Center Of Pressure Velocity Research Articles

Proprioceptive Training Improves Postural Stability and Reduces Pain in Cervicogenic Headache Patients: A Randomized Clinical Trial

Background: Headache is one of the leading causes of disability in the world. Neck proprioception, pain, and postural control are interconnected in both healthy individuals and those with chronic neck pain. This study examines the effects of proprioceptive training using a gaze direction recognition task on postural stability and pain in cervicogenic headache patients. Methods: Patients with cervicogenic headache (n = 34, age: 35–49 y) were randomized into a control group (CON), receiving only selected physical therapy rehabilitation or to an experimental group (EXP), performing proprioceptive training using a gaze direction recognition task plus selected physical therapy rehabilitation. Both programs consisted of 24, 60 min long sessions over 8 weeks. Postural stability was assessed by the modified clinical test of sensory integration of balance (mCTSIB) and a center of pressure test (COP) using the HUMAC balance system. Neck pain was assessed by a visual analog scale. Results: In all six tests, there was a time main effect (p < 0.001). In three of the six tests, there were group by time interactions so that EXP vs. CON improved more in postural stability measured while standing on foam with eyes closed normalized to population norms, COP velocity, and headache (all p ≤ 0.006). There was an association between the percent changes in standing on foam with eyes closed normalized to population norms and percent changes in COP velocity (r = 0.48, p = 0.004, n = 34) and between percent changes in COP velocity and percent changes in headache (r = 0.44, p = 0.008, n = 34). Conclusions: While we did not examine the underlying mechanisms, proprioceptive training in the form of a gaze direction recognition task can improve selected measures of postural stability, standing balance, and pain in cervicogenic headache patients.

Anticipatory postural adjustment deficits in children with developmental coordination disorder during a self-induced prehension task while standing on one leg

Effective postural control is essential for motor skill development, yet the specific nature of anticipatory control in children with Developmental Coordination Disorder (DCD) remains poorly understood for complex or dynamic stability tasks. This study investigated anticipatory postural adjustments (APA) during a self-initiated dynamic stability task. The Can Placement Task (CPT)—a self-initiated dynamic stability task—was performed by 23 children with DCD and 30 typically developing (TD) children aged 9–12 years. The task involved standing on one leg while also repositioning a can on the floor. Center of pressure (COP) movement was recorded by two force platforms during the five phases of the movement. The ground reaction force measured external support during both descent to pick up the can and ascent after replacing the can. The study used a mixed-design approach with group (DCD, TD) as a between-subject factor and condition (can position close or far) and phase of movement as within-subject. Distinct movement control characteristics were shown for children with DCD including a greater range of COP movement and higher COP velocity in the anterior-posterior direction prior to movement initiation compared with TD. The DCD group also relied more on external support during both the downward and upward phases of the CPT and needed more trials to complete the task. Only two significant interaction effects involving Group and the within-subject factors emerged. Children with DCD swayed significantly more at specific phases of the task, especially when coming up and restoring balance, and did not adapt COP velocity as a function of reaching distance. Dynamic control of posture in children with DCD is impaired as they struggle to generate the effective APAs necessary to maintain dynamic stability which leads to greater reliance on external support and more corrective movements. The CPT provides a valuable assessment of posture and dynamic balance control during a complex prehension movement performed on one leg; the task highlights distinct movement patterns between children with and without DCD.

Ankle torque variance is a better indicator of balance control performance than plantar perceptual sensitivity threshold.

