Center Of Pressure Sway Velocity Research Articles

Test-Retest Reliability and Convergent Validity of Piezoelectric Force Plate Measures of Single-Leg Sit-to-Stand Performance in Trained Adults.

Makaracı, Y, Nas, K, Ruiz-Cárdenas, JD, Gündüz, K, Aydemir, M, and Orange, ST. Test-retest reliability and convergent validity of piezoelectric force plate measures of single-leg sit-to-stand performance in trained adults. J Strength Cond Res 37(12): 2373-2380, 2023-The single-leg sit-to-stand (STS) test has emerged as a promising method of assessing lower-limb functional strength and asymmetry. However, the reliability of its performance parameters on a force plate has not been explored. This study examined the test-retest reliability and convergent validity of the single-leg STS test performed on a piezoelectric-based force plate in trained subjects. Thirty trained male adults (age: 21.4 ± 1.7 years) performed 3 separate single-leg STS days of testing to assess both intraday and interday reliability. Performance parameters included STS time, ground reaction force (GRF), and center of pressure (CoP) sway velocity. The relationship between single-leg STS parameters and unilateral countermovement jump (CMJ) variables was assessed for convergent validity. Intraclass correlation coefficient (ICC) and coefficient of variation (CV) were calculated for reliability analyses, and convergent validity was assessed with Spearman's correlation coefficient (ρ). In the dominant leg, single-leg performance parameters showed moderate-to-excellent intraday reliability (ICC = 0.65-0.90, CV = 4.3-11.2%) and moderate interday reliability (ICC = 0.54-0.74, CV = 5.8-13.5%). In the nondominant leg, all single-leg STS performance parameters showed good intraday (ICC = 0.79-0.86, CV = 3.8-9.8%) and interday reliability (ICC = 0.75-0.82, CV = 4.6-9.7%). STS times in the dominant and nondominant legs were inversely related to unilateral CMJ velocity (ρ = -0.47 and -0.38, respectively). CoP sway velocity in the nondominant leg showed positive correlations with unilateral CMJ power and velocity (ρ = 0.38 and 0.54, respectively). In conclusion, the force plate-based single-leg STS test provides reliable measures of STS time, GRF, and CoP sway velocity in trained adults and could be used to assess lower-limb function and asymmetry.

Sex differences concerning the effects of ankle muscle fatigue on static postural control and spinal proprioceptive input at the ankle.

The main aim of this study was to determine sex differences in postural control changes with ankle muscle fatigue during a standing forward leaning (FL) task under different vision conditions. The secondary aim was to examine sex differences in the effect of fatigue on soleus (SOL) H-reflex amplitude, a measure of motoneuron excitability with activation of Ia afferents. Fifteen healthy young adult males (mean age: 28.0 years) and 16 healthy young adult females (mean age: 26.1 years) were asked to perform four consecutive FL tasks [30 s; two with eyes open (EO) and two with eyes closed (EC)] before, and immediately following a fatiguing exercise consisting of alternating ankle plantarflexion (6 s) and dorsiflexion (2 s) maximal isometric contractions, and at 5 and 10 min of recovery. Center of pressure (COP) sway variables (mean position, standard deviation, ellipse area, average velocity, and frequency), an ankle co-contraction index, and a ratio of SOL H-reflex to the maximum amplitude of the compound muscle action potential (M-max) were obtained during the FL tasks. A rating of perceived fatigue (RPF) was also documented at the different time points. Time to task failure (reduction of 50% in maximal voluntary isometric contraction torque of ankle plantar flexors) and the increase in RPF value were not significantly different between males and females. Both sex groups showed similar and significant increases (p < 0.05) in mean COP sway velocity with no significant changes in co-contraction indices. No significant effects of fatigue and related interactions were found for SOL H/M-max ratio. The absence of a significant sex difference in postural control change (sway and co-contraction) with fatigue could be explained by similar perceived (RPF) and performance fatigability (exercise duration) between males and females in the present study. Fatigue did not lead to significant changes in SOL spinal motoneuron excitability with activation of Ia afferents.

