measured displacement of the center of pressure (COP) during quiet standing in double-leg, tandem, and single-leg stances with eyes closed pre- and post-assessment. COP measurements included mediolateral (ML) and anterior–posterior (AP) directions for root mean square (RMS), peak-to-peak displacement (MAXD), total excursion (TE), and 95% confidence area ellipse (AE) parameters. Post-training assessments showed improvements (significant decreases) in the COP parameters. Control group COP parameters improved in various stances ranging from a 3% to 40% decrease on average. The VR group improved MAXD, TE, and 95% AE ranging from a 5% to 47% decrease, on average, across various stances post- compared to pre-training. VR-based exercise training programs may encourage older adults to engage in mobility exercises, leading to a reduced risk of falls or injuries. [ABSTRACT FROM AUTHOR]

When examining postural sway measures of single-leg squat (SLS), there is a lack of consensus on how many trials are required to obtain reliable and clinically relevant data. Forty adults with chronic low back pain performed five consecutive trials of SLS for each side on a portable force plate. The left and right sides were categorized into problem and non-problem sides by Clinical Pilates assessment. SLS performance was characterized by terminal knee flexion angle, squat duration, peak vertical force and postural sway parameters. Data across five trials were first examined with repeated measures analysis of variance; variables with significant differences were further analyzed using intraclass correlation coefficients (ICC). Using all trials as a reference, the reliability of other trial combinations was assessed to examine the potential effects of learning (2-5 squats, 3-5 squats, 4-5 squats), fatigue (1-2 squats, 1-3 squats, 1-4 squats) and steady-state (2-4 squats). For the non-problem side, postural sway measures were highly reliable (ICC≥0.9) regardless of the number of trials analyzed. For the problem side, analyzing the 1-4 squats combination offered consistently reliable results across all postural measures (ICC≥0.72). Thus, it is recommended to analyze the first four consecutive trials to obtain reliable postural sway measures. [ABSTRACT FROM AUTHOR]

Background: The 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). Methods: Sixty 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. Results: Statistical 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). Conclusion: After 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. [ABSTRACT FROM AUTHOR]

This paper proposes a scheme for predicting ground reaction force (GRF) and center of pressure (CoP) using low-cost FSR sensors. GRF and CoP data are commonly collected from smart insoles to analyze the wearer's gait and diagnose balance issues. This approach can be utilized to improve a user's rehabilitation process and enable customized treatment plans for patients with specific diseases, making it a useful technology in many fields. However, the conventional measuring equipment for directly monitoring GRF and CoP values, such as F-Scan, is expensive, posing a challenge to commercialization in the industry. To solve this problem, this paper proposes a technology to predict relevant indicators using only low-cost Force Sensing Resistor (FSR) sensors instead of expensive equipment. In this study, data were collected from subjects simultaneously wearing a low-cost FSR Sensor and an F-Scan device, and the relationship between the collected data sets was analyzed using supervised learning techniques. Using the proposed technique, an artificial neural network was constructed that can derive a predicted value close to the actual F-Scan values using only the data from the FSR Sensor. In this process, GRF and CoP were calculated using six virtual forces instead of the pressure value of the entire sole. It was verified through various simulations that it is possible to achieve an improved prediction accuracy of more than 30% when using the proposed technique compared to conventional prediction techniques. [ABSTRACT FROM AUTHOR]

Objective: To assess postural stability, specifically center of body sway during single-leg standing balance, among individuals with and without forward head posture (FHP) during smartphone use. Methods: The research recruited 53 healthy smartphone users, aged 18–25, and categorized them into FHP group comprising 26 subjects and the normal (control) group with 27 subjects. Participants were assigned the task of maintaining balance while engaged in smartphone typing during single-leg standing. The experiment involved four specific conditions according to neck posture and stable of surface. The study meticulously quantified body center of pressure (COP) sway amplitudes using the Nintendo Wii Balance Board. Results: The research revealed that individuals with FHP exhibited significantly greater body sway compared to the control group when using smartphones. Notably, distinct variations were observed in path length sway, anteroposterior (AP), and mediolateral (ML) sway amplitude, particularly evident when maintaining flexed neck positions on a soft surface while engaged with smartphones. Conclusion: These findings strongly suggest that individuals with FHP encounter deteriorated postural stability during smartphone use, particularly in challenging head positions. [ABSTRACT FROM AUTHOR]