We explored whether ankle torque variability or plantar perceptual threshold explains human balance control more effectively. We hypothesized that ankle torque variance is a better indicator of center of pressure (COP) velocity variance than plantar perceptual sensitivity. Two conditions were tested: loaded (23-kg vest added) and unloaded, as loading should diminish plantar sensitivity and increase COP velocity variability. We created a linear feedback model to assess the noise change in the sensorimotor loop induced by loading. Plantar sensitivity was quantified using a psychophysical approach while participants stood barefoot. A linear motor applied a force impulse on the participant's heel. A "yes-no" method of limits was selected to identify plantar sole sensory thresholds in both conditions. We observed reduced plantar sensitivity in loaded compared with unloaded conditions. In the loaded condition, participants exhibited greater COP velocity variance, with significant positive Pearson's correlations confirming a substantial association between ankle torque and COP velocity variances for both loaded [variance accounted for (VAF): r2 = 44.56%, P = 0.018] and unloaded conditions (VAF: r2 = 58.83%, P = 0.004). No significant correlation existed between COP velocity variance and plantar sensitivity threshold for both loaded (VAF: r2 = 0.002%, P = 0.99) and unloaded conditions (VAF: r2 = 21.81%, P = 0.35). The model confirmed an ∼88% rise in sensorimotor loop noise in the loaded condition. Ankle torque variance assesses the precision of nonperceptual and perceptual detection mechanisms in evaluating whole body motions and the accuracy in converting sensory cues into ankle torque.NEW & NOTEWORTHY Plantar cutaneous information contributes to balance control by modulating motor commands, but plantar perceptual sensitivity is a suboptimal indicator of balance performance. Multiple sensory cues encode whole body dynamics, guiding sensorimotor mechanisms to minimize body sway variability. Ankle torque variance is proposed as a superior measure for explaining balance control performance and evaluating the sensorimotor loop's functioning in balance control.

Effects of four weeks intervention combining high-definition transcranial direct current stimulation and foot core exercise on dynamic postural stability

This study aimed to evaluate the effect of combining high-definition transcranial direct current stimulation (HD-tDCS) with foot core exercise (FCE) on dynamic postural stability and to determine whether the improvement achieved through this mix-type intervention outperforms the intervention of HD-tDCS and FCE alone. Sixty healthy males were recruited and randomly divided into four groups: (1) HD-tDCS + FCE group (HD-tDCS combined with FCE intervention); (2) s-tDCS + FCE (sham tDCS combined with FCE intervention); (3) HD-tDCS group which only received HD-tDCS; (4) FCE group which only performed FCE. All participants received a four-week intervention (3 times a week, 20 min each time). The Y-balance task was completed before and after the intervention. The maximum reaching distance was recorded, and the data of the center of pressure (COP) were collected by a three-dimensional force plate to calculate COP displacement and velocity. No significant change in COP displacement was found among the four groups. However, the COP velocity decreased significantly in the posteromedial direction after HD-tDCS + FCE intervention compared with the baseline. The maximum reach distance was significantly increased after HD-tDCS + FCE intervention in the posteromedial (p < 0.001) and posterolateral (p < 0.001) directions of the Y balance task compared with the baseline, and the extent of increase was greater than that in the three other groups. The intervention of HD-tDCS combined with FCE may exert a synergistic effect and more effectively improve dynamic postural stability.

THE RELATIONSHIPS AMONG GYMNASTS’ TRAINING AGE, BODY MASS INDEX, BALANCE CONTROL, AND GYMNASTICS PERFORMANCE

The aim of the study was the examination of the relationships among gymnasts’ training age, body mass index (BMI), balance control during the execution of handstand, standing scale forward, and stork standing in relevé position, and their performance in competition settings. Forty young competitive gymnasts (20 males; age: 12.20 ± 1.98 years, and 20 females; age: 12.33 ± 2.07 years, mean ± SD) participated in this study. A portable digital platform for posturography was used to measure maximal pressure, center of pressure (CoP) sway area, CoP linear distance displacement and CoP velocity. The resulting data were analyzed using an integrated software module (Foot Checker, version 4.0). The results confirm the reliability of the measurements. Strong positive correlations were found between gymnasts' performance in the gymnastics competition, and their training age and BMI, with relationships also identified between performance and variables related to balance control. Regression analysis revealed that gymnasts' training age, BMI, and balance control in performing the assessed gymnastics skills had predictive significance in determining their performance in the competition, taking into account differences between age groups. Despite the limitations of the study, the results represent a valuable contribution to the literature by expanding knowledge about predicting gymnastics performance in competition. Furthermore, the results provide evidence for the identification of talent in gymnasts, offer coaches insights to improve training efficiency, and provide recommendations for future research in this area.

