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Voluntary stepping tasks are used to measure the ability of an individual to step and has been associated with fall risk in older adults. Although electromyography (EMG) amplitude is measured during stepping tasks, there is no consensus about the reference EMG value that should be used to normalize the signal. The purpose of the present study was to 1) investigate the impact of using different EMG parameters as a reference to normalize the rate of activation (RoA) of the hip abductor muscles across lateral voluntary step trials and the differences between trials, and 2) to investigate the reliability among trials of the reference EMG values. Nineteen older adults (>65 years of age) performed ten lateral choice reaction stepping test (CRST), while the gluteus medius and tensor fascia latae EMG were recorded. Three reference EMG values were calculated and used to normalize RoA during the stepping task. A repeated-measures ANOVA was used (normalized RoA[3] x trial[3]) to compare normalized EMG across trials, and an intraclass correlation coefficient and coefficient of variation were used for the inter-trial reliability of the reference EMG values. The present study showed that gluteus medius and tensor fascia latae RoA normalized values from the stance and stepping leg (right or left side) measured during CRST are different according to the reference EMG value(P<0.001), with no differences across trials. Overall, the EMG procedures showed high inter-trial reliability, with a few exceptions. Therefore, after careful examination of our results, the peak and mean EMG amplitudes showed consistently higher intraclass correlation coefficients; however, the former may provide a more intuitive reference value. • Normalized rate of activation values from the stance or stepping leg are different accordingly to the reference value. • Overall great inter-trial reliability for all reference EMG values. • The peak and mean EMG amplitudes showed consistently higher intraclass correlation coefficients. [ABSTRACT FROM AUTHOR]

People with degenerative cervical myelopathy are known to have impaired standing balance and walking abilities, but less is known about balance responses during walking. The aim of this project was to assess reactive balance impairments during walking in people with degenerative cervical myelopathy (PwDCM). We hypothesized that center of mass motion following perturbations would be larger in PwDCM and gluteus medius electromyographic amplitude responses would be decreased in PwDCM. Reactive balance responses were quantified during unanticipated lateral pulls to the waist while treadmill walking. Walking biomechanics data were collected from 10 PwDCM (F=6) and 10 non-myelopathic controls (F=7) using an 8 camera Vicon System (Vicon MX T-Series). Electromyography was collected from lower limb muscles. Participants walked on an instrumented treadmill and received lateral pulls at random intervals and in randomized direction at 5% and 2.5% body mass. Participants walked at 3 prescribed foot placements to control for effects of the size of base of support. As compared with controls, the perturbation-related positional change of the center of mass motion (ΔCOM) was increased in PwDCM (p=0.001) with similar changes in foot placement (p>0.05). Change in gluteus medius electromyography, however, was less in PwDCM than in controls (p<0.001). After experimentally controlling step width, people with mild-to-moderate degenerative cervical myelopathy at least 3 months following cervical spine surgery have impaired reactive balance during walking likely coupled with reduced gluteus medius electromyographic responses. Rehabilitation programs focusing on reactive balance and power are likely necessary for this population. • Following surgical decompression, people with degenerative cervical myelopathy have residual balance impairments during walking. • Impairments exist regardless of pre-perturbation step width. • People with degenerative cervical myelopathy have a blunted hip abductor muscle response following perturbation. [ABSTRACT FROM AUTHOR]

