A comparison of the efficacy of textured insoles on balance performance in older people with versus without plantar callosities

BackgroundTextured insoles have been suggested to enhance foot sensation, which contributes to controlling upright balance. However, the interaction between plantar callosity and the textured surface has not been studied.Research questionFirstly, to compare the efficacy of textured insoles on balance performance and foot position sense between two groups of older people: one group had plantar callosity, and the other did not. Secondly, to investigate the efficacy of textured insoles within each study group.MethodsThirty older people with a history of falls (15 with plantar callosity and 15 without callosity) participated in this study. All participants underwent assessments of postural sway on a force plate, joint position sensation of the ankle with a slope box, and mobility using the "Timed Up and Go" test under three insole surface conditions: 1) smooth (control), 2) placebo and 3) textured surface. Two-way analyses of variance were used to compare the outcomes of the two groups and three conditions.ResultsOlder people with plantar callosity had worse ankle joint position sense and slower antero-posterior and mediolateral postural sway velocity than their peers who did not have plantar callosity. The textured insoles improved ankle joint position sense and mobility regardless of callus status in the plantar surface of older peoples’ feet. The insole-callosity interaction was not significant for any study outcome.SignificanceTextured insoles could be beneficial to older people with and without callosity as they have shown immediate improvements in ankle joint position sense and mobility.     

Intrinsic foot muscles act to stabilise the foot when greater fluctuations in centre of pressure movement result from increased postural balance challenge

BackgroundIncreased postural balance challenge is associated with more fluctuations in centre of pressure movement, indicating increased interference from the postural control system. The role of intrinsic foot muscles in balance control is relatively understudied and whether such control system interference occurs at the level of these muscles is unknown.Research QuestionDo fewer fluctuations in intrinsic foot muscle excitation occur in response to increased postural balance challenge?MethodsSurface EMGs were recorded using a grid of 13 × 5 channels from the plantar surface of the foot of 17 participants, who completed three balance tasks: bipedal stance; single leg stance and bipedal tip-toe. Centre of pressure (CoP) movement was calculated from simultaneously recorded force plate signals. Fluctuations in CoP and EMGs for each task were quantified using a sample entropy based metric, Entropy Halflife (EnHL). Longer EnHL indicates fewer signal fluctuations.ResultsThe shortest EMG EnHL, 9.27 ± 3.34 ms (median ± interquartile range), occurred during bipedal stance and the longest during bipedal tip-toe 15.46 ± 11.16 ms, with 18.80 ± 8.00 ms recorded for single leg stance. Differences were statistically significant between bipedal stance and both bipedal tip-toe (p < 0.001) and single leg stance (p < 0.001). CoP EnHL for both anterior-posterior and medial-lateral movements also differed significantly between tasks (p < 0.001, both cases). However, anterior-posterior CoP EnHL was longest for bipedal stance 259.84±230.22 ms and shortest for bipedal tip-toe 146.25±73.35 ms. Medial-lateral CoP EnHL was also longest during bipedal stance 215.73±187.58 ms, but shortest for single leg stance 113.48±83.01 ms.SignificanceFewer fluctuations in intrinsic foot muscle excitation occur in response to increased postural balance challenge. Fluctuations in CoP movement during balance must be predominantly driven by excitation of muscles extrinsic to the foot. Intrinsic foot muscles therefore likely play a greater role in stabilisation of the foot than balance control during the postural tasks studied.     

Age- and low back pain-related differences in trunk muscle activation during one-legged stance balance task

