Lower-limb inter-joint coordination during balance recovery after trips.

BACKGROUND: Trips are one of the most common external perturbations that can lead to accidental falls. Knowledge about postural control attributes of balance recovery after trips could help reveal the biomechanical causes for trip-induced falls and provide implications for fall prevention interventions. RESEARCH QUESTION: The objective of the present study was to examine coordinated lower-limb movements during balance recovery after trips. METHODS: One hundred and twenty-three volunteers participated in an experimental study. They were tripped unexpectedly by a metal pole when walking on a linear walkway at their self-selected speed. Lower-limb inter-joint coordination quantified by continuous relative phase measures, including the mean of the absolute relative phases (MARP) and the deviation phase (DP), was analyzed during the execution of the first recovery step after unexpected trips. RESULTS: Compared to unsuccessful balance recovery, smaller MARPknee-ankle and DPknee-ankle of successful recovery were observed with distal inter-joint coordination on the swing side. Inter-joint coordination of the stance limb did not significantly differ between successful and unsuccessful recovery conditions. These findings indicate that the control of the swing limb's distal joints is crucial for regaining balance after trips. SIGNIFICANCE: An implication derived from this study is that greater in-phase coordination and smaller coordination variability in distal joints of the swing limb could be considered as potential targets for interventions aimed at preventing trip-induced accidental.

(Interfering) Cortical mechanisms of standing balance and cognition in old-age depression: A functional near-infrared spectroscopy (fNIRS) study.

Major depressive disorder in old age can cause changes in the cerebral cortex that might lead to postural imbalance and thus increase fall risk. We aim to examine cortical activation during standing balance in depressed older patients compared to healthy controls and to determine how an additional cognitive task affects this activation. Eleven older patients (age ≥65 years) diagnosed with major depressive disorder and sixteen age-matched healthy controls participated in the study. Functional near-infrared spectroscopy (fNIRS) was used to assess cortical activation of the prefrontal (PFC) and motor (MC) cortex during standing balance with eyes closed under single and dual task (counting backwards). The present study generally revealed tendencies in the MC - and partly the PFC too - for more activation whilst balancing compared to baseline. Also, in the MC, patients tended to show more cortical activation compared to controls and dual task tended to elicit more activation. The results suggest that depressed older patients, to compensate for their illness, may require increased cortical activation to perform motor and cognitive tasks than healthy controls. The absence of PFC activation in the main analyses may be related to the small participant number and possibly to too simple task conditions.

Assessing postural stability in flatfoot using a time-in-boundary method during single-leg standing.

Flatfoot, a foot deformity characterized by the collapse of the arch, significantly impacts an individual's balance and stability. This study explored postural adjustments and sway excursions in individuals with and without flatfoot using the Time-in-Boundary method. This method assessed relative stability by exploring various center of pressure radius thresholds during three trials of single-leg stance. We observed significant interactions in threshold levels (F = 4.37, p = 0.04) and normalized relative stable times (F = 7.64, p = 0.01), particularly in the initial trials. Initially, the flatfoot group showed marked decreases in stable times at 10 mm, 15 mm, and 20 mm thresholds, which expanded to 25 mm and 30 mm in subsequent trials. Despite a significant decrease in stability at the 30 mm threshold in early trials, participants exhibited improved stability control as trials progressed. This enhancement likely reflects a combination of a learning effect and an increased understanding of the task requirements, underscoring the adaptability of postural control systems to the biomechanical challenges posed by flatfoot. The Time-in-Boundary method has proven to be an effective tool for clinicians to assess postural control, playing a vital role in developing customized rehabilitation strategies for individuals with flatfoot.

Postural control strategies with alterations in visual input conditions in a standing position.

