Tibialis anterior architecture, strength, and gait in individuals with cerebral palsy

3D ultrasound-based determination of skeletal muscle fascicle orientations

Architectural parameters of skeletal muscle such as pennation angle provide valuable information on muscle function, since they can be related to the muscle force generating capacity, fiber packing, and contraction velocity. In this paper, we introduce a 3D ultrasound-based workflow for determining 3D fascicle orientations of skeletal muscles. We used a custom-designed automated motor driven 3D ultrasound scanning system for obtaining 3D ultrasound images. From these, we applied a custom-developed multiscale-vessel enhancement filter-based fascicle detection algorithm and determined muscle volume and pennation angle. We conducted trials on a phantom and on the human tibialis anterior (TA) muscle of 10 healthy subjects in plantarflexion (157 ± 7∘ ), neutral position (109 ± 7∘ , corresponding to neutral standing), and one resting position in between (145 ± 6∘ ). The results of the phantom trials showed a high accuracy with a mean absolute error of 0.92 ± 0.59∘ . TA pennation angles were significantly different between all positions for the deep muscle compartment; for the superficial compartment, angles are significantly increased for neutral position compared to plantarflexion and resting position. Pennation angles were also significantly different between superficial and deep compartment. The results of constant muscle volumes across the 3 ankle joint angles indicate the suitability of the method for capturing 3D muscle geometry. Absolute pennation angles in our study were slightly lower than recent literature. Decreased pennation angles during plantarflexion are consistent with previous studies. The presented method demonstrates the possibility of determining 3D fascicle orientations of the TA muscle in vivo.

Effects of elastic therapeutic taping on along-muscle fascicle local length changes: Magnetic resonance and diffusion tensor imaging based assessment

Elastic therapeutic taping is utilized for prevention and treatment of various neuromusculoskeletal disorders and sports injuries. Kinesio taping (KT) is a popular version of this practice. Despite being widely used to improve muscular function, an understanding of KT effects on muscular mechanics are lacking. Considering the continuity of the fascial system and its mechanical interaction with muscle fascicles intramuscularly, the aim was to test the following hypothesis: mechanical loading induced on the skin by KT leads to along-muscle fascicle local length changes and shear strains in the targeted muscle. Magnetic resonance imaging (MRI)-based local tissue deformation analyses and diffusion tensor imaging (DTI)-based fiber tracking analyzes were combined. Anatomical MRI and DTI were acquired for 5 healthy female volunteers in 3 conditions: (1) without tape, (2) following sham application, and (3) after KT application. Local length changes and shear strains were calculated using image registration between conditions (1-2) and (2-3). Non-parametric Wilcoxon signed-rank test was performed to compare the two conditions. Data pooled from all subjects show that KT-imposed along-muscle fascicle lengthening (mean ± SD 0.026 ± 0.020), shortening (0.032 ± 0.027) and shearing (0.087 ± 0.049) occur and are significantly higher than those caused by sham application (0.012 ± 0.010; 0.013 ± 0.015; 0.029 ± 0.021, respectively) (p < 0.001). KT induced along-muscle fascicle length changes locally show heterogeneity. Our findings indicate that KT affects both along-muscle fascicle length changes and shear strains. This can be explained by KT imposed myofascial loads over the skin being transmitted via the fascial system, non-uniformly manipulating the mechanical equilibrium locally at different parts along the muscle fascicles.

Architectural anatomy of the human tibialis anterior presents morphological asymmetries between superficial and deep unipennate regions

The tibialis anterior muscle plays a critical role in human ambulation and contributes to maintaining the upright posture. However, little is known about its muscle architecture in males and females. One hundred and nine physically active males and females were recruited. Tibialis anterior muscle thickness, pennation angle, and fascicle length were measured at rest in both unipennate regions of both legs using real-time ultrasound imaging. A linear mixed model was used with muscle thickness, pennation angle, or fascicle length as the dependent variables. All models were carried out with and without total leg lean mass and shank length as covariates. Causal mediation analysis was computed to explore the effect of muscle thickness on the relationship between fascicle length and pennation angle. There were no significant differences between dominant and nondominant legs regarding muscle architecture. Muscle thickness and pennation angle were greater in the deep than the superficial unipennate region in males (1.9 mm and 1.1°, p < 0.001) and women (3.4 mm and 2.2°, p < 0.001). However, the fascicle length was similar in both regions for both sexes. The differences remained significant after accounting for differences in leg lean mass and shank length. In both regions, muscle thickness was 1-3 mm greater in males and superficial pennation angle 2° smaller in females (both, p < 0.001). After accounting for leg lean mass and shank length, sex differences remained for muscle thickness (1.6 mm, p < 0.05) and pennation angle (3.4°, p < 0.001) but only in the superficial region. In both regions, leg lean mass and shank-adjusted fascicle length were 1.4 mm longer in females than males (p < 0.05). The causal mediation analysis revealed that the estimation of fascicle length was positive, suggesting that a 10% increase in muscle thickness would augment the fascicle length, allowing a 0.38° pennation angle decrease. Moreover, the pennation angle increases in total by 0.54° due to the suppressive effect of the increase in fascicle length. The estimated mediation, direct, and total effects were all significantly different from zero (p < 0.001). Overall, our results indicate that the architectural anatomy of the tibialis anterior shows sexual dimorphism in humans. Tibialis anterior presents morphological asymmetries between superficial and deep unipennate regions in both sexes. Lastly, our causal mediation model identified a suppressive effect of fascicle length on the pennation angle, suggesting that increments in muscle thickness are not always aligned with increments in fascicle length or the pennation angle.

Foot drop after gastrocsoleus lengthening for equinus deformity in children with cerebral palsy

BACKGROUND

Gastrocsoleus lengthening (GSL) is the most common surgical procedure to treat equinus deformity in ambulant children with cerebral palsy (CP). Foot drop, where the ankle remains in plantarflexion during swing phase, can persist in some children post-operatively. There is currently limited understanding of which children will demonstrate persistent foot drop after GSL.

RESEARCH QUESTION

Which children develop persistent foot drop after GSL surgery for equinus?