123 Early Postural Stability Changes in Patients Undergoing Correction of Spinal Deformity

INTRODUCTION: Adult spinal deformity (ASD) is an increasingly prevalent cause of pain and disability. It is known that ASD correction results in improved alignment, but not whether this alignment results in objective improvements in postural stability. METHODS: A retrospective review of a prospectively maintained database identified 16 patients undergoing ASD correction surgery with five or more segments. Balance was assessed via a force plate pre- and three months postoperatively. Participants were instructed to stand still, with their hands at their sides and eyes open. Center of pressure (COP) and center of gravity (COG) parameters were analyzed and used to derive head sway in the Dubousset cone of economy (COE). Spinopelvic parameters (PI, PT, SVA, and LL) on standing scoliosis radiographic films were also measured pre- and three months postoperatively. RESULTS: In our 16-patient series, there was a mean age of 61.3 years-old, and a median of 10 segments fused. Postoperative force plate assessment showed a decrease in total COP sway and sway velocity (p &lt; 0.05). Coronal COP sway and sway velocity also decreased (p &lt; 0.05). There was a decrease in total, coronal and sagittal COG sway and sway velocity postoperatively (p &lt; 0.05). In the COE, total head sway decreased (p &lt; 0.05). PT remained unchanged following surgical correction, while LL and SVA improved from 44.9° to 56.7° (p &lt; 0.01) and 82.2 to 22.5 mm (p &lt; 0.01), respectively. PI-LL mismatch also improved from 16.2° to 4.8° (p &lt; 0.01). CONCLUSIONS: Following long segment fusion for ASD, postural stability may improve as early as three months, concomitant with improved spinopelvic alignment. We believe force plate assessment warrants further study for postoperative evaluation of postural alignment and clinical outcomes in ASD patients.

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

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

Sex differences in the effect of muscle fatigue on static postural control under different vision and task conditions.

The main aim of this study was to compare the effects of ankle plantar flexors fatigue on postural control between healthy young adult males and females. The secondary aim was to determine the effects of vision on the fatigue-induced postural changes. Ten healthy young males and nine females were asked to perform quiet standing (QS) and standing forward lean (FL) tasks with eyes open (EO) and closed (EC) before and immediately following exercise, and throughout a 15-min recovery period. A sustained isometric exercise of ankle plantar flexors was performed until participants were no longer able to maintain a target torque of 50% of maximal voluntary isometric contraction (MVIC). Mean anteroposterior (AP) and mediolateral (ML) positions of the center of pressure (COP), mean COP sway velocity, and 95% ellipse area of COP sway were measured. Ankle plantar flexors fatigue had significant effects on all dependent variables, except for sway area. A fatigue X sex interaction was found for sway velocity with the most challenging task condition (FL-EC), where males showed a significant increase in sway velocity up to 15 min following exercise, whereas females did not. Fatigue X vision interactions for AP position were also found, with the withdrawal of vision leading to a greater backward shift during recovery for both the QS (5 to 15 min) and FL (5 to 10 min) tasks. Our findings suggest the use of different postural control strategies with ankle fatigue between males and females, and also a contribution of vision to compensate for fatigue-induced instability that is not dependent on task difficulty.

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

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

Low-Back Pain and Knee Position-Related Differences on Postural Control Measures During a One-Legged Stance in Athletes.

Chronic low-back pain (CLBP) may be associated with changes in postural balance in athletes as poor postural control during sports practice. To compare the postural control of athletes with and without CLBP during 2 one-legged stance tasks and identify the center of pressure (COP) cutoff values to determine the main differences. Designed: A cross-sectional study. Laboratory of functional evaluation and human motor performance. A total of 56 male athletes, 28 with and 28 without CLBP (mean age = 26y). The one-legged stance with knee extension and with the knee at 30° flexion tasks were measured and analyzed on a force platform. The participants completed three 30-second trials (30s of rest between each trial). The COP parameters: the area of COP, mean COP sway velocity in both the anteroposterior and mediolateral directions, and total COP displacement were computed, and a receiver operating characteristics curve analysis was applied to determine the group differences. Athletes with CLBP had poorer postural control (P < .01) in both tasks. The 30° knee flexion reported more postural instability than the knee extension for all COP parameters (a large effect size d = 0.80).The knee extension cutoffs identified were >7.1 cm2 for the COP area, >2.6 cm/s for the COP sway velocity in the anterior-posterior direction, and >3.2 cm/s for the mediolateral direction. Whereas, the 30° knee flexion cutoffs were >10.9 cm2 for the COP area, >2.9 cm/s for the COP sway velocity in the anterior-posterior direction, and >4.1 cm/s for the mediolateral direction. Both measures showed enough sensitivity and specificity (ie,area under the curve = 0.88 in and 0.80, respectively) to discriminate both groups. The athletes with CLBP had poorer postural control than the healthy athletes and obtained specific cutoff scores from the COP values.

