Reliability of center of pressure measures of postural stability in healthy older adults: effects of postural task difficulty and cognitive load

The effect of foot somatosensory loss in postural control during Functional reach test in patients with diabetic polyneuropathy: A controlled study

BACKGROUND

In patients with diabetic polyneuropathy (DPN), differences in postural control due to losing the lower limb somatosensory information were reported. However, it is still unclear by which mechanisms the dynamic postural instability is caused.

OBJECTIVES

This study aimed to investigate postural control differences and neuromuscular adaptations resulting from foot somatosensory loss due to DPN.

METHODS

In this controlled cross-sectional study, fourteen DPN patients and fourteen healthy controls performed the Functional Reach Test (FRT) as a dynamic task. The postural control metrics were simultaneously measured using force plate, motion capture system, and surface electromyography (sEMG). The main metrics including reach length (FR), FR to height ratio (FR/H), displacement of CoM and CoP, moment arm (MA), and arch height ratio. Also, kinematic (range of motion of ankle, knee, and hip joints), and sEMG metrics (latencies and root mean square amplitudes of ankle and hallux muscles) were measured. To compare variables between groups, the independent sample T-test for (normally distributed) and the Mann-Whitney U test (non-normally distributed) were used.

RESULTS

The subjects' reach length (FR), FR to height ratio, absolute MA, and displacement of CoM were significantly shorter than controls, while displacement of CoP was not significant. Arch height ratio was found significantly lower in DPN patients. We observed that CoM was lagging CoP in patients (MA = + 0.89) while leading in controls (MA = -1.60). Although, the muscles of patients showed significantly earlier activation, root mean square sEMG amplitudes were found similar. Also, DPN patients showed significantly less hip flexion, knee extension, and ankle plantar flexion.

CONCLUSIONS

This study presented that decreasing range of motion at lower limbs' joints and deterioration in foot function caused poor performance at motor execution during FRT in DPN patients.

A study on the effects of visual condition on postural stability in adults with and without chronic low back pain

This study was conducted to compare postural stability during repeated unilateral standing tasks between adults with and without chronic low back pain (LBP) while considering visual input. The study involved 26 participants with LBP and 39 control participants. Each participant performed three trials of standing tasks on the dominant limb using a stable platform. The Falls Efficacy Scale was utilized to assess fall-related self-efficacy and fear of falling due to potential physical frailty. The center of pressure (COP) sway excursion was analyzed at 10 mm and 20 mm thresholds for the time-in-boundary (TIB). The results indicated a significant fear of falling difference in the LBP group compared to the control group (t = 3.27, p = 0.001). The LBP group demonstrated a significant interaction between visual condition and TIB (F = 8.45, p = 0.01), particularly in the LBP group, which demonstrated a notable decrease in TIB at 10 mm (54.02 % compared to the control group's 70.40 %) and 20 mm (70.93 % compared to the control group's 85.92 %) thresholds during the second trial and at 10 mm (59.73 % compared to the control group's 73.84 %) during the third trial in the eyes open condition. Overall, visual condition demonstrated significant interactions on thresholds (F = 15.80, p = 0.001, η2p = 0.21) as well as trials  ×  thresholds (F = 4.21, p = 0.04, η2p = 0.07). These findings indicate a potential adaptation in postural control among the LBP group with visual feedback. Further research is warranted to explore group differences when considering visual conditions and sway excursion thresholds.

Postural control and trunk stability on sway parameters in adults with and without chronic low back pain

BACKGROUND

Postural sway changes often reflect functional impairments in adults with chronic low back pain (LBP). However, there is a gap in understanding how these individuals adapt their postural strategies to maintain stability.

PURPOSE

This study investigated postural sway distance and velocity, utilizing the center of pressure (COP) and center of gravity (COG), between adults with and without LBP during repeated unilateral standing trials.

METHODS

Twenty-six subjects with LBP and 39 control subjects participated in the study. Postural sway ranges, COP/COG sways, and sway velocities (computed by dividing path length by time in anteroposterior (AP) and mediolateral (ML) directions over 10 s) were analyzed across three unilateral standing trials.

RESULTS

A significant group interaction in sway range difference was observed following repeated trials (F = 5.90, p = 0.02). For COG sway range, significant group interactions were demonstrated in both directions (F = 4.28, p = 0.04) and repeated trials (F = 5.79, p = 0.02). The LBP group demonstrated reduced ML sway velocities in the first (5.21 ± 2.43 for the control group, 4.16 ± 2.33 for the LBP group; t = 1.72, p = 0.04) and second (4.87 ± 2.62 for the control group, 3.79 ± 2.22 for the LBP group; t = 1.73, p = 0.04) trials.

CONCLUSION

The LBP group demonstrated decreased ML sway velocities to enhance trunk stability in the initial two trials. The COG results emphasized the potential use of trunk strategies in augmenting postural stability and optimizing neuromuscular control during unilateral standing.

Correlations between plantar pressure and postural balance in healthy subjects and their comparison according to gender and limb dominance: A cross-sectional descriptive study

BACKGROUND

Lower extremity injuries rank among the most common injuries affecting young population, and numerous factors affect the outcomes of plantar pressure and balance assessment.

RESEARCH QUESTION

Does a correlation exist between plantar pressure and postural balance in healthy subjects and are there any difference in the results based on gender and limb dominance?

METHODS

This study involved thirty healthy recreationally active young adults (15 females, 15 males). Plantar pressures were analyzed using the MatScan Pressure Mat System, and postural balance was evaluated using Biodex Balance System. All assessments conducted under both static and dynamic conditions. Correlations were tested by Spearman Correlation Coefficient, and comparative tests were performed for gender and limb dominance.

RESULTS

Correlations were observed between plantar pressure parameters and balance scores, particularly in the dynamic conditions (p < 0.05). Gender-based differences were noted in plantar pressure parameters (p < 0.05), with females demonstrating improved balance stability scores. No significant differences were found based on limb dominance in plantar pressure and postural balance data (p > 0.05).

SIGNIFICANCE

This study provides valuable detailed insights into the existing literature concerning plantar pressure and postural balance assessments within the healthy population. A strong correlation was observed between plantar pressure and postural balance, and the comparisons of these assessments were affected by gender but not by limb dominance. These results could lead the way for better rehabilitation approaches by considering the correlations and differences across diverse populations.

Plantar intrinsic foot muscle activity and its relationship with postural sway during tiptoe standing in ballet dancers and non-dancers

BACKGROUND

Minimizing postural sway during tiptoe standing is essential for ballet dancers. Investigation of the activity of the plantar intrinsic foot muscles (PIFMs) may provide insight into postural sway in dancers. Herein, we compared PIFM activity during tiptoe standing between dancers and non-dancers and examined its relationship with postural sway.

METHODS

We enrolled 14 female ballet dancers and 13 female non-dancers. Electromyography (EMG) amplitudes of 64 channels of PIFMs and center of pressure (COP) data were recorded during bipedal tiptoe standing tasks performed with ankle plantarflexion angles of 20°, 40°, and 60° (dancers only). The EMG amplitudes were normalized to those during the maximum voluntary contraction, and the muscle activity level and its coefficient of variation over time (EMG-CVtime) during the task were assessed. Standard deviations in the anteroposterior and mediolateral directions, velocity, and area were calculated from the COP data.

RESULTS

Most COP and EMG variables were significantly lower in dancers than in non-dancers in both the 20° and 40° tasks (p < 0.05). Significant correlations were found between most combinations of the COP and EMG variables in both the 20° and 40° tasks in the whole cohort (r = 0.468-0.807, p ≤ 0.014). In the 60° task in dancers, COP velocity was strongly correlated with EMG-CVtime (r = 0.700, p = 0.005).

CONCLUSION

These results provide novel evidence that the PIFMs do not require high activity, but rather that its low, steady activity is the key, to achieve less postural sway during bipedal tiptoe standing in dancers.

Normalized stability time analysis within the boundaries between adults with and without fear of falling

BACKGROUND

The unilateral stance test, measured by the center of pressure (COP), has been widely used to identify balance deficits. However, there is a critical gap in understanding the specific COP thresholds on postural stability in adults with a fear of falling (FOF).

AIMS

To investigate the normalized stability time, which was defined as the ratio of time spent within stability boundaries to the total test duration, under different visual conditions and specific thresholds between adults with and without FOF.

METHODS

Twenty-one older adults with FOF and 22 control subjects completed the unilateral limb standing test in eyes-open and eyes-closed conditions. Normalized stability times were computed based on five pre-determined COP sway range thresholds: 10 mm, 15 mm, 20 mm, 25 mm, and 30 mm.

RESULTS

Receiver operating characteristic analysis determined the diagnostic accuracy of FOF. There were significant differences in the effects of both visual conditions (F = 46.88, p = 0.001) and threshold settings (F = 119.38, p = 0.001) on stability time between groups. The FOF group significantly reduced normalized stability time at the 10 mm COP threshold under eyes-closed conditions (t = - 1.95, p = 0.03).

DISCUSSION

The findings highlight the heightened sensitivity of the 10 mm COP threshold in identifying group variances in postural stability when eyes are closed. Moreover, the FOF group displayed a marked reduction in stability duration based on visual scenarios and normalized thresholds.

CONCLUSION

The study highlights the need to account for both COP boundaries and visual conditions in adults with FOF. When assessing postural control during unilateral stances, clinicians must also give attention to non-visual cues.

