Center Of Pressure Displacement Research Articles

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

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

Static posturography as a novel measure of the effects of aging on postural control in dogs

Aging is associated with impairment in postural control in humans. While dogs are a powerful model for the study of aging, the associations between age and postural control in this species have not yet been elucidated. The aims of this work were to establish a reliable protocol to measure center of pressure excursions in standing dogs and to determine age-related changes in postural sway. Data were obtained from 40 healthy adult dogs (Group A) and 28 senior dogs (Group B) during seven trials (within one session of data collection) of quiet standing on a pressure sensitive walkway system. Velocity, acceleration, root mean square, 95% ellipse area, range and frequency revolve were recorded as measures of postural sway. In Group A, reliability was assessed with intraclass correlation, and the effect of morphometric variables was evaluated using linear regression. By means of stepwise linear regression we determined that root mean square overall and acceleration in the craniocaudal direction were the best variables able to discriminate between Group A and Group B. The relationship between these two center-of-pressure (COP) measures and the dogs' fractional lifespan was examined in both groups and the role of pain and proprioceptive deficits was evaluated in Group B. All measures except for frequency revolve showed good to excellent reliability. Weight, height and length were correlated with most of the measures. Fractional lifespan impacted postural control in Group B but not Group A. Joint pain and its interaction with proprioceptive deficits influence postural sway especially in the acceleration in the craniocaudal direction, while fractional lifespan was most important in the overall COP displacement. In conclusion, our study found that pressure sensitive walkway systems are a reliable tool to evaluate postural sway in dogs; and that postural sway is affected by morphometric parameters and increases with age and joint pain.

Differences in balance control despite self-reported resolution of pregnancy-related pelvic girdle pain. A cross-sectional study

BackgroundMotor control patterns are altered when women with pregnancy-related pelvic girdle pain (PGP) experience pain. In low back pain, these adaptations can persist after recovery. ObjectivesThis study aimed to assess balance control in postpartum women with and without a history of PGP during pregnancy. DesignCross-sectional study. MethodEighteen postpartum women who reported to be recovered from PGP, and twelve postpartum women without a history of PGP during pregnancy performed two clinical tests: the single leg stance and active straight leg raise test. Primary outcomes were ground reaction forces measured with a force platform. ResultsMultiple linear regression analyses showed smaller lateral displacement (β = −11cm; 95%CI: 19 to −3; p = 0.008) and lower displacement velocity of the Centre of Pressure (COP) (Ratio of Geometric Means (RGM) 0.76; 95%CI: 0.59 to 0.99; p = 0.043) during single leg stance in the participants with a history of PGP compared to participants without a history of PGP. Push-off force (β = −4.8 N; 95%CI: 22.0 to 12.5; p = 0.57) and asymmetry of push-off force (RGM 1.77; 95%CI: 0.62 to 5.04; p = 0.27) did not differ between groups. During the active straight leg raise test, no differences in lateral displacement (β = 3 cm; 95%CI: 3 to 8; p = 0.30) and COP displacement velocity (RGM 1.03; 95%CI: 0.70 to 1.52; p = 0.87) were observed. ConclusionsAlthough the women with a history of PGP considered themselves recovered, their balance control during single leg stance was poorer compared to those without a history of PGP. No differences were found during the active straight leg raise test.

Is acrobatic pyramid performance determined by the individual balance of the gymnasts?