BackgroundPostural control declines with age and can be affected by low back pain. Poor balance has been reported in people with chronic low back pain (CLBP), which in turn could be explained by the changes in trunk muscle activation.Research QuestionAre there differences between younger and older adults with and without chronic low back pain (CLBP) on trunk muscle activity during one-legged stance task?MethodsTwenty (20) with, and 20 subjects without nonspecific CLBP participated in the study. Each group was comprised of 10 younger (50% males; mean age: 31 years) and 10 older adults (50% males; mean age: 71 years). Subjects performed 3 × 30-second trials of one-legged stance, with eyes open, on a force platform, while surface electromyography (EMG) measurements were obtained bilaterally on the multifidus at L5, iliocostalis lumborum at L3, rectus abdominis and biceps femoris muscles.EMG amplitude analysis was processed by the Root Mean Square (250 ms window epochs) and normalized by the peak of activation during the balance tasks, to determine the muscular activity of each muscle.ResultsParticipants with CLBP presented 15% lower lumbar muscle activation (p < 0.05), and 23% higher co-activation (ratio between rectus adominis by multifidus) than participants without CLBP, regardless of age. Significant differences (p < 0.05) between older and young groups were observed only for lower lumbar muscles (mean 24% lower in older than younger adults) and rectus adominis muscles (mean 17% lower in older than younger adults).SignificanceCLBP individuals have different trunk muscle activity than those without CLBP, and older adults exhibit lower trunk activation during one-legged stance balance task. The use of the EMG in evaluation of trunk neuromuscular function during one-legged stance may thus be a valuable tool when assessing balance in CLBP and older people.     

Comparison of muscle torque, balance, and confidence in older tai chi and healthy adults

PURPOSE: The objectives of this cross-sectional study were to examine whether older Tai Chi practitioners had better knee muscle strength, less body sway in perturbed single-leg stance, and greater balance confidence than healthy older adults. METHODS: Tai Chi and control subjects (N = 24 each, aged 69.3 +/- 5.0 and 71.6 +/- 6.1 yr, respectively) were matched with respect to age, gender, height, weight, and physical activity level. Concentric and eccentric isokinetic tests of the subjects" dominant knee extensors and flexors were conducted at an angular velocity of 30 degrees.s(-1). Control of body sway was assessed in static double-leg stance and in single-leg stance perturbed by forward or backward platform perturbations. The Activities-specific Balance Confidence (ABC) scale was used to investigate subjects" balance confidence in daily activities. RESULTS: Tai Chi practitioners had higher peak torque-to-body weight ratios in concentric and eccentric isokinetic contractions of their knee extensors and flexors (P = 0.044). They manifested less anteroposterior body sway angles in perturbed single-leg but not static double-leg stance than did control subjects (P < 0.001). Tai Chi practitioners also reported significantly higher balance confidence score ratios (P = 0.001). Older adults" knee muscle strengths showed negative correlations with body sway angles in perturbed single-leg stance and positive correlations with ABC score ratios. Moreover, their body sway angles in perturbed single-leg stance were negatively correlated with their ABC score ratios (all P < 0.05). CONCLUSION: Our results demonstrate that long-term Tai Chi practitioners had better knee muscle strength, less body sway in perturbed single-leg stance, and greater balance confidence. Significant correlations among these three measures uncover the importance of knee muscle strength and balance control during perturbed single-leg stance in older adults" balance confidence in their daily activities.     

Effects of assistive devices on postural control following a balance disturbance along the anterior-posterior direction

BackgroundAssistive devices provide balance and stability to those who require a greater base of support, especially during ambulation or in tasks essential to functional daily living. In ambulatory assistive device use, center of pressure (COP) movement as one of the measurements of postural control is a factor when assessing fall risk, with an overall goal of maintaining postural equilibrium. There is a lack of research on assistive devices, such as walkers, regarding measurable outcome variables related to fall risk. The purpose of this study was to determine how much the postural control in single limb stance during a balance perturbance is affected by utilizing three different walker types designed to promote stability: the standard walker, the front-wheeled walker with straight wheels and the front-wheeled walker with caster wheels.Research questionIs postural sway control in single limb stance during a balance perturbance affected by walker type?MethodsTwenty-three healthy adults participated and gave consent. The NeuroCom® SMART EquiTest® system was utilized to simulate forward falls. Subjects stood on the system’s force plate, which was tipped backwards quickly, forcing subjects to attempt to maintain balance. Each participant experienced 18 simulated perturbations, during which they were asked to maintain balance while using one of three walkers in single-limb stance. Each trial was completed using random assignment of three different walker types. Leg dominance of the stance leg was also randomized for each trial.ResultsThe type of walker and the leg dominance in the standing limb significantly affected postural control in a balance perturbance in the A-P direction. The walker type significantly affected the COP maximum displacement in anterior-posterior (AP) direction. However, the leg dominance significantly affected COP maximum displacement in AP and medio-lateral (ML) directions and COP velocity in AP direction.SignificanceThe findings suggest that when fully grounded, a standard walker is more stable than the front-wheeled walker. However, this does not indicate that the standard walker is more stable than other types of walkers when it is being picked up and moved forward during normal use.     