Adipose tissue deposition region affects fall risk in people with obesity: A systematic review and meta-analysis

This review sought to meta-analyze previous research observing the effects of fat mass distribution on the fall risk among people with obesity. The literature search yielded five qualified studies enrolling 1218 participants (650 with android vs. 568 with gynoid). The outcome variables included the annual fall prevalence (primary outcome) and the center of pressure (COP) movement measurements during a posturography test (secondary) among people with android or gynoid obesity. Meta-analyses were conducted using the inverse variance weighted random-effects model. The odds ratio (OR) and standardized mean difference (SMD) were used as the effect size for the primary and secondary variables, respectively. The results revealed that more people with android obesity fall annually than their gynoid obesity counterparts (OR = 1.78 [1.34, 2.37], p < 0.0001). People with android obesity also exhibited significantly faster overall COP velocity (SMD = 0.49 [0.11, 0.88], p = 0.01) during standing compared to individuals with gynoid obesity. Our results indicated that people with android obesity could have a greater fall risk than those with gynoid obesity. Given the limited number of studies included, more well-designed and quality work is desired to further clarify how fat mass distribution alters the fall risk among people with obesity. A standardized approach to quantify the fat mass distribution (android vs. gynoid) is imperatively needed for people with obesity.

Pain alleviation improves balance control and muscular coordination of lower limbs in patients with chronic ankle instability during sinusoidal perturbations

BACKGROUND

It is well established that individuals with chronic ankle instability manifest deficits in balance control and muscle activation. Given the prevalence of pain as a prominent symptom in this population, there is a need for in-depth investigation of its role in contributing to these impairments.

METHODS

A Stewart platform was used to generate translational sinusoidal perturbations in the antero-posterior direction. Eighteen individuals with chronic ankle instability and concurrent ankle pain were recruited. They were instructed to assume a central stance on the support surface with open eyes both before and 30 min after local analgesia. Data of center of pressure and electromyography of the tibialis anterior and medial gastrocnemius were recorded. Statistical analysis was performed to make comparisons pre- and post-analgesia using two-tailed paired t-test for the continuous variables.

FINDINGS

Pain intensity was significantly decreased after local anesthetic injections. Antero-posterior center of pressure parameters significantly decreased following the injection. Also, there was an increase in the regularity of the center of pressure pattern. The electromyographic pattern of the tibialis anterior and medial gastrocnemius exhibited various activation patterns. After pain alleviation, the characteristic electromyographic response of the tibialis anterior and medial gastrocnemius was reciprocal contraction and relaxation that corresponded with the sinusoidal pattern of the perturbations.

INTERPRETATION

Individuals who had chronic ankle instability and ankle pain demonstrated impaired balance control during sinusoidal perturbations. Mitigating pain improved their balance performance, evident in the center of pressure pattern and the coordination of lower limb muscles.

Postural adaptations within normalized stability between older adults with and without chronic low back pain

BACKGROUND

Adaptations of dynamic balance performance are related to sway excursions in older adults with chronic low back pain (LBP). However, there is a lack of understanding on postural control within different thresholds of radius from the center of pressure (COP).

PURPOSE

This study was conducted to compare the normalized stability based on the time-in-boundary (TIB) during repeated unilateral limb standing trials between subjects with and without chronic LBP.

METHODS

There were 26 older adults with LBP and 39 control subjects who completed three trials of repeated unilateral limb standing on a force plat.

RESULTS

The TIB based on the seven thresholds was analyzed, and the groups demonstrated a significant interaction on thresholds for TIB (F = 8.76, p = 0.01). The TIB was significantly different in the 10 mm (F = 4.01, p = 0.04), 15 mm (F = 5.21, p = 0.03), and 20 mm (F = 4.48, p = 0.04) radius of thresholds only in the second trial. However, there was no group difference on TIB at the first and third trials due to potential compensatory and/or adaptive reactions to avoid fall risks.

CONCLUSION

The LBP group lacked postural stability within the thresholds less than a 20 mm radius at the second trial of unilateral standing. The significant group interaction with the thresholds indicates an adaptation strategy on sway thresholds. This postural reaction from repeated trials should be considered with sway excursion adjustments and fall prevention in older adults with LB.

Comparison of the Dynamic Postural Control During Lifting and Lowering an External Load in Low Back Pain: A Cross-Sectional Study

OBJECTIVE

This study aimed to compare dynamic postural control between individuals with and without chronic low back pain (LBP) through load lifting and lowering.

METHODS

This cross-sectional study included 52 male patients with chronic LBP (age: 33.37 ± 9.23 years) and 20 healthy male individuals (age: 31.75 ± 7.43 years). The postural control parameters were measured using a force plate system. The participants were instructed to stand barefoot (hip-width apart) on the force plate and lift a box (10% of the weight of the participants) from the waist height to overhead and then lower it from overhead to waist height. The interaction between the groups and tasks was determined using a 2-way repeated-measures analysis of variance.

RESULTS

There was no significant interaction between the groups and tasks. Regardless of the groups, postural control parameters including amplitude (P = .001) and velocity (P < .001) in anterior-posterior (AP) direction, phase plane in medial-lateral (ML) direction (P = .001), phase plane in AP-ML direction (P = .001), and the mean total velocity (P < .001) were lesser during the lowering compared with lifting. The results indicated that, regardless of the tasks, the postural control parameters including velocity (P = .004) and phase plane in AP direction (P = .004), velocity in ML direction (P < .001), phase plane (AP-ML) (P = .028), and mean total velocity (P = .001) in LBP were lesser compared with the normal group.

CONCLUSION

Different tasks affected postural control differently in patients with LBP and healthy individuals. Moreover, postural control was more challenged during the load-lowering than the load-lifting task. This may have been a result of a stiffening strategy. It may be that the load-lowering task might be considered as a more influential factor for the postural control strategy. These results may provide a novel understanding of selecting the rehabilitation programs for postural control disorders in patients.

The influence of reduced foot dorsum cutaneous sensitivity on the vestibular control of balance

PURPOSE

Foot sole cooling increases vestibular-evoked balance responses, but less is known about foot dorsum temperature alterations. The purpose was to determine whether decreasing cutaneous receptor sensitivity via foot dorsum cooling modulates the vestibular control of balance.

METHODS

Eighteen participants (9 males; 9 females) stood quietly on a force plate with feet together, eyes closed, and head rotated leftward during 4, 90-s trials (2 control; 2 cooled) of continuous electrical vestibular stimulation (EVS). Icepacks placed on the dorsum of both feet for 15 min induced cooling and remained throughout the EVS trials. Monofilament testing was performed at multiple locations before and after cooling to determine tactile detection thresholds. T-type thermocouples monitored skin temperature over the tibialis anterior, soleus, foot dorsum and arch of the right leg. Vestibular-evoked balance responses were characterized using time (cumulant density) and frequency (coherence and gain) domain analyses to determine the relationship between the EVS input and motor output (anteroposterior force-AP force; right medial gastrocnemius electromyography-MG EMG).

RESULTS

Skin temperature of the foot dorsum and arch decreased ~ 70 and 15%, respectively during cooling (p < 0.05), but was unaltered at other locations (p ≥ 0.10). Detection thresholds for the foot dorsum increased following cooling (p < 0.05). Surprisingly, cooling reduced EVS-AP force and EVS-MG EMG coherence and gain at multiple frequencies, and peak-to-peak amplitude compared to control (p < 0.05).

CONCLUSION

Our results indicate that vestibular-driven balance responses are reduced following foot dorsum cooling, likely owing to alterations in cutaneous mechanoreceptor sensitivity and subsequent alterations in the transformation of vestibular cues for balance control.

The influence of local pain on balance control in patients with chronic ankle instability

Background

Local pain around the ankle joint is a common symptom in patients with chronic ankle instability (CAI). However, whether the local pain would impose any influence on the balance control performance of CAI patients is still unknown.

Methods

A total of twenty-six subjects were recruited and divided into the following two groups: pain-free CAI (group A) and pain-present CAI (group B). Subjects in both groups received two independent tests: the star excursion balance test and the single-leg stance test, in order to reflect their balance control ability more accurately.

Results

Compared with group A, the group B showed significantly more episodes of the history of sprains, decreased ankle maximum plantarflexion angle, and lower Cumberland scores (all p < 0.05). In the star excursion balance test, group B demonstrated a significantly reduced anterior reach distance than group A (p < 0.05). During the single leg stance test, group B showed a significant increase in the magnitude of electromyographic signals both in peroneus longus and soleus muscles than group A (each p < 0.05). Additionally, group B had a significantly more anterolaterally positioned plantar center of pressure than group A (p < 0.05).

Conclusion

CAI patients with local pain around the ankle joint had more episodes of sprains and lower functional scores when compared to those without pain. The balance control performance was also worse in the pain-present CAI patients than those without pain.

Measuring the Reliability of Postural Sway Measurements for a Static Standing Task: The Effect of Age

Background: A force plate is used to determine the ability to balance ability. However, only some medical centers or laboratories are equipped with force plates because they are costly so a low-cost force plate is required for home care or health care institutes. Few studies compare the reliability of postural sway measurements in terms of age. This study proposes a low-cost force plate to select reliable parameters to evaluate postural sway.

Objectives: To determine the intra-rater reliability of a novel force plate and the effect of age difference on the intra-rater test-retest reliability for the center of pressure (COP).