Background: People with hip osteoarthritis (OA) typically display altered gluteus minimus (GMin) and gluteus medius (GMed) activity during gait, in addition to reduced walking speed and stride length. It is unknown if current rehabilitation programs address changes in gluteal muscle activity in people with hip OA.Research Question: Can a targeted gluteal intervention restore normal gluteal muscle segment activity during gait in people with hip OA?Methods: This study presents secondary outcomes from a multi-site, double-blinded clinical trial in which participants with radiologically confirmed mild-moderate hip OA were randomised into a targeted gluteal or sham intervention for 12-weeks following baseline testing. Electromyography (EMG) outcomes were only conducted at a single site and data were collected from 22 participants. Intramuscular electrodes were inserted into two segments of GMin (anterior, posterior) and three segments of GMed (anterior, middle, posterior) to record average amplitude, peak amplitude and time to peak (TTP) during the first 60 % of the gait cycle (stance phase) at baseline and post-intervention.Results: Following the targeted gluteal intervention, posterior GMin displayed a decrease in average (P = 0.032, ES=1.04) and peak (P = 0.017, ES=1.17) muscle activity during late stance phase with a shift to an earlier TTP (P = 0.034, ES=1.02). There were no further significant changes between groups for other outcome measures. Similar trends for an earlier TTP were observed for the posterior segment of GMed following the targeted intervention (P = 0.095, ES=0.87). The earlier TTP in the posterior segments of both GMin and GMed post-intervention resembled patterns observed in a healthy young population.Significance: A targeted gluteal intervention can positively impact activity in posterior GMin during gait in people with hip OA when compared to a sham intervention. [ABSTRACT FROM AUTHOR]

Background: An 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 Questions: In 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?Methods: Ten 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.Results: Activation 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.Significance: During 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. [ABSTRACT FROM AUTHOR]

Background: Although foot orthoses are often used in the management of lower limb musculoskeletal conditions, their effects on muscle activation is unclear, especially in more proximal segments of the lower limb.Research Question: Primary aim: Is there an immediate effect of foot orthoses on gluteal muscle activity during overground walking in healthy young adults? Secondary aim: Is there an immediate effect of foot orthoses on the activity of hamstring, quadriceps and calf muscles?Methods: In eighteen healthy young adults, muscle activity was recorded using fine wire electrodes for gluteus minimus (GMin; anterior, posterior) and gluteus medius (GMed; anterior, middle, posterior); and surface electrodes for gluteus maximus (GMax), hamstring, quadriceps and calf muscles. Participants completed six walking trials for two conditions; shoe and shoe with prefabricated foot orthoses. Muscle activity was normalised to the peak activity of the shoe condition and analysed using one-dimensional statistical non-parametric mapping to identify differences across the gait cycle.Results: Activity of GMed (anterior, middle, posterior) and GMin (posterior) was reduced in early stance phase when the orthosis was worn in the shoe (p < 0.05). GMin (anterior) activity was significantly reduced during swing (p < 0.05). Muscle activity was also significantly reduced during the orthoses condition for the lateral hamstrings and calf muscles (p < 0.05).Significance: Using foot orthoses may provide a strategy to reduce demand on GMin, GMed, lateral hamstring and calf muscles while walking. [ABSTRACT FROM AUTHOR]

Background: Research investigating differences in gluteus medius muscle activity in those with and without chronic nonspecific low back pain is both limited and conflicting. Additionally, in these populations the relationship between gluteus medius muscle activity, foot type, and transversus abdominis muscle thickness is unclear.Research Question: We aimed to investigate gluteus medius muscle activity during gait in those with and without chronic nonspecific low back pain. Secondarily, we aimed to explore the association between gluteus medius muscle activity, foot type, and transversus abdominis muscle thickness within groups.Methods: This case control study recruited 30 people with and 30 people without chronic nonspecific low back pain and matched participants by age (±5 years), sex, and body mass index (±2 BMI units). Gluteus medius muscle activity was measured with surface electromyography during walking gait, with foot type and transversus abdominis muscle thickness measured with the Foot Posture Index and ultrasound respectively. The Mann-Whitney U test was used to investigate differences in gluteus medius muscle activity between groups. Spearman rank order correlation was performed to explore the association between gluteus medius muscle activity, foot type, and transversus abdominis thickness within each group. A linear regression was used to analyse significant correlations (P < 0.05).Results: We found no significant differences in gluteus medius muscle activity between groups. However, there was a moderate correlation between the Foot Posture Index score and gluteus medius peak amplitude (P = 0.04) for those with mild to moderate chronic nonspecific low back pain.Significance: Clinicians should be aware that patients with mild to moderate chronic nonspecific low back pain may not demonstrate significant differences in gluteus medius muscle activity compared to those without back pain. Additionally, higher peak gluteus medius muscle activity is likely to occur in people with mild to moderate chronic nonspecific low back pain and planus feet. [ABSTRACT FROM AUTHOR]