Postural stabilization after single-leg vertical jump in individuals with chronic ankle instability

ObjectivesTo investigate the impact different ways to define reference balance can have when analysing time to stabilization (TTS). Secondarily, to investigate the difference in TTS between people with chronic ankle instability (CAI) and healthy controls.DesignCross-sectional study.SettingLaboratory.ParticipantsFifty recreational athletes (25 CAI, 25 controls).Main outcome measuresTTS of the center of pressure (CoP) after maximal single-leg vertical jump using as reference method the single-leg stance, pre-jump period, and post-jump period; and the CoP variability during the reference methods.ResultsThe post-jump reference period had lower values for TTS in the anterior-posterior (AP) direction when compared to single-leg stance (P = 0.001) and to pre-jump (P = 0.002). For TTS in the medio-lateral (ML) direction, the post-jump reference period showed lower TTS when compared to single-leg stance (P = 0.01). We found no difference between CAI and control group for TTS for any direction. The CAI group showed more CoP variability than control group in the single-leg stance reference period for both directions.ConclusionsDifferent reference periods will produce different results for TTS. There is no difference in TTS after a maximum vertical jump between groups. People with CAI have more CoP variability in both directions during single-leg stance.     

Contribution of calf muscle-tendon properties to single-leg stance ability in the absence of visual feedback in relation to ageing

We tested the hypothesis that the importance of calf muscle-tendon properties for maintaining balance during single-leg stance increases in the absence of visual feedback. Trial duration, centre of pressure displacement normalized for trial duration (nD), electromyographic (EMG) activity of the main ankle plantarflexors and dorsiflexors, and ground reaction forces (F(P)), were measured in 20 younger (aged 18+/-1 years; mean+/-S.E.M.) and 28 older (aged 68+/-1 years) healthy participants during single-leg stance in eyes-open (EO) and eyes-closed (EC) conditions. Plantarflexor muscle strength, activation capacity and tendon stiffness were assessed by dynamometry, electrical stimulation and ultrasonography, respectively. Muscle-tendon characteristics in the older participants were up to 55% (P<0.0001) lower compared with their younger counterparts. Trial duration, F(P), nD and EMG changed in EC compared with EO by 21% and up to approximately 4.6 times (P<0.01) in the two population groups. Multiple linear regression with age and the three muscle-tendon properties showed a substantial increment in EC compared to EO for trial duration (R(2)=0.86 versus R(2)=0.72), but a similarity for nD (R(2)=0.36 versus R(2)=0.33). These results suggest that factors other than the ones that we examined become important when steadiness rather than stance duration is the object of single-leg stance in the absence of vision.     

Perceptual distortion in virtual reality and its impact on dynamic postural control

BackgroundVoluntary movement such as lifting a foot in preparation to stepping acts as a self-initiated perturbation that disturbs postural equilibrium. To maintain and restore equilibrium, humans utilize early, anticipatory, and compensatory postural adjustments. Despite technological progress in accessible virtual reality (VR) devices, little is known on the usage of VR in control and maintenance of balance while standing.Research questionHow does VR modulate early, anticipatory, and compensatory postural adjustments during a dynamic task of leg lifting while avoiding an obstacle?MethodsFirst, the postural adjustments in a single-leg obstacle avoidance were compared between real and VR settings, where a statistical reanalysis was performed with data subsets that minimize the difference of foot elevation speed. Second, the effect of simple foot elevation was examined to identify the fundamental nature of leg lifting motion as a self-initiated perturbation. Lastly, perceptual distortion in VR was assessed by evaluating how the spatial scale of the virtual scene used in the single-leg obstacle avoidance experiment was recognized by participants.ResultsThe VR setting reduced the activities of lower leg muscles on the supporting side not only in the compensatory phase but also in the preparatory early and anticipatory phases. On the other hand, simple foot elevation resulted in a significant increase of muscle activities with lifting height only found in the compensatory phase. Furthermore, it is suggested that the VR induced perceptual distortion in estimating the sizes of the virtual objects.SignificanceThe findings provide more definitive evidence that VR presentation modulates the components of postural adjustments for maintaining upright stance while being perturbed. One of the potential psychophysical factors is perceptual distortion in VR, and this provides critical information for further development of VR based training system.     