BACKGROUND: Mediated by balance systems, postural control relies heavily on visual input. However, the precise relationship between various visual conditions and postural strategies for balance remains unclear. This study investigated alterations in the center of pressure (COP) and ankle muscle activity during standing positions in healthy individuals under different visual conditions. METHOD: Fifty-three healthy university students participated in the study. Stabilometry was conducted to evaluate the total path length and outer circumferential area for the COP. Further, surface electromyography was utilized to assess the activity of the bilateral tibialis anterior (TA) and lateral head of gastrocnemius muscles. Participants were instructed to maintain an upright posture under three visual conditions: binocular (eyes open) and monocular (either closing the dominant or nondominant eye). The three conditions were compared using a one-way analysis of variance. RESULTS: No significant differences were observed in the COP across visual conditions. However, in the TA of the nondominant leg, the mean values for the binocular, dominant eye, and nondominant eye conditions were 0.91, 1.08, and 1.14 times that of the resting standing position. Notably, the TA of the nondominant leg was significantly lower in the binocular condition than the dominant and nondominant eye conditions. CONCLUSION: The study findings indicate that the COP remain consistent despite variations in external visual input. This stability is likely maintained through compensatory adjustments, such as increased TA muscle activity in the nondominant leg under the nondominant eye condition. These observations highlight the complex interplay between the visual perception and postural stability.

Association between freezing of gait and anticipatory postural adjustments in Parkinson's disease.

[Purpose] One-leg standing motion was measured in patients with Parkinson's disease (PD) to evaluate the association between freezing of gait (FOG) and anticipatory postural adjustments (APA). [Participants and Methods] The participants included10 healthy older individuals, seven patients with PD without FOG (PD-FOG group), and seven patients with PD and FOG (PD+FOG group). An accelerometer that was built into a smartphone was attached to the lower back of each participant, and acceleration in the mediolateral direction was measured during one-leg standing. For the mediolateral component of acceleration, the time to the maximum value in the stance direction (peak latency, PL) and the amount of displacement of the maximum value (peak magnitude, PM) were analyzed as APA features. A one-way analysis of variance (ANOVA) was used to compare PL and PM among the three groups. In addition, the APA ratio (APAr), which is the ratio of PL to PM, was compared between study cohorts. [Results] Delayed PL and decreased PM were observed in the PD+FOG group, compared with the older and PD-FOG groups. In addition, APAr levels were significantly lower in the PD+FOG group. [Conclusion] Patients with PD with FOG had greater APA impairment than those with PD without FOG.

Effects of shuttle balance exercises on gait speed, postural control, and quality of life in older males: A randomized controlled trial.

BACKGROUND AND PURPOSE: Enhancing physical function and quality of life in older adults at higher risk of falls is challenging because of the lack of established interventions. This study examines the impact of a 6-week balance training program using the shuttle balance device on gait speed, postural control, and quality of life in older men. METHODS: This single-blinded randomized controlled trial was conducted in a research laboratory. Thirty-two participants aged ≥60 years were randomly assigned to either an experimental group (EG; n = 16) or a control group (CG; n = 14). The EG participated in a 6-week shuttle balance exercise program, while the CG maintained regular physical activity routines. The main outcome measures included gait speed (assessed via the timed up and go test), postural control (assessed via center of pressure data on a force plate), and quality of life (evaluated using the SF-36 questionnaire). RESULTS: Post-intervention, the EG showed significant improvements compared with the CG (p < 0.05). The 95% confidence intervals for the differences between groups were as follows: closed eyes (CE) mean velocity (-39.07, -0.13), CE sway area (-48.86, -0.18), SF-36 total score (9.01, 16.81), SF-36 physical functioning (7.00, 24.81), SF-36 physical role functioning (1.80, 27.57), SF-36 pain (15.01, 36.82), SF-36 general health state (7.48, 26.08), SF-36 vitality (5.60, 28.35), and SF-36 mental health (0.21, 21.12). DISCUSSION: A 6-week shuttle balance training program significantly improves postural control and quality of life in older males. These findings suggest the potential effectiveness of shuttle balance exercises in enhancing physical function and well-being in this population. Further research is needed to validate these findings and explore the long-term effects with larger sample sizes.

Reliability and validity of the ratings of perceived stability scale as a measure of balance exercise intensity in persons with multiple sclerosis.