METHODS

We conducted a retrospective cohort study on ambulant children with CP who had GSL surgery for fixed equinus deformity. The aims of the study were: to determine the frequency of persistent foot drop post-operatively and to compare outcome parameters from physical examination and three-dimensional gait analysis for children with hemiplegia or diplegia.

RESULTS

One hundred and ten children functioning at GMFCS Levels I/II/III of 28/75/7 met the inclusion criteria for this study. There were 71 boys and mean age was 9.1 years at time of GSL surgery. The overall frequency of persistent foot drop was 25%, with a higher frequency of persistent foot drop in children with hemiplegia (42%) than children with diplegia (19%). There were significant improvements in dorsiflexor strength and in selective motor control in children with diplegia but not in children with hemiplegia. Mean (SD) pre-operative mid-swing ankle dorsiflexion for children with hemiplegia was - 14.0° (9.9°) and improved post-operatively to - 1.6° (5.5°). For children with diplegia, the pre-operative mid-swing ankle dorsiflexion was - 12.1° (12.9°) and improved post-operatively to + 4.2° (6.9°).

SIGNIFICANCE

Foot drop is present following GSL surgery for fixed equinus deformity in a significant number of children with hemiplegia and to a lesser extent in children with diplegia, which may reflect a difference in the central nervous system lesion between these groups. New management approaches are required for this important and unsolved problem.

Skeletal Muscle Measurements in Pediatric Hematology and Oncology: Essential Components to a Comprehensive Assessment

Children with hematologic and oncologic health conditions are at risk of impaired skeletal muscle strength, size, and neuromuscular activation that may limit gross motor performance. A comprehensive assessment of neuromuscular function of these children is essential to identify the trajectory of changes in skeletal muscle and to prescribe therapeutic exercise and monitor its impact. Therefore, this review aims to (a) define fundamental properties of skeletal muscle; (b) highlight methods to quantify muscle strength, size, and neuromuscular activation; (c) describe mechanisms that contribute to muscle strength and gross motor performance in children; (d) recommend clinical assessment measures; and (e) illustrate comprehensive muscle assessment in children using examples of sickle cell disease and musculoskeletal sarcoma.

Ultrasound Measurement of Rectus Femoris Muscle Parameters for Discriminating Sarcopenia in Community-Dwelling Adults

OBJECTIVES

Sarcopenia patients require more medical attention and caretaking. As such, early detection of sarcopenia and appropriate interventions are crucial for decreasing medical costs and meeting the challenges of aging populations. The aim of the present study was to develop a reliable and accurate model to estimate muscle mass using ultrasound-derived parameters from the rectus femoris (RF), referenced by dual-energy X-ray absorptiometry.

METHODS

Cross-sectional study was performed. The study patients were recruited by Taipei Veterans General Hospital (No. 2016-07-013C) between 2016 and 2019. A total of 91 community-dwelling adults (35 men and 56 women) were enrolled in this study. Ultrasound measurements of RF muscle thickness (MT), cross-sectional area (CSA), and muscle volume (MV) were performed in B-mode. Muscle strength and physical performance were also examined. Multivariate linear regression was used to build models for the prediction of appendicular skeletal muscle index (ASMI) based on MT, CSA, and MV values. The accuracy of ultrasound RF measurements for predicting sarcopenia was evaluated by using receiver operating characteristic (ROC) curve analysis.

RESULTS

The regression equations used for ASMI prediction (adjusted body mass index, sex, and leg length) had high precision and low error. Moreover, the MV model results were close to those of the CSA model and higher than those of the MT model. The ROC analysis showed that both MV and CSA had excellent discrimination when assessing sarcopenia (AUC = 0.83 and 0.81, respectively), whereas MT showed acceptable discrimination (AUC = 0.73).

CONCLUSIONS

Ultrasound-derived RF MV was accurate when predicting ASMI and diagnosing sarcopenia in community-dwelling adults.

Effect of extracorporeal shock wave therapy on spastic equinus foot in children with unilateral cerebral palsy

Objectives

This study aims to investigate the effects of radial extracorporeal shock wave therapy on selective motor control, spasticity, gross motor function, and balance in children with unilateral cerebral palsy.

Methods

This randomised controlled study recruited 34 children aged 7–9 with spastic unilateral cerebral palsy. They were randomly allocated to either the control or study group. Both groups undertook traditional exercises for 12 weeks. The study group received shock waves (one session/week) on the calf muscle (1500 shocks, frequency of 4 Hz, energy of 0.030 mJ/mm²). All children were evaluated at baseline and after 12 weeks using the Modified Ashworth Scale, a Biodex System 4 isokinetic dynamometer, dimensions D (standing) and E (walking) of the Gross Motor Function Measure – 88, the Trost Selective Motor Control test, and the single leg standing test.

Results

Mixed analysis of variance and Mann–Whitney results showed significant improvement in eccentric peak torque, torque threshold angles, gross motor function, selective motor control, and balance in the study group compared with the control group (p < 0.05).

Conclusions

Shock wave therapy may be a valuable instrument for reducing spasticity, improving the ability to isolate and control movement, and consequently, improving balance and gross motor function in children with unilateral cerebral palsy.

Relationship between ankle function and walking ability for children and young adults with cerebral palsy: A systematic review of deficits and targeted interventions

BACKGROUND

A primary goal of treatment for children with cerebral palsy is improved walking ability to allow for a more active and independent lifestyle. With the importance of ankle function to walking ability, and the deficits in ankle function associated with cerebral palsy, there is good rationale for targeting this joint in an effort to improve walking ability for this population.

RESEARCH QUESTION

How do deficits and targeted interventions of the ankle joint influence walking ability in children with cerebral palsy?

METHODS

A specific search criteria was used to identify articles that either (1) provided information on the relationship between ankle function and walking ability or (2) investigated the effect of a targeted ankle intervention on walking ability in cerebral palsy. PubMed, Embase, CINAHL, and Web of Science databases were searched from 1980-April, 2020. Resulting citations were compared against a prospective set of inclusion and exclusion criteria. Data relevant to the original research question was extracted, and the level of evidence for each intervention study was scored. Interpretation was focused on specific, pre-determined mobility measures.