ABSTRACT The influence of individual gymnasts’ balance on final pyramid performance is unknown. The principal objective of this study was to evaluate associations between the balance capacity of base and top gymnasts (BG, BT) on the pyramid performance using different balance tasks. Forty acrobatic gymnasts were divided in two groups (20 BG, 20 TG) and performed three different static tests on a force platform: unipedal (open and closed eyes), and headstand. Centre of pressure (COP) measurements were obtained including length travelled in the anteroposterior and mediolateral axis, surface area and the mean speed. Pairs of gymnasts performed a pyramid which involved the BG standing upright while holding a TP in handstand with arms flexed at the elbow. Pyramid scores were obtained from judges to assess the performance. Principal component analysis (PCA) was used to reduce the number of balance COP variables. Linear regression analysis was applied with pyramid performance and scores of PCA separated by role. TG’s PCA 2 was a significant predictor of pyramid performance. Higher pyramid performance was associated with better headstand balance capacity in TG. The results suggest that measuring COP displacement during headstands could help coaches and gymnasts to assess the handstand pyramid performance.

Influence of Cognitive Task Difficulty in Postural Control and Hemodynamic Response in the Prefrontal Cortex during Static Postural Standing

In daily life, we perform several tasks simultaneously, and it is essential to have adequate postural control to succeed. Furthermore, when performing two or more tasks concurrently, changes in postural oscillation are expected due to the competition for the attentional resources. The aim of this study was to evaluate and compare the center of pressure (CoP) behavior and the hemodynamic response of the prefrontal cortex during static postural standing while performing cognitive tasks of increasing levels of difficulty on a smartphone in young adults. Participants were 35 healthy young adults (mean age ± SD = 22.91 ± 3.84 years). Postural control was assessed by the CoP analysis (total excursion of the CoP (TOTEX CoP), displacements of the CoP in medial–lateral (CoP-ML) and anterior–posterior (CoP-AP) directions, mean total velocity displacement of CoP (MVELO CoP), mean displacement velocity of CoP in medial–lateral (MVELO CoP-ML) and anterior–posterior (MVELO CoP-AP) directions, and 95% confidence ellipse sway area (CEA)), the hemodynamic response by the oxyhemoglobin ([oxy-Hb]), deoxyhemoglobin ([deoxy-Hb]), and total hemoglobin ([total-Hb]) concentrations using a force plate and functional near-infrared spectroscopy (fNIR), respectively. The results showed that the difficult cognitive task while performing static postural standing caused an increase in all CoP variables in analysis (p &lt; 0.05) and of [oxy-Hb] (p &lt; 0.05), [deoxy-Hb] (p &lt; 0.05) and [total-Hb] (p &lt; 0.05) compared to the postural task. In conclusion, the increase in the cognitive demands negatively affected the performance of the postural task when performing them concurrently, compared to the postural task alone. The difficult cognitive task while performing the postural task presented a greater influence on postural sway and activation of the prefrontal cortex than the postural task and the easy cognitive task.

Comparison of Postural Control of Females with and without Urinary Incontinence: A Case-Control Study.

Background: So far, there is much less information about the effects of urinary incontinence on postural control. Therefore the aim of this study is to investigate the differences in postural control using linear and non-linear analyses of the center of pressure (COP) time-series in anteroposterior (AP) and mediolateral (ML) directions between females with and without stress urinary incontinence (SUI). Methods: This case-control study included 22 continent females and 22 SUI females. In this study, static postural control during four different postural tasks was evaluated using a force plate. All participants performed separate 60-sec standing trials with eyes open in the empty bladder and full bladder conditions. Mean, range, velocity, area circle of COP displacements, and approximate entropy (ApEn) of COP time-series were calculated from the 60-sec standing trials for all participants. The independent sample t-test was also used to compare COP variables between the two groups and paired sample t-test was used to assess changes between the full bladder and empty bladder conditions within each group. The effect size of Cohen's d was used to assess the magnitude of the differences between the two groups. Results: The findings revealed a significant group × task interaction for the mean of ML displacement and ApEn of COP. SUI females showed more AP displacement range in the full bladder (pvalue= 0.020, effect size=0.74) and a higher velocity (empty bladder: p=0.040, effect size=0.63) (full bladder: p=0.020, effect size=0.75) than the continent group. Generally, the SUI females had lower ApEn than the continent females, although the differences were not significant. While the variables of COP were unaffected by bladder fullness in the continent group, the SUI group in full bladder condition experienced more AP range (p=0.030), and area circle (p=0.007) of COP sway in quiet standing. Conclusion: These results provide more support for the hypothesis that postural control can be impaired following SUI, although future investigations on this topic are recommended.