Background: Altered gluteus minimus (GMin) activity has been identified in people with hip osteoarthritis (OA) during gait with some evidence of altered gluteus medius (GMed) activity in patients with advanced OA. It is not known whether these muscles also exhibit altered activity during other functional tasks.Research Question: Does gluteal muscle activity during stepping tasks differ between people with hip OA and healthy older adults?Methods: Participants included 20 people with unilateral hip OA and 20 age-and sex-matched controls. Muscle activity in the three segments within GMed and two segments of GMin were examined using intramuscular electromyography during step-up, step-down and side-step tasks.Results: Participants in the OA group demonstrated reduced muscle activity early in the step-up task and a later time to peak activity in most muscle segments. Greater activity was identified in anterior GMin in people with hip OA during the side-step task. A delay in time to peak activity was identified in most muscle segments in people with OA during the side-step task.Significance: For participants with OA, reduced activity in most muscle segments and increased time spent in double limb stance during the step-up task could reflect the decreased strength and pain associated with single limb stance on the affected limb. This study provides further evidence of altered function of the deep gluteal muscles in people with hip OA and highlights the importance of addressing these muscles in rehabilitation. [ABSTRACT FROM AUTHOR]

Background: Hip 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 Question: This 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.Methods: Ten 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.Results: During 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.Significance: Greater 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. [ABSTRACT FROM AUTHOR]

Occupations requiring prolonged periods of static standing are associated with the development of low back pain (LBP). Certain individuals are susceptible to LBP development during prolonged standing (pain developers, PDs) while others are not (non-pain developers, NPDs). Linear centre of pressure (COP) measures suggest that standing balance control is negatively influenced following prolonged standing, and that PDs and NPDs may be differentially affected. The objective of this study was to determine if nonlinear standing balance control, quantified on COP, using sample entropy, is altered after 2-h of standing. Thirty two participants stood for 2-h. Separate 2-min standing trials, performed with eyes open and eyes closed, were collected before and after the 2-h standing protocol. Sample entropy, median power frequency and RMS amplitude of the COP time-series, was calculated from the 2-min standing trials for all participants. For comparison, participants were classified, post hoc, as PDs or NPDs according to visual analog scale pain scores. Sample entropy decreased after 2-h of standing for both PDs and NPDs, however, the decrease for NPDs was only 21% of the decrease observed in PDs. This study demonstrated that nonlinear control of upright standing changes after 2- hours of standing, resulting in an increase in COP regularity post 2- hours of standing for both PDs and NPDs. PDs displayed a greater change in COP regularity, which is supported by the theory that increased COP regularity occurs with pain/pathology. [ABSTRACT FROM AUTHOR]

Background: Atypical frontal plane hip kinematics are associated with iliotibial band syndrome in women runners. Gluteus medius is the primary muscle controlling the hip adduction angle during the loading response of stance. It is unclear if differences exist in gluteus medius activity magnitude and activity duration between runners with previous iliotibial band syndrome and controls. Furthermore, hip neuromechanics may change after a prolonged run.Research Question: Do differences exist in the hip adduction angle and gluteus medius activity between women with previous iliotibial band syndrome and controls at the beginning and end of a 30-minute moderate paced treadmill run?Methods: Thirty women participated (n = 15 controls). Lower extremity kinematics and gluteus medius activity were recorded at the start and end of a 30-minute treadmill run at participants' self-selected pace. Hip kinematics and gluteus medius activity were analyzed via separate two-way (group x time) mixed-model analysis of variance with time as the repeated measure.Results: Hip neuromechanics were similar at the start and end of a 30-minute treadmill run in women with previous iliotibial band syndrome and controls. However, hip adduction excursion was less in women with previous iliotibial band syndrome compared to controls. Average gluteus medius activity magnitude and activity duration were not significantly different between groups.Significance: These findings support the growing body of literature that smaller hip adduction motion is related to previous iliotibial band syndrome in women. Regardless of injury history, gluteus medius activity was similar between groups during the loading phase of stance. [ABSTRACT FROM AUTHOR]