Long-range cross-correlations between center of pressure velocity and colored noises provided during quiet standing

Unperceivable electrical noise stimulation has been applied to improve postural control through the enhancement of somatosensory feedback. It has been observed that stimulation with a pink noise (1/f) structure is more effective than stimulation with other noise structures. In addition, the 1/f structure embedded in the postural control system may have a superior effect on postural control stabilization. However, the direct relationship between the long-range correlations of the pink-noise signal applied to somatosensory receptors and those of the postural control system has not been elucidated. Thus, we aimed to explore a common long-range correlation factor shared in the time series of the provided noise and foot center of pressure (CoP) during quiet standing. Sixteen young adults stood quietly on the force platform for 65 s. Four noise conditions (no stimulation and stimulation of knee joints with white-, pink-, and red-noise-like signals) were employed during the standing trials. The detrending moving-average cross-correlation analysis revealed that in each of the anteroposterior and mediolateral directions, the CoP velocity time series displayed significant long-range cross-correlations with the white and pink noise signals provided at that time, whereas such an effect was not observed in the red noise signal. This result indicates that pink and white noise signals would alter the temporal behavior of the CoP during quiet standing, although the mechanism remains to be elucidated.

Temporal adaptation of the postural control following a prolonged fin swimming.

Postural control deteriorates following a transition between two environments, highlighting a sensory conflict when returning to natural conditions. Aquatic immersion offers new perspectives for studying postural control adaptation in transitional situations. Our aim is to study immediate and post-task static postural control adaptation on land after a prolonged fin swimming exercise in total immersion. Standing static postural control was assessed in 14 professional or recreational SCUBA divers (11 men, 3 women; 33.21 ± 10.70years), with eyes open and closed, before, immediately after, and in the following 20min following a fully-immersed 45-min fin swimming exercise. Centre-of-pressure metrics (COP) including average position, amplitude, velocity, length and 95% ellipse were evaluated in medial-lateral (x-axis) and anterior-posterior (y-axis) directions with a force platform. The Romberg ratio was also assessed for each metric. A two-way repeated measures analysis of variance revealed a significant effect of the measurement period on COPx vel (p = 0.01), COPy vel (p < 0.01) and Length (p < 0.01), and of the visual condition on COPy vel (p < 0.01) and Length (p < 0.01). Eyes closed measures were systematically higher than eyes open measures despite there being no significant difference in the Romberg ratio in all periods. Post-immersion, the velocity and total trajectory of the centre of pressure remained systematically lower than baseline values in both visual conditions. Post-immersion, COP velocity and length significantly decreased, suggesting a sensory reweighting strategy potentially associated with ankle stiffening.

Concern about falling is related to threat-induced changes in emotions and postural control in older adults

BackgroundConcern about falling is reportedly related to mobility and balance in older adults. While increased concern about falling may be directly related to balance deficits, establishing a causal relationship remains limited. This study aimed to investigate whether concern about falling affects threat-induced changes in emotions and postural control in older adults. Research questionHow does concern about falling affect threat-induced changes in emotions and postural control among older adults? MethodsSixty-two older adults (age; 78.8 ± 5.7 years, height; 152.7 ± 6.3 cm) were exposed to height-related fear while standing, leaning forward, and leaning backward on the floor and a higher surface. The mean position, root mean square, and mean velocity of the center of pressure (COP) displacement were measured during the standing task, as well as the forward and backward limits of stability (LOS) tasks. The degree of self-reported fear of falling (FoF) was also obtained during the standing and LOS tasks. The participants were categorized into lower and higher concerns about falling based on the short form of the Falls Efficacy Scale International (FESI). ResultsLower and higher concern about falling groups scored 10.2 ± 2.2 and 17.3 ± 3.3 in the short FESI. Both groups experienced increased FoF during the standing and forward LOS tasks on a higher surface. Leaning away from the edge of the surface resulted in increased COP velocity, decreased COP amplitude while standing, and decreased forward LOS. Participants with higher concern about falling had increased FoF during the backward LOS task and decreased backward LOS on a higher surface, while those with lower concern about falling did not. SignificanceConcern about falling can directly affect emotions and balance control owing to the occurrence of threat-related changes.

Comparison of Biomechanical, Clinical Indicators, and Quality of Life in People Undergoing Hip Replacement Surgery with Anterior and Posterior Approaches