RESULTS

Sixty-one citations met all criteria for data extraction, six of which were observational, and fifty-five of which were interventional. Level of evidence ranged from 2 to 4. Self-selected walking speed was the most common measure of walking ability, while physical activity level was the least common.

SIGNIFICANCE

Ankle function is an important contributor to the walking ability of children with cerebral palsy, and most interventions targeting the ankle seem to demonstrate a benefit on walking ability, but future higher-powered and/or controlled studies are necessary to confirm these findings.

An overview of the effects of whole-body vibration on individuals with cerebral palsy

The purpose of this review is to examine how whole-body vibration can be used as a tool in therapy to help improve common physical weaknesses in balance, bone density, gait, spasticity, and strength experienced by individuals with cerebral palsy. Cerebral palsy is the most common movement disorder in children, and whole-body vibration is quickly becoming a potential therapeutic tool with some advantages compared to traditional therapies for individuals with movement disorders. The advantages of whole-body vibration include less strain and risk of injury, more passive training activity, and reduced time to complete an effective therapeutic session, all of which are appealing for populations with physiological impairments that cause physical weakness, including individuals with cerebral palsy. This review involves a brief overview of cerebral palsy, whole-body vibration's influence on physical performance measures, its influence on physical performance in individuals with cerebral palsy, and then discusses the future directions of whole-body vibration therapy in the cerebral palsy population.

Reliability of Processing 3-D Freehand Ultrasound Data to Define Muscle Volume and Echo-intensity in Pediatric Lower Limb Muscles with Typical Development or with Spasticity

This investigation assessed the processer reliability of estimating muscle volume and echo-intensity of the rectus femoris, tibialis anterior and semitendinosus. The muscles of 10 typically developing children (8.15 [1.40] y) and 15 children with spastic cerebral palsy (7.67 [3.80] y; Gross Motor Function Classification System I = 5, II = 5, III = 5) were scanned with 3-D freehand ultrasonography. For the intra-processer analysis, the intra-class correlations coefficients (ICCs) for muscle volume ranged from 0.943-0.997, with relative standard errors of measurement (SEM%) ranging from 1.24%-8.97%. For the inter-processer analysis, these values were 0.853 to 0.988 and 3.47% to 14.02%, respectively. Echo-intensity had ICCs >0.947 and relative SEMs <4% for both analyses. Muscle volume and echo-intensity can be reliably extracted for the rectus femoris, semitendinosus and tibialis anterior in typically developing children and children with cerebral palsy. The need for a single processer to analyze all data is dependent on the size of the expected changes or differences.

Reliability of Shear Wave Elastography and Ultrasound Measurement in Children with Unilateral Spastic Cerebral Palsy

In clinical practice, few data exist on the feasibility of performing reliable shear wave elastography (SWE) and ultrasonography (US) measurements in spastic muscles of children with cerebral palsy (CP). Ten children with unilateral CP took part in SWE and US assessment of the tibialis anterior and medialis gastrocnemius muscles during two sessions separated by a 1-wk interval. Intra- and inter-investigator reliability of shear modulus (µ) and muscle thickness (MT) measurements, at neutral and maximal dorsiflexion angles on both legs, was assessed by two investigators with different levels of experience. Reliability was assessed with the coefficient of variation (CV), standard error of measurement and intra-class correlation coefficient (ICC). Reliability of the µ measurement was insufficient, regardless of angle position (CV >10% and >20% for neutral and maximal dorsiflexion angles, respectively). The intra- and inter-investigator reliability of MT measurements was good (CV >10%, ICC >0.74) for both muscles in both legs. SWE measurements must be performed using a rigorous standardized protocol while MT should be considered an important parameter to monitor change in muscle morphology.

An Analytical Insight Into How Walking Speed and Spatial and Temporal Symmetry Are Related to Ankle Dysfunctions in Children With Hemiplegic Cerebral Palsy

OBJECTIVE

The aim of the study was to identify the major determining factors among ankle dysfunctions for walking speed and symmetry in children with hemiplegic cerebral palsy.

DESIGN

This was a prospective analysis that included 52 children with hemiplegic cerebral palsy, aged between 5 and 8 yrs, had mild spasticity, and were functioning at Gross Motor Function Classification System level I or II. The dorsiflexor and plantar flexor strength, dynamic spasticity (represented by gastrocnemius muscle lengthening velocity during stance phase), plantar flexors stiffness, ankle joint position sense, and walking performance (spatiotemporal parameter) were assessed.

RESULTS

The least absolute shrinkage and selection operator regression analyses showed that the dorsiflexor strength of the paretic limb was the major determining factor of walking speed (R2 = 0.38, P < 0.001). Dynamic spasticity of the plantar flexors explained a portion of the variance in walking speed (R2 = 0.15, P < 0.001) and the highest portion of the variance in spatial walking symmetry (R2 = 0.18, P = 0.002). In addition, the ankle joint position sense was the primary determinant of temporal walking symmetry (R2 = 0.10, P = 0.021).

CONCLUSIONS

In children with hemiplegic cerebral palsy, walking speed is mostly influenced by dorsiflexor muscle strength, temporal walking symmetry is associated with the joint position sense, whereas spatial walking symmetry is explicated by the dynamic spasticity of the plantar flexor muscles.

Machine learning analysis to predict the need for ankle foot orthosis in patients with stroke

We investigated the potential of machine learning techniques, at an early stage after stroke, to predict the need for ankle–foot orthosis (AFO) in stroke patients. We retrospectively recruited 474 consecutive stroke patients. The need for AFO during ambulation (output variable) was classified according to the Medical Research Council (MRC) score for the ankle dorsiflexor of the affected limb. Patients with an MRC score of < 3 for the ankle dorsiflexor of the affected side were considered to require AFO, while those with scores ≥ 3 were considered not to require AFO. The following demographic and clinical data collected when patients were transferred to the rehabilitation unit (16.20 ± 6.02 days) and 6 months after stroke onset were used as input data: age, sex, type of stroke (ischemic/hemorrhagic), motor evoked potential data on the tibialis anterior muscle of the affected side, modified Brunnstrom classification, functional ambulation category, MRC score for muscle strength for shoulder abduction, elbow flexion, finger flexion, finger extension, hip flexion, knee extension, and ankle dorsiflexion of the affected side. For the deep neural network model, the area under the curve (AUC) was 0.887. For the random forest and logistic regression models, the AUC was 0.855 and 0.845, respectively. Our findings demonstrate that machine learning algorithms, particularly the deep neural network, are useful for predicting the need for AFO in stroke patients during the recovery phase.