Background: Individuals with CAI have demonstrated a more inverted foot position during walking when compared to a healthy control group. Copers are individuals who have had an ankle sprain but learn to cope and return to pre-injury levels of function and may be a better comparison group than healthy controls because they have had the same initial injury.Research Question: A controlled laboratory study was performed to simultaneously analyze differences in lower extremity walking gait kinematics, kinetics, and surface electromyography (EMG) between individuals with CAI and copers at a preferred walking speed (PWS), 120% preferred walking speed (120WS), and standardized walking speed (SWS) of 1.34 m/s.Methods: Thirty-six (18 coper, 18 CAI) physically active individuals participated. Three-dimensional kinematics and kinetics at the ankle, knee, and hip and EMG amplitude for fibularis longus, tibialis anterior, medial gastrocnemius, and gluteus medius muscles were analyzed. Ten consecutive strides from each speed were analyzed using statistical parametric mapping (SPM). A 2 × 3 group by speed ANOVA and post-hoc t-tests were used to compare differences between the coper and CAI groups.Results: The CAI group had more ankle inversion at IC (PWS: MD = 4.2°, d = 1.08; 120WS: MD = 5.0°, d = 1.28; SWS: MD = 6.6°, d = 1.37) and greater peak inversion throughout swing at all three walking speeds (PWS: MD = 4.2°, d = 0.89; 120WS: MD = 4.4°, d = 0.91; SWS: MD = 6.2°, d = 1.21). The CAI group had greater peak hip adduction during swing (PWS: MD = 4.5°, d = 0.96; 120WS: MD = 4.1°, d = 1.04; SWS: MD = 3.6°, d = 0.98).Significance: The CAI group demonstrated greater ankle inversion at IC and during the swing phase and greater peak hip adduction during the swing phase compared to the copers. As the speed increased, ankle inversion in the CAI group also increased which could be linked to greater risk of recurrent sprains. Therefore, modeling gait training programs after the coper mechanics may be advantageous. [ABSTRACT FROM AUTHOR]

Background: Altered gait mechanics are frequently reported in individuals with chronic ankle instability (CAI), and increasing information suggests proximal muscle adaptations occur in this population. Ultrasound imaging (USI) offers a visual means to evaluate muscle activity during movement, and overcomes limitations of electromyography (EMG) to detect hip muscle activity.Research Question: A descriptive laboratory study was conducted to determine if gluteus maximus (GMAX) and medius (GMED) muscle activity differed throughout gait in patients with CAI compared to healthy counterparts.Methods: Twenty young adults with CAI (21.6 ± 2.4 years, 10 males) and 20 healthy participants (21.2 ± 2.8 years, 10 males) walked on a treadmill at 1.35 m/s while researchers obtained 10-second clips of bilateral USI of the GMAX and GMED. USI clips were reduced to 55 frames consisting of 11 points over five full gait cycles. Muscle thickness values during walking were normalized to quiet bipedal standing USI images to obtain functional activity ratios (FARs). FARs with 90% confidence intervals (CI) were plotted as 10% interludes from 0 to 100% of the gait cycle to compare groups and limbs. Mean differences and Cohen's d effect sizes were used to assess the extent of differences. The CAI group had decreased GMED activity bilaterally from 0 to 40% of walking gait compared to healthy counterparts with large effect sizes (d≥0.60). CAI group FARs were below quiet stance levels (FARs<1.0) throughout the entire gait cycle. There were no differences noted between groups or limbs for GMAX measures.Significance: Proximal stabilizing musculature was altered bilaterally in CAI individuals compared to healthy counterparts, which may contribute to movement dysfunction. Previous studies using EMG have not detected this extent of bilateral gluteal muscle alterations in CAI groups during gait, however our findings suggest USI was able to detect significant proximal alterations during walking in this population. [ABSTRACT FROM AUTHOR]