PURPOSE: The study aimed to determine the test-retest reliability and concurrent validity of the Ratings of Perceived Stability (RPS) scale as a measure of balance exercise intensity in persons with multiple sclerosis (MS). METHODS: Twenty participants with MS (mean age: 58.1 ± 15.29; 60% female) performed 14 balance tasks on two separate occasions wearing body-worn inertial sensors and rated their perceived stability for each task. Sensor data included sway velocity and angle, gait speed, turn velocity, and lean angle. Intraclass correlation coefficients (ICC) and Spearman rank correlations (rs) were employed to assess reliability and validity, respectively. RESULTS: The RPS showed good to excellent test-retest reliability (ICC> 0.75) on 12 out of the 14 tasks. The stability ratings revealed moderate relationships with postural sway outcomes in static balance tasks (rs: 0.49 to 0.77) and weak to moderate associations with gait speed (rs: -0.69 to -0.14). Ratings of stability were also strongly related to turn velocity (rs= -0.77) and moderately related to lean angle (rs= 0.58). CONCLUSIONS: The RPS scale offers a promising clinical tool to measure balance exercise intensity for persons with MS. This standardized scale allows for tailored balance training with a novel means for exercise monitoring and progression in this population.

The Ratings of Perceived Stability (RPS) scale is a reliable and valid measure for determining balance exercise intensity in persons with multiple sclerosis.The RPS scale can contribute to clear evaluation, description, and replication of balance training intensity in future balance interventions.

European Portuguese version of the Mini-BESTest: a cross-cultural adaptation and psychometric measurements in individuals with sensorimotor impairments.

PURPOSE: This study aimed to translate and cross-culturally adapt the Mini-BESTest into European Portuguese and to evaluate its psychometric properties in individuals with sensorimotor impairments. MATERIAL AND METHODS: A cross-sectional cross-cultural adaptation and validation study was conducted according to the COSMIN guidelines and the STROBE statement. The study included 100 participants with sensorimotor impairments who were able to walk 6 m. Cronbach's alpha and item-total correlations were used to assess internal consistency. Interpretability was assessed by examining floor and ceiling effects and skewness. To investigate construct validity, Spearman correlation coefficients and Bland-Altman analysis were performed to compare the Berg Balance Scale and the Mini-BESTest Inter- and intra-rater reliability were assessed by calculating the ICC, SEM and MDC based on video recordings of the participants during the Mini-BESTest assessments. RESULTS: The European Portuguese Mini-BESTest showed good internal consistency (Cronbach's α = 0.892) and no significant floor or ceiling effects. Excellent inter- and intra-rater reliability (ICC = 0.97) were also demonstrated, with MDC of 2.58 and 2.57, respectively. Furthermore, this instrument showed a significant correlation with the BBS (r = 0.902). Bland-Altman analysis showed small absolute differences. CONCLUSION: The European Portuguese Mini-BESTest is comparable to the original English version in terms of validity and reliability and is therefore highly recommended for use by Portuguese-speaking professionals to assess postural control.

The Mini-BESTest, increasingly recommended for addressing impaired postural control, has undergone its first comprehensive cross-cultural adaptation into European Portuguese.The Mini-BESTest may be a superior assessment tool compared to others because it can identify the specific postural control system that is impaired.In a clinical setting, the Mini-BESTest will aid in the development of appropriate intervention approaches, tailoring rehabilitation interventions to the specific needs of each patient.The Mini-BESTest is recommended for use by Portuguese-speaking professionals to assess postural control, as it has demonstrated good internal consistency, excellent inter- and intra-rater reliability, and significant correlation with the Berg Balance Scale.

Vestibular Function and Postural Control in Children with Autism Spectrum Disorder.

Background: Postural control deficits have been documented in children with autism spectrum disorder (ASD), yet vestibular system contributions to postural control have not been widely considered. The purpose of this study is to explore the relationship between functional balance, postural sway, and vestibular function in children with ASD. Methods: Ten children with a confirmed diagnosis of ASD according to DSM-V guidelines along with ten children with no known neurodevelopmental or motor delays participated in the study. Bruininks-Oseretsky Test of Motor Proficiency and the Paediatric Balance Scale measured functional balance ability, and postural sway was measured using static posturography with modified sensory inputs. Peripheral vestibular function was measured using cervical vestibular evoked myogenic potentials and video head impulse testing. Correlations between measures were performed. Results: When visual cues were removed, children with ASD demonstrated larger path velocities indicative of reduced postural control, and different patterns of postural sway. Functional balance was correlated with path velocities for conditions where sensory information was modified. No differences in peripheral vestibular function were noted between groups, and functional balance was not correlated with vestibular function. Conclusions: Findings suggest that while peripheral vestibular function is similar between groups, postural control differences in children with ASD remain, particularly for conditions where sensory information is modified. Furthermore, demonstrated patterns of postural sway suggest sensory system integration is less developed in children with ASD. These findings highlight the importance of utilising a range of clinical tools to quantify balance ability and consideration of postural control measures to inform intervention.