Virtual-Reality-Induced Visual Perturbations Impact Postural Control System Behavior.

Background: Virtual reality (VR) is becoming a widespread tool in rehabilitation, especially for postural stability. However, the impact of using VR in a “moving wall paradigm” (visual perturbation), specifically without and with anticipation of the perturbation, is unknown. Methods: Nineteen healthy subjects performed three trials of static balance testing on a force plate under three different conditions: baseline (no perturbation), unexpected VR perturbation, and expected VR perturbation. The statistical analysis consisted of a 1 × 3 repeated-measures ANOVA to test for differences in the center of pressure (COP) displacement, 95% ellipsoid area, and COP sway velocity. Results: The expected perturbation rendered significantly lower (p < 0.05) COP displacements and 95% ellipsoid area compared to the unexpected condition. A significantly higher (p < 0.05) sway velocity was also observed in the expected condition compared to the unexpected condition. Conclusions: Postural stability was lowered during unexpected visual perturbations compared to both during baseline and during expected visual perturbations, suggesting that conflicting visual feedback induced postural instability due to compensatory postural responses. However, during expected visual perturbations, significantly lowered postural sway displacement and area were achieved by increasing the sway velocity, suggesting the occurrence of postural behavior due to anticipatory postural responses. Finally, the study also concluded that VR could be used to induce different postural responses by providing visual perturbations to the postural control system, which can subsequently be used as an effective and low-cost tool for postural stability training and rehabilitation.

Increased Postural Demand Is Associated With Greater Cognitive Workload in Healthy Young Adults: A Pupillometry Study.

Introduction: Balance tasks require cognitive resources to ensure postural stability. Pupillometry has been used to quantify cognitive workload of various cognitive tasks, but has not been studied in postural control. The current investigation utilized pupillometry to quantify the cognitive workload of postural control in healthy young adults. We hypothesized that cognitive workload, indexed by pupil size, will increase with challenging postural control conditions including visual occlusion and cognitive dual tasking.Methods: Twenty-one young healthy adults (mean ± standard error of the mean), (age = 23.2 ± 0.49 years; 12 females) were recruited for this study. Participants completed four tasks: (1) standing with eyes open; (2) standing with eyes occluded (3) standing with eyes open while performing an auditory Stroop task; and (4) standing with eyes occluded while performing an auditory Stroop task. Participants wore eye tracking glasses while standing on a force platform. The eye tracking glasses recorded changes in pupil size that in turn were converted into the Index of Cognitive Activity (ICA). ICA values were averaged for each eye and condition. A two-way Analysis of Variance with post-hoc Sidak correction for pairwise comparisons was run to examine the effect of visual occlusion and dual tasking on ICA values as well on Center of Pressure (CoP) sway velocity in anterior–posterior (AP) and medio-lateral (ML) directions. A Pearson’s correlation coefficient was utilized to determine the relationship between ICA values and CoP sway velocity.Results: Significant within-condition effect was observed with visual occlusion for the right eye ICA values (p = 0.008). Right eye ICA increased from eyes open to eyes occluded conditions (p = 0.008). In addition, a significant inverse correlation was observed between right eye ICA values and CoP sway velocity in the ML direction across all the conditions (r = -0.25, p = 0.02).Conclusion: This study demonstrated support for increased cognitive workload, measured by pupillometry, as a result of changes in postural control in healthy young adults. Further research is warranted to investigate the clinical application of pupillometry in balance assessment.

Effects of visual cue and cognitive motor tasks on standing postural control following a chronic stroke.

[Purpose] The objective of the study was to examine the effects of visual cue and cognitive motor tasks on quiet standing posture center of pressure (COP) and the weight loads to the paretic and non-paretic legs in chronic stroke patients. [Subjects and Methods] Twenty chronic stroke patients were included in the study. COP total distance, sway velocity, and the weight loads to the paretic and non-paretic legs of the participants were measured while they performed a visual cue task, cognitive motor task, and dual task. The parameters were compared using a repeated three-way analysis of variance. [Results] When the visual cue was provided, the COP total distance and sway velocity were significantly reduced compared with when no visual cue was given. When the cognitive motor task was performed, the COP total distance and sway velocity decreased significantly compared to when the task was not performed. [Conclusion] These findings suggest that visual cue and cognitive motor tasks could be used as parts of a rehabilitative training program to improve the control of standing in chronic stroke patients. In addition, visual cues can be used as an intervention to train the paretic leg of stroke patients.