Background: There are ongoing debates among surgeons regarding the most effective surgical method for hip replacement, with varying preferences for the anterior and posterior approaches. Both methods have demonstrated excellent long-term outcomes, with clinical differences primarily observed in the early postoperative period. Objectives: This study aimed to compare the anterior and posterior methods of hip replacement after six months of surgery in terms of biomechanical and clinical indicators, as well as quality of life. Methods: In this cross-sectional observational study, 42 patients who underwent hip replacement surgery using either the anterior (n = 22) or posterior method (n = 20) at least six months (and a maximum of 12 months) post-surgery, along with 20 healthy individuals, were evaluated. Biomechanical indices of the center of pressure (COP) were measured using a force plate during two-leg standing with eyes open and closed. Functional balance, independence, self-perception of performance, satisfaction, and quality of life were assessed using the timed up and go test (TUG), Barthel Index, Canadian Occupational Performance Measure (COPM), and the SF-36, respectively. Results: No significant differences were found between the anterior and posterior groups in terms of COP, clinical variables, and quality of life (P &gt; 0.05). However, when compared to the control group, the anterior replacement group exhibited significantly higher COP displacement in the medial-lateral direction (P = 0.03) and COP velocity in the anterior-posterior direction (P = 0.02) during two-leg standing with eyes open. No significant differences in COP variables were observed in the posterior replacement group compared to the control group (P &gt; 0.05). Conclusions: The findings indicate no significant differences between the anterior and posterior approaches to hip replacement in terms of biomechanical and clinical indicators, as well as quality of life after six months. Therefore, the choice of surgical method can be based on the patient's condition and the surgeon’s expertise in the respective approach.

Comparison of Subjective and Biomechanical Outcomes Between Proprioceptive Training and Modified Broström-Gould Surgery for Chronic Ankle Instability: A Randomized Controlled Trial.

Both proprioceptive training and modified Broström-Gould surgery can improve ankle stability in patients with chronic ankle instability (CAI), but further biomechanical evaluation is necessary to determine the optimal treatment. To compare the clinical outcomes and biomechanical changes after proprioceptive training versus modified Broström-Gould surgery in patients with CAI. Randomized controlled trial; Level of evidence, 2. A total of 56 patients with CAI were assigned randomly to either a nonoperative group (n = 28) who underwent 3 months of proprioceptive training or an operative group (n = 28) who underwent modified Broström-Gould surgery. Foot and Ankle Ability Measure (FAAM) scores, foot pressure during walking, center of pressure (COP) velocity, and time for the COP to reach the balance boundary (time to boundary [TTB]) during single-leg standing were collected before the intervention (baseline) and at 3, 6, and 12 months after the intervention. Two-way repeated-measures analysis of variance was used to compare group differences and changes over time. The nonoperative group had significant improvements from baseline in FAAM-Sports score and significantly decreased TTB in both the anterior-posterior and medial-lateral directions at all timepoints, while the operative group showed significant improvements only in FAAM-Sports scores and TTB and COP velocity in the anterior-posterior direction at 6 and 12 months postintervention. During walking, the nonoperative group had significantly increased peak force under the medial foot at 3 months, which dropped back to baseline levels at 12 months, while the operative group had significantly increased peak force under the medial midfoot and hindfoot that persisted until 12 months (P < .05). In this study, both proprioceptive training and modified Broström-Gould surgery led to improved subjective functional scores, foot pressure distribution during walking, and postural stability during standing for patients with CAI but with different biomechanical patterns. Proprioceptive training led to an earlier recovery of sports function and better medial-lateral stability recovery, while surgery provided more persistent results. ChiCTR1900023999 (Chinese Clinical Trial Registry).

The correlation of gait and muscle activation characteristics with locomotion dysfunction grade in elderly individuals.

To investigate the differences and regularity of gait and muscle activation characteristics parameters in the Locomotion Dysfunction Grade (LDG) scale assessment in elderly individuals, and analyse the correlation between objective parameters and scale grading. Thus, to propose a novel detection mode for elderly individuals, which combined the LDG scale with objective detection. It can not only provide quantitative data for intelligent evaluation and rehabilitation, but also provided more accurate reference for the classification of care levels in elderly care policies. Elderly individuals (n = 159) who underwent gait analysis and sEMG at the Chinese Rehabilitation Research Center from January 2019 to September 2023 were included. According to the LDG scale, the elderly individuals were divided into four groups, namely, the LDG4, LDG5, LDG6 groups and the healthy control group. Four indicators, namely, spatiotemporal, kinematic, dynamic gait parameters and muscle activation characteristics data, were collected. Changes in these characteristics of elderly individuals with lower extremity motor dysfunction were evaluated and analysed statistically. The spatiotemporal gait parameters were significantly lower in the LDG4, LDG5, LDG6 groups than in the healthy control group. The double support phase was positively correlated with the LDG, while the swing phase, step length and velocity were negatively correlated (P < 0.05). The movement angles of both hips, knees and ankles were significantly limited and negatively correlated with the LDG (P < 0.05). Compared with those in the healthy control group, the centre of pressure (COP) path length were greater, and the average COP velocity was significantly lower (P < 0.05) in the LDG4, LDG5, LDG6 groups. The regularity of muscle activation clearly changed. The root mean square of the gastrocnemius medialis was positively correlated with LDG (P < 0.05), while the tibialis anterior showed no regularity. As the LDG increased, the differences in spatiotemporal, kinematic and dynamic gait parameters between elderly individuals with motor dysfunction and the healthy individuals gradually increased. The muscle activation characteristics parameters showed an abnormal activation pattern. These parameters were correlated with the LDG, providing a more comprehensive and objective assessment of lower extremity motor function in elderly individuals, improve assessment accuracy, and help accurate rehabilitation.