Effects of Physical and Mental Fatigue on Postural Sway and Cortical Activity in Healthy Young Adults.

Physical fatigue (PF) negatively affects postural control, resulting in impaired balance performance in young and older adults. Similar effects on postural control can be observed for mental fatigue (MF) mainly in older adults. Controversial results exist for young adults. There is a void in the literature on the effects of fatigue on balance and cortical activity. Therefore, this study aimed to examine the acute effects of PF and MF on postural sway and cortical activity. Fifteen healthy young adults aged 28 ± 3 years participated in this study. MF and PF protocols comprising of an all-out repeated sit-to-stand task and a computer-based attention network test, respectively, were applied in random order. Pre and post fatigue, cortical activity and postural sway (i.e., center of pressure displacements [CoPd], velocity [CoPv], and CoP variability [CV CoPd, CV CoPv]) were tested during a challenging bipedal balance board task. Absolute spectral power was calculated for theta (4–7.5 Hz), alpha-2 (10.5–12.5 Hz), beta-1 (13–18 Hz), and beta-2 (18.5–25 Hz) in frontal, central, and parietal regions of interest (ROI) and baseline-normalized. Inference statistics revealed a significant time-by-fatigue interaction for CoPd (p = 0.009, d = 0.39, Δ 9.2%) and CoPv (p = 0.009, d = 0.36, Δ 9.2%), and a significant main effect of time for CoP variability (CV CoPd: p = 0.001, d = 0.84; CV CoPv: p = 0.05, d = 0.62). Post hoc analyses showed a significant increase in CoPd (p = 0.002, d = 1.03) and CoPv (p = 0.003, d = 1.03) following PF but not MF. For cortical activity, a significant time-by-fatigue interaction was found for relative alpha-2 power in parietal (p < 0.001, d = 0.06) areas. Post hoc tests indicated larger alpha-2 power increases after PF (p < 0.001, d = 1.69, Δ 3.9%) compared to MF (p = 0.001, d = 1.03, Δ 2.5%). In addition, changes in parietal alpha-2 power and measures of postural sway did not correlate significantly, irrespective of the applied fatigue protocol. No significant changes were found for the other frequency bands, irrespective of the fatigue protocol and ROI under investigation. Thus, the applied PF protocol resulted in increased postural sway (CoPd and CoPv) and CoP variability accompanied by enhanced alpha-2 power in the parietal ROI while MF led to increased CoP variability and alpha-2 power in our sample of young adults. Potential underlying cortical mechanisms responsible for the greater increase in parietal alpha-2 power after PF were discussed but could not be clearly identified as cause. Therefore, further future research is needed to decipher alternative interpretations.

Characteristics of Plantar Pressure Distribution in Diabetes with or without Diabetic Peripheral Neuropathy and Peripheral Arterial Disease.