Methods: Forty participants were enrolled for this study: 20 youths and 20 older adults. Participants stood on a custom-made and low-cost force plate with eyes opened and eyes closed to measure COP-related parameters. The within-day test-retest reliability was measured at two sessions on the same day and the between-days reliability was measured on two different days. The COP-related parameters include the average velocity of COP, the average velocity in the antero-posterior and medio-lateral directions, the mean distance of COP and the mean distance in the antero-posterior and medio-lateral directions. An intra-class correlation coefficient test with one-way random model was performed to determine the reliability of different variables within-days and between-days. The results were presented in single measurement of intraclass correlation coefficient (ICC), the standard error of measurements, and the minimal detectable changes of each COP-related parameters.

Results: The novel low-cost force plate demonstrates excellent reliability in terms of the COP velocity related parameters for within- and between-day measurements. The ICC of COP distance related parameters were good to excellent reliability for between-day measurements (range: 0.43–0.84). Older adults demonstrated excellent reliability in terms of the mean distance for antero-posterior and the results were better than those for younger participants for the eyes-opened and eyes-closed conditions. The reliability in terms of the mean distance for medio-lateral was poor to good for older adults (range: 0.38–0.55), and excellent for younger participants.

Conclusion: The novel and low-cost force plate reliably measured balance and age affects the reliability of different COP variables, so the results of this study were pertinent to the selection of COP measures.

Age-related changes to vestibular heave and pitch perception and associations with postural control

Falls are a common cause of injury in older adults (OAs), and age-related declines across the sensory systems are associated with increased falls risk. The vestibular system is particularly important for maintaining balance and supporting safe mobility, and aging has been associated with declines in vestibular end-organ functioning. However, few studies have examined potential age-related differences in vestibular perceptual sensitivities or their association with postural stability. Here we used an adaptive-staircase procedure to measure detection and discrimination thresholds in 19 healthy OAs and 18 healthy younger adults (YAs), by presenting participants with passive heave (linear up-and-down translations) and pitch (forward-backward tilt rotations) movements on a motion-platform in the dark. We also examined participants' postural stability under various standing-balance conditions. Associations among these postural measures and vestibular perceptual thresholds were further examined. Ultimately, OAs showed larger heave and pitch detection thresholds compared to YAs, and larger perceptual thresholds were associated with greater postural sway, but only in OAs. Overall, these results suggest that vestibular perceptual sensitivity declines with older age and that such declines are associated with poorer postural stability. Future studies could consider the potential applicability of these results in the development of screening tools for falls prevention in OAs.

A review of center of pressure (COP) variables to quantify standing balance in elderly people: Algorithms and open-access code

Postural control is often quantified by recording the trajectory of the center of pressure (COP)-also called stabilogram-during human quiet standing. This quantification has many important applications, such as the early detection of balance degradation to prevent falls, a crucial task whose relevance increases with the aging of the population. Due to the complexity of the quantification process, the analyses of sway patterns have been performed empirically using a number of variables, such as ellipse confidence area or mean velocity. This study reviews and compares a wide range of state-of-the-art variables that are used to assess the risk of fall in elderly from a stabilogram. When appropriate, we discuss the hypothesis and mathematical assumptions that underlie these variables, and we propose a reproducible method to compute each of them. Additionally, we provide a statistical description of their behavior on two datasets recorded in two elderly populations and with different protocols, to hint at typical values of these variables. First, the balance of 133 elderly individuals, including 32 fallers, was measured on a relatively inexpensive, portable force platform (Wii Balance Board, Nintendo) with a 25-s open-eyes protocol. Second, the recordings of 76 elderly individuals, from an open access database commonly used to test static balance analyses, were used to compute the values of the variables on 60-s eyes-open recordings with a research laboratory standard force platform.

Investigating balance, gait, and physical function in people who have undergone thoracic surgery for a diagnosis of lung cancer: A mixed-methods study

Objectives

Symptoms associated with lung cancer and thoracic surgery might increase fall risk. We aimed to investigate: 1) balance, gait and functional status in people post-thoracic surgery compared to healthy controls; 2) perceptions of balance, gait and functional status.

Methods

Recruitment targeted older adults (≥50 years) who had undergone thoracic surgery for a diagnosis of lung cancer in the previous 3 months, and healthy age-matched controls. Dynamic and static balance, gait velocity, knee-extension strength and physical activity levels were assessed using the BESTest, Kistler force plate, GAITRite system, Biodex System 3 and CHAMPS questionnaire, respectively. Two-part semi-structured interviews were conducted post-surgery.

Results

Individuals post-surgery (n = 15) had worse dynamic balance and gait, and lower levels of moderate/vigorous physical activity (MVPA) (all p<0.05) versus healthy controls (n = 15). Strength did not differ between groups (p > 0.05). No associations between BESTest and strength or physical activity existed post-surgery (p > 0.05). Three themes were identified: 1) Symptoms affect daily activities; 2) Functional assessments alter perceptions of balance ability and 3) Open to supervised rehabilitation.

Conclusion

Balance, gait and MVPA are impaired post-thoracic surgery, yet balance was not viewed to be important in enabling activities of daily living. However, supervised rehabilitation was considered acceptable.

Co-contraction of ankle muscle activity during quiet standing in individuals with incomplete spinal cord injury is associated with postural instability

Previous findings indicate that co-contractions of plantarflexors and dorsiflexors during quiet standing increase the ankle mechanical joint stiffness, resulting in increased postural sway. Balance impairments in individuals with incomplete spinal cord injury (iSCI) may be due to co-contractions like in other individuals with reduced balance ability. Here we investigated the effect of co-contraction between plantar- and dorsiflexors on postural balance in individuals with iSCI (iSCI-group) and able-bodied individuals (AB-group). Thirteen able-bodied individuals and 13 individuals with iSCI were asked to perform quiet standing with their eyes open (EO) and eyes closed (EC). Kinetics and electromyograms from the tibialis anterior (TA), soleus and medial gastrocnemius were collected bilaterally. The iSCI-group exhibited more co-contractions than the AB-group (EO: 0.208% vs. 75.163%, p = 0.004; EC: 1.767% vs. 92.373%, p = 0.016). Furthermore, postural sway was larger during co-contractions than during no co-contraction in the iSCI-group (EO: 1.405 cm/s² vs. 0.867 cm/s², p = 0.023; EC: 1.831 cm/s² vs. 1.179 cm/s², p = 0.030), but no differences were found for the AB-group (EO: 0.393 cm/s² vs. 0.499 cm/s², p = 1.00; EC: 0.686 cm/s² vs. 0.654 cm/s², p = 1.00). To investigate the mechanism, we performed a computational simulation study using an inverted pendulum model and linear controllers. An increase of mechanical stiffness in the simulated iSCI-group resulted in increased postural sway (EO: 2.520 cm/s² vs. 1.174 cm/s², p < 0.001; EC: 4.226 cm/s² vs. 1.836 cm/s², p < 0.001), but not for the simulated AB-group (EO: 0.658 cm/s² vs. 0.658 cm/s², p = 1.00; EC: 0.943 cm/s² vs. 0.926 cm/s², p = 0.190). Thus, we demonstrated that co-contractions may be a compensatory strategy for individuals with iSCI to accommodate for decreased motor function, but co-contractions may result in increased ankle mechanical joint stiffness and consequently postural sway.

Application of Interactive Video Games as Rehabilitation Tools to Improve Postural Control and Risk of Falls in Prefrail Older Adults

The purpose of this study was to examine whether interactive video game (IVG) training is an effective way to improve postural control outcomes and decrease the risk of falls. A convenience sample of 12 prefrail older adults were recruited and divided into two groups: intervention group performed IVG training for 40 minutes, twice per week, for a total of 16 sessions. The control group received no intervention and continued their usual activity. Outcome measures were centre of pressure (COP), mean velocity, sway area, and sway path. Secondary outcomes were Berg Balance Scale, Timed Up and Go (TUG), Falls Efficacy Scale International (FES-I), and Activities-Specific Balance Confidence (ABC). Assessment was conducted with preintervention (week zero) and postintervention (week eight). The intervention group showed significant improvement in mean velocity, sway area, Berg Balance Scale, and TUG (p < 0.01) compared to the control group. However, no significant improvement was observed for sway path (p = 0.35), FES-I (p = 0.383), and ABC (p = 0.283). This study showed that IVG training led to significant improvements in postural control but not for risk of falls.

Effect of Yogasana Intervention on Standing Balance Performance among People with Diabetic Peripheral Neuropathy: A Pilot Study

Background

Diabetic peripheral neuropathy (DPN) is known to cause impaired balance and eventually increased risk of fall. Yogasanas characterized by slow, gentle transitions into postures with a varying base of support and focus on body awareness during movement hold potential for training balance control. Therefore, the current study aimed to evaluate effect of structured Yogasana intervention compared to conventional balance exercise on static and dynamic balance performance among people with diabetic neuropathy.

Methods

: Thirty-five people with DPN aged 42-70 years were recruited to Yogasana intervention group (n = 11), conventional balance exercises group (n = 10), and Control group (n = 14) following ethical approval. All participants were evaluated at baseline and post 12-week intervention on star excursion balance test, single-limb stance test, and center of pressure (CoP) excursion for balance performance, Modified fall efficacy scale for fear of falls and lower extremity strength using chair stand test and step-up test.