Right cerebral hemisphere specialization for quiet and perturbed body balance control: Evidence from unilateral stroke

Our aim in this investigation was to assess the relative importance of each cerebral hemisphere in quiet and perturbed balance, based on uni-hemispheric lesions by stroke. We tested the hypothesis of right cerebral hemisphere specialization for balance control. Groups of damage either to the right (RHD, n=9) or the left (LHD, n=7) cerebral hemisphere were compared across tasks requiring quiet balance or body balance recovery following a mechanical perturbation, comparing them to age-matched nondisabled individuals (controls, n=24). They were evaluated in conditions of full and occluded vision. In Experiment 1, the groups were compared in the task of quiet standing on (A) rigid and (B) malleable surfaces, having as outcome measures center of pressure (CoP) amplitude and velocity sway. In Experiment 2, we evaluated the recovery of body balance following a perturbation inducing forward body oscillation, having as outcome measures CoP displacement, peak hip and ankle rotations and muscular activation of both legs. Results from Experiment 1 showed higher values of CoP sway velocity for RHD in comparison to LHD and controls in the anteroposterior (rigid surface) and mediolateral (malleable surface) directions, while LHD had lower balance stability than the controls only in the mediolateral direction when supported on the rigid surface. In Experiment 2 results showed that RHD led to increased values in comparison to LHD and controls for anteroposterior CoP displacement and velocity, time to CoP direction reversion, hip rotation, and magnitude of muscular activation in the paretic leg, while LHD was found to differ in comparison to controls in magnitude of muscular activation of the paretic leg and amplitude of mediolateral sway only. These results suggest that damage to the right as compared to the left cerebral hemisphere by stroke leads to poorer postural responses both in quiet and perturbed balance. That effect was not altered by manipulation of sensory information. Our findings suggest that the right cerebral hemisphere plays a more prominent role in efferent processes responsible for balance control.

Time-dependent postural control adaptations following a neuromuscular warm-up in female handball players: a randomized controlled trial

BackgroundFemale handball athletes are at a particular risk of sustaining lower extremity injuries. The study examines time-dependent adaptations of static and dynamic balance as potential injury risk factors to a specific warm-up program focusing on neuromuscular control.MethodsFourty one (24.0 ± 5.9 years) female handball athletes were randomized to an intervention or control group. The intervention group implemented a 15-min specific neuromuscular warm-up program, three times per week for eleven weeks, whereas the control group continued with their regular warm-up. Balance was assessed at five time points. Measures included the star excursion balance test (SEBT), and center of pressure (COP) sway velocity during single-leg standing.ResultsNo baseline differences existed between groups in demographic data. Adherence to neuromuscular warm-up was 88.7 %. Mean COP sway velocity decreased significantly over time in the intervention group (−14.4 %; p < .001), but not in the control group (−6.2 %; p = 0.056). However, these effects did not differ significantly between groups (p = .098). Mean changes over time in the SEBT score were significantly greater (p = .014) in the intervention group (+5.48) compared to the control group (+3.45). Paired t-tests revealed that the first significant balance improvements were observed after 6 weeks of training.ConclusionsA neuromuscular warm-up positively influences balance variables associated with an increased risk of lower extremity injuries in female handball athletes. The course of adaptations suggests that a training volume of 15 min, three times weekly over at least six weeks produces measurable changes.Trial registrationRetrospectively registered on 4th October 2016. Registry: clinicaltrials.gov. Trial number: NCT02925377.Electronic supplementary materialThe online version of this article (doi:10.1186/s13102-016-0058-5) contains supplementary material, which is available to authorized users.

Task-Specific Balance Training Improves the Sensory Organisation of Balance Control in Children with Developmental Coordination Disorder: A Randomised Controlled Trial.