Background Excessive plantar pressure leads to increased risk of diabetic foot ulcers. Diabetic peripheral neuropathy (DPN) and peripheral arterial disease (PAD) have been considered to be associated with alterations in gait and plantar pressure in diabetic patients. However, few studies have differentiated the effects with each of them. Objective To investigate the plantar pressure distribution in diabetic patients, with DPN and PAD as independent or combined factors. Methods 112 subjects were recruited: 24 diabetic patients with both DPN and PAD (DPN-PAD group), 12 diabetic patients with DPN without PAD (DPN group), 10 diabetic patients with PAD without DPN (PAD group), 23 diabetic patients without DPN or PAD, and 43 nondiabetic healthy controls (HC group). The in-shoe plantar pressure during natural walking was measured. Differences in peak pressure, contact area, proportion of high pressure area (%HP), and anterior/posterior position of centre of pressure (COP) were analysed. Results Compared with HC group, in DPN-PAD group and DPN group, the peak pressures in all three forefoot regions increased significantly; in PAD group, the peak pressure in lateral forefoot increased significantly. The contact area of midfoot in the DPN-PAD group decreased significantly. PAD group had larger HP% of lateral forefoot, DPN group had larger HP% of inner forefoot, and DPN-PAD group had larger HP% of total plantar area. There was a significant tendency of the anterior displacement of COP in the DPN-PAD group and DPN group. No significant differences were observed between the D group and HC group. Conclusion DPN or PAD could affect the plantar pressure distribution in diabetic patients independently or synergistically, resulting in increased forefoot pressure and the area at risk of ulcers. DPN has a more pronounced effect on peak pressure than PAD. The synergistic effect of them could significantly reduce the plantar contact area of midfoot.

Differences in postural control between healthy and subjects with chronic ankle instability

IntroductionChronic ankle instability (CAI) is characterized by the occurrence of repetitive inversion mechanism of the ankle, resulting in numerous ankle sprains. CAI occurs in approximately 70% of patients with a history of a lateral ankle sprain. Many causes of functional ankle instability have been postulated and include deficits in proprioception, impaired neuromuscular-firing patterns, disturbed balance and postural control. ObjectiveThe purpose of this study was to compare postural control behaviour in subjects with chronic ankle instability and healthy subjects, using the traditional linear and nonlinear variables for the centre of pressure (CoP) displacement, during one-leg stance on stable and unstable surfaces. Methods16 CAI subjects and 20 healthy subjects were evaluated with the single leg stance on a stable surface and an unstable surface, for 60 s with a force plate. The traditional linear variables like CoP displacement, CoP amplitude and CoP velocity were calculated. Variability of CoP displacement was also submitted to nonlinear analysis and the approximated entropy, sample entropy, correlation dimension and Lyapunov exponent were calculated. ResultsOn the stable surface, no differences between groups for all the traditional variables were found but the correlation dimension of CoP mediolateral displacement had lower values on the CAI group with statistical significance (p < 0.05). On the unstable surface, no differences were found neither with linear variable neither with variability nonlinear analysis. ConclusionCorrelated dimension of CoP displacement during one-leg stance on a stable surface was the only variable that show significant differences between the two groups. The lower values of this variable in the CAI subjects may implicate a balance control system with more difficulties to adapt to the environment and the task demands. More studies are needed to better understand CAI subjects balance control.

The influence of goal-directed reaching distance on standing postural control variability in non-disabled individuals

BACKGROUND: Performing everyday standing tasks is relevant to the individuals independence. It is a challenging postural action that requires upper extremity (UE) movements to interact with objects of the environment. Postural movement variability is a strategy of the postural system for exploring postural boundaries during the action. The distance to the target to be reached may affect the variability in postural control parameters. AIM: To test if the variability in postural control parameters is enhanced by reaching beyond the UE-length during a goal-directed standing task. METHOD: Twelve non-disabled adult individuals performed reaching to turn on a light switch (target) while standing, which was placed at 100% and 130% of the UE-length distance. The kinetic data were recorded using a force plate during the UE movement, and the centre of pressure (CoP) displacement variability index was calculated. RESULTS: The variability index of the CoP displacement for reaching was greater at the distance of 130% of UE-length compared to 100% in both anterior-posterior and medial-lateral directions (p = 0.019). No differences in time to complete the task were observed. CONCLUSION: Postural system increases the variability in postural controlling variable CoP displacement for reaching beyond the UE-length while standing. This movement variability helps individuals explore the boundaries of this standing action and may be useful for learning processes and counterbalancing postural disturbances.