Results

Balance performance (static and dynamic measured by star excursion balance test, single-limb stance test, and CoP excursion, lower extremity strength (using chair stand test and step-up test) demonstrated improvement and fear of fall reduced among Yogasana intervention group (p = 0.05) and conventional balance exercises group (p = 0.05) post 12-week intervention. CoP excursion increased in the control group indicating deterioration in balance performance after 12 weeks (p = 0.05). Post hoc comparison revealed that Yogasana intervention was marginally more effective in improving static and dynamic balance performance compared to conventional balance exercises in all variables of standing balance performance (p = 0.025).

Conclusion

Yogasana and conventional balance exercises were effective in improving static and dynamic balance performance, lower extremity muscle strength, and reducing fear of fall among people with DPN. Yogasana intervention demonstrated marginally greater improvement in static and dynamic balance performance and lower extremity muscle strength compared to conventional exercise.

Age-related differences in stair descent balance control: Are women more prone to falls than men?

Stair descent is one of the most common forms of daily locomotion and concurrently one of the most challenging and hazardous daily activities performed by older adults. Thus, sufficient attention should be devoted to this locomotion and to the factors that affect it. This study investigates gender and age-related differences in balance control during and after stair descent on a foam mat. Forty-seven older adults (70% women) and 38 young adults (58% women) performed a descent from one step onto a foam mat. Anteroposterior (AP) and mediolateral (ML) centre of pressure velocity (CoP) and standard deviation of the CoP sway were investigated during stair descent and restabilization. A two-way analysis of variance (ANOVA) revealed the main effects of age for the first 5 s of restabilization. Older women exhibited significantly higher values of CoP sway and velocity in both directions compared to the younger individuals (CoP SD_AP5, 55%; CoP SD_ML5, 30%; CoP V_AP5, 106%; CoP V_ML5, 75%). Men achieved significantly higher values of CoP sway and velocity only in the AP direction compared to their younger counterparts (CoP SD_AP5, 50% and CoP V_AP5, 79%). These findings suggest that with advancing age, men are at higher risk of forward falls, whereas women are at higher risk of forward and sideways falls.

A systematic review of center of pressure measures to quantify gait changes in older adults

Measures of gait center of pressure (COP) can be recorded using simple available technologies in clinical settings and thus can be used to characterize gait quality in older adults and its relationship to falls. The aim of this systematic review was to investigate the association between measures of gait COP and aging and falls. A comprehensive search of electronic databases including MEDLINE, Embase, Cochrane Central Register of Controlled Trials, CINAHL (EBSCO), Ageline (EBSCO) and Scopus was performed. The initial search yielded 2809 papers. After removing duplicates and applying study inclusion/exclusion criteria, 34 papers were included in the review. Gait COP has been examined during three tasks: normal walking, gait initiation, and obstacle negotiation. The majority of studies examined mean COP position and velocity as outcome measures. Overall, gait in older adults was characterized by more medial COP trajectory in normal walking and lower average anterior-posterior and medio-lateral COP displacements and velocity in both gait initiation and obstacle crossing. Moreover, findings suggest that Tai chi training can enhance older adults' balance control during gait initiation as demonstrated by greater COP backward, medial and forward shift in all three phases of gait initiation. These findings should be interpreted cautiously due to inadequacy of evidence as well as methodological limitations of the studies such as small sample size, limited numbers of 'fallers', lack of a control group, and lack of interpretation of COP outcomes with respect to fall risk. COP measures can be adopted to assess fall-related gait changes in older adults but more complex measures of COP that reveal the dynamic nature of COP behavior in step-to-step variations are needed to adequately characterize gait changes in older adults.

Assessing Postural Stability Using Coupling Strengths between Center of Pressure and Its Ground Reaction Force Components

The center of pressure (COP), which is defined as the point at which the resultant ground reaction force (GRF) is applied on a body, provides valuable information for postural stability assessment. This is because the fundamental goal of balance control is to regulate the center of mass (COM) of the human body by adaptively changing the position of the COP. By using Newtonian mechanics to develop two equations that relate the two-dimensional COP coordinates to the GRF components, one can easily determine the location of the COP using a force plate. An important property of these two equations is that for a given COP position, there exists an infinite number of GRF component combinations that can satisfy these two equations. However, the manner in which a postural control system deals with such redundancy is still unclear. To address this redundancy problem, we introduce four postural stability features by quantifying the coupling strengths between the COP coordinates and their GRF components. Experiments involving younger (18–24 years old) and older (65–73 years) participants were conducted. The efficacy of the proposed features was demonstrated by comparing the differences between variants of each feature for each age group (18–24 and 65–73 years). The results demonstrated that the coupling strengths between the anterior–posterior (AP) direction coordinate of the COP and its GRF components for the older group were significantly higher than those of the younger group. These experimental results suggest that (1) the balance control system of the older group is more constrained than that of the younger group in coordinating the GRF components and (2) the proposed features are more sensitive to age variations than one of the most reliable and accurate conventional COP features. The best testing classification accuracy achieved by the proposed features was 0.883, whereas the testing classification accuracy achieved by the most accurate conventional COP feature was 0.777. Finally, by investigating the interactions between the COP and its GRF components using the proposed features, we found that that the AP component of the GRF of younger people plays a more active role in balance control than that of the GRF of older people. Based on these findings, it is believed that the proposed features can be used as a set of stability measures to assess the effects on posture stability from various health-related conditions such as aging and fall risk.

Reliability of center of pressure excursion as a measure of postural control in bipedal stance of individuals with intellectual disability: A pilot study

The high prevalence of postural instability in individuals with intellectual disability (ID) warrants the need for reliable and practical postural control assessments. Stabilometry is a postural control assessment that has been widely used for clinical populations. However, the scant systematic knowledge about the reliability of stabilometric protocols for adults with ID renders results questionable and limits its value for clinicians and researchers. The study's purpose was to develop a stabilometric protocol for adults with and without ID based on optimal combinations of shortest necessary trial durations and the least number of trial repetitions that guarantee sufficient reliability. Participants performed six trials of bipedal standing in 2 vision (eyes open vs eyes closed) x 2 surface (solid vs compliant) conditions on a force platform. Several parameters were calculated from the first 10-, 20-, and 30-s interval of every center-of-pressure (COP) trial data. For different trial durations, we identified the number of trials that yielded acceptable relative (intraclass correlation coefficient ≥ 0.70) and absolute (standard error of measurement < 20%) reliability using the Spearman-Brown prophecy formula. To determine the optimal combination of trial duration and number of repetition for each COP parameter, we implemented a two-step process: 1) identify the largest number of repetition for each of the three trial durations and then 2) select the trial duration with the lowest number of repetition. For both ID- and non-ID groups, we observed a trend whereby shorter trial durations required more repetitions and vice versa. The phase plane and ellipse area were the most and least reliable center-of-pressure parameter, respectively. To achieve acceptable reliability, four 30-s trials of each experimental condition appeared to be optimal for testing participants with and without ID alike. The results of this research can inform stabilometric test protocols of future postural control studies of adults with ID.

Balance control during stair descent on compliant surface is associated with knee flexor and ankle plantar flexor strength in older adults

Balance and lower limb strength deficits are associated with a high incidence of falls in older adults. This study investigated the association between balance control during and after stair descent onto a compliant surface and lower limb strength. Thirty-five women and 14 men participated in this study. Stair descent time, mean center of pressure velocity in anteroposterior and mediolateral direction during stair descent (CoP V_AP and CoP V_ML), and CoP velocity in the first 5 s of restabilization phase (CoP V₅) were evaluated. Bilateral strength of the knee flexors and extensors, and ankle plantar and dorsal flexors was evaluated. Spearman correlation analysis with Bonferroni correction yielded a significant association between the strength of the knee flexors on the trailing limb and stair descent time in women (r = 0.502, p = 0.002, R² = 0.246). The same analysis in men revealed a significant association between the strength of the knee flexors on the trailing limb and CoP V_AP (r = -0.820, p < 0.001, R² = 0.280) and CoP V_ML (r = -0.697, p = 0.006, R² = 0.359). The strength of the ankle plantar flexors on the trailing limb was significantly associated with stair descent time (r = 0.684, p = 0.007, R² = 0.429) and CoP V_AP (r = -0.723, p = 0.003, R² = 0.408) in men. Stair descent balance control is associated with knee flexion strength on trailing limb in women, and with ankle plantar flexion and knee flexion strength on the same limb in men.

Reliability of postural control during double-leg standing in subjects with nonspecific chronic low back pain: Dual-task paradigm and manipulated visual and somatosensory inputs

BACKGROUND

The aim of this study is to evaluate the test-retest reliability of the Center of Pressure (COP) parameters in quiet double-leg standing in subjects with Non-Specific Chronic Low Back Pain (NSCLBP) during dual taking associated with manipulated visual and somatosensory inputs.

MATERIALS AND METHODS

In this observational cross-sectional study, the static balance of thirty NSCLBP patients were assessed during a double-leg stance by using the force platform. Subjects were accosted by manipulated somatosensory and visual inputs during dual taking in eight different conditions (with and without vibration, eyes-open and eyes-closed, and with and without auditory Stroop test). The COP parameters were recorded as follows: range sideways and range fore-aft as well as mean velocity and area variables. The cognitive task parameters included the reaction time and error ratio. The intra-class correlation coefficient (ICC) was computed to assess the intersession reliability of COP parameters.

RESULTS

in intersession, range sideways, range fore-aft, and mean velocity measures possessed moderate to high ICC, but area owned high ICC only in one condition (double-leg stance, eyes-close, with vibration, and with auditory Stroop test). Notably, other conditions had low ICC, and moderate to high and low to very high ICC were reported for reaction time and error ratio.