To evaluate the concurrent validity and test–retest reliability of common movement, strength, and balance tests using portable uniaxial dual force plates. Repeated measures cross-sectional study. Sixteen healthy individuals participated in two testing sessions, where they performed 12 different movement, strength, and balance tests. Vertical ground reaction force and centre of pressure data were collected using the VALD ForceDecks simultaneously with ground-embedded laboratory force plates. Concurrent validity was assessed using root mean square error for raw time-series data and Bland–Altman plots for discrete metrics. Test–retest reliability was assessed using intraclass correlation coefficients and minimal detectable changes. ForceDecks recorded vertical ground reaction forces and center of pressure with high accuracy compared to laboratory force plates. The mean bias between systems was negligible (<2 N or 0.1 mm), with small limits of agreement (<5 N or 1 mm). Overall, 530/674 (79%) showed good or excellent validity (<10% difference) and 611/773 (79%) had good or excellent reliability (intraclass correlation coefficient >0.75). ForceDecks reliability was similar to laboratory force plates (<0.07 intraclass correlation coefficient median difference for all metrics). Portable uniaxial force plates record highly accurate vertical ground reaction forces and center of pressure during a range of movement, strength, and balance tests. The VALD ForcDecks are a valid and reliable alternative to laboratory force plates when strict standardized testing and data analysis procedures are followed. Users should be aware of the validity and reliability characteristics of the tests and metrics they choose. [ABSTRACT FROM AUTHOR]

Introduction: Differences in motor control between the lower limbs may influence the risk of sports injury and recovery from rehabilitation. In this study, differences in the visual feedback ability of the left and right lower limbs were assessed using visual target tracking tasks. Methods: Thirty-four healthy young subjects (aged 20.4 ± 1.2 years) were asked to move their bodies back and forth while tracking a visual target displayed on a monitor in front of them for 30 s. The two target motions were sinusoidal (i.e., predictable patterns) and more complex (random) patterns. To assess the ability of the lower limbs to follow visual target tracking, antero-posterior CoP (right limb, CoPap–r; left limb, CoPap–l) and medio-lateral CoP (right limb, CoPml–r; left limb, CoPml–l) data were measured using a stabilometer. Tracking ability by visual feedback ability was calculated as the difference in displacement between the target signal and the trajectories of the right and left pressure centers as trapezoidal areas, and a smaller sum of area (SoA) over the entire measurement time was defined as a greater tracking ability. Results: Regarding the SoA in the anterior-posterior CoP, the mean SoA in the sinusoidal and random tasks was significantly lower in the CoP-r data than in the CoP-l data, indicating that the right lower limb had a more remarkable ability to follow visual target tracking. Regarding the SoA in the medial-lateral direction (CoP), the mean SoA in the sinusoidal and random tasks did not significantly differ between the two legs. Discussion: The right lower limb may have a tracking function activated by the target signal when responding to visual stimuli. Identifying the motor strategies of each lower limb in response to visual stimuli will not only help identify potential differences between each lower limb but also suggest the possibility of enhancing the role of each lower limb in balance control. [ABSTRACT FROM AUTHOR]