Impact of Gender, Change of Base of Support, and Visual Deprivation on Postural Balance Control in Young, Healthy Subjects

Background: Vision, vestibular sense, proprioception and muscle strength are required to maintain balance. However, gender could also play a crucial role in postural sway. Objectives: This study was used to examine (i) the impact of gender, surface type, and vision on postural sway; (ii) the effects of gender and vision on the limb symmetry of postural sway; and (iii) to understand the effects of gender, stance, surface type and vision on the alterations of dynamic postural sway alterations. Methods: This was a cross-sectional study in which young, healthy men (n = 15) and women (n = 12) underwent a balance control assessment using a force plate (SATEL, 40 Hz). Postural stances were evaluated in different conditions: Opened eyes (EO) and closed eyes (EC), on different surface foam vs. firm, a dominant leg stance (DL) vs. a non-dominant leg stance (NDL), and a mediolateral stance (ML) vs. an anteroposterior stance (AP). The mediolateral sway (ML sway), anteroposterior sway (AP sway), and sway area were calculated from the centre of pressure displacements. Results: ML sway, AP sway and sway area increased when eyes were closed (P &lt; 0.000). Foam surface perturbs balance control more than firm surface under EO and EC conditions for both genders, as observed in the AP sway curve (P &lt; 0.000). A functional symmetry exists between the DL and NDL for all sway parameters: The ML sway, AP sway, and sway area (P = 0.720; P = 0.292; P = 0.954). The AP stance is more stable for the ML sway than the ML stance for both genders (P &lt; 0.001). For the AP sway, the ML stance is more stable than the AP sway AP direction stance for both genders (P &lt; 0.001). Women were significantly more stable than men in the ML stance when vision was absent (P &lt; 0.01). Conclusions: Postural sway was altered more significantly on a foam surface than on a firm surface and symmetry between the DL and NDL was observed. Furthermore, we concluded that women have better dynamic balance control than men.

Postural control during single leg stance in individuals with clinical indication for combined reconstruction of the anterior cruciate and the anterolateral ligaments of the knee: a cross-sectional study

BackgroundSeveral studies have shown persistent postural control deficits and rotatory instability in patients after isolated Anterior Cruciate Ligament (ACL) reconstruction. There is evidence to support that the Anterolateral Ligament (ALL) plays an important role in the remaining anterolateral rotatory laxity of the knee. There are no further evidences in order to understand how patients with a combined ACL + ALL reconstruction surgery indication behave regarding postural control. The aim of this cross-sectional study was to assess if patients with a clinical indication for the combined ACL + ALL surgery showed a deficient postural control in single leg stance compared to subjects with a regular ACL reconstruction indication and to a control group.MethodsAn assessment of static postural control on single leg stance was performed on a force plate, with eyes open and closed, and the center of pressure (COP) displacement variables were analyzed: maximum and mean amplitude in anteroposterior (AP) and in mediolateral (ML) direction; mean velocity of displacement and area of displacement. Eighty-nine male individuals participated and were divided into 3 groups: ACL Group, ACL + ALL Group and Control Group.ResultsThe ACL+ ALL Group showed significantly greater COP displacement in most variables in the injured leg for the eyes closed test, compared to the ACL Group, as detailed: Total ML displacement (9.8 ± 6.77 vs. 13.98 ± 6.64, p < 0.001); Mean ML displacement (2.58 ± 2.02 vs. 3.72 ± 1.99, p < 0.001); Total AP displacement (9.5 ± 3.97 vs. 11.7 ± 3.66, p = 0.001); Mean AP displacement (1.77 ± 0.87 vs. 2.27 ± 0.86, p = 0.001); Area of displacement (111.44 ± 127.3 vs. 183.69 ± 131.48, p < 0.001).ConclusionSubjects with a clinical indication for ACL + ALL combined reconstruction surgery showed increased COP displacement compared to patients with indication for an ACL isolated reconstruction surgery.