CONCLUSION

Among the parameters studied in the present study, the mean velocity measure seems to be the most reliable variable of postural control in the subjects with NSLBP especially in more challenging conditions, i.e., quiet double-leg standing with eyes closed and adding vibratory inputs during dual-tasking.

Center of pressure displacement characteristics differentiate fall risk in older people: A systematic review with meta-analysis

Falling is the second most prevalent cause of accidental death in the world. Currently available clinical tests to assess balance in older people are insufficiently sensitive to screen for fall risk in this population. Laboratory tests that record the center of pressure (COP) trajectory could overcome this problem but despite their widespread use, the choice of COP trajectory features for use as a biomarker of fall risk lacks consensus. This systematic review and meta-analysis aimed at identifying the best COP characteristics to predict risk of falling in older adults. More than 4000 articles were screened; 44 (7176 older adults) were included in this study. Several COP parameters emerged as good indices to discriminate fallers from non-fallers. From sensitivity analysis, Sway area per unit time, anteroposterior mean velocity, and radial mean velocity were the best traditional features. In this study, identification of older people with a high fall risk was demonstrated using quiet-standing recordings. Such screening would also be useful for routine follow-up of balance changes in older fallers in clinical practice.

Dual-Task Conditions on Static Postural Control in Older Adults: A Systematic Review and Meta-Analysis

Dual-task (DT) consists of the performance of two tasks simultaneously. An index of DT difficulty has been linked to decreased postural control. Because a wide range of DT is employed, this study aimed to evaluate its effects in static balance in older adults. PubMed, Web of Science, and Scopus were screened, and the secondary tasks were grouped as manual, reaction time, discrimination and decision making, mental tracking, verbal fluency, working memory, or "other" tasks. A total of 66 studies have been included. The meta-analysis was conducted on 28 effects and showed a significant mean effect size of d = 0.24 (p = .02, SE = 0.10; confidence interval [0.04, 0.44]), indicating a worsening in stability during DT. In conclusion, postural control was worsened by the Stroop test and the arithmetic tasks improved it. The results do not underpin any conclusive statement on the impact of DT, and a standard operating procedure was created.

Validation of a Portable Force Plate for Evaluating Postural Sway

Measurements of postural sway are used to assess physiological changes due to therapy or sport training, or to describe group differences based on activity history or disease status. Portable force plates have been widely adopted for this purpose, leading us in this study to validate with linear and nonlinear metrics the posturographic data derived from both a portable plate (Natus) when compared to an in-ground plate (Bertec). Twenty participants stood on each plate for two trials each, with and without a foam perturbation and with and without eyes open on each surface. We calculated measures of path length, range, root mean squares, sample entropy, and correlation dimensions from center of pressure traces on each plate. An intraclass correlation coefficient across trials from each plate in each condition indicated satisfactory overall reliability (ICC consistency), supporting the use of either plate for postural sway research and interventions. Additionally, our results generally supported common validity (ICC absolute agreement), though, the specific degree of similarity differed for each of the tested metrics of postural sway, especially when considering whether or not data was filtered. For situations in which participants cannot visit a laboratory (e.g. performing athletes, community dwelling clinical patients, and virus risk concerns) an in-home portable force plate is a trusted and valuable data collection tool.

Relationships Between Body Mass Index and Static and Dynamic Balance in Active and Inactive Older Adults

BACKGROUND AND PURPOSE

Although the association between higher body mass index and poorer balance has been observed in older adults, the role of physical activity in this relationship is not well established. This study aimed to provide scientific evidence about the relationship between body mass index and balance, taking into account the amount of physical activity performed as a confounding variable.

METHODS

We collated cross-sectional data from 160 community-dwelling older adults whom we divided into 3 body mass index categories: normal weight (≥18.50-24.99 kg/m), overweight (25.00-29.99 kg/m), and obese (≥30.00-34.99 kg/m). We classified the participants as inactive or active by means of the Yale Physical Activity Questionnaire. We carried out static and dynamic balance measurements by means of a force platform and through the performance of the Timed Up and Go test, respectively.

RESULTS

We found statistically significant correlations between static balance, dynamic balance, and body mass index in inactive normal (r = 0.280; P = .035; r = 0.300; P = .031) and inactive overweight (r = 0.395; P = .025; r = 0.339; P = .023) people. We observed moderately strong and fair significant correlations between static/dynamic balance and BMI in inactive (r = .603; P = .028; and r = 0.720; P = .020) and active (r = 0.406; P = .037; and r = 0.378; P = .037) obese people, respectively.

CONCLUSION

We conclude that the amount of physical activity performed is a potential contributing factor affecting the association between body mass index and balance in older persons. These findings could be of importance when identifying the main factors that influence postural control among older adults with obesity.

The potential influence of stochastic resonance vibrations on neuromuscular strategies and center of pressure sway during single-leg stance

BACKGROUND

Stochastic resonance vibrations are known to enhance balance in the elderly and patients with impaired plantar sensation. However, the underlying mechanisms of plantar vibrations on balance capacity are not well resolved. This study investigated the impact of stochastic resonance vibrations on activities of major extrinsic foot muscles and center of pressure sway in tactile inhibited subjects.

METHODS

Using a customized vibration insole, single-leg stance tests were performed in fourteen healthy subjects at control, ice-intervention-only (inhibited foot sensation) and ice-intervention plus vibration conditions. The sway parameters and the root mean square of electromyography of medial gastrocnemius, tibialis anterior, peroneus longus, and extensor digitorum longus were examined.

FINDINGS

The sway area in the ice-intervention-only condition was significantly increased compared with the control (P < .001). Following vibrations, the sway area, however, was significantly decreased. Regression analysis showed the activity levels of all extrinsic foot muscles were positively correlated with sway area when foot sensation was inhibited. In contrast, following vibrations, only that of the tibialis anterior muscle was positively correlated with sway area, indicative of a muscle control strategy similar to the control condition.

INTERPRETATION

The study showed that stochastic resonance vibrations could effectively reduce body sway in the healthy subjects with inhibited foot sensation. The effects seemed to be associated with improved muscle activities in particular to the tibialis anterior muscle. It suggested that vibration insole may be used as a means to affect neuromuscular strategies to enhance balance control in people with diminished plantar sensations.

The development of postural control among children: Repeatability and normative data for computerized dynamic posturography system

BACKGROUND

The purpose of this study was to investigate the normal development of postural control in children aged 2-18 years in Tehran, and to provide normative data of computerized dynamic posturography (CDP) device variables.

METHODS

The study population included 400 boys and 400 girls aged 2-18 years (eight age groups with 2-year interval) and 100 adults aged 22-25 years. In each age group, 100 people were selected based on the inclusion and exclusion criteria. To evaluate the postural control of the subjects, the sensory organization test (SOT) was performed by using a CDP.

RESULTS

The results of this study led to the determination and presentation of normative data for the development of postural control in boys, girls and children aged 2-18 years. The results related to the repeatability of data produced by the CDP, thereby showing that this system is highly reliable. The results of an independent t-test also showed that girls across all age groups performed better than boys (p ≤ 0.05).

CONCLUSION

The results of this study demonstrated a nonlinear trend of natural development of postural control. Overall, according to the results of the present study, it seems that like adults, 14-16 year-old teens are capable of processing, integrating and organizing sensory systems information for postural control.

Comparative study of muscle energy technique, craniosacral therapy, and sensorimotor training effects on postural control in patients with nonspecific chronic low back pain

Background:

Malalignment in the pelvic and spinal column disturbs the balance and decreases the postural control ability. Malalignment is known as one of the main causes of back pain particularly the nonspecific chronic low back pain (NSCLBP). The aim of the study is to compare the effect of muscle energy technique (MET), craniosacral therapy (CST), and sensorimotor training (SMT) on postural control in patients with NSCLBP.

Materials and Methods:

In this randomized clinical trial study, 45 NSCLBP patients were accidentally allocated in three groups including CST (n = 15), MET (n = 15), and SMT (n = 15). Clinical interventions including CST, MET, and SMT were performed in 10 sessions in 5 weeks (2 sessions per week). The parameters of center of pressure (COP) were assessed in 8 positions such as standing position on double or single leg with open or closed eyes or half squat position on double or single leg with open or closed eyes.

Results:

The results of this study showed that all three methods of CST, MET, and SMT are effective in postural control in patients with NSCLBP, although it seems that CST is effective on more balance factors. CST has a greater effect on balance in standing position on a single leg with closed eye. It was also found that the effect of CST was continuous after follow-up.

Conclusion:

Moreover, MET and SMT methods were effective in balance control in NSCLBP patients and postural control was more affected by CST.