This study aimed to compare the ground reaction forces (GRF) and lower limb muscles correlation and activation time delay between Forward (FW) and Backward (BW) walking. Twenty-four male students participated in this research. Electromyogram activities of gluteus medius, biceps femoris, medial gastrocnemius, soleus and anterior tibialis muscles along with GRFs were measured. Each participant performed two FW and two BW trials bare foot. Statistical parametric mapping (SPM) analysis was performed over anterior-posterior and vertical GRFs time series. The paired t-test was used in SPM analysis. Cross-correlation analysis compared similarity in shape and time delay of EMG pattern. SPM analysis of GRFs showed that these two walking modes have asymmetrical kinetic behavior during most parts of stance phase. Based on cross-correlation analysis, the shape of EMG activation profiles differed, where a phase shift in the muscle activation pattern of approximately 60% occurred. This shift may indicate different control mechanisms, at the spinal level, underpin FW and BW walking modalities. [ABSTRACT FROM AUTHOR]

The purpose of this study was to investigate the effects of treadmill training (TT) with functional electrical stimulation (FES) applied to the gluteus medius (GM) and tibialis anterior (TA) muscles on gait and balance performance in individuals with chronic hemiparetic stroke. Thirty-six participants with chronic hemiparesis were recruited to this study and randomly distributed into three groups: TT with FES applied to the GM and TA muscles (TTFES-GM + TA group, 12 patients); TT with FES applied to the TA muscle (TTFES-TA group, 12 patients); and TT only (control group, 12 patients). All participants underwent 20 sessions of TT with a harness (30 min five times per week for 4 weeks). They also received regular physical therapy for 1 h five times per week for 4 weeks. All participants were assessed before and after training using digital muscle testing, the Medical Research Council (MRC) scale, the 6-min walk test (6MWT), and spatiotemporal parameters. After training, the TTFES-GM + TA group showed significant improvement in hip abductor strength, Berg Balance Scale score, 6MWT result, MRC scale score grade, gait velocity, and cadence compared to the TTFES-TA group and control group. These findings show that TT with FES applied to the GM and TA muscles increased lower limb muscle strength and improved balance and gait capacities. Therefore, TT with FES applied to the GM and TA could be a beneficial intervention in clinical settings for individuals with chronic hemiparetic stroke. [ABSTRACT FROM AUTHOR]

Surface electromyography (sEMG) is used to assess muscle activation during therapeutic exercise, but data are significantly affected by inter-individual variability and requires normalisation of the sEMG signal to enable comparison between individuals. The purpose of this study was to compare two normalisation methods, a maximal method (maximum voluntary isometric contraction (MVIC)) and non-maximal peak dynamic method (PDM), on gluteus medius (GMed) activation using sEMG during three weight-bearing exercises in people with hip osteoarthritis (OA) and healthy controls. Thirteen people with hip OA and 20 controls performed three exercises (Squat, Step-Up, Step-Down). Average root-mean squared EMG amplitude based on MVIC and PDM normalisation was compared between groups for both involved and uninvolved hips using Mann–Whitney tests. Using MVIC normalisation, significantly higher normalised GMed EMG amplitudes were found in the OA group during all Step-up and down exercises on the involved side ( p = 0.02–0.001) and most of the Step exercises on the uninvolved side ( p = 0.03–0.04), but not the Squat ( p > 0.05), compared to controls. Using PDM normalisation, significant between-group differences occurred only for Ascending Squat ( p = 0.03) on the involved side. MVIC normalisation demonstrated higher inter-trial relative reliability (ICCs = 0.78–0.99) than PDM (ICCs = 0.37–0.84), but poorer absolute reliability using Standard Error of Measurement. Normalisation method can significantly affect interpretation of EMG amplitudes. Although MVIC-normalised amplitudes were more sensitive to differences between groups, there was greater variability using this method, which raises concerns regarding validity. Interpretation of EMG data is strongly influenced by the normalisation method used, and this should be considered when applying EMG results to clinical populations. [ABSTRACT FROM AUTHOR]