The Effect of Cochlear Implant Stimulation on Postural Control.

Objective: There are contradictory reports on the effect of cochlear implantation on postural control. Associated vestibular loss, electrode insertion trauma, and electrical stimulus of a cochlear implant can influence postural control. This study focused on the electrical stimulation of the cochlea. We aimed to examine whether a cochlear implant's electrical stimulation affects postural control measured by posturography. Methods: Thirty-three patients with unilateral cochlear implants were included. We used three preprogrammed main tests and their nine subtests in posturography. Postural stability [general stability index (GSI)], fall risk index (FRI), and sensory integration [modified clinical test of sensory integration of balance (m-CTSIB)] were calculated. All tests were performed under three conditions: implant off (1), implant on (2), and implant on music (3). Results: The mean age was 46.29±16.09 years. GSI was above normal limits in 78% of adult cochlear implant users. We found that FRI was high in 30% of patients, and m-CTSIB was defective in 42%. There were no statistically significant differences in GSI, FRI, and m-CTSIB. Cochlear implant stimulation was found to have positively affected postural control when the subject's data were visualized individually. GSI, FRI, and m-CTSIB dropped to 39%, 24%, and 24%, respectively, when music was on. There was a significant correlation between age and fall index. But this correlation disappeared when music was playing. Conclusion: Cochlear implant stimulation affected the vestibular system in almost all patients. The effect was positive in most patients.

Transcutaneous spinal cord stimulation modulates quiet standing in healthy adults: stimulation site and cognitive style matter.

The study explored the effects of transcutaneous electrical spinal cord stimulation (tES) on postural control. Subjects were divided into field-dependent (FD) and field-independent (FI) groups according to their cognitive style. FD subjects use an exteroceptive afferent stream for spatial orientation, while FI subjects use an interoceptive stream. In darkness, vertical posture is maintained by head-trunk stabilization in FD subjects and by independent movements of body segments in FI subjects. Previously, we showed that tES at the L1-L2 vertebral level decreased postural stability in FD subjects. Now, stimulation was applied at the T11-T12 vertebral level (midline, above the left or right dorsal roots). Quiet standing was assessed using stabilometry in 18 FD and FI participants. Participants stood on a force platform in soundproof chamber with eyes closed during tES. Midline and left tES significantly improved postural stability by up to 28% in FD participants, while posture did not change significantly in FI participants. Pronounced differences between the effects of T11-T12 and L1-L2 stimulation are associated with selective topographical activation of proximal and distal leg muscles during tES of the lumbar enlargement. This study highlights the importance of considering cognitive style in postural control research.

Reliability of the Instrumented Modified Clinical Test of Sensory Interaction on Balance Using a Virtual Balance Device.

The purpose of this study was to evaluate the test-retest reliability of the instrumented version of the modified Clinical Test of Sensory Interaction on Balance (i-mCTSIB) using the VirtuSense VirtuBalance System™ (VSTBalance), a virtual balance device, in healthy young adults. Fifty-four subjects aged 20-27 years (Mean age 23.07, SD ± 1.6), participated in the study. A one-group design was utilized. Three trials of the i-mCTSIB were performed on two separate days to measure the mean sway velocity of the trunk under four conditions. Within-day reliability of trials 1-3 was estimated with intraclass correlation coefficients (ICC3,1) and between-day reliability was estimated using the averages of trials 1-3 on day 1 and day 2 (ICC3,3). Within-day reliability was moderate on day 1 (ICC = 0.511-0.672) and day 2 (ICC = 0.539 -0.677). Between-day reliability was moderate to good (ICC = 0.705-0.810). The lower bounds of the confidence intervals of within-day reliability estimates were 0.341-0.548, while the lower bounds of the confidence interval for the between-day reliability estimates were 0.390-0.671. Reliability of the VSTBalance for balance assessment using the i-mCTSIB test is moderate to good. Between-day reliability was higher than within-day reliability. When using the VSTBalance to assess balance with the i-mCTSIB, clinicians should provide practice of each condition contained in the test to improve reliability. The higher between-day reliability as compared to within-day reliability suggests that clinicians should use the averages of three trials when assessing balance performance change across time for each condition of the i-mCTSIB test when assessing balance using the VSTBalance.