Postural sway and balance testing: a comparison of normal and anterior cruciate ligament deficient knees

The purpose of this study was to assess postural sway and balance in normal and anterior cruciate ligament (ACL) deficient (ACLD) knees. Performance was assessed in 15 ACLD and 15 matched control (CON) subjects whilst standing on a postural sway meter and on a balance board. On both pieces of apparatus subjects attempted to maintain balance for 30 s under six different conditions; (1) and (2) standing on both legs with eyes open and closed; (3) and (4) standing on the injured leg with eyes open and closed; and (5) and (6) standing on the non-injured leg with eyes open and closed. Performance on the postural sway meter and balance board deteriorated significantly when both ACLD and CON stood on one leg (P<0.01), and when eyes were closed (P<0.01). This was independent of whether the leg was injured or not. The interaction of vision loss and single leg stance resulted in a significant deterioration in balance board performance on the injured leg compared to the non-injured leg in the ACLD group. Results suggest that use of a postural sway meter for predicting function and stability during dynamic activities in ACLD subjects may be inappropriate. Copyright 1998 Elsevier Science B.V.     

Gluteal muscle activity during running in asymptomatic people

BackgroundHip abductor muscle function is associated with running-related injuries. Previous electromyography (EMG) studies that reporting gluteal muscle activity when running have failed to account for the multiple segments of the gluteals, and have used surface electrodes, which may be contaminated by cross-talk of surrounding muscles.Research questionThis study aimed to: (i) develop EMG profiles of gluteus medius (GMed – anterior, middle and posterior) and gluteus minimus (GMin – anterior and posterior) segments during running; (ii) compare the activation patterns of each gluteal segment between running and walking; and (iii) compare surface EMG signals of running and walking to fine wire EMG signals of middle GMed.MethodsTen physically active and asymptomatic people participated. Gluteal segment activation was assessed during running and walking over 10 m. Muscle activation was assessed using bipolar fine wire intramuscular EMG electrodes and GMed activation was also assessed using surface EMG.ResultsDuring running, all gluteal segments presented peak amplitude during the stance phase and anterior GMin presented additional second peak amplitude during the swing phase. All gluteal segments evaluated demonstrated consistently higher amplitudes during the stance and swing phases of running compared to walking. The mean amplitude assessed using surface EMG was 32–87% higher compared to fine wire during both phases for running and walking.SignificanceGreater activation of GMed segments during the stance phase and the increased anterior GMin activity during the swing phase indicate a potentially important role for pelvis and hip stabilization, respectively, which should be considered during development of targeted rehabilitation for running populations. The overestimated activation using surface electrodes highlights a limitation of using surface EMG during running and walking.     

Neuromuscular response to the stimulation of plantar cutaneous during walking at different speeds.

BackgroundA lot of authors have been studied the consequence of postural control strategies through investigating the effects of foot-surface contact. In this context an important variable of textured surfaces or insoles could be related to material stiffness. We apply a particular textured insoles to evaluate neuromuscular response of plantar stimulation during walking. Research question: Could textured insoles alter the human locomotion during walking at different speeds? Methods: Ten adults (age: 27 ± 5 years) completed three trials on the multifunction treadmill at 0.42 ms^-1, 0.89 ms^-1, and 1.5 ms^-1 walking speed. Temporal-spatial parameters, gait line, and kinetic parameters were analyzed. The Co-Contraction Index (CCI) and electromyography (EMG) of the right leg muscles were assessed during four phases of gait: first half stance (FHS), half stance (HS), second half stance (SHS), swing phase (SP). Textured insole and soft control insole were worn while walking. Results: Plantar stimulation improved cadence, stride time, stride length and gait line parameters with increasing speed. First force peaks and maximum force forefoot were always significant. The maximum force midfoot was significant at 0.42 and 0.89 ms^-1. The maximum force heel only was significant in lower velocity. The maximum pressure showed different significant values except for the heel. Significant differences in the CCI were always found in the FHS and SHS for the plantar muscles, and in the FHS and HS for the knee muscles. The differences in gait analysis in biomechanical and in electromyographic parameters were more significant in the higher speed tested. Significance: The perception of shape and texture through its linear response to skin deformation over a wide range of deformations could be the reason why the significant differences increase in the higher speed. In conclusion, sensory interventions fallowing appropriate insoles can influence significantly gait. Walking strategy positively adjusts locomotion with high efficiency.     