The use of individually preferred colored glasses has gained popularity with the expectation that it may improve balance control and sports performance, however, the results of previous studies remain inconclusive. In the present pilot study, we aimed to determine the association between participants' subjective preference and standing balance performance when wearing five different colored glasses. Thirteen participants stood on one or two legs on a pair of synchronized force platforms for 30 seconds with 60 seconds rest between the five-five randomized stance trials, while wearing red, blue, yellow, green, or transparent colored glasses. In addition to 7 CoP-related variables, we analyzed five features of EMG data from three lower limb muscles on both legs. No significant effect of colored glasses was found. Some CoP (velocity: χ² (4, 13) = 10.086; p = 0.039; Kendall's W = 0.194, root mean square [RMS]: χ² (4, 13) = 12.278; p = 0.015; Kendall's W = 0.236) and EMG-related (RMS of biceps femoris: χ² (4, 13) = 13.006; p = 0.011; Kendall's W = 0.250) variables showed differences between the colored glass conditions during dominant-leg stance, however, participants failed to consecutively determine these differences in standing stability. Overall, our results may suggest that lens color preference, irrespective of the color itself, may influence dominant leg standing balance most probably due to psychological factors, however, only subjective determination have no potential to determine the color of the glasses that would support the individual's standing balance the most. • Different colored glasses do not affect bilateral stance strategy. • Participants' subjective preference was not in line with the CoP and EMG data. • Only subjective determination cannot determine the most supportive colored glass. [ABSTRACT FROM AUTHOR]

Implementation of the Sensory Organization Test (SOT) under the rambling-trembling (RM-TR) framework allows for an examination of both individual sensory contributions and compensatory mechanisms, a valuable insight in research and clinical settings. Such investigation could substantially improve our ability to assess and treat fall risk in older adults and people living with neurological disorders. How are RM and TR components of sway influenced by SOT-induced challenges in healthy adults? Twenty-three healthy adults (27.4±8 years; 10 male) volunteered to participate in this cross-sectional study. Each participant completed a VR-based SOT program, which included six conditions with varied visual environments (normal, blacked-out, conflict) and support surfaces (stable, unstable foam), while a force plate captured forces at the plantar surface. Center of pressure (COP) was calculated and decomposed into RM-TR components. For each time series, range, root-mean-square (RMS) and sample entropy (SampEn) were extracted. Individual contributions of somatosensation, vision, and vestibular sense, as well as the preference ratio, were calculated. Repeated measures ANOVA were used to compare the effects of time series type (COP, RM, TR) and SOT condition. Paired t-tests were used to assess the difference in preference ratio between RM and TR components. TR sway behavior was impacted significantly by the sensory challenges induced by the SOT procedure, while RM was largely unaffected. Such findings are characteristic of healthy individuals, capable of competently re-weighting sensory input, but still facing challenge-based adaptations. Additionally, the mediolateral SampEn preference ratio was higher in TR compared to RM, indicating potential differences in compensation strategies between supraspinal and spinal/peripheral control mechanisms. These findings serve as a foundation for future RM-TR analyses using SOT procedures, aiding in our ability to implement targeted diagnostic and treatment methods, ultimately reducing the incidence of falls in aging and individuals with neurological conditions. • Sensory re-weighting requires distinct rambling and trembling sway adaptations. • Spinal postural control mechanisms are greatly influenced by sensory conflict. • Rambling-trembling decomposition may be able to differentiate balance deficits by their sources. [ABSTRACT FROM AUTHOR]

Challenges to postural stability emerge in the transition from locomotion to a standing posture as during gait termination, often accompanied by another task (e.g., opening a door), which may complicate control. However, less is known about postural control during terminating gait while engaged in a secondary manual task. What are the changes in postural control when terminating gait with and without a prehension task? In a cross-sectional design, 15 healthy young adults (M=8, F=7; 27±2 years; 69±13 kg; 171±8 cm) underwent both a single task gait termination (GTO) and dual task (gait termination plus reaching; GTR). Postural Time-to-Contact (TtC) was measured using Center of Pressure (CoP) and the sternum position in anterior-posterior (AP) and medial-lateral (ML) directions over two different phases: preparatory phase and stabilization phase. Five successful trials were recorded to obtain a mean TtC. For statistical analysis of TtC, a two-tailed paired t -test was used (p =.05) as normality was satisfied. For the preparatory phase, there were no differences for the CoP, but TtC of the sternum position in AP was shorter in GTR than GTO (p =.001). Meanwhile, for the stabilization phase, TtCs of both the CoP and sternum position were longer in GTR in both AP and ML directions (p's <.001). We suggest that for the preparatory phase, the shorter TtC of the sternum position with intact TtC of the CoP in GTR indicates that healthy young individuals are flexible, in that they smoothly integrate CoP control with the upper body demands required to also perform the prehension task. Meanwhile, for the stabilization phase, the longer TtC in dual termination and prehension task indicates that the perturbation imposed by the prehension movement did not result in reduced stabilization when returning to an upright posture. • Time-to-Contact (TtC) stability boundaries was assessed during gait termination. • Prehension combined with gait termination reduces TtC during the preparatory phase. • This reduction was observed for the trunk but not the center of pressure. • The addition of a manual task led to better stabilization after gait termination. • Longer TtC in the dual task may result from greater awareness of stability limits. [ABSTRACT FROM AUTHOR]