Does weight loss affect the center of pressure of children with obesity: a follow-up study

BackgroundChildren with obesity were found to show the greater postural instability compared to the normal-weighted children. However, it’s still unclear if their altered postural control ability would recover towards normal pattern after weight loss. The purpose of this study was to investigate the effect of weight loss on the center of pressure (COP) for obese children.MethodTotally 147 children were conducted a follow-up study in three years. A total number of 22 participants aged 7–13 years were recruited for their remission of obesity problem after 36 months. Their dynamic plantar pressure data were collected by Footscan pressure plate. The normalized time of four sub-phases, displacements and velocities of COP in anterior–posterior (AP) and medial–lateral (ML) directions were calculated to perform the Kolmogorov–Smirnov test and paired sample t test for statistical analyses.ResultsAfter weight loss, children’s normalized time of forefoot contact phase (FFCP) increased significantly, and their duration of flat foot phase (FFP) decreased significantly. They also exhibited the more medial and posterior orientated COP path after weight loss. In ML-direction, the COP displacement during FFP and FFPOP increased, and the COP velocity during FFPOP increased. In AP-direction, COP velocity during FFP and FFPOP increased.ConclusionsThe findings indicated that weight loss would have effects on the COP characteristics and postural stability for obese children. COP trajectory can provide essential information for evaluating foot function. The findings may be useful for obese children, medical staff, and healthcare physician.Graphical

Resilience of visually guided weight shifting to a proprioceptive perturbation depends on the complexity of the guidance stimulus

BackgroundWhole-body tracking of visual motion cues is used in balance training to improve weight shifting ability in old age and sports. Research questionHow tracking of a complex (pink noise) and a periodic visual target motion during anteroposterior weight shifting affects postural and muscle responses to unilateral hip vibration. MethodsTwenty-six participants performed 160 anteroposterior weight shifting cycles while tracking the vertical motion of a visual target, concurrently receiving Center of Pressure (CoP) feedback. They were randomly divided to groups; (a) the Constant group tracked a visual target motion constructed by 3 sinusoids of different amplitude, and (b) the Pink group tracked a complex visual target motion constructed by a pink noise generation process. Between the 60th and the 120th cycle, vibration was applied to the right gluteus medius, introducing a sideways CoP deviation. CoP displacement and electromyographic (EMG) responses of soleus, tibialis anterior and peroneus longus were recorded and summarized in blocks of 3 cycles. ResultsSideways CoP deviation induced at the onset/offset of unilateral hip vibration was smaller for the Pink than the Constant group. The Pink group demonstrated greater tibialis anterior and peroneus longus EMG activity around the most anterior sway peak while soleus EMG was similar for the two groups. Both groups successfully coupled weight shifting amplitude to the target motion, but the Pink group tracked the target motion with a greater delay compared to the Constant group. SignificanceWhole body tracking of complex visual motions evokes perception-based action and increases ankle muscle co-activation making sway more resilient to a proprioceptive perturbation induced by unilateral hip vibration. Complex visual guidance motions should be considered when designing balance rehabilitation regimes, aiming at improving weight shifting ability and dynamic balance control.

Balance control in unstable sitting in individuals with an acute episode of low back pain