Lifespan data on postural balance in multiple standing positions

BackgroundMaintaining balance is important throughout life. The Nintendo Wii Balance Board (WBB) can give reliable quantitative measures of postural balance, but reference data are lacking. Furthermore, one-leg standing balance across the adult lifespan is not fully described. The aim of the study was (1) to provide reference data on postural balance in multiple standing positions using a WBB, (2) to determine an age cut-off for the ability to stand on one-leg in men and women.MethodsThis was a cross-sectional study and data was collected in two cities in Denmark (Aalborg and Odense) and Norway (Oslo and Ålesund) during spring and summer of 2016.Postural balance was assessed in individuals across the adult lifespan in three different bases of support positions (hip-wide and narrow two-legged stance, and one-legged stance) using a WBB. Reference data were analyzed and presented in 10-year intervals.ResultsA total of 354 individuals aged 20–99 years were recruited. Reference data were presented in percentiles stratified by gender for the following age categories: 20–29, 30–39, 40–49, 50–59, 60–69, 70–79, and 80+. Data showed that the difference between men and women’s balance was larger at older age with men performing worst. The cut-off ability to stand on one-leg was 72.5 years without statistical evidence of gender difference.ConclusionThis study reports reference data for postural balance across the entire adult lifespan using a WBB. More than half of the individuals over 72.5 years of age were unable to stand balanced on one-leg.     

Intrinsic foot muscle hardness is related to dynamic postural stability after landing in healthy young men

BackgroundThe human foot has competent mechanisms for supporting weight and adapting movement to various surfaces; in particular, the toe flexor muscles aid in supporting the foot arches and may be important contributors to postural stability. However, the role of intrinsic foot muscle morphology and structure in the postural control system remains unclear, and the relationship between them is not well known.Research questionAre intrinsic foot muscle morphology and toe flexor strength related to static and dynamic postural stability in healthy young men?.MethodsA total of 27 healthy men aged 19–27 years participated in this study. intrinsic foot muscle morphology included muscle hardness and thickness. Cross-sectional area was measured by ultrasonography at an ankle dorsiflexion angle of 0°. The hardness of the abductor hallucis (AbH), flexor hallucis brevis, and flexor digitorum brevis (FDB) muscles was measured using ultrasound real-time tissue elastography. Static postural stability during single-leg standing on a single force platform with closed eyes was assessed for the right leg. In the assessment of dynamic postural stability, the subjects jumped and landed on single-leg onto a force platform and the dynamic postural stability index (DPSI) was measured.ResultsFDB muscle thickness showed a positive correlation with anteroposterior stability index (APSI) (r = 0.398, p = 0.040). AbH muscle hardness was negatively correlated with APSI (r = −0.407, p = 0.035); whereas FDB muscle hardness was positively correlated with DPSI (r = 0.534, p = 0.004), vertical stability index (r = 0.545, p = 0.003), and maximum vertical ground reaction force (r = 0.447, p = 0.020). Multiple regression with forced entry revealed that only DPSI was significantly correlated with FDB muscle hardness (p = 0.003).SignificanceThe results indicated that intrinsic foot muscle hardness plays an important role in dynamic postural control among healthy young men, which may enable a more rapid muscular response to changes in condition during jump landing and better performance in balance tasks.     