Measuring skeletal muscle morphology and architecture with imaging modalities in children with cerebral palsy: a scoping review

AIM

To investigate the use of ultrasound and magnetic resonance imaging (MRI) methodologies to assess muscle morphology and architecture in children with cerebral palsy (CP).

METHOD

A scoping review was conducted with systematic searches of Medline, Embase, Scopus, Web of Science, PubMed, and PsycInfo for all original articles published up to January 2019 utilizing ultrasound and/or MRI to determine morphological and architectural properties of lower limb skeletal muscle in children with CP.

RESULTS

Eighty papers used ultrasound (n=44), three-dimensional ultrasound (n=16), or MRI (n=20) to measure at least one muscle parameter in children and adolescents with CP. Most research investigated single muscles, predominantly the medial gastrocnemius muscle, included children classified in Gross Motor Function Classification System levels I (n=62) and II (n=65), and assessed fascicle length (n=35) and/or muscle volume (n=35). Only 21 papers reported reliability of imaging techniques. Forty-six papers assessed measures of Impairment (n=39), Activity (n=24), and Participation (n=3).

INTERPRETATION

Current research study design, variation in methodology, and preferences towards investigation of isolated muscles may oversimplify the complexities of CP muscle but provide a foundation for the understanding of the changes in muscle parameters in children with CP.

WHAT THIS PAPER ADDS

Current evidence is biased towards the medial gastrocnemius muscle and more functionally able children with cerebral palsy (CP). Variations in imaging techniques and joint positioning limit comparisons between studies. Clinimetric testing of parameters of CP muscle is not always considered. Assessment of parameter(s) of muscle with measures of participation is sparse.

Is shortening of Tibialis Anterior in addition to calf muscle lengthening required to improve the active dorsal extension of the ankle joint in patients with Cerebral Palsy?

INTRODUCTION

Shortening of the tibialis anterior tendon (TATS) has been shown to improve the ankle dorsiflexion in swing following the calf muscle lengthening procedure (CMLP) in patients with cerebral palsy (CP). Others have reported the similar improvements following CMLP but without TATS. However there are no studies comparing both procedures. Therefore the purpose of the study was to compare the ankle dorsiflexion in swing and foot position in the sagittal plane during gait following TATS and CMLP to that of CMLP alone.

MATERIALS AND METHODS

A retrospective study was carried out in CP patients who presented with fixed equinus deformity. They were grouped into unilateral CP and bilateral CP. Depending on the procedures, each group was again subdivided into subgroup CMLP only and subgroup CMLP and TATS (CMLPTATS). All patients were subjected to pre and postoperative clinical and gait analysis.

RESULTS

44 feet in 44 patients were included in the study. Of these, 24 feet (24 patients) belonged to unilateral and 20 feet (20 patients) to bilateral CP group. The mean age of the patients at surgery was 11.5 years (6.0 - 29.0) in the unilateral CP group and 10.5 years (5.0-34.0) in the bilateral CP group. In the unilateral CP group, 12 feet belonged to subgroup CMLP and 12 to subgroup CMLPTATS with a mean equinus contracture of 7.5° in both subgroups. In bilateral CP group, 11 feet belonged to subgroup CMLP with a mean equinus contracture of 5° and 9 to subgroup CMLPTATS, with a mean equinus contracture of 10°. The subgroups did not vary significantly in the demographics, anthropometry, kinematics and kinetics of ankle joint preoperatively. The mean follow up time was 19.7 months. The surgery produced significant changes in both groups and subgroups. However, none of the relevant gait parameters were significantly different between groups and subgroups.

SIGNIFICANCE

Adding TATS to CMLP, compared to CMLP alone did not improve ankle dorsiflexion in swing and the foot position more than CMLP alone.

The size and echogenicity of the tibialis anterior muscle is preserved in both limbs in young children with unilateral spastic cerebral palsy

PURPOSE

The primary of this study was to compare the volume, length, echo intensity, and growth rate of the medial gastrocnemius (MG) and tibialis anterior (TA) muscle of both limbs (more-involved and less-involved) in children with unilateral spastic cerebral palsy (USCP), with those of an age-matched typically developing (TD) group. A secondary aim in the USCP group was to explore the associations between these muscle parameters and discrete ankle positions during phase of gait.

METHODS

Muscle parameters were assessed using 3D ultrasound. Maximal ankle dorsiflexion in stance and swing during walking were determined from 2D video analysis. Group differences in muscle size and echo intensity were assessed using a two-way analysis of covariance (age-by-group), with the interaction term used to compare muscle growth rates. Associations between muscle parameters and maximal ankle dorsiflexion in stance and swing were assessed using backwards multiple linear regression analyses.

RESULTS

The MG of both limbs in children with USCP had signs of impaired muscle development (smaller volume and length, higher echo intensity and lower growth rate). There was no evidence of impaired muscle development of TA between limbs or compared the TD children. Tibialis anterior volume, length, echo intensity and MG volume explained 66% and 83% of the variance in maximal ankle dorsiflexion position in the stance and swing phases of walking, respectively.

CONCLUSIONS

Unlike the MG, the TA volume and growth rate in children with USCP are equivalent between limbs and compared to TD children. For the more-involved limb only, TA volume, length, and echo intensity appear associated with maximal ankle dorsiflexion during walking and represent important muscle parameters that could be targeted in with early exercise therapy.Implications for rehabilitationTibialis anterior (TA) size and echogenicity appear normal in both limbs in young children with unilateral spastic cerebral palsy (USCP); findings that could indicate sufficient mechanical stimulus and muscle anabolism to maintain normal muscle growth.Tibialis anterior size and echogenicity are associated with maximal ankle dorsiflexion in both stance and swing phase of walking in young children with USCP; though such relations appear isolated to the more-involved limb.Early therapeutic interventions that target TA are likely to be successful in maintaining muscle size and may offset the negative effects of medial gastrocnemius atrophy in the development of fixed ankle equinus of the more-involved limb and improve ankle positioning during gait.