Increases in step width have been reported for several clinical populations, including older adults and stroke survivors. These populations often also exhibit decreased hip abductor strength, suggesting that walking with wider steps may be an adaptive response in order to reduce the mechanical demands on the hip abductors. The purpose of this study was to quantify the relationship between step width and gluteus medius (GM) activity during walking. Fourteen young, uninjured adults walked on a treadmill at 1.25 m/s for four step width conditions ( Normal , Narrow , Medium , and Wide ) while step width and stance phase GM electromyographic (EMG) activity were quantified. We also measured hip abduction torque and GM activity during maximum voluntary isometric contractions (MVICs) at three hip angles (neutral, abducted 10°, and abducted 20°). During walking trials, GM activity was significantly ( p < 0.0001) influenced by step width; compared to Normal walking, GM activity was 47% higher with Wide steps and 24% lower with Narrow steps. We also observed a weak positive correlation ( r = 0.18 ± 0.14) between step width and GM activity during Normal walking, as GM activity was higher with wider steps. These results cannot be attributed to changes in GM conformation under the recording electrode, as GM activity was not influenced by hip angle during MVICs. The increased GM activity with wider steps does not support the proposal that increasing step width would be a beneficial adaptation to weakened hip abductors. A likely alternative explanation is that increased step width is a response to decreased gait balance. [ABSTRACT FROM AUTHOR]

The purpose of this study was to determine the therapeutic effects of functional electrical stimulation (FES) applied to the gluteus medius and tibialis anterior muscles during the gait cycle in individuals with hemiparetic stroke. Eighteen patients who had suffered a stroke were enrolled in this study. The participants were divided into either the gluteus medius and tibialis anterior (GM+TA) training group (n=9) or the control group (n=9). The GM+TA group received FES-triggered gait training to the gluteus medius (GM) in the stance phase and the tibialis anterior (TA) in the swing phase for 30min, 5 session a week over a 6-week period, and control group who received only gait training without FES-triggered for the same duration of time. A foot-switch sensor was used to trigger the device in the stance (GM) and swing (TA) phases of the gait cycle reciprocally. This study measured three types of outcome measures, including spatiotemporal gait parameters, muscles activities, and balance function. After 6 weeks training, there was a significant improvement in gait velocity, cadence, stride length, and gait symmetry in the GM+TA training group compared to the control group. Dynamic balance function was significantly improved in the GM+TA training group compared to the control group. The mean changeable values of the GM was significantly greater strength in the GM+TA training group than the control group. These findings suggest that FES-triggered gait training of the GM in the stance phase and TA in the swing phase may improve the spatiotemporal parameters of gait in persons with hemiparetic stroke. [ABSTRACT FROM AUTHOR]

Highlights: [•] Forward simulations of very slow and normal speed walking are generated. [•] Muscle contributions to three-dimensional center of mass control are calculated. [•] Uncoupling of gluteus medius contribution in the different directions is required. [•] Destabilization by gravity increases in ML direction with decreasing speed. [•] Tight balance between gravity and gluteus medius is necessary to ensure stability. [ABSTRACT FROM AUTHOR]

Abstract: Our current theoretical understanding of gluteus minimus (GMin) and gluteus medius (GMed) function is primarily based on cadaveric studies and biomechanical modelling. There is an absence of electromyographic (EMG) research that aims to verify this understanding, particularly in relation to the potentially unique functional roles of structurally distinct segments within GMin (anterior and posterior) and GMed (anterior, middle and posterior). The aim of this paper is to provide a comprehensive technical description for inserting intramuscular EMG electrodes into uniquely oriented segments of GMin and GMed; and to report the levels of discomfort associated with gluteal intramuscular electrode insertions. Fifteen healthy volunteers took part in a series of walking trials after intramuscular EMG electrodes were inserted into segments of GMin (×2) and GMed (×3) according to previously verified guidelines. Visual analogue scores following walking trials at comfortable and fast speed indicate that discomfort levels associated with these insertions were low (2.4±1.4 and 1.6±0.7 respectively). The technical descriptions and illustrations provided in this paper will allow trained intramuscular electromyographers to insert electrodes into these muscle segments with confidence. [Copyright &y& Elsevier]