BackgroundLow back pain (LBP) is associated with altered postural control, mostly observed at later stages in the LBP trajectory. It is unclear whether postural control differs in the acute phase of LBP. Research questionIs postural control different in the acute phase of LBP (<2 weeks) and do differences depend on pain intensity, psychological features and/or availability of vision to control posture? MethodsCross-sectional study design. An unstable sitting paradigm (to reduce the contribution of the legs) assessed postural control of participants with acute LBP (n = 133) and pain-free controls (n = 74). Centre of pressure (CoP) reflected seat movements. Participants balanced with eyes closed, open, or with visual feedback of the anteroposterior CoP position. Balance performance was expressed by CoP displacement and velocity, and stabilogram diffusion analysis. Generalised estimating equations (GEEs) including body mass index, sex, and safety bar touch, tested differences between groups and between balance conditions. Separate GEEs were used to model performance measures and bar touch (yes/no) including pain intensity, disability and psychological features. ResultsCoP displacement and critical point coordinates (time and distance where CoP diffusion rate or spread slows) were larger in LBP than pain-free controls independent of balance condition. Long-term diffusion rate was greater in LBP than controls with eyes closed. CoP velocity measures (RMS, short term diffusion rate) were not different between groups. Pain intensity and psychological features were not linearly related to balance performance in participants with acute LBP. Higher pain catastrophizing was associated with touching the safety bar. SignificancePostural control differs in acute LBP than pain-free controls. Findings might be explained by altered sensory processing, lesser ability to reweight proprioceptive information and/or less accurate trunk muscle control. Although not linearly related to pain-intensity or psychological features in the acute stage, reduced balance performance could potentially have impact on LBP recovery.

The effect of increased cognitive processing on reactive balance control following perturbations to the upper limb.

Reactive balance control following hand perturbations is important for everyday living as humans constantly encounter perturbations to the upper limb while performing functional tasks while standing. When multiple tasks are performed simultaneously, cognitive processing is increased, and performance on at least one of the tasks is often disrupted, owing to attentional resources being divided. The purpose here was to assess the effects of increased cognitive processing on whole-body balance responses to perturbations of the hand during continuous voluntary reaching. Sixteen participants (8 females; 22.9 ± 4.5years) stood and grasped the handle of a KINARM - a robotic-controlled manipulandum paired with an augmented visual display. Participants completed 10 total trials of 100 mediolateral arm movements at a consistent speed of one reach per second, and an auditory n-back task (cognitive task). Twenty anteroposterior hand perturbations were interspersed randomly throughout the reaching trials. The arm movements with random arm perturbations were either performed simultaneously with the cognitive task (combined task) or in isolation (arm perturbation task). Peak centre of pressure (COP) displacement and velocity, time to COP displacement onset and peak, as well as hand displacement and velocity following the hand perturbation were evaluated. N-back response times were 8% slower and 11% less accurate for the combined than the cognitive task. Peak COP displacement following posterior perturbations increased by 8% during the combined compared to the arm perturbation task alone, with no other differences detected. Hand peak displacement decreased by 5% during the combined compared to the arm perturbation task. The main findings indicate that with increased cognitive processing, attentional resources were allocated from the cognitive task towards upper limb movements, while attentional resources for balance seemed unaltered.

Pelvic Floor Muscle Strength and the Postural Balance in Middle-Aged Women: A Pilot Study

Aim To investigate if pelvic floor muscles’ (PFMs’) strength is associated with postural balance in middle-aged women. Methods The participants were 22 middle-aged women (age: 57 ± 6 years). They completed a clinical and urogynecological evaluation, PFMs’ strength testing using a perineometer, and balance testing on a force platform. The balance variables analyzed were anteroposterior (AP) and side-to-side (SS) center of pressure (COP) displacement; 95% elliptical COP area (cm2), AP and SS COP displacement median frequency. Results PFMs’ strength was moderately correlated with SS COP displacement and with AP COP median frequency in semi-tandem. Age and educational level affected the relationship between PFMs’ strength and balance. Conclusion PFMs’ strength had the strongest associations with SS COP displacement in eyes-open semi-tandem and AP COP median frequency in eyes-closed semi-tandem. Thus, these results allow us to conclude that there may be some relationship between pelvic floor muscle strength and postural balance in middle-aged women.

Vibratory cue training elicits anticipatory postural responses to an external perturbation.