Effects of motor practice on learning a dynamic balance task in healthy young adults: A wavelet-based time-frequency analysis

BackgroundPrevious research showed changes in amplitude- or time-derived measures of electromyographic (EMG) activity with motor learning. However, an analysis of the EMG spectral content (e.g., via wavelet technique) has not been included in these investigations yet.ObjectiveThe aim of this study was to use conventional, amplitude-derived EMG parameters along with modern, wavelet-based time-frequency EMG measures to assess the effects of motor practice on learning a dynamic balance task.MethodsNineteen young male adults (mean age: 26 ± 6 years) practiced a dynamic balance task for two days. Delayed retention test was performed on the third day. On a behavioral level, the root-mean-square error (RMSE) of the stability platform angle was calculated and used as outcome measure. On a neuromuscular level, EMG data from the tibialis anterior (TA) and the gastrocnemius medialis (GM) muscle were unilaterally recorded and analysed by calculating the integrated EMG (iEMG) and the EMG intensity (via continuous wavelet transforms).ResultsTwo days of practice resulted in significantly improved balance performance (i.e., lower RMSE) and TA/GM activation (i.e., reduced iEMG and EMG intensity) that was still present during the retention test on day 3. There was also evidence of practice-related changes in the EMG intensity pattern as indicated by an intensity shift from higher to lower frequency components.ConclusionsWe conclude that motor practice leads to improvements in movement effectiveness as indicated by reduced RMSE and in movement efficiency (i.e., decreased iEMG and EMG intensity, intensity shift). In addition to conventional amplitude-derived EMG parameters, modern, wavelet-based time-frequency EMG measures are appropriate to detect practice-related changes in muscle activation.     

The effects of stroboscopic balance training on cortical activities in athletes with chronic ankle instability

ObjectivesTo investigate the effect of a 6-week stroboscopic balance training program on cortical activities in athletes with chronic ankle instability.DesignRandomized controlled trial. Setting: Single-center.ParticipantsThirty-nine participants were assigned to the strobe group (SG, n = 13), non-strobe group (NSG, n = 13), and control group (CG, n = 13).Main outcome measuresCortical activity and balance velocity were evaluated while the athletes were on the HUBER balance device. Electroencephalographic measurements of cortical activity were made at the transition from bipedal stance to single-leg stance.ResultsThe SG showed significant increases in Cz theta and alpha values and COP-v (center of pressure velocity) between pretest and posttest (p < 0.001, p = 0.003, p < 0.001). Posttest Cz theta was significantly higher in the SG compared to the CG (p = 0.009) and posttest Cz alpha was significantly higher in the SG compared to the NSG (p = 0.039) and CG (p = 0.001). Posttest COP-v was significantly higher in the SG than in the CG (p = 0.031) and NSG (p = 0.03).ConclusionsStroboscopic training may be clinically beneficial to improve balance parameters in athletes with CAI, and may have utility in sport-specific activity phases of rehabilitation to reduce visual input and increase motor control.     

Effects of initial foot position on postural responses to lateral standing surface perturbations in younger and older adults

BackgroundAn age-related decline in standing balance control in the medio-lateral direction is associated with increased risk of falls. A potential approach to improve postural stability is to change initial foot position (IFP).Research questionsIn response to a lateral surface perturbation, how are lower extremity muscle activation levels different and what are the effects of different IFPs on muscle activation patterns and postural stability in younger versus older adults?MethodsTen younger and ten older healthy adults participated in this study. Three IFPs were tested [Reference (REF): feet were placed parallel, shoulder-width apart; Toes-out with heels together (TOHT): heels together with toes pointing outward; Modified Semi-Tandem (M-ST): the heel of the anterior foot was placed by the big toe of the posterior foot]. Unexpected lateral translations of the standing surface were applied. Electromyographic (EMG) activity of the lower extremity muscles, standard deviation (SD) of the body’s CoM acceleration (SD of CoMAccel), and center of pressure (CoP) sway area were compared across IFPs and age.ResultsActivation levels of the muscles serving the ankle and gluteus medius were greater than for the knee joint muscles and gluteus maximus in the loaded leg across all IFPs in both groups. TOHT showed greater EMG peak amplitude of the soleus and fibularis longus compared to REF, and had smaller SD of CoMAccel and CoP sway area than M-ST. Compared to younger adults, older adults demonstrated lower EMG peak amplitude and delayed peak timing of the fibularis longus and greater SD of CoMAccel and CoP sway area in all IFPs during balance recovery.SignificanceDuring standing balance recovery, ankle muscles and gluteus medius are important active responders to unexpected lateral surface perturbations and a toes-out IFP could be a viable option to enhance ankle muscle activation that diminishes with age to improve postural stability.     