Multi-Exergames to Set Targets and Supplement the Intensified Conventional Balance Training in Patients With Stroke: A Randomized Pilot Trial

People who survive a stroke usually suffer movement disorders resulting in involuntary abnormal movements. Intensive and repetitive physiotherapy is often a key to functional restoration of movements. Rehabilitation centers have recently offered balance training supported by exergames in addition to conventional therapy. The primary objective was to investigate different types of balance training (multi-exergaming and conventional) in addition to a conventional 6-week physiotherapy program. Furthermore, we examined the choice of an appropriate exergame to target balance training. We designed a randomized pilot trial. Hospital inpatients with stroke aged 33–65 were recruited and randomized into 2 groups by drawing lots; a control group receiving 1 week of conventional balance training and an exergaming group 1 week of multiple-game exergaming, comprising single leg exercises, weight shifting, balancing and standing up. Center of pressure was monitored for the exergaming group and clinical data were collected (non-blinded assessment) using Four Square Step Test, Timed Up and Go, 10 m Walk Test, Romberg, Sharpened Romberg, Clinical Test for Sensory Interaction in Balance in both groups. Statistical tests were used to find significant (p < 0.05) differences and Cohen’s U3 for effect sizes. Recruited participants (20/30) met the inclusion criteria and were randomized; 10 per group. 1 participant of the exergaming group was excluded from center of pressure analysis. Both groups demonstrated substantively and statistically significant improvements of functional balance, in particular the exergaming group (FSST p = 0.009, U3 = 0.9 and 10 MWT p = 0.008, U3 = 0.9). However, significant differences between the groups were found in tests with eyes closed, Sharpened Romberg test (p = 0.05) and standing on the right leg (p = 0.035). The center of pressure area decreased up to 20% for the exergaming group. Both types of additional balance training demonstrated comparable outcomes, however, the multi-exergaming could target specific motor control disorders by the selection of exergames according to Gentile’s taxonomy. We may not prioritize exergaming due to the low statistical power of clinical outcomes. However, exergaming enables independent balance training, which is feasible without strenuous physiotherapy and may thus be crucial for future home or telerehabilitation services.

Clinical Trial Registration:www.clinicaltrials.gov/, identifier NCT03282968.

Are Accelerometer-based Functional Outcome Assessments Feasible and Valid After Treatment for Lower Extremity Sarcomas?

BACKGROUND

Aspects of physical functioning, including balance and gait, are affected after surgery for lower limb musculoskeletal tumors. These are not routinely measured but likely are related to how well patients function after resection or amputation for a bone or soft tissue sarcoma. Small, inexpensive portable accelerometers are available that might be clinically useful to assess balance and gait in these patients, but they have not been well studied.

QUESTIONS/PURPOSES

In patients treated for lower extremity musculoskeletal tumors, we asked: (1) Are accelerometer-based body-worn monitor assessments of balance, gait, and timed up-and-go tests (TUG) feasible and acceptable? (2) Do these accelerometer-based body-worn monitor assessments produce clinically useful data (face validity), distinguish between patients and controls (discriminant validity), reflect findings obtained using existing clinical measures (convergent validity) and standard manual techniques in clinic (concurrent validity)?

METHODS

This was a prospective cross-sectional study. Out of 97 patients approached, 34 adult patients treated for tumors in the femur/thigh (19), pelvis/hip (3), tibia/leg (9), or ankle/foot (3) were included in this study. Twenty-seven had limb-sparing surgery and seven underwent amputation. Patients performed standard activities while wearing a body-worn monitor on the lower back, including standing, walking, and TUG tests. Summary measures of balance (area [ellipsis], magnitude [root mean square {RMS}], jerkiness [jerk], frequency of postural sway below which 95% of power of acceleration power spectrum is observed [f95 of postural sway]), gait [temporal outcomes, step length and velocity], and TUG time were derived. Body-worn monitor assessments were evaluated for feasibility by investigating data loss and patient-reported acceptability and comfort. In addition, outcomes in patients were compared with datasets of healthy participants collected in parallel studies using identical methods as in this study to assess discriminant validity. Body-worn monitor assessments were also investigated for their relationships with routine clinical scales (the Musculoskeletal Tumour Society Scoring system [MSTS], the Toronto Extremity Salvage Score [TESS], and the Quality of life-Cancer survivors [QoL-CS)] to assess convergent validity and their agreement with standard manual techniques (video and stopwatch) to assess concurrent validity.

RESULTS

Although this was a small patient group, there were initial indications that body-worn monitor assessments were well-tolerated, feasible to perform, acceptable to patients who responded (95% [19 of 20] of patients found the body-worn monitor acceptable and comfortable and 85% [17 of 20] found it user-friendly), and produced clinically useful data comparable with the evidence. Balance and gait measures distinguished patients and controls (discriminant validity), for instance balance outcome (ellipsis) in patients (0.0475 m/s [95% confidence interval 0.0251 to 0.0810]) was affected compared with controls (0.0007 m/s [95% CI 0.0003 to 0.0502]; p = 0.001). Similarly gait outcome (step time) was affected in patients (0.483 seconds [95% CI 0.451 to 0.512]) compared with controls (0.541 seconds [95% CI 0.496 to 0.573]; p < 0.001). Moreover, body-worn monitor assessments showed relationships with existing clinical scales (convergent validity), for instance ellipsis with MSTS (r = -0.393; p = 0.024). Similarly, manual techniques showed excellent agreement with body-worn monitor assessments (concurrent validity), for instance stopwatch time 22.28 +/- 6.93 seconds with iTUG time 21.18 +/- 6.23 seconds (intraclass correlation coefficient agreement = 0.933; p < 0.001). P < 0.05 was considered statistically significant.

CONCLUSIONS

Although we had a small, heterogeneous patient population, this pilot study suggests that body-worn monitors might be useful clinically to quantify physical functioning in patients treated for lower extremity tumors. Balance and gait relate to disability and quality of life. These measurements could provide clinicians with useful novel information on balance and gait, which in turn could guide rehabilitation strategies.

LEVEL OF EVIDENCE

Level III, diagnostic study.

Number of Trials Needed to Assess Postural Control of Young Adults in Single and Dual-Task

Despite its popularity, there is a lack of standardization when assessing postural control. This study aimed to suggest how many trials should be used when assessing young adults' postural control with a specific single-task and dual-task quiet stance protocol. Two groups of 15 participants performed 20 trials of 60 s (feet together, eyes open) with or without a dual-task. The number of trials needed to obtain two consecutive intra-class correlation coefficients (ICC(2,k)) ≥0.900 was then assessed for seven center of pressure variables. Although inconsistency was observed between variables and tasks, five trials seems to be a good compromise.

Evaluation of Langevin Model for Human Stabilogram Based on Reproducibility of Statistical Indicators

Fall risk is a serious problem especially for the elderly. Fall accident causes fracture, and it leads to bedridden. Early detection of balance inability and rehabilitation training is important to decrease the risk. Quiet standing test is one of the physical tests to assess the balance inability of human. When the human is standing, he/she controls the plantar force to keep the balance. Center of pressure (COP) is the representative parameter to explain the plantar force movement. During the quiet standing test, COP fluctuates unconsciously. There are many researches that analyze the relationship between the COP fluctuation and balance inability. Many statistical indicators have been developed to assess the fluctuation specification.In contrast, several researchers have been tried to reveal the COP fluctuation mechanism by introducing stochastic mathematical model. Ornstein-Uhlenbeck process and diffusion equation are often introduced to the model. The mathematical models have been developed, and analyzed how visual input is related to the model parameters. If the mathematical model can explain the COP fluctuation completely, it becomes easier to assess the balance ability by comparing the model parameters.However, statistical indicators are still used in the clinical cases, thus there is room to discuss which statistical indicators to be used for assessment. The purpose of this research is to explore the relationship between statistical indicators and numerical model by evaluating whether the numerical model reproduces the same values with real data. The reproduced indicators and original indicators are compared, and the magnitude of the errors are evaluated.

Reliability of centre of pressure, plantar pressure, and plantar-flexion isometric strength measures: A systematic review

BACKGROUND

Centre of pressure (COP), plantar pressure (PP), and plantar-flexion isometric strength (PF_isom) are often examined in relation to postural control and gait.

RESEARCH QUESTION

Our aim was to systematically review and quality appraise articles addressing the reliability of COP and PP measures in static stance and PF_isom measures.

METHODS

Three electronic databases (SCOPUS®, SportDISCUS™, and PubMed) were searched and supplemented by a manual search. Peer-reviewed original research on the reliability of COP, PP, and PF_isom in healthy adults (≥18 years) was included. Quality appraisal was done according to the updated COnsensus-based Standards for the selection of health Measurement INstruments reliability checklist. Data regarding study characteristics, test protocols, outcome measures, and reliability metrics were extracted.

RESULTS

Forty articles met inclusion and were assessed for their methodological quality. Only four articles (10%) obtained uppermost quality scores. From the reviewed studies, the most reliable measures were: COP sway area and path length; PP mean pressure, percentage body weight distribution, and contact area; and PF_isom peak torque and force. Although these measures generally exhibited good-to-excellent relative reliability based on correlation coefficients, absolute reliability based on typical errors were not always optimal (variation > 10%). Literature on PP reliability was scarce (n = 2).

SIGNIFICANCE

Our findings highlight the need for better quality methodological reliability studies to be undertaken to make stronger inferences about the reliability of COP, PP, and PF_isom measures. The most reliable measures based on the current review are: COP sway area and path length; PP mean pressure, percentage of body weight distribution, and contact area; and PF_isom peak torque and peak force. These measures are the ones that should be selected preferentially in clinical settings, bearing in mind that their typical errors might be suboptimal despite exhibiting strong relative reliability.

Stumbling prediction based on plantar pressure distribution

BACKGROUND

Stumbles are common accidents that can result in falls and serious injuries, particularly in the workplace where back and forth movements are involved and in offices where high heels are imperative. Currently, the characteristics of plantar pressure during a stumble and the differences between stumbling and a normal gait remain unclear.

OBJECTIVE

This paper is aimed at providing insights into the feasibility of the data mining technique for interventions in stumble-related occupational safety issues.