Sensory organisation of balance control is compromised in children with developmental coordination disorder (DCD). A randomised controlled trial involving 88 children with DCD was conducted to evaluate the efficacy of a task-specific balance training (functional-movement training, FMT) programme in improving balance deficits in a DCD population. The DCD participants were randomly assigned to either a FMT group or a control group. The FMT group received two training sessions/ week for 3 months. Measurements of the participants’ sensory organisation (somatosensory, vestibular and visual ratios), balance and motor proficiency (Movement Assessment Battery for Children, MABC scores) and center of pressure sway velocity (Unilateral Stance Test, UST scores) were taken at baseline, immediately after FMT and 3 months after FMT. The FMT group showed greater improvements than the controls in somatosensory ratio at 3 and 6 months (all P < 0.001), but the within-group changes were not significant (P > 0.05). The results of both the MABC and the UST also indicated that the balance performance of the FMT group was significantly better than that of the control group at 3 and 6 months (all P < 0.05). Task-specific balance training was found to marginally improve the somatosensory function and somewhat improve the balance performance of children with DCD.

Postural control and freezing of gait in Parkinson's disease

IntroductionThe relationship between freezing of gait (FOG) and postural instability in Parkinson's disease (PD) is unclear. We analyzed the impact of FOG on postural control. Methods31 PD patients with FOG (PD+FOG), 27 PD patients without FOG (PD-FOG) and 22 healthy control (HC) were assessed in the ON state. Postural control was measured with the Fullerton Advanced Balance (FAB) scale and with center of pressure (COP) analysis during quiet stance and maximal voluntary forward/backward leaning. ResultsThe groups were balanced concerning age, disease duration and disease severity. PD+FOG performed significantly worse in the FAB scale (21.8 ± 5.8) compared to PD-FOG (25.6 ± 5.0) and HC (34.9 ± 2.4) (mean ± SD, p < 0.01). PD+FOG had impaired ability to voluntary lean forward, difficulties to stand on foam with eyes closed and reduced limits of stability compared to PD-FOG (p < 0.05). During quiet stance the average anterior–posterior COP position was significantly displaced towards posterior in PD+FOG in comparison to PD-FOG and HC (p < 0.05). The COP position correlated with severity of FOG (p < 0.01). PD+FOG and PD-FOG did not differ in average COP sway excursion, sway velocity, sway regularity and postural control asymmetry. ConclusionsPD+FOG have reduced postural control compared to PD-FOG and HC. Our results show a relationship between the anterior–posterior COP position during quiet stance and FOG. The COP shift towards posterior in PD+FOG leads to a restricted precondition to generate forward progression during gait initiation. This may contribute to the occurrence of FOG or might be a compensatory strategy to avoid forward falls.

Time course and dimensions of postural control changes following neuromuscular training in youth field hockey athletes

Injury prevention effects of neuromuscular training have been partly attributed to postural control adaptations. Uncertainty exists regarding the magnitude of these adaptations and on how they can be adequately monitored. The objective was to determine the time course of neuromuscular training effects on functional, dynamic and static balance measures. Thirty youth (14.9 ± 3 years) field hockey athletes were randomised to an intervention or control group. The intervention included a 20-min neuromuscular warm-up program performed twice weekly for 10 weeks. Balance assessments were performed at baseline, week three, week six and post-intervention. They included the star excursion balance test (SEBT), balance error scoring system (BESS), jump-landing time to stabilization (TTS) and center of pressure (COP) sway velocity during single-leg standing. No baseline differences were found between groups in demographic data and balance measures. Adherence was at 86%. All balance measures except the medial-lateral TTS improved significantly over time (p < 0.05) in both groups. Significant group by time interactions were found for the BESS score (p < 0.001). The intervention group showed greater improvements (69.3 ± 10.3%) after 10 weeks in comparison to controls (31.8 ± 22.1%). There were no significant group by time interactions in the SEBT, TTS and COP sway velocity. Neuromuscular training was effective in improving postural control in youth team athletes. However, this effect was not reflected in all balance measures suggesting that the neuromuscular training did not influence all dimensions of postural control. Further studies are needed to confirm the potential of specific warm-up programs to improve postural control.