Architectural Changes in Superficial and Deep Compartments of the Tibialis Anterior During Electrical Stimulation Over Different Sites

Electrical stimulation is widely used in rehabilitation to prevent muscle weakness and to assist the functional recovery of neural deficits. Its application is however limited by the rapid development of muscle fatigue due to the non-physiological motor unit (MU) recruitment. This issue can be mitigated by interleaving muscle belly (mStim) and nerve stimulation (nStim) to distribute the temporal recruitment among different MU groups. To be effective, this approach requires the two stimulation modalities to activate minimally-overlapped groups of MUs. In this manuscript, we investigated spatial differences between mStim and nStim MU recruitment through the study of architectural changes of superficial and deep compartments of tibialis anterior (TA). We used ultrasound imaging to measure variations in muscle thickness, pennation angle, and fiber length during mStim, nStim, and voluntary (Vol) contractions at 15% and 25% of the maximal force. For both contraction levels, architectural changes induced by nStim in the deep and superficial compartments were similar to those observed during Vol. Instead, during mStim superficial fascicles underwent a greater change compared to those observed during nStim and Vol, both in absolute magnitude and in their relative differences between compartments. These observations suggest that nStim results in a distributed MU recruitment over the entire muscle volume, similarly to Vol, whereas mStim preferentially activates the superficial muscle layer. The diversity between spatial recruitment of nStim and mStim suggests the involvement of different MU populations, which justifies strategies based on interleaved nerve/muscle stimulation to reduce muscle fatigue during electrically-induced contractions of TA.

Impact of Altered Gastrocnemius Morphometrics and Fascicle Behavior on Walking Patterns in Children With Spastic Cerebral Palsy

Spastic cerebral palsy (SCP) affects neural control, deteriorates muscle morphometrics, and may progressively impair functional walking ability. Upon passive testing, gastrocnemius medialis (GM) muscle bellies or fascicles are typically shorter, thinner, and less extensible. Relationships between muscle and gait parameters might help to understand gait pathology and pathogenesis of spastic muscles. The current aim was to link resting and dynamic GM morphometrics and contractile fascicle behavior (both excursion and velocity) during walking to determinants of gait. We explored the associations between gait variables and ultrasonography of the GM muscle belly captured during rest and during gait in children with SCP [n = 15, gross motor function classification system (GMFCS) levels I and II, age: 7–16 years] and age-matched healthy peers (n = 17). The SCP children’s plantar flexors were 27% weaker. They walked 12% slower with more knee flexion produced 42% less peak ankle push-off power (all p < 0.05) and 7/15 landed on their forefoot. During the stance phase, fascicles in SCP on average operated on 9% shorter length (normalized to rest length) and displayed less and slower fascicle shortening (37 and 30.6%, respectively) during push-off (all p ≤ 0.024). Correlation analyses in SCP patients revealed that (1) longer-resting fascicles and thicker muscle bellies are positively correlated with walking speed and negatively to knee flexion (r = 0.60–0.69, p < 0.0127) but not to better ankle kinematics; (2) reduced muscle strength was associated with the extent of eccentric fascicle excursion (r = −0.57, p = 0.015); and (3) a shorter operating length of the fascicles was correlated with push-off power (r = −0.58, p = 0.013). Only in controls, a correlation (r = 0.61, p = 0.0054) between slower fascicle shortening velocity and push-off power was found. Our results indicate that a thicker gastrocnemius muscle belly and longer gastrocnemius muscle fascicles may be reasonable morphometric properties that should be targeted in interventions for individuals with SCP, since GM muscle atrophy may be related to decreases in walking speed and undesired knee flexion during gait. Furthermore, children with SCP and weaker gastrocnemius muscle may be more susceptible to chronic eccentric muscle overloading. The relationship between shorter operating length of the fascicles and push-off power may further support the idea of a compensation mechanism for the longer sarcomeres found in children with SCP. Nevertheless, more studies are needed to support our explorative findings.

The effect of ankle Kinesio™ taping on ankle joint biomechanics during unilateral balance status among collegiate athletes with chronic ankle sprain

OBJECTIVES

To determine the effects of ankle Kinesio-taping (KT) on postural sway, lower limb ROM, and muscle activity during a unilateral balance tasks.

DESIGN

Case control study design.

SETTING

Data were collected at the human movement analysis laboratory.

PARTICIPANTS

30 collegiate athletes with chronic ankle sprain (11 females and 19 males, 23.91 ± 2.58 years).

MAIN OUTCOME MEASURE

Hip, knee and ankle joints ranges of motion (ROMs); postural sway area and velocities in both anteroposterior and mediolateral directions; and muscular activity amplitudes (% peak) of lateral and medial gastrocnemius, tibialis anterior and peroneus longus in a 20s single leg balance test in two non-taped (control) and KT (intervention) conditions.

RESULTS

Significant decrease observed in ankle lateral ROM (p = 0.048, d = 0.52), mediolateral postural sway velocity (p = 0.029, d = 1.25), and peroneus longus activity amplitudes (p = 0.042, d = 0.55) after KT application.

CONCLUSION

Acute application of KT among athletes with chronic ankle instability could provide lateral mechanical support to the ankle, potentially decreasing the velocity of frontal plane sway, and decreasing the magnitude of muscle activation. These data suggest that KT may be beneficial for improving static joint stability among individuals with chronic ankle sprain, and thus could be considered an option to allow safe return-to-activity.