The foot placement is a determinant of the base of support and influences standing balance. The reliability of postural stability tests with different foot placement angles is unclear. To determine and compare the intra- and inter-day reliability of the center of pressure-based postural stability while standing with different foot placement angles. Twenty-five healthy adults (16 females and 9 males; age: 29 ± 6 years) completed 70 s trials of eyes open and eyes closed stability tests with 0°, 15°, 30°, and 45° angles between the feet while standing on a forceplate in three sessions: two sessions were in the same day, and the third session was one-week apart. The repeatability of measurements was tested using analysis of variance, interclass correlation, and standard error of measurements. Throughout the three study sessions, there was no difference in postural stability while participants stood with different foot placement angles. The interclass correlation scores ranged from 0.71 to 0.96, the standard error of measurements ranged from 2.1% to 12.9%, and no significant systematic changes (p < 0.05) occurred between the testing sessions for any foot placements. Standing with a 45° angle between the feet with closed eyes showed higher reliability values than other conditions. The intra-day reliability scores were greater than inter-day reliability. The relative reliability of postural stability could be impacted by foot placement angles, which might alter ankle mobility and base of support dimensions. The advantages of larger foot placement angles on improving the relative reliability of postural stability could be better demonstrated in healthy people under challenging conditions such as standing with closed eyes. Standing with foot placement angles between 0° and 45° are reliable and a quantitative assessment of the center of pressure could be used to monitor the changes in postural stability between sessions. • Between-sessions reliability of postural stability varies based on between foot angle. • Mean velocity of CoP has moderate to excellent ICC. • 45° between foot angle has higher reliability values than 0°, 15°, and 30°. • The intra-day reliability values are greater than inter-day reliability. [ABSTRACT FROM AUTHOR]

Objective: This study compared postural control and neuromuscular activation in athletic swimmers (A-S) and non-athletic swimmers (N-A-S) in older children. Methods: Ten A-S and ten N-A-S underwent assessments of center of pressure (CoP) parameters under static and dynamic surfaces in two directions (dynamic mediolateral (DML) and dynamic anteroposterior (DAP)) in eyes-open (EO) and eyes-closed (EC) conditions, and electromyography (EMG) parameters under DAP and DML directions in EO and EC conditions. Results: Results showed that A-S demonstrated significantly superior postural control (p < 0.05), with smaller CoP area and lower CoP mean velocity compared with N-A-S, particularly in static with EC, DAP with EO and EC, and DML with EO conditions. A-S exhibited significantly larger neuromuscular activation amplitudes (p < 0.05), especially in the AP direction. Conclusions: These findings suggested that athletic swimming training may enhance postural control and neuromuscular activation in 11–13-year-old children, emphasizing the potential benefits of incorporating swimming exercises in these children. [ABSTRACT FROM AUTHOR]