METHODS

The characteristics of plantar pressure distribution during stumbling and normal gait were analyzed by using the power spectrum density (PSD) and the Support Vector Machine (SVM). The PSD, a novel pattern recognition feature, was used to mathematically describe the image signal. The SVM, a powerful data mining technique, was used as the classifier to recognize a stumble. Dynamic plantar pressures were measured from twelve healthy participants as they walked.

RESULTS

The plantar pressures of the stumbling gaits had significantly different patterns compared to the normal ones, from either a qualitative or quantitative perspective. The mean recognition accuracy of the proposed method reached 96.7%.

CONCLUSIONS

This study helps better understand stumbles and provides a theoretical basis for stumble-related occupational injuries. In addition, the stumble is the precursor of a fall and the research on stumble recognition would be of value to predict and provide warnings of falls and to design anti-fall devices for potential victims.

Influence of Textured Indoor Footwear on Posture Stability of Older Women Based on Center-of-Pressure Measurements

OBJECTIVE

The objective of this study is to evaluate the efficacy of indoor footwear with a textured surface to improve control of balance and reduce excessive plantar pressure in older women.

BACKGROUND

Balance instability is a common condition in older people. Textured insoles with protrusions on the entire insole have been examined for enhancing somatosensory feedback in the elderly to improve control over balance. However, these insoles have significant challenges in distributing the plantar pressure. Textured insoles with tailored protrusions should be therefore investigated for the same purpose but provide better plantar pressure distribution.

METHOD

A total of 24 older women have undergone both static standing and walking tests with the use of the in-shoe Pedar® system.

RESULTS

The results indicate that wearing textured indoor footwear provides a significant reduction in postural sway, particularly in the medial-lateral direction during walking. As compared to walking barefoot, the center-of-pressure trajectory when wearing the textured indoor footwear remains supported with less variance among the steps, which is statistically significant in the medial-lateral direction. A significant reduction in the peak pressure is found in the forefoot and rearfoot regions as the plantar pressure is redistributed to the midfoot regions.

CONCLUSION

The textured surface of the insole improves balance control of older women and effectively reduces foot pressure at high pressure areas.

APPLICATION

The findings enhance current understanding on textured footwear as a form of intervention associated with changes in functional impairments, therefore providing basis for footwear design in balance control.

Trunk velocity-dependent Light Touch reduces postural sway during standing

Light Touch (LT) has been shown to reduce postural sway in a wide range of populations. While LT is believed to provide additional sensory information for balance modulation, the nature of this information and its specific effect on balance are yet unclear. In order to better understand LT and to potentially harness its advantages for a practical balance aid, we investigated the effect of LT as provided by a haptic robot. Postural sway during standing balance was reduced when the LT force (~ 1 N) applied to the high back area was dependent on the trunk velocity. Additional information on trunk position, provided through orthogonal vibrations, further reduced the sway position-metric of balance but did not further improve the velocity-metric of balance. Our results suggest that limited and noisy information on trunk velocity encoded in LT is sufficient to influence standing balance.

Abnormal trunk control determines postural abnormalities in Amyotrophic Lateral Sclerosis

BACKGROUND:

Postural instability in Amyotrophic Lateral Sclerosis (ALS) occurs at an early stage of the disease and often results in falls. As ALS is considered a multisystem neurodegenerative disorder, postural instability may result from motor, sensory and central processing deficits.

OBJECTIVE AND METHODS:

We analysed postural control of 12 ALS patients and 12 healthy age-matched control subjects. Postural control was characterised by spontaneous sway measures and measures of postural reactions to pseudorandom anterior-posterior platform tilts, which were then correlated with clinical test scores.

RESULTS:

Spontaneous sway amplitudes and velocities were significantly larger and sway frequencies higher in ALS patients than in control subjects. ALS patients’ body excursions following platform tilts were smaller, with relatively higher upper body excursions. We found high correlations between abnormal postural reactions and clinical tests representing motor or balance deficits.

CONCLUSIONS:

We conclude that ALS patients’ postural abnormalities are mainly determined by an abnormal axial control and abnormally small body excursions as a function of support surface tilts, seemingly indicating better postural stabilization than control subjects. The latter contradicts the hypothesis that muscle weakness is the main source for this deficit. Instead, we suggest an altered central control strategy.

How many balance task trials are needed to accurately assess postural control measures in older women?

Taking the average of different trials is recommended for better balance assessment, but few studies have really proven this point under different balance conditions.

OBJECTIVE

To assess the effects of averaging trials of five different balance tasks on postural control measures in older women.

METHODS

A total of 90 older women (means: Age: 68 years; Weight: 67 kg; Height: 1.56 m; Body mass index, 27 kg/m²) participated in this study. The participants completed five balance tasks with three performance trials for each task on a force platform in random order. The participants completed a total of three 30-s trials of tasks with 30 s of rest between trials. Repeated measure ANOVA and coefficient of variation were computed to compare differences for one trial vs. averaging across two or three trials on center of pressure (COP) sway values.

RESULTS

There were no significant differences (P > 0.05) in COP sway values when comparing one vs. the average of two or three trials for all balance tasks. However, the coefficient of variation was higher for three trials (10-40%) than two (6-37%) or one trial (3-23%) for COP parameters.

CONCLUSIONS

Based on reduction of variability, the present study recommends the averaging of a minimum of two trials for balance assessment in older women. The results of the current study have implications for balance assessment in older people in fall prevention programs.

Can Postural Instability in Individuals with Distal Radius Fractures Be Alleviated by Concurrent Cognitive Tasks?

BACKGROUND

Although impaired postural control may be a risk factor for distal radius fractures (wrist fractures), which often are caused by falls, little attention has been given thus far to the various performance and neurophysiologic aspects involved. Although studies suggest that external focus and cognitive tasks can improve postural control, it remains unclear whether these benefits are observed in individuals with a history of distal radius fracture and to what extent.

QUESTIONS/PURPOSES

(1) To compare patients with a history of distal radius fracture to age- and sex-matched controls in terms of postural stability while standing on stable and unstable support surfaces, using both postural sway and neurophysiological measures as endpoints; and (2) to determine whether internal- and external-focus strategies and cognitive tasks can improve postural stability in these patients.

METHODS

Forty patients with distal radius fracture (33 females and seven males with a mean ± SD age of 56 ± 4 years) and 40 sex- and age-matched control participants participated in the study. We recruited patients with a history of fall-induced distal radius fractures occurring between 6 and 24 months before the start of our study. We excluded patients who had any of the following: fear of falling, taking any medication that may affect balance, neurologic disorders, dizziness, vestibular problems, Type II diabetes, musculoskeletal disorders or recent history of lower extremity fracture, any recent surgical interventions in the spine or lower limbs, and/or cognitive impairment. Of 120 patients who were being treated for distal radius fracture over the 18-month period, 91 (76%) agreed to participate and 40 eligible patients were finally enrolled. The control group included sex- and age-matched (within 2-year intervals) individuals who had never had a wrist fracture. This group was selected from attendants/relatives of the patients attending the neurology and physical medicine and rehabilitation outpatient departments, as well as other volunteers with no history of balance problems or wrist fractures. To address our primary research question, we compared the postural control of individuals with a history of distal radius fracture with the control group while quietly standing on different support surfaces (rigid and foam surfaces) using both postural sway measures obtained by a force plate as well as neurophysiological measures (electromyography [EMG] activity of tibialis anterior and medial gastrocnemius). To address our secondary research question, we compared the postural sway measures and EMG activity of the ankle muscles between different experimental conditions (baseline, internal focus (mentally focusing on their feet without looking), external focus (mentally focusing on rectangular papers, placed on the force plate or foam, one under each foot), difficult cognitive task (recalling maximum backward digits plus one) and easy cognitive task (recalling half of the maximum backward digits).

RESULTS

Patients with distal radius fractures presented with greater postural sway (postural instability) and enhanced ankle muscle activity compared with their control counterparts, but only while standing on a foam surface (mean velocity: 5.4 ± 0.8 versus 4.80 ± 0.5 [mean difference = 0.59, 95% CI of difference, 0.44-0.73; p < 0.001]; EMG root mean square of the tibialis anterior: 52.2 ± 9.4 versus 39.30 ± 6 [mean difference = 12.9, 95% CI of difference, 11.4-14.5; p < 0.001]). Furthermore, a decrease in postural sway was observed while standing on both rigid and foam surfaces during the external focus, easy cognitive, and difficult cognitive conditions compared with the baseline (for example, mean velocity in the baseline condition compared with external focus, easy cognitive task and difficult cognitive task was: 4.9 ± 1.1 vs 4.7 ± 1 [mean difference = 0.14, 95% CI of difference, 0.11-0.17; p < 0.001], 4.6 ± 1 [mean difference = 0.25, 95% CI of difference, 0.21-0.29; p < 0.001], and 4.5 ± 1 [mean difference = 0.34, 95% CI of difference, 0.29-0.40; p < 0.001] in the wrist fracture group). The same result was obtained for muscle activity while standing on foam (EMG root mean square of tibialis anterior in the baseline condition compared with external focus, easy cognitive task and difficult cognitive task: 58.8 ± 7.2 versus 52.3 ± 6.6 [mean difference = 6.5, 95% CI of difference, 5.5-7.6; p < 0.001], 48.8 ± 7.1 [mean difference = 10.1, 95% CI of difference, 9-11.1; p < 0.001], 42.2 ± 5.3 [mean difference = 16.7 95% CI of difference, 15.1-18.2; p < 0.001] in the wrist fracture group).