Alterations in Muscle Architecture: A Review of the Relevance to Individuals After Limb Salvage Surgery for Bone Sarcoma

Osteosarcoma and Ewing's sarcoma are the most common primary bone malignancies affecting children and adolescents. Optimal treatment requires a combination of chemotherapy and/or radiation along with surgical removal when feasible. Advances in multiple aspects of surgical management have allowed limb salvage surgery (LSS) to supplant amputation as the most common procedure for these tumors. However, individuals may experience significant impairment after LSS, including deficits in range of motion and strength that limit function and impact participation in work, school, and the community, ultimately affecting quality of life. Muscle force and speed of contraction are important contributors to normal function during activities such as gait, stairs, and other functional tasks. Muscle architecture is the primary contributor to muscle function and adapts to various stimuli, including periods of immobilization-protected weightbearing after surgery. The impacts of LSS on muscle architecture and how adaptations may impact deficits within the rehabilitation period and into long-term survivorship is not well-studied. The purpose of this paper is to [1] provide relevant background on bone sarcomas and LSS, [2] highlight the importance of muscle architecture, its measurement, and alterations as seen in other relevant populations and [3] discuss the clinical relevance of muscle architectural changes and the impact on muscle dysfunction in this population. Understanding the changes that occur in muscle architecture and its impact on long-term impairments in bone sarcoma survivors is important in developing new rehabilitation treatments that optimize functional outcomes.

Corticospinal excitability of tibialis anterior and soleus differs during passive ankle movement

The purpose of this study was to assess corticospinal excitability of soleus (SOL) and tibialis anterior (TA) at a segmental level during passive ankle movement. Four experimental components were performed to assess the effects of passive ankle movement and muscle length on corticospinal excitability (MEP/M_max) at different muscle lengths, subcortical excitability at the level of lumbar spinal segments (LEP/M_max), intracortical inhibition (SICI) and facilitation (ICF), and H-reflex in SOL and TA. In addition, the degree of fascicle length changes between SOL and TA was assessed in a subpopulation during passive ankle movement. Fascicles shortened and lengthened with joint movement during passive shortening and lengthening of SOL and TA to a similar degree (p < 0.001). Resting motor threshold was greater in SOL compared to TA (p ≤ 0.014). MEP/M_max was facilitated in TA during passive shortening relative to the static position (p ≤ 0.023) and passive lengthening (p ≤ 0.001), but remained similar during passive ankle movement in SOL (p ≥ 0.497), regardless of muscle length at the point of stimulus (p = 0.922). LEP/M_max (SOL: p = 0.075, TA: p = 0.071), SICI (SOL: p = 0.427, TA: p = 0.540), and ICF (SOL: p = 0.177, TA: p = 0.777) remained similar during passive ankle movement. H-reflex was not different across conditions in TA (p = 0.258), but was reduced during passive lengthening compared to shortening in SOL (p = 0.048). These results suggest a differential modulation of corticospinal excitability between plantar and dorsiflexors during passive movement. The corticospinal behaviour observed might be mediated by an increase in corticospinal drive as a result of reduced afferent input during muscle shortening and appears to be flexor-biased.

Muscle volume reconstruction from several short magnetic resonance imaging sequences

The gold standard to determine muscle morphological parameters is magnetic resonance imaging (MRI). To measure large muscles like the vastus lateralis (VL) in one sequence, scanners with a large field of view (FOV) and a high flux density are needed. However, large scanners are expensive and not always available. The purpose of the current study was to develop a marker-based approach to reconstruct the VL from several separate MRI sequences, acquired with a low-field MRI scanner. The VL muscle of 21 volunteers was marked at one-third and two-third of thigh length using fish oil capsules. Three consecutive MRI sequences (i.e. proximal, medial and distal part) of the thigh were captured between the markers and the muscle insertion and origin. After a manual segmentation of the VL the muscle was reconstructed using the developed approach. The muscle volume, maximal anatomical cross-sectional area and length were 715.1 ± 93.4 cm³, 34.0 ± 4.0 cm² and 34.4 ± 2.2 cm respectively. The procedure showed an average error between 0.9% and 2.2% for the reconstructed muscle volume, the averaged RMSD between the cross-sectional areas of two overlapping sequences were between 0.80 ± 0.71 cm² and 0.88 ± 0.78 cm². The proposed approach provides an appropriate accuracy for muscle volume assessment, as the estimated error for muscle volume calculation was quite small. The reconstruction quality depends mainly on the proper marker attachment and identification, as well as the spatial resolution of the image sequences. We are confident that the presented method can be used in most investigations regarding muscle morphology.

Reduced corticospinal responses in older compared with younger adults during submaximal isometric, shortening, and lengthening contractions

The aim of this study was to assess differences in motor performance, as well as corticospinal and spinal responses to transcranial magnetic and percutaneous nerve stimulation, respectively, during submaximal isometric, shortening, and lengthening contractions between younger and older adults. Fifteen younger [26 yr (SD 4); 7 women, 8 men] and 14 older [64 yr (SD 3); 5 women, 9 men] adults performed isometric and shortening and lengthening dorsiflexion on an isokinetic dynamometer (5°/s) at 25% and 50% of contraction type-specific maximums. Motor evoked potentials (MEPs) and H reflexes were recorded at anatomical zero. Maximal dorsiflexor torque was greater during lengthening compared with shortening and isometric contractions ( P < 0.001) but was not age dependent ( P = 0.158). However, torque variability was greater in older compared with young adults ( P < 0.001). Background electromyographic (EMG) activity was greater in older compared with younger adults ( P < 0.005) and was contraction type dependent ( P < 0.001). As evoked responses are influenced by both the maximal level of excitation and background EMG activity, the responses were additionally normalized {[MEP/maximum M wave (M_max)]/root-mean-square EMG activity (RMS) and [H reflex (H)/M_max]/RMS}. (MEP/M_max)/RMS and (H/M_max)/RMS were similar across contraction types but were greater in young compared with older adults ( P < 0.001). Peripheral motor conduction times were prolonged in older adults ( P = 0.003), whereas peripheral sensory conduction times and central motor conduction times were not age dependent ( P ≥ 0.356). These data suggest that age-related changes throughout the central nervous system serve to accommodate contraction type-specific motor control. Moreover, a reduction in corticospinal responses and increased torque variability seem to occur without a significant reduction in maximal torque-producing capacity during older age. NEW & NOTEWORTHY This is the first study to have explored corticospinal and spinal responses with aging during submaximal contractions of different types (isometric, shortening, and lengthening) in lower limb musculature. It is demonstrated that despite preserved maximal torque production capacity corticospinal responses are reduced in older compared with younger adults across contraction types along with increased torque variability during dynamic contractions. This suggests that the age-related corticospinal changes serve to accommodate contraction type-specific motor control.