Patellar bracing affects sEMG activity of leg and thigh muscles during stance phase in patellofemoral pain syndrome

BackgroundDecreases in patellofemoral pain symptoms with bracing treatment have been established; but, the mechanisms remain unclear. The purpose of this study was to determine the immediate and long-term effects of the patellar bracing on electromyography (EMG) activity of the Vastus Medialis (VM) and Lateralis (VL), Rectus Femoris, lateral Gastrocnemius, Biceps Femoris and Semitendinosus (ST) muscles during level walking.Methods12 eligible women aged 20–30 years with diagnosis of patellofemoral pain participated in the before and after study. Intervention consisted of 8 weeks of patellar bracing. First, patients were tested without brace, then with a brace, and finally eight weeks later without a brace. Surface EMG activation of the selected muscles during level walking was recorded.ResultsAfter eight weeks of patellar bracing, EMG activity of VM muscle was significantly higher when compared to first session without brace (p = 0.011) at mid-stance sub-phase. Additionally, EMG activity of ST muscle during first session with brace was significantly lower when compared to first session without brace at mid-stance sub-phase (without brace) (p = 0.012). EMG activity of VM muscle after eight weeks of patellar bracing was significantly higher than the first session without brace at late stance and preswing sub-phase (p = 0.013).ConclusionLong-term wearing of patellar bracing increases EMG activity of VM during mid-stance and late stance and preswing sub-phases of gait and immediate effect of patellar brace is decrease of EMG activity of ST muscle during mid-stance.     

Integration of reginal shear measurements at the foot-ground interface during routine balance assessment of the elderly population

BackgroundForce-plate posturography offers a convenient way for quantitative assessment of postural stability in the elderly. However, studies focusing on routine balance assessment have usually not taken reginal shear distributions (i.e., arising from horizontal forces) into consideration.Research question(1) Does plantar shear distribution differ between young and elderly subjects during upright standing? (2) How do the maximum plantar shear forces vary at different regions of the foot?MethodsThe new reginal shear measurement (RSM) method can simultaneously capture the three-dimensional force distributions at regional plantar sites while subjects maintaining standing balance. The feasibility of the proposed method in characterizing the magnitude and distribution of plantar shear forces was tested in thirty-two normal young and nineteen elderly subjects. Statistical analysis was performed using the independent samples t-test for both the continuous and ordinal variables.ResultsFor regional AP shear forces, statistically significant differences were found between the two groups for the toe region of the right foot and the midfoot of both feet. For ML shear distributions, statistically significant differences were found at nearly all plantar sites expect for the hallux and lateral metatarsal. The maximum increase in ML shear forces occurred in the toe region of the right foot, where the peak shear values were 113.16% higher than those of the young subjects. The peak ML shear occurred in the midfoot were averagely 83.19% and 70.57% higher in the elderly’s left and right feet, respectively.SignificanceThe RSM method may offer unique solutions to identify functional decline in postural control of the elderly. The plantar shear pattern has potential to become an important parameter in evaluating one’s balance performance during upright standing.     

Double-leg stance and dynamic balance in individuals with functional ankle instability

To investigate whether double-leg stance could reveal balance deficits in subjects with functional ankle instability (FAI) and whether such an assessment of static balance would be correlated with measures of dynamic instability, 16 individuals with FAI and 16 healthy controls participated in this study. Static postural control was tested using double-leg stance (either with the eyes open (EO) or closed (EC)) on a dual-plate force platform. Dynamic balance was evaluated using the Multiple Hop Test (MHT) and a weight-shifting task. FAI subjects were significantly less stable in the anteroposterior direction during double-leg stance (as assessed by velocity of centre of pressure, VCP), both for the EO and EC condition. In the mediolateral direction the VCP values were also higher in FAI, but significance was only found for the EC condition (p = .02). FAI subjects made significantly more balance errors compared to healthy controls (p < .001) on both the affected and less affected leg during MHT. There were no significant differences between FAI and healthy subjects during the weight-shifting task. No relationship was found between double-leg stance and MHT measures (all correlations (r_s) less than .30). This study suggests that static postural control during double-leg stance is impaired in FAI subjects. Although dynamic balance during MHT is also affected, no significant relationship was found between static and dynamic measurements, which indicate that they are most probably related to different aspects of postural control.