Effects of anodal transcranial direct current stimulation on postural stability in subacute stroke: A randomized control trial.

Anodal transcranial direct current stimulation (tDCS) promotes neuromodulation and neuroplasticity in the brain. The aim of this study was to determine the long-term effects of the anodal tDCS on postural and trunk stability, physical performance, anticipatory postural adjustment and quality of life in sub-acute stroke patients. Thirty-six participants with sub-acute stroke were divided into experimental and control groups using sealed envelope randomization. Outcome measures comprised the Postural Assessment Scale for Stroke, Trunk Impairment Scale, Time Up and Go Test, Functional Reach Test, and Stroke-Specific Quality of Life Scale. Assessments were conducted at 0, 3, 6, 9, and 12 weeks. Within-group analysis revealed significant improvement in both the experimental (p-value < 0.05) and control groups (p-value < 0.005). Notably, significant effects were observed in postural stability after intervention, and during one of the detraining assessments, the experimental group showed superior results compared to the control group in subacute stroke. Anodal tDCS yield significant short- and long-term effects on postural stability, while short term effects on trunk stability. Additionally, long term effects were observed on the physical performance and anticipatory postural adjustments while no effects at quality of life either short or long term basis among the subacute stroke patients.

Tai Chi for balance and postural control in people with peripheral neuropathy: A scoping review.

BACKGROUND: Peripheral neuropathy can affect balance and increase fall risk. Tai Chi is known to activate neuromuscular systems and may help improve balance and postural control. We conducted a scoping review of clinical studies that evaluated the impact of Tai Chi on balance and related neurobiological outcomes among individuals with peripheral neuropathy. METHODS: We systematically searched three databases from inception to December 19, 2023 and identified 11 eligible clinical studies. We extracted trial information from each study and performed a qualitative study features analysis to summarize the clinical evidence and neurobiological mechanisms of Tai Chi in regulating balance among people with peripheral neuropathy. RESULTS: We found that among 508 participants with clinical peripheral neuropathy, Tai Chi significantly improved single leg stance, 6-min walk, timed up-and-go tests, and gait speed when measured pre- and post-exercise. However, the differences between Tai Chi and sham exercise control that involved active calisthenics and stretching exercises were not statistically significant. Studies that used quantitative sensory testing showed that Tai Chi was associated with significant increases in plantar vibration and tactile sensitivity. The effect of Tai Chi on postural control varied depending on plantar sensory loss status, and results on muscle strength remained mixed. Other neurobiological effects involve strengthening muscle performance and proprioception and consolidating cognitive awareness of walking strategy and practical behavioral techniques. CONCLUSIONS: The findings indicated that Tai Chi may enhance balance, postural control, and gait speed in patients with peripheral neuropathy, possibly through sensory restoration, although further research is needed to confirm this. Whether Tai Chi improves muscle strength or other gait health parameters is inconclusive. Rigorous randomized clinical trials should be conducted to determine the effect of Tai Chi on balance in this population by measuring functional balance and quantitative sensory outcomes.

Acute and chronic effects of stretching on balance: a systematic review with multilevel meta-analysis.

Introduction: Balance is a multifactorial construct with high relevance in, e.g., everyday life activities. Apart from sensorimotor control, muscle strength and size are positively linked with balance performance. While commonly trained for via resistance training, stretch training has emerged as a potential substitution in specific conditions. However, no review has investigated potential effects of stretching on balance, yet. Methods: PubMed, Web of Science and Scopus were searched with inception to February, 2024. Studies were included if they examined acute and/or chronic effects of any stretching type against passive and/or active controls on balance parameters - without any population-related restrictions concerning sex/gender, age, health status, activity level. Methodological quality was assessed using PEDro scale. Meta-analyses were performed if two or more studies reported on the same outcome. Certainty of evidence was determined based on GRADE criteria. Results: Eighteen acute and eleven chronic effect studies were included. Stretching studies exhibited significant improvements for sway parameters with eyes open against passive controls of moderate magnitude for chronic (ES: 0.63, p = 0.047) and of small magnitude for acute studies (ES: 0.21, p = 0.032). Most other subgroups against passive controls as well as actively-controlled comparisons resulted in trivial and/or non-significant effects. Conclusion: Even though some pooled effects slightly reached the level of significance, the overall results are biased by (very) low certainty of evidence (GRADE criteria downgrading for risk of bias, imprecision, publication bias). Moderators suggested by literature (strength, muscle size, flexibility, proprioception) were rarely assessed, which prevents conclusive final statements and calls for further, high quality evidence to clarify potential mechanisms-if any exist.