Anticipatory postural adjustments (APAs) represent the feedforward mechanism of neuromuscular control essential for maintaining balance under predictable perturbations. The importance of vision as a distal sensory modality in the generation of APAs is well established. However, the capabilities of external cues in generating APAs are less explored. In the present study, vibratory cue was investigated for its reliability among healthy individuals in generating anticipatory response under external perturbation in the absence of vision. Ten participants, in quiet stance, were provided with external perturbation in the form of pendulum impact in anterior-posterior (AP) direction under conditions of: both vision and vibratory cue absent; vision present but vibratory cue was absent; vision and vibratory cue both were present; only vibratory cue is present with vision being absent. EMG activities of the leg muscles and displacement of center of pressure (COP) in AP direction were recorded. The data were later analyzed and quantified in the time frame of anticipatory and compensatory phases. The results showed that with training, participants were able to generate significant APAs relying on the vibratory cue alone. Improvement in APAs was accompanied by minimizing the need for larger CPA and improved stability (COP displacement) under perturbation. The study outcome indicates the possibility of using vibratory cues for APA-based interventions.

The Effects of Combining High-Top Shoes with Twister Wrap Orthoses on Balance Parameters of Children with Spastic Diplegic Cerebral Palsy.

Background: Cerebral palsy (CP) is a non-progressive encephalopathy before, during, or after childbirth with almost the most common type, i.e. spastic diplegic, leading to a frequent walking problem, In-toeing. Orthoses can reduce the consequences of CP.Objective: This study aimed to evaluate the effect of combining twister wrap orthoses (TWO) with high-top shoes on the balance parameters of children with spastic diplegic CP.Material and Methods: In this quasi-experimental study, twenty children (aged 6.8 ± 0.5 years) with spastic diplegic CP with in-toeing gait participated. The tests were conducted in three conditions: 1) in bare-foot, 2) with high-top shoes, and 3) with high-top shoes plus TWO and the orthoses effects on balance parameters were compared.Results: High-top shoes positively decreased center of pressure (COP) sway in the anterior-posterior (AP) direction. Both high-top shoes and high-top shoes with TWO conditions compared to bare-foot conditions significantly improved standing balance by decreasing the ellipse area. Pairwise, wearing TWO and high-top shoes significantly reduced the COP sway in the medial-lateral (ML) and AP directions with a significant difference between using the combined orthoses and the shoe without TWO in ML of COP displacement.Conclusion: High-top shoes alone and the combination of high-top shoes with TWO conditions may enhance the stability of children with spastic diplegia more than barefoot. Although the use of combined orthoses induced significant improvement in the ML direction of COP displacement.

Reliability of Center of Pressure measures of Postural Stability in Anterior Cruciate Ligament Reconstructed Athletes: Effect of Vibration and Cognitive Load.

To evaluate intra and intersession reliability of the Center of Pressure (COP) parameters in Anterior Cruciate Ligament Reconstructed (ACLR) athletes with and without ankle vibration using a dual-task paradigm. Postural sway of 14 ACLR individuals was assessed during a single-leg stance on a force platform. COP parameters were assessed with manipulating sensory inputs via vision and ankle vibration under single and dual-task conditions. The outcome variables included COP displacement in medial-lateral (ML) and anterior-posterior (AP) range, mean velocity (mV), and area. During dual-task conditions, the auditory Stroop Task was applied. Intraclass correlation coefficient (ICC) values and standard error of measurement (SEM) were assessed for relative and absolute reliability. The COP measures had moderate to very high intrasession reliability (ICC range: 0.51-0.93) for conditions with vibration and cognitive task, with the highest ICCs for mV and the lowest for area, regardless of eyes being open or closed. The intersession reliability was moderate to high for mV (ICC range: 0.60-0.82) and little to very high (ICC range: 0.21-0.97) for the range of ML and AP, as well as an area in conditions with vibration and cognitive task. The mV is the most reliable COP parameter for assessing postural control under ankle vibration and dual-task conditions for both operated and non-operated sides. During closed-eye conditions, the application of vibration affected the intersession reliability with decreased ICCs on the operated side and increased ICCs on the non-operated side.