Combining muscle morphology and neuromotor symptoms to explain abnormal gait at the ankle joint level in cerebral palsy

BACKGROUND

Individuals with spastic cerebral palsy (CP) have neuromotor symptoms contributing towards their gait patterns. However, the role of altered muscle morphology alongside these symptoms is yet to be fully investigated.

RESEARCH QUESTION

To what extent can medial gastrocnemius and tibialis anterior volume and echo-intensity, plantar/dorsiflexion strength and selective motor control, plantarflexion spasticity and passive ankle dorsiflexion explain abnormal ankle gait.

METHOD

In thirty children and adolescents with spastic CP (8.6 ± 3.4 y/mo) and ten typically developing peers (9.9 ± 2.4 y/mo), normalised muscle volume and echo-intensity were estimated. Both cohorts also underwent three-dimensional gait analysis, whilst for participants with spastic CP, plantar/dorsi-flexion strength and selective motor control, plantarflexion spasticity and maximum ankle dorsiflexion were also measured. The combined contribution of these parameters towards five clinically meaningful features of gait were evaluated, using backwards multiple regression analyses.

RESULTS

With respect to the typically developing cohort, the participants with spastic CP had deficits in normalised medial gastrocnemius and tibialis anterior volume of 40% and 33%, and increased echo-intensity values of 19% and 16%, respectively. The backwards multiple regression analyses revealed that the combination of reduced ankle dorsiflexion, muscle volume, plantarflexion strength and dorsiflexion selective motor control could account for 12-62% of the variance in the chosen features of gait.

SIGNIFICANCE

The combination of altered muscle morphology and neuromotor symptoms partly explained abnormal gait at the ankle in children with spastic CP. Both should be considered as important measures for informed treatment decision-making, but further work is required to better unravel the complex pathophysiology.

Skeletal Muscle Adaptations and Passive Muscle Stiffness in Cerebral Palsy: A Literature Review and Conceptual Model

This literature review focuses on the primary morphological and structural characteristics, and mechanical properties identified in muscles affected by spastic cerebral palsy (CP). CP is a non-progressive neurological disorder caused by brain damage and is commonly diagnosed at birth. Although the brain damage is not progressive, subsequent neuro-physiological developmental adaptations may initiate changes in muscle structure, function, and composition, causing abnormal muscle activity and coordination. The symptoms of CP vary among patients. However, muscle spasticity is commonly present and is one of the most debilitating effects of CP. Here, we present the current knowledge regarding the mechanical properties of skeletal tissue affected by spastic CP. An increase in sarcomere length, collagen content, and fascicle diameter, and a reduction in the number of satellite cells within spastic CP muscle were consistent findings in the literature. Studies differed, however, in changes in fascicle lengths and fiber diameters. We also present a conceptual mechanical model of fascicle force transmission that incorporates mechanisms that impact both serial and lateral force production, highlighting the connections between the macro and micro structures of muscle to assist in deducing specific mechanisms for property changes and reduced force production.

Medial gastrocnemius structure and gait kinetics in spastic cerebral palsy and typically developing children: A cross-sectional study

To compare medial gastrocnemius muscle-tendon structure, gait propulsive forces, and ankle joint gait kinetics between typically developing children and those with spastic cerebral palsy, and to describe significant associations between structure and function in children with spastic cerebral palsy.A sample of typically developing children (n = 9 /16 limbs) and a sample of children with spastic cerebral palsy (n = 29 /43 limbs) were recruited. Ultrasound and 3-dimensional motion capture were used to assess muscle-tendon structure, and propulsive forces and ankle joint kinetics during gait, respectively.Children with spastic cerebral palsy had shorter fascicles and muscles, and longer Achilles tendons than typically developing children. Furthermore, total negative power and peak negative power at the ankle were greater, while total positive power, peak positive power, net power, total vertical ground reaction force, and peak vertical and anterior ground reaction forces were smaller compared to typically developing children. Correlation analyses revealed that smaller resting ankle joint angles and greater maximum dorsiflexion in children with spastic cerebral palsy accounted for a significant decrease in peak negative power. Furthermore, short fascicles, small fascicle to belly ratios, and large tendon to fascicle ratios accounted for a decrease in propulsive force generation.Alterations observed in the medial gastrocnemius muscle-tendon structure of children with spastic cerebral palsy may impair propulsive mechanisms during gait. Therefore, conventional treatments should be revised on the basis of muscle-tendon adaptations.

Comparison of calf muscle architecture between Asian children with spastic cerebral palsy and typically developing peers

OBJECTIVE

To compare the muscle thickness, fascicle length, and pennation angle of the gastrocnemius, soleus, and tibialis anterior between Asian children with spastic cerebral palsy (CP) and typically developing (TD) peers.

METHODS

This cross-sectional study involved a total of 72 children with hemiplegic CP (n = 24), and diplegic CP (n = 24) and their TD peers (n = 24). Muscle architecture was measured at rest using ultrasound. Clinical measures included gross motor function and a modified Ashworth scale.

RESULTS

The thicknesses of the tibialis anterior and medial gastrocnemius muscles were smaller in the affected calf of children with CP (p<0.05) than in those of their TD peers. Additionally, the lengths of the lateral gastrocnemius and soleus fascicle were shorter (p<0.05) in children with diplegic CP than in their TD peers. The fascicle length was shorter in the affected calf of children with CP (p<0.05) than in the calves of their TD peers or the unaffected calf of children with hemiplegic CP. However, the length of the lateral gastrocnemius fascicle was similar between the two legs of children with hemiplegic CP. The pennation angles of the medial gastrocnemius and soleus muscles were larger (p<0.05) in the affected calf in children with hemiplegic CP than in the calves of their TD peers. The fascicle length of the lateral gastrocnemius and the thickness of the soleus muscle were positively correlated with gross motor function scores in children with CP (p<0.05).

CONCLUSIONS

Muscle thickness and fascicle length were lower in the affected tibialis anterior, gastrocnemius, and soleus in children with spastic CP. These changes may limit the ability to stand and walk, and indicate a need to strengthen the affected muscle.