Abstract Background and Aims Gait initiation (GI) in individuals with chronic ankle instability (CAI) has shown differences in the center of pressure (COP) and muscular measures compared to healthy controls. Some studies reported that these alterations appeared when GI was with the affected leg, while others indicated that they occurred when GI was with the non‐affected leg. This systematic review aimed to understand kinetic and muscular differences between individuals with CAI, healthy controls, and the affected and non‐affected legs of individuals with CAI. Methods PubMed, Science Direct, Web of Science, Google Scholar, and Scopus databases (1990–2023) were searched using the Population, Exposure, Comparator, and Outcome measure. The PRISMA guidelines were followed. The outcome measures were the peak and rate of COP displacement in the medial‐lateral and anterior‐posterior directions, and resultant plane during phases 1, 2, and 3 of COP trace during GI and the duration of each phase. The other measures included the onset time of the tibialis anterior and soleus muscle activity between individuals with CAI, healthy controls, and the affected and non‐affected legs of the individuals with CAI. The studies' quality assessment was conducted based on the Strengthening the Reporting of Observational Studies in Epidemiology checklist. Results Five studies were included in the final evaluation. The results of included studies showed, individuals with CAI spent less time during phases 1 and 2, as well as a shorter peak of COP displacement in the lateral direction during phase 1 compared to healthy controls, regardless of whether the GI was with the affected or non‐affected leg. Conclusion Individuals with CAI have probably adopted a strategy involving adjusting the peak of COP displacement to manage internal sway while in a single‐leg stance. Overall, there was no comprehensive conclusion about differences between the two legs in individuals with CAI.

Background: Combined knee valgus and tibial internal rotation (VL + IR) moments have been shown to stress the anterior cruciate ligament (ACL) in several in vitro cadaveric studies. To utilize this knowledge for non-contact ACL injury prevention in sports, it is necessary to elucidate how the ground reaction force (GRF) acting point (center of pressure (CoP)) in the stance foot produces combined knee VL + IR moments in risky maneuvers, such as cuttings. However, the effects of the GRF acting point on the development of the combined knee VL + IR moment in cutting are still unknown. Methods: We first established the deterministic mechanical condition that the CoP position relative to the tibial rotational axis differentiates the GRF vector's directional probability for developing the combined knee VL + IR moment, and theoretically predicted that when the CoP is posterior to the tibial rotational axis, the GRF vector is more likely to produce the combined knee VL + IR moment than when the CoP is anterior to the tibial rotational axis. Then, we tested a stochastic aspect of our theory in a lab-controlled in vivo experiment. Fourteen females performed 60° cutting under forefoot/rearfoot strike conditions (10 trials each). The positions of lower limb markers and GRF data were measured, and the knee moment due to GRF vector was calculated. The trials were divided into anterior- and posterior-CoP groups depending on the CoP position relative to the tibial rotational axis at each 10 ms interval from 0 to 100 ms after foot strike, and the occurrence rate of the combined knee VL + IR moment was compared between trial groups. Results: The posterior-CoP group showed significantly higher occurrence rates of the combined knee VL + IR moment (maximum of 82.8%) at every time point than those of the anterior-CoP trials, as theoretically predicted by the deterministic mechanical condition. Conclusion: The rearfoot strikes inducing the posterior CoP should be avoided to reduce the risk of non-contact ACL injury associated with the combined knee VL + IR stress.

The main aim of the study was to investigate the relationship between ground reaction force (GRF) derived postural sway and 180° turn performance in soccer players on the axis of dominant and non-dominant legs. Twenty-seven male soccer players (mean age 22.45 ± 2.7 years) from the same league level agreed to participate in the study. The participants underwent GRF-derived postural sway and 180⁰ turn tests using a force plate in separate sessions, with at least 24-hour intervals between sessions. Postural sway was assessed in anteroposterior and mediolateral directions during a single-leg stance, while the 180° turn performance was evaluated through GRF-derived turn time and turn sway. The correlation, multiple regression, and group differences were computed to test study hypotheses. Positive correlations were observed between postural sway measures and 180⁰ turn time for dominant and non-dominant legs (r-range from 0.384 to 0.550). No measure of postural sway was significantly related to the 180⁰ turn sway (p> 0.05). Multiple stepwise regression analysis indicated that mediolateral sway velocity explained 30% and 17% of the variance of 180⁰ turn time for dominant and non-dominant legs, respectively. No statistical inter-limb differences were noted for 180⁰ turn and postural sway parameters. The results suggest that improving single-leg postural performance may enhance male soccer players' 180° turn performance. Therefore, unilateral stability in the mediolateral direction should be considered a potential indicator of change of direction-based performances.