CAN SIMPLE REACTION TIME TO A VISUAL STIMULUS BE USED AS A MEASURE OF THE BALANCE TASK INTENSITY?

Correctly determining the frequency, intensity and duration of balance tasks (BT) is crucial for effective balance training. While the frequency and BT duration are well defined, understanding BT intensity remains limited. Higher BT intensity demands greater attentional capacity for postural control. To assess the role of attention in postural control the dual-task paradigm including BT with reaction time (RT) is often used, suggesting RT as a potential measure of BT relative intensity. The study aimed to determine whether simple RT can be a surrogate for the relative BT intensity. Twenty randomly selected participants performed six repetitions of two-legged and one-legged stances on firm and compliant surfaces on a force plate. During the execution of the BT, the participants had to react on illumination of the light by pressing a switch held in their dominant hand. The center of pressure (COP) velocity and the RT were investigated. The BT were categorized into low, moderate and high intensities. The results showed a significant increase in COP velocity from low to high intensity BT (p=0.001; η2=0.79). Moderate intensity BT resulted in a 123.6% increase in COP velocity compared to the low intensity BT. During high-intensity BT COP velocity increased by 244.2 % (p &lt; 0.001). There were no differences in RT between different BT intensities (p=0.596; η2=0.03). The results suggest that RT may not accurately reflect the BT intensity. Therefore, it can be concluded that simple visual RT could not be used as a measure of relative intensity of BT.

Center of Pressure Velocity and Dynamic Postural Control Strategies Vary During Y-Balance and Star Excursion Balance Testing.

Dynamic postural control (DPC) describes an individual's ability to maintain balance within their base of support in both anticipatory and reactive balance situations and has been measured using center of pressure (COP) velocity. Common standardized DPC assessments for active adults include the modified Star Excursion Balance Test (MSEBT) and the Y-Balance Test (YBT). The purpose of this study was to explore DPC during performance of the MSEBT, the YBT, and a modified version of the YBT, the MYBT. It was hypothesized that feedback from the YBT/MYBT reach indicator would enhance DPC. Cross-sectional study. Twenty-one participants (9 females, 12 males, mean age 24.5±1.2 years) performed three trials in each direction (anterior-AN, posteromedial-PM, and posterolateral-PL) on each balance test during one session. The YBT frame was placed atop a force plate for all testing. Frontal and sagittal plane COP velocities (COPx and COPy, respectively) were recorded throughout each trial and resultant COP (COPr) velocities were calculated. Significant main effects were present for test (F=4.485, p\<0.001) and reach direction (F=61.594, p\<0.001). Post hoc analyses for test indicated significant differences in COPy between YBT and MSEBT (p=0.034) and between MYBT and MSEBT (p\<0.001), as well as significant differences in COPr between MYBT and MSEBT (p=0.002). Post hoc analyses for reach direction revealed significant differences in COPx between AN and both PM (p\<0.001) and PL (p\<0.001) directions, in COPy between AN and PM (p\<0.001) and PL (p\<0.001) directions, and COPr between AN and PL (p=0.043) directions only. External proprioceptive feedback from the reach indicator improved DPC during the YBT and MYBT when compared to the MSEBT. Sagittal plane COP velocities were reduced when external proprioceptive feedback from the reach indicator was present, while frontal plane COP velocities were not affected in this group of participants. 2b.