CONCLUSIONS

The current results suggest that patients with a history of distal radius fractures have postural instability while standing on unstable support surfaces. This instability, which is associated with enhanced ankle muscle activity, conceivably signifying an inefficient cautious mode of postural control, is alleviated by external attention demands and concurrent cognitive tasks.

CLINICAL RELEVANCE

The findings of this study may serve as a basis for designing informed patient-specific balance rehabilitation programs and strategies to improve stability and minimize falls in patients with distal radius fractures. The integrative methodology presented in this work can be extended to postural control and balance assessment for various orthopaedic/neurological conditions.

Standard reference values of the postural control in healthy young female adults in Germany: an observational study

OBJECTIVE

Many people of all ages suffer from vertigo due to different reasons. The comparison of patient data with standard values can highlight deteriorations or changes in postural control and thus indicate, for example, an increased risk of falling. Our aim is to measure standard values for the postural control of young healthy women.

DESIGN

Observational study.

SETTING

Institute of Occupational Medicine, Social Medicine and Environmental Medicine, Goethe-University Frankfurt/Main.

PARTICIPANTS

106 healthy German female subjects aged between 21 and 30 years (25±2.7 years) were measured. Their average body mass index (BMI) was 21.1±2.61 kg/m².

OUTCOME MEASURES

A pressure measuring platform was used to measure the weight distribution and postural sway in habitual standing. Median, tolerance range and CI were calculated.

RESULTS

Height, weight and BMI are comparable to the average young German female population. The load distribution between right and left foot was 49.91%:50.09%. The forefoot was less loaded than the rear foot (33.3%:66.67%). The right rear foot carried most of the body weight (34.34%). The average body sway was 9.50 mm in the frontal and 13.00 mm in the sagittal plane.

CONCLUSIONS

Standard values for the postural control of the women aged 21-30 years correlate with the already collected data of healthy subjects and can therefore be described as representative. The standard values enable diagnosing and treating impaired balance.

Alterations in Cortical Activation Among Individuals With Chronic Ankle Instability During Single-Limb Postural Control

CONTEXT

Chronic ankle instability (CAI) is characterized by repetitive ankle sprains and perceived instability. Whereas the underlying cause of CAI is disputed, alterations in cortical motor functioning may contribute to the perceived dysfunction.

OBJECTIVE

To assess differences in cortical activity during single-limb stance among control, coper, and CAI groups.

DESIGN

Cross-sectional study.

SETTING

Biomechanics laboratory.

PATIENTS OR OTHER PARTICIPANTS

A total of 31 individuals (10 men, 21 women; age = 22.3 ± 2.4 years, height = 169.6 ± 9.7 cm, mass = 70.6 ± 11.6 kg), who were classified into control (n = 13), coper (n = 7), and CAI (n = 11) groups participated in this study.

INTERVENTION(S)

Participants performed single-limb stance on a force platform for 60 seconds while wearing a 24-channel functional near-infrared spectroscopy system. Oxyhemoglobin (HbO2) changes in the supplementary motor area (SMA), precentral gyrus, postcentral gyrus, and superior parietal lobe were measured.

MAIN OUTCOME MEASURE(S)

Differences in averages and standard deviations of HbO2 were assessed across groups. In the CAI group, correlations were analyzed between measures of cortical activation and Cumberland Ankle Instability Tool (CAIT) scores.

RESULTS

No differences in average HbO2 were present for any cortical areas. We observed differences in the standard deviation for the SMA across groups; specifically, the CAI group demonstrated greater variability than the control (r = 0.395, P = .02; 95% confidence interval = 0.34, 0.67) and coper (r = 0.38, P = .04; 95% confidence interval = -0.05, 0.69) groups. We demonstrated a strong correlation that was significant in the CAI group between the CAIT score and the average HbO2 of the precentral gyrus (ρ = 0.64, P = .02) and a strong correlation that was not significant between the CAIT score and the average HbO2 of the SMA (ρ = 0.52, P = .06).

CONCLUSIONS

The CAI group displayed large differences in SMA cortical-activation variability. Greater variations in cortical activation may be necessary for similar static postural-control outcomes among individuals with CAI. Consequently, variations in cortical activation for these areas provide evidence for an altered neural mechanism of postural control among populations with CAI.

The effect of cervical spine subtypes on center of pressure parameters in a large asymptomatic young adult population

BACKGROUND

Recent research highlighted that non-lordotic subtypes are common within an asymptomatic population of young adults. The potential mechanisms responsible for the decreased postural control witnessed in healthy participants exhibiting non-lordotic cervical alignment are unclear.

RESEARCH QUESTION

Therefore, the aim of this study is to compare and contrast asymptomatic radiographically derived sagittal cervical alignment subtypes with Center of Pressure (CoP) parameters.

METHODS

In this cross-sectional study strict asymptomatic inclusion criteria were met by 150 of the original 182 volunteers. All radiographs were assessed using a multi-method subtype system with participants classified into lordotic and non-lordotic groups. Participants performed 90s narrow stance trials with their eyes closed whilst standing on both a firm surface (FS) and compliant surface (CS) (3 trials per surface). CoP parameters were recorded from a force platform sampling at 100 Hz. Nonparametric statistical tests were conducted to assess differences between groups for each surface type and to determine differences in CoP parameters between FS and CS types.

RESULTS

Significant differences were found between groups on both surfaces for the anterior to posterior range (FS: p = 0.013; CS: p = 0.023), total excursion (FS: p = 0.029; CS: p = 0.005) and mean velocity of total excursion (FS: p = 0.032; CS: p = 0.004).

SIGNIFICANCE

Our data suggest that sagittal plane cervical alignment is a measure capable of distinguishing between the postural control of asymptomatic lordotic and non-lordotic young adult participants on both surfaces types. Furthermore, decreased postural control is present in asymptomatic participants across all non-lordotic subtypes and is not isolated exclusively to those with forward head posture. Consequently, future research endeavours should investigate the clinical significance of these non-lordotic findings in relation to both the potential for early cervical osseous degeneration and the transitional stages of non-specific pain sufferers from previously asymptomatic young adults.

Smartphone technology can measure postural stability and discriminate fall risk in older adults

BACKGROUND

Falls are the leading cause of injury related death in older adults. Impaired postural stability is a predictor of falls but is seldom objectively assessed in clinical or home settings. Embedded accelerometers within smartphones offer potential to objectively measure postural stability. The purpose of this study was to determine if a smartphone embedded accelerometer can measure static postural stability and distinguish older adults at high levels of fall risk.

METHODS

Thirty older adults (age: 65.9 ± 8.8) underwent seven balance tests while standing on a force plate and holding a smartphone against their chest in a standardized order. Participants also completed the Physiological Profile Assessment to assess their fall risk. Center of pressure (COP) parameters from the force plate including velocity in the anterioposterior (AP) and mediolateral (ML) directions and 95% confidence ellipse were derived. Maximum acceleration and root mean square (RMS) in ML, AP and vertical axes were derived from the smartphone. Spearman rank-order correlations between force plate and smartphone measures were conducted, and receiver operating characteristic (ROC) and the area under the curves (AUC) were constructed to distinguish between low and high fall risk.

RESULTS

There were moderate to strong significant correlations between measures derived from the force plate and measures derived from the smartphone during challenging balance conditions (ρ = 0.42-0.81; p < 0.01-0.05). The AUC for ROC plots were significant for all COP measures during challenging balance conditions (p < 0.01-0.05). The AUC for ROC plots were significant for RMS vertical and AP during challenging balance conditions (p = 0.01-0.04).

SIGNIFICANCE

This study provides evidence that a smartphone is a valid measure of postural stability and capable of distinguishing fall risk stratification in older adults. There is potential for smartphones to offer objective, fall risk assessments for older adults.

Effects of DanceSport on walking balance and standing balance among the elderly

BACKGROUND:

Dancesport is a popular activity among older adults who look for fun and fitness in Korea. Studies reported positive sociological and psychological effects of dancesport. But, little studies were performed to evaluate the effects of dancesport on balance performances.

OBJECTIVE:

The objective of the present study was to evaluate the effects of dancesport for 15 weeks on walking balance and standing balance of older adults.

METHODS:

Older adults regularly participated in the dancesport program 3 times a week for 15 weeks. The program included Rumba, Cha-cha-cha, and Jive. They exercised the prescribed dancesport at intermediate level for 50–60 mins for each time. A total 22 reflective markers were placed on the anatomical landmarks and 8 cameras were used to measure 3-D positions of participants. Also, center of pressure (COP) data were measured to analyze standing balance using a ground reaction board at 1200 Hz for 30 seconds. One-way analysis of variance (ANOVA) was performed to test the effects of 15 weeks of dancesport on walking balance and standing balance.

RESULTS:

The results suggested that, after 15 weeks of dancesport participation, older adults’ walking balance (48.3 ± 20.3 cm2 vs 38.2 ± 18.2 cm2) and standing balance (COP area: 189.4 ± 85.4 mm2 vs 103.5 ± 55.4mm2, COP distance: 84.2 ± 34.4 cm vs 76.5 ± 21.4 cm) were significantly improved.

CONCLUSION:

Performing dancesport would require moving center of mass rapidly and frequently while maintaining posture. This may result in improving walking balance and standing balance in the present study. The study concluded that dancesport would be an effective exercise method in enhancing postural stability of older adults.