Effects of fatiguing treadmill running on sensorimotor control in athletes with and without functional ankle instability

BackgroundSensorimotor control is permanently impaired following functional ankle instability and temporarily decreased following fatigue. Little is known on potential interactions between both conditions. The purpose was to investigate the effect of fatiguing exercise on sensorimotor control in athletes with and without (coper, controls) functional ankle instability. Methods19 individuals with functional ankle instability, 19 ankle sprain copers, and 19 non-injured controls participated in this cohort study. Maximum reach distance in the star excursion balance test, unilateral jump landing stabilization time, center of pressure sway velocity in single-leg-stance, and passive ankle joint position sense were assessed before and immediately after fatiguing treadmill running. A three factorial linear mixed model was specified for each outcome to evaluate the effects of group, exhausting exercise (fatigue) and their interactions (group by fatigue). Effect sizes were calculated as Cohen's d. FindingsMaximum reach distance in the star excursion balance test, jump stabilization time and sway velocity, but not joint position sense, were negatively affected by fatigue in all groups. Effect sizes were moderate, ranging from 0.27 to 0.68. No significant group by fatigue interactions were found except for one measure. Copers showed significantly larger prefatigue to postfatigue reductions in anterior reach direction (P≤0.001; d=−0.55) compared to the ankle instability (P=0.007) and control group (P=0.052). InterpretationFatiguing exercise negatively affected postural control but not proprioception. Ankle status did not appear to have an effect on fatigue-induced sensorimotor control impairments.

Immediate Effect of Bilateral Talocrural Joint Manipulation on Postural Balance in Healthy Subjects

The aim of this study was to assess the immediate effect of bilateral talocrural joint manipulation on the postural balance of healthy subjects. Ninety healthy subjects (21 males and 69 females) were included in this study. The mean age, height and body weight of the subjects were 22.21 years, 165.1 cm and 62.58 Kg, respectively. Following collection of anthropometric data, the subjects were allocated randomly into an experimental group (receiving real talocrural joint manipulation), a placebo group and a control group. Before and after manipulation, the subjects performed two postural balance tasks, inquiet standing position (eyes open and eyes closed) on a force platform. The stabilometric data were recorded for 60 seconds in each condition. Sway area, medio-lateral (ML) and anteroposterior (AP) velocities and median frequency were calculated from the center of pressure (COP) displacements. The results showed that in the experimental group the COP sway velocity decreased in both directions of movement (AP and ML) and in both visual tasks (eyes open and eyes closed). In general, the placebo and control groups had similar postural balance across balance parameterss. Significant effect of the bilateral talocrural joint manipulation was found on main balance parameter like COP velocity in the anteroposterior and mediolateral directions. These results have some much implications for manual therapy rehabilitation of individuals with ankle instability.

슬링 요부안정화 운동프로그램이 청소년기 특발성 척추측만증 환자의 균형에 미치는 영향

본 연구의 목적은 청소년기 특발성 척추측만증 환자를 대상으로 슬링을 이용한 요부안정화 운동프로그램이 정적 선 자세의 균형에 미치는 영향을 알아보고자 하였다. 본 연구의 대상자는 특발성 척추측만증을 진단 받은 환자 40명을 무작위로 두군으로 나눈 후 실험군(n=20)은 슬링 요부안정화 운동, 대조군(n=20)은 단지 자세교육만 실시하였다. 두군 모두 실험 전 후 균형 수행 모니터(Balance performance monitor)을 이용하여 눈을 감은 상태에서의 양발서기 자세와 눈을 뜬 상태에서의 양발서기에서 동요거리(총, 좌우방향, 전후방향)와 동요속도(총, 좌우방향, 전후방향)를 측정하였다. 운동프로그램 적용 후에 두그룹간에 모든 변수에서 유의한 차이를 보였다. 실험군은 운동 전 후 모든 변수에서 유의한 감소를 보였다. 그러나 대조군에서는 유의한 차이를 보이지 않았다. 이상의 결과를 통해서 슬링 요부안정화 운동프로그램은 특발성 척추측만증 환자의 체중심 동요거리와 동요속도를 감소시켜 정적 선 자세 균형능력을 향상시켰으며 슬링 요부안정화 운동프로그램이 청소년기 특발성 척추측만증 환자의 균형 증진 중재가 될 수 있을 것으로 보인다. The purpose of this study lies in examining how sling lumbar stabilization exercise affects static standing balance of adolescent idiopathic scoliosis patients. The subjects were forty patients who were diagnosed with idiopathic scoliosis. They were randomly assigned either to a experimental group (n=20) that received sling lmubar stabilization exercise program or to a control group (n=20) that received only education. Data were obtained for each patient from total sway path and sway velocity in standing on both feet with eyes closed and standing on both feet with eyes open were measured, using balance performance monitor. All variables were measured at pre- and post-exercise. There were significantly differences between the both groups for all variables at post-exercise (p<.05). The experimental group showed a significantly decreases in all variables at pre- and post-exercise (p<.05). But the control group showed a no significantly differences. These results revealed that sling lumbar stabilization exercise improved static standing balance, by reducing COP(center of pressure) sway path and sway velocity of idiopathic scoliosis patients, and it is expected that sling lumbar stabilization exercise will be used as balance enhancement exercise intervention for the treatment of adolescent idiopathic scoliosis patients.