Vestibular control of standing balance following 24 h of sleep deprivation.

Sleep deprivation alters cognitive and sensorimotor function, but its effects on the control of standing balance are inconclusive. The vestibular system is critical for standing balance, and is modified by sleep deprivation; however, how sleep deprivation affects vestibular-evoked balance responses is unknown. Thus, this study aimed to examine the effect of 24 h of sleep deprivation on the vestibular control of standing balance. During both a well-rested (i.e., control) and sleep deprivation condition, nine females completed two 90-s trials of bilateral, binaural stochastic electrical vestibular stimulation (EVS) and two 120-s trials of quiet stance on a force plate. Quiet stance performance was assessed by center of pressure displacement parameters. Mediolateral ground reaction force (ML force) and surface electromyography (EMG) of the right medial gastrocnemius (MG) were sampled simultaneously with the EVS signal to quantify vestibular control of balance within the frequency (gain and coherence) and time (cumulant density) domains. Twenty-four hours of sleep deprivation did not affect quiet stance performance. Sleep deprivation also had limited effect on EVS-MG EMG and EVS-ML Force coherence (less than control at 8-10.5 Hz, greater at ~ 16 Hz); however, gain of EVS-MG EMG (< 8, 11-24 Hz) and EVS-ML force (0.5-9 Hz) was greater for sleep deprivation than control. Sleep deprivation did not alter peak-to-peak amplitude of EVS-MG EMG (p = 0.51) or EVS-ML force (p = 0.06) cumulant density function responses. Despite no effect on quiet stance parameters, the observed increase in vestibular-evoked balance response gain suggests 24-h sleep deprivation may lead to greater sensitivity of the central nervous system when transforming vestibular-driven signals for standing balance control.

Rapid reconfiguration of cortical networks after repeated exposure to visual-vestibular conflicts.

Visual-vestibular conflicts can induce motion sickness and further postural instability. Visual-vestibular habituation is recommended to reduce the symptoms of motion sickness and improve postural stability with an altered multisensory reweighting progress. However, it is unclear how the human brain reweights multisensory information after repeated exposure to visual-vestibular conflicts. Therefore, we synchronized a rotating platform and a virtual scene to present visual-vestibular congruent (natural visual stimulation) and incongruent (conflicted visual stimulation) conditions and collected EEG and center of pressure (COP) data. We constructed the effective brain connectivity of region of interest (ROI) derived from source-space EEG in theta-band activity, and quantified the postural stability and the inflow and outflow of each ROI. We found repeated exposure to congruent and incongruent conditions both decreased COP path length and increased COP complexity. Besides, we found that repeated exposure to the incongruent environment decreased the inflow into visual cortex, suggesting the brain down-weighted the less reliable visual information for postural stability. In contrast, repeated exposure to the congruent environment increased the inflow into posterior parietal cortex and the outflow from visual cortex and S1, suggesting an increase in efficiency of multisensory integration. We concluded that repeated exposure to congruent and incongruent conditions both improved postural stability with different multisensory reweighting patterns as revealed by different dynamic changes of brain networks.

The Influence of Ankle Mobility and Foot Stability on Jumping Ability and Landing Mechanics: A Cross-Sectional Study.