Can kinesio tape be used as an ankle training method in the rehabilitation of the stroke patients?

OBJECTIVE

To investigate the effects of the kinesio tape application to the tibialis anterior on rehabilitation outcomes of the stroke patients.

DESIGN AND SETTING

Twenty patients with stroke were allocated into two groups: the first group of ten patients was assigned to receive kinesio tape in addition to the conventional rehabilitation program while a second group of 10 patients was assigned to receive a conventional rehabilitation program only.

MAIN OUTCOME MEASURES

The clinical variables and health-related quality of life (HRQoL) were evaluated at baseline and at the end of the forth week.

RESULTS

The present study showed that kinesio tape application to the tibialis anterior has significant effects on motor recovery of the lower extremity, spasticity, ambulation capacity, HRQoL and gait compared to the control group and baseline.

CONCLUSIONS

The results of this study suggest that kinesio tape can be used as an ankle training method.

A cohort study of tibialis anterior tendon shortening in combination with calf muscle lengthening in spastic equinus in cerebral palsy

The aim of this study was to evaluate the outcome of combined tibialis anterior tendon shortening (TATS) and calf muscle-tendon lengthening (CMTL) in spastic equinus. Prospectively collected data was analysed in 26 patients with hemiplegic (n=13) and diplegic (n=13) cerebral palsy (CP) (GMFCS level I or II, 14 males, 12 females, age range 10-35 years; mean 16.8 years). All patients had pre-operative 3D gait analysis and a further analysis at a mean of 17.1 months (±5.6months) after surgery. None was lost to follow-up. Twenty-eight combined TATS and CMTL were undertaken and 19 patients had additional synchronous multilevel surgery. At follow-up 79% of patients had improved foot positioning at initial contact, whilst 68% reported improved fitting or reduced requirement of orthotic support. Statistically significant improvements were seen in the Movement Analysis Profile for ankle dorsi-/plantarflexion (4.15°, p=0.032), maximum ankle dorsiflexion during swing phase (11.68°, p<0.001), and Edinburgh Visual Gait Score (EVGS) (4.85, p=0.014). Diplegic patients had a greater improvement in the EVGS than hemiplegics (6.27 -vs- 2.21, p=0.024). The originators of combined TATS and CMTL showed that it improved foot positioning during gait. The present study has independently confirmed favourable outcomes in a similar patient population and added additional outcome measures, the EVGS, foot positioning at initial contact, and maximum ankle dorsiflexion during swing phase. Study limitations include short term follow-up in a heterogeneous population and that 19 patients had additional surgery. TATS combined with CMTL is a recommended option for spastic equinus in ambulatory patients with CP.

Foot Dorsiflexion Velocity and Torque Variance Explained through Architectural and Electromyography Variables Comparing Elders and Stroke Survivors

OBJECTIVES

The objectives of this study are to analyze the relationship between electromyographic variables, tibialis anterior (TA) architecture, and functional variables (torque and kinematic variables) during maximal isometric and isotonic foot dorsiflexion (FD), and to compare the described relationship between stroke survivors (SS) and healthy elders (HE).

METHODS

Twenty-eight participants (14 SS and 14 HE) over 65 years old performed 3 maximal isometric and isotonic FDs parameterized by ultrasound, electromyography (EMG), inertial sensor, and load cell. Common variables (TA) include muscle thickness, pennation angle, muscle activation, and EMG area under the curve. Specific variables include torque for isometric FD, and velocity and displacement for isotonic FD.

RESULTS

There are significant differences in all variables when comparing the 2 groups. Among these differences, all the outcome variables show higher values in the HE group than in the SS group. However, in the 2 dependent variables obtained during isometric FD (median and maximal torques), the independent variables can explain nearly 70% of the variability of the dependent variable, with values of 68.4%-71.9% for SS and 69.1%-70.2% for HE. Similar results were found during isotonic FD.

CONCLUSIONS

Even though the TA of the SS group is capable of generating less force (isometric FD) and is slower (isotonic FD) than that of the HE group, the contribution of the independent variables (muscle activation, pennation angle,and muscle thickness) can explain the same proportion of variability of the dependent variables.

Tibialis anterior analysis from functional and architectural perspective during isometric foot dorsiflexion: a cross-sectional study of repeated measures

Background

The purpose of the present study is to establish the relationship and degree of contribution between torque and sonomiography variables (pennation angle – muscle thickness), and electromyography variables (EMG_{AreaUnderCurve} – EMG_MaximalPeak) of the tibialis anterior muscle during (TA) maximal and relative isometric foot dorsiflexion (IFD). Secondary aim: To determine the measurement’s reliability.

Methods

Cross-sectional study. 31 participants (15 men; 16 women) performed IFD at different intensities (100, 75, 50, and 25 %) of the maximal voluntary contraction (MVC) (three times for each intensity). Outcome variables: To determine the torque, pennation angle, muscle thickness, EMG_MaximalPeak, and EMG_{AreaUnderCurve}. Statistical analysis: In order to test the measurement’s reliability, Cronbach’s alpha and standard error of the measurement were determined. An inferential analysis was carried out using Pearson correlations(r). For each contraction intensity, a multiple regression analysis was performed, where the dependent variable was torque and the independent variables were EMG_{AreaUnderCurve}, EMG_MaximalPeak, muscle thickness and pennation angle.

Results

All outcome variables show excellent reliability. The highest correlation value was 0.955 (thickness 100 % – thickness 25 %). R² values ranged from 0.713 (100 % MVC) to 0.588 (25 % MVC).

Conclusion

The outcome variables demonstrated excellent reliability in terms of measuring IFD at different intensities. The correlations between all outcome variables were moderate-to-strong. TA functional and architectural variables have a significant impact on the torque variance during IFD at different intensities.

Gait analysis of children with spastic hemiplegic cerebral palsy

An experiment was carried out in the key laboratory for Technique Diagnosis and Function Assessment of Winter Sports of China to investigate the differences in gait characteristics between healthy children and children with spastic hemiplegic cerebral palsy. With permission of their parents, 200 healthy children aged 3 to 6 years in the kindergarten of Northeastern University were enrolled in this experiment. Twenty children aged 3 to 6 years with spastic hemiplegic