Abstract: Hip abductors play an important role in maintaining trunk and pelvis stability during unipedal tasks. The purpose of the study was to compare postural stability between individuals with patellofemoral pain (PFP) and pain-free controls. A secondary purpose was to evaluate the effect of a hip stabilizing brace on postural stability. Twenty females with PFP (27.3±6.3 years) and 19 controls (26.1±4.5 years) participated. Each subject performed a unipedal step-down balance task with the stance leg on a force platform from which center of pressure (COP) excursion was recorded. Quantitative COP excursion patterns (mean and peak displacements) were used as measures of postural stability. For subjects with PFP, postural stability also was quantified following the application of a hip stabilizing brace. Hip abductor strength was significantly lower in PFP group compared to the control group (1.39±0.4 vs. 1.62±0.26N/kg-BW, p =0.046). Peak and mean medial–lateral COP displacements during the balance task were greater in the PFP group (39.8±6.7 vs. 24.3±3.8mm, p <0.001; 24.7±16.3 vs. 13.5±4.4mm, p =0.005). Application of the hip stabilizing brace reduced the peak and mean COP displacement (39.8±6.7 vs. 24.7±4.7mm, p <0.001; 24.7±16.3 vs. 16.8±15.1mm, p =0.02). Our results demonstrate that females with PFP exhibit impaired medial–lateral postural stability when compared to control subjects. Application of a hip stabilizing brace significantly improved stability to a level comparable to the controls. [Copyright &y& Elsevier]

Abstract: The World Health Organization warns that, in 2000, as many as 33 million Europeans suffered from diabetes, approximately 15% will likely develop foot ulcers, and approximately 15–20% of these patients will face lower-extremity amputation. Changes in some gait parameters that appear to be specific in diabetes have been identified in the literature: shorter stride length, reduced walking speed, and altered lower limb and trunk mobility. The present study aimed at evaluating the role of altered muscle activity in gait alterations of diabetic subjects with and without neuropathy. This study involved 50 subjects: 10 controls (BMI 24.4±2.8, age 61.2±5.07), 20 diabetics (BMI 26.4±2.5, age 56.53±13.29) and 20 neuropathics (BMI 26.8±3.4, age 61.2±7.7). The electrical activity of six muscles was collected bilaterally on the lower limb during gait: gluteus medius, rectus femoris, tibialis anterior, peroneous longus, gastrocnemius lateralis, and extensor digitorum communis. Electromyographic activity was represented through linear envelopes. Time and space parameters were also evaluated by means of two Bertec force plates and a six cameras motion capture system (BTS, 60–120Hz). At initial contact and loading response, an early peak of rectus femoris activity occurred in diabetic subjects with and without neuropathy. During midstance a delay of gastrocnemius activity was observed in diabetic non-neuropathic subjects. During terminal swing a delay of rectus femoris and gluteus medius activity was seen in diabetic non-neuropathic subjects’. The results suggest that important muscle activity deviations are present in diabetic subjects although these are not directly related to neuropathy. [Copyright &y& Elsevier]

Abstract: The purpose of this study was to determine the influence of functional electrical stimulation (FES) applied to the tibialis anterior and gluteus medius muscles on the improvement of the spatiotemporal parameters of gait in individuals with a hemiparetic stroke. Thirty-six patients who had suffered a hemiparesis post stroke were enrolled in this study. The participants walked at a self-selected velocity on three different FES applications: (1) FES-triggered gait on the gluteus medius in the stance phase and the tibialis anterior in the swing phase (GM+TA), (2) FES-triggered gait on the tibialis anterior in the swing phase (TA only), and (3) gait without FES-triggered (Non-FES). FES was triggered when the heel in the affected lower limb was placed in contact with an on or off foot switch sensor. The effect of FES applications was assessed using GAITRite for spatiotemporal data. The gait speed, cadence, and stride length were significantly higher under the GM+TA condition than under the TA only and None-FES conditions. The gait speed, cadence and stride length were increased significantly in the TA only condition compared with the Non-FES condition. The double support time and gait symmetry were significantly improved in the GM+TA condition compared to the TA only and Non-FES conditions. These findings suggest that walking with FES of the gluteus medius in the stance phase and tibialis anterior in the swing phase can improve the spatiotemporal parameters of gait in individuals with hemiparetic stroke. [Copyright &y& Elsevier]