IMMEDIATE EFFECT OF CUSTOM-MADE BOSTON-TYPE THORACO-LUMBO-SACRAL ORTHOSIS ON BALANCE AND POSTURAL STABILITY IN ADOLESCENT IDIOPATHIC SCOLIOSIS

Adolescent idiopathic scoliosis (AIS) can impair postural stability and balance functions. Boston brace systems with varying external corrective force strategies are used as one of the common conservative treatments in AIS. Although multiple studies have found that various orthotic therapies enhance curve advancement, the effects of spinal bracing on postural equilibrium and stability remain unknown. The primary objective of this study was to examine the effect of the immediate use of custom-made Boston-type thoraco-lumbo-sacral orthosis (TLSO) on balance and postural stability in AIS. Postural balance using the center of pressure (CoP) measures was measured by the HUMACⓇ Balance &amp; Tilt System (CSMi, Stoughton, MA). The line laser tool (Bosch, GLL 3 X P, Stuttgart, Germany) was used for measuring the decompensation distance for postural evaluation. The balance parameters such as stability score (%), path length (cm), average velocity (cm/s), and compensation–decompensation for posture were evaluated and compared between brace-on and brace-off conditions. Improvement of standing posture indicates spinal symmetry and cosmesis whereas enhancement of static balance was statistically nonsignificant ([Formula: see text] &gt; 0.05). Although the mean stability score, path length and average velocity of CoP in braced condition (91.4 ± 4.57, 115.62 ± 22.34 cm and 1.05 ± 0.12 cm/s) was found to be improved than unbraced condition (90.5 ± 5.09, 121.46 ± 35.52 cm and 1.11 ± 0.24 cm/s), the results were nonsignificant ([Formula: see text] = 0.078, 0.425 and 0.263). The scoliotic compensation was improved in the braced condition (0.64 ± 0.60 cm) compared to brace-off condition (1.74 ± 0.61 cm) showing improved posture ([Formula: see text] = 0.00013). Wearing the custom-made Boston-type TLSO showed positive effects on static posture and mean balance parameters. In future studies, the long-term effectiveness of this brace should be examined in patients with different spinal curve patterns and degrees of scoliosis.

Gait dynamic stability evaluation in patients undergoing hip joint fractures – tools to measure rehabilitation effectiveness

A hip joint fracture includes a break in the thigh (femur) or coxa bone near the pelvis. During fracture healing, stability and weight bearing by the affected limb are key indicators to measure patients’ improvement. Conventionally, the rehabilitation effectiveness is monitored through clinical examinations, patients’ feedback, and few studies also reported instrumented gait evaluations. A gap remains there to numerically quantify the recovery in patients’ stability and weight bearing in response to rehabilitation therapies. This study introduces Nyquist and Bode (N&B) methods to analyse the instrumented gait signals further and evaluate gait stability in hip fracture patients during weight loading and unloading transitions. The centre of pressure (CoP) data was recorded using force plates for conditions: coxa hip fracture (HC), femur hip fracture (HF), and normal hip joint (NH). The time rate of CoP signals illustrated two major impulses during the loading and unloading phases which were modelled in time and frequency domains. The frequency models were further analysed by applying N&B methods and stability margins were computed for both impaired and healthy conditions. Results illustrated a significant decrease (Kruskal–Wallis’s test, p < 0.001) in the intralimb walking stability of both fracture conditions. Further, Spearman’s correlation between CoP velocities of fractured and intact limbs illustrated significant interlimb dependencies to maintain walking stability (p < 0.001) during weight loading and unloading transitions. Overall, the HF impairment illustrated the least intralimb walking stability and relatively greater interlimb dependencies. Clinically, these methods and findings are important to measure the recovery in patients undergoing rehabilitation after a hip joint or other lower limb impairments.

Balance, Landing Biomechanics, and Functional Movement Screen Characteristics With and Without Knee Exoskeleton in Military Soldiers.