Abstract Background We hypothesized that postural instability observed in individuals with Parkinson's disease (PD) can be classified as distinct subtypes based on comprehensive analyses of various evaluated parameters obtained from time-series of center of pressure (CoP) data during quiet standing. The aim of this study was to characterize the postural control patterns in PD patients by performing an exploratory factor analysis and subsequent cluster analysis using CoP time-series data during quiet standing. Methods 127 PD patients, 47 aged 65 years or older healthy older adults, and 71 healthy young adults participated in this study. Subjects maintain quiet standing for 30 s on a force platform and 23 variables were calculated from the measured CoP time-series data. Exploratory factor analysis and cluster analysis with a Gaussian mixture model using factors were performed on each variable to classify subgroups based on differences in characteristics of postural instability in PD. Results The factor analysis identified five factors (magnitude of sway, medio-lateral frequency, anterio-posterior frequency, component of high frequency, and closed-loop control). Based on the five extracted factors, six distinct subtypes were identified, which can be considered as subtypes of distinct manifestations of postural disorders in PD patients. Factor loading scores for the clinical classifications (younger, older, and PD severity) overlapped, but the cluster classification scores were clearly separated. Conclusions The cluster categorization clearly identifies symptom-dependent differences in the characteristics of the CoP, suggesting that the detected clusters can be regarded as subtypes of distinct manifestations of postural disorders in patients with PD.

Multiple obstacle avoidance induces a higher potential of falls among older adults. This study attempted to add other important measurements by investigating the pressure-related gait parameters when stepping over multiple obstacles on a portable pressure-sensing walkway. Twenty-six young and 26 older participants were recruited in this study. A portable pressure-sensing Zeno walkway and cyclogram intersection point analysis method was introduced to collect both spatial–temporal and pressure-related gait parameters. Older adults significantly reduced foot integrated pressure of the leading leg when stepping over the second obstacle compared with young adults (p =.0078). A significantly larger cyclogram intersection point shift in medial–lateral direction was found in older adults than in young adults (p =.024) when stepping over the second obstacle, especially in the lateral direction. The results of this study showed that a pressure-sensing walking combined with cyclogram intersection point method could detect foot pressure distribution differences caused by aging. [ABSTRACT FROM AUTHOR]

Introduction: The human foot has evolved over the past seven million years from a relatively mobile, grasping appendage to a highly derived structure with a heel pad and longitudinal arch that can absorb shock at heel strike and weight- bearing yet also function as a powerful lever at toe-off. It has been proposed that the modern human foot evolved to allow our species to use "variable gearing" during walking and running. In this model, the gears of the human foot are defined relative to the ankle center of rotation as R, the distance from the ground reaction resultant vector, and r, the distance from the calf muscle vector. The gear ratio defines the torque generated to propel the body or stretch the triceps surae muscles. We test the hypothesis that variable gearing is associated with modern human pedal anatomy and a heel-to-toe rollover that allows a shift from "low gear" to "high gear" during stance. Methods: Using force plate and video analysis, we examined variable gearing in adults and children engaging in adult heel strike (AHS = 35), flat foot contact (FFC = 39), or initial heel contact (IHC = 26). Results and Discussion: Our hypothesis was partly supported. Although variable gearing was observed in IHC steps and was greater than in FFC steps, it was notas developed as in AHS steps. This may be related to anatomical and motor control differences between juvenile and adult feet, suggesting that adult anatomy, including a high arch, and neural control are critical for full use of variable gearing and that this feature would have evolved in later hominins around two million years ago with the appearance of a fully modern foot. [ABSTRACT FROM AUTHOR]