Practicing physical activities or sports that involve frequent jumping and landing can strain the muscles and joints of the lower limbs, especially in those who do not have adequate physical preparation. The objective of this study was to (a) determine the correlation between ankle range of motion (ROM) and landing stability following jumps; (b) assess the association between the jump height in a counter-movement jump (CMJ) test and ankle ROM; and (c) examine the connection between stabilometry during specific jumps movements present in many sports and in ankle stabilization. Sixty-two healthy amateur volleyball players participated in the study (age: thirty-seven females and twenty-five males; age (years): 16.5 ± 4.25; height (cm): 166 ± 11.4; weight (Kg): 61.6 ± 13.7). Participants were recruited for the study in collaboration with student sports associations. The evaluations encompassed the measurement of ankle joint mobility for both lower limbs using an inertial sensor, a static baropodometric and stabilometric analysis using a pressure platform, and the CMJ test using the Microgate system. After the assessments, participants performed a "specific jump landing task". Significant correlations were found between foot range of motion (ROM) and counter-movement jump (CMJ) performance. Specifically, the ROM of the right foot had a strong correlation with the CMJ (r = 0.81, p < 0.001), while the left foot ROM showed a moderate correlation (r = 0.46, p < 0.001). The specific jump task revealed substantial changes in stabilometry parameters, particularly during forward hops compared to lateral jumps. Dorsiflexion ROM significantly impacts jumping ability. Evaluating landing patterns and stabilometry during targeted activities can help optimize training, improve dynamic balance, and reduce ankle injury risk.

Effect of Forward Reaching With a Modified Sitting Position on Muscle Contraction in the Paretic Lower Extremity of Individuals in the Early Sub-Acute Phase of Stroke: A Randomized Control Trial.

Introduction Forward reaching in sitting has been shown to facilitate muscle contraction in the paretic lower limb of stroke survivors. Change in the sitting surface has been shown to alter the contribution of lower extremity muscles to maintain postural control. This study investigated the effect of forward reaching in a modified sitting position on the paretic lower extremity muscles of patients with stroke. Methods First-time cerebral stroke survivors in their early sub-acute phase were randomly allocated to the experimental or control group. The experimental group engaged in training sessions focusing on reaching a target while seated with only the paretic foot placed on a support, whereas the control group performed the same task with both feet supported on the surface. Each group completed three sets of 10 repetitions of forward reaching for eight days as a part of the training. Quadriceps and tibialis anterior muscle activity in the paretic leg were measured using surface electromyography before the first and after the last session of intervention. Statistical analysis was conducted using parametric tests with a significance level set at p < 0.05. Results Sixty-three subjects completed the study, with 31 in the experimental group and 32 in the control group. The results of the post-intervention analysis indicated a statistically significant increase in the EMG activity of the tibialis anterior and quadriceps muscle surfaces in both groups (p < 0.001). Notably, the experimental group exhibited significantly higher muscle activity in both quadriceps and tibialis anterior compared to the control group (p < 0.001). Conclusion Forward reaching with only the paretic lower limb grounded effectively improves quadriceps and tibialis anterior muscle recruitment in the early sub-acute phase of stroke.

Role of Thigh Muscle Strength and Joint Kinematics in Dynamic Stability: Implications for Y-Balance Test Performance.

CONTEXT: The Y-Balance Test Lower Quarter (YBT-LQ) is a widely utilized tool for evaluating dynamic postural control, requiring a combination of mobility and strength. This study aimed to investigate the combined relationship between isometric thigh muscle strength and joint kinematics on YBT-LQ performance. DESIGN: Cross-sectional laboratory study. METHODS: Isometric quadriceps and hamstrings strength were measured before the YBT-LQ in 39 healthy participants (27 females and 12 males). The test was performed under 3-dimensional markerless motion capture, where joint kinematics were extracted from the maximum reach position from each direction. Three multivariable linear regression models were then used to determine the strongest combination of predictors for YBT-LQ performance. RESULTS: Greater hamstrings strength and increased knee flexion, ankle dorsiflexion, and trunk ipsilateral-flexion joint angles explained 56.8% (P < .001) of the variance in anterior reach. Hip flexion, knee flexion, and ankle dorsiflexion angles were the strongest predictors for posteromedial reach distance, explaining 73.0% of the variance (P < .001). Last, 43.3% (P < .001) of the variance in posterolateral reach distance was predicted by hamstring strength and knee-flexion angle. CONCLUSIONS: These results emphasize the importance of hamstring strength in YBT-LQ performance across different reach directions. Additionally, the kinematics illustrate a potential movement strategy for maximizing reach distance on the YBT-LQ in healthy individuals. Clinicians can utilize this information to guide interventions aimed at improving dynamic postural control, particularly by focusing on increasing hamstring strength and testing for impairments in specific movement patterns.