A light-weight pneumatic-powered knee exoskeleton could augment mobility and lifting capabilities for a variety of occupational settings. However, added weight/bulkiness and artificially produced knee extension torque could compromise sensorimotor characteristics. Ten healthy participants conducted 3 visits within 10 days to the biomechanics laboratory. Participants were asked to complete the following tasks on each visit: single-leg balance, single-leg drop-landing, and select functional movement tasks. Balance characteristics (the ground reaction forces variability and center-of-pressure velocity) were derived from force plates while knee flexion angles during drop-landing and functional movement tasks were captured using a motion capture system. Descriptive statistics as well as paired t-tests or Wilcoxon signed-rank tests were used to compare between conditions. Significance was set at P < .05 a priori. During single-leg balance, the ground reaction force variabilities were significantly increased (P = .013-.019) and the center of pressure velocity was decreased (P = .001-.017) when wearing knee exoskeleton. During single-leg drop-landing, the exoskeleton condition showed lower knee flexion angles at the initial contact (P = .004-.021) and peak (P = .006-.010). Additionally, the peak vertical ground reaction force was higher in the exoskeleton condition (P = .007). During functional movement tasks, the exoskeleton condition showed less knee flexion range-of-motion during the overhead squat (P = .007-.033) and hurdle step-over (P = .004-.005). Participants exhibited stiffer landing technique with the exoskeleton. Given that these compromised sensorimotor characteristics have been associated with musculoskeletal injury risk, modifications to exoskeletons to promote softer landing and greater knee flexion range-of-motion during dynamic activities may be warranted.

Impact of plantar flexion resistive moment of dynamic ankle foot orthosis on measures of center of pressure and clinical gait outcomes in individuals with post-stroke hemiparesis

BackgroundAn 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. ObjectivesTo 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. MethodIn 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. ResultsSignificant 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). ConclusionMedium 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.

Additional visual information on postural control mechanisms in Parkinson's disease: a pilot study

Additional visual information on postural control mechanisms in Parkinson's disease: a pilot study

How the multiplanar trunk resistance affects the dynamic postural control during single-leg vertical jumps in college athletes with poor movement quality

BACKGROUND: Poor movement quality of the trunk and the lower limbs as well as dynamic postural control have a strong relation with non-contact injuries in sport. Aiming to reduce the risk of injuries, training approaches using loaded jumps with trunk resistance have been proposed. AIM: To describe how a multiplanar trunk load affects the dynamic postural control and the peak vertical ground reaction force of college athletes with poor movement quality of the trunk and the lower limbs. METHOD: Center of Pressure (COP) variables and peak vertical ground reaction force of 24 female college athletes during single-leg jumps with and without a trunk resistance were compared. RESULTS: There was a significant decrease of the COP displacement (p=0.006), RMS (p=0.009) and velocity (p=0.007) in the anteroposterior direction, and an increase of the COP displacement (p=0.016), RMS (p=0.043) and velocity (p=0.043) in the mediolateral direction, with a moderate effect size. No significant difference was found in the peak vertical ground reaction force. CONCLUSION: Exercises involving multiplanar trunk resistance may negatively impact dynamic postural control in women with poor movement quality.

Effects of Combining Transcranial Direct Current Stimulation With Balance Training on Anticipatory Postural Adjustments in Persons With Chronic Ankle Instability.

The combination of transcranial direct current stimulation (tDCS) with balance training could integrate central and peripheral neural mechanisms. This study aimed to investigate the effects of concurrent balance training and tDCS over the supplementary motor area (SMA) on anticipatory postural adjustments during gait initiation (GI) in persons with chronic ankle instability (CAI). Balance training will increase the center of pressure (COP) velocity and displacement during GI phases in all participants, and those receiving real tDCS will show greater increases. Randomized controlled trial. Level 2. A total of 32 subjects were allocated to 2 groups: (1) intervention (balance training plus real tDCS) and (2) control (balance training plus sham tDCS). Outcome measures were COP-related parameters (displacement and velocity) during phases of GI (anticipatory, weight transition, and locomotor). The results showed that, in the anticipatory phase, the anteroposterior displacement of the COP was increased significantly at posttest relative to pretest across both groups, F(1,30) = 5.733, P = 0.02. In addition, both groups revealed an increase in the mediolateral COP velocity at posttest, F(1,30) = 10.523, P < 0.01. In the weight transition phase, both groups had higher mediolateral COP velocity at posttest, F(1,30) = 30.636, P < 0.01. In the locomotor phase, in both groups, the anteroposterior COP velocity was increased significantly at posttest compared with pretest, F(1,30) = 5.883, P = 0.02. Both groups demonstrated improvements in the anticipatory and execution phases of GI. Since no between-group difference was found, it can be interpreted that the anodal tDCS applied over the SMA has no added value over sham stimulation. Balance training is beneficial for persons with CAI and can improve the anticipation and execution phases of GI without the aid of brain stimulation.