Effects of Localized and General Fatigue on Static and Dynamic Postural Control in Male Team Handball Athletes

In team sports, sensorimotor impairments resulting from previous injuries or muscular fatigue have been suggested to be factors contributing to an increased injury risk. Although it has been widely shown that physical fatigue affects static postural sway, it is still questionable as to what extent these adaptations are relevant for dynamic, sports-related situations. The objective of this study was to determine the effects of whole-body and localized fatigue on postural control in stable and unstable conditions. Nineteen male team handball players were assessed in 2 sessions separated by 1 week. Treadmill running and single-leg step-up exercises were used to induce physical fatigue. The main outcome measures were center of pressure (COP) sway velocity during a single-leg stance on a force plate and maximum reach distances of the star excursion balance test (SEBT). The COP sway velocity increased significantly (p < 0.05) after general (+47%) and localized fatigue (+10%). No fatigue effects were found for the SEBT. There were no significant correlations between COP sway velocity and SEBT mean reach in any condition. The results showed that although fatigue affects static postural control, sensorimotor mechanisms responsible for regaining dynamic balance in healthy athletes seem to remain predominantly intact. Thus, our data indicate that the exclusive use of static postural sway measures might not be sufficient to allow conclusive statements regarding sensorimotor control in the noninjured athlete population.

Trunk Neuromuscular Control is Associated with ACL Loading Mechanisms During an Athletic Cutting Task

Trunk position and postural control influence lower extremity biomechanics during athletic tasks. Triplanar loading of the knee results in high levels of stress in the anterior cruciate ligament (ACL). Excessive trunk motion has been reported during movements resulting in ACL injury. However, the relationship between trunk neuromuscular control (NMC) and triplanar knee loads during an athletic cutting task (ACT) has not been examined. PURPOSE: To investigate the relationship between a laboratory measure of trunk NMC during unstable-sitting (UST) and triplanar knee loads during an ACT. METHODS: 30 physically active subjects (15 male, 15 female, age: 20.5 ± 2.5 yrs, mass: 67.50 ± 11.39 Kg, height: 173.78 ± 9.28 cm) from the university setting participated in this study. During each 1-minute UST trial subjects were required to maintain balance atop a rigid hemisphere with their arms crossed at the chest and with their feet in contact with a footrest fixed to the unstable-sitting device. Center of pressure (CoP) sway data were collected during the UST using a forceplate. For the ACT subjects were instructed to take 3 running steps, jump over a 17 cm hurdle, and cut at 60° in the opposite direction of their dominant plant leg. Peak triplanar trunk angles and knee loads were collected using an infrared motion capture system and forceplate during the first 50% of stance time during the side-step ACT. Pearson product-moment correlation coefficients were calculated among CoP sway data and external knee loads. RESULTS: CoP sway velocity (1.34 ± 0.23 cm/s) was directly associated with anterior tibial shear force (0.114 ± 0.092) (r = 0.382, p = 0.049), and tibial external rotation moment (0.032 ±.013) (r = 0.451, p = 0.018). CoP sway area (50.29 ± 18.50 cm2) was positively associated (r = 0.548, p = 0.006) with knee flexion moment (0.115 ± 0.032). CoP sway path (81.02 ± 14.44 cm) was positively associated with knee flexion moment (r = 0.407, p = 0.032) and tibial external rotation moment (r = 0.474, p = 0.011). CONCLUSION: The results of this study provide evidence of a relationship between trunk NMC and triplanar knee loading associated with ACL injury. These relationships suggest that poor NMC of the trunk is associated with increased triplanar loading at the knee joint. Interventions with a focus on improving trunk NMC may decrease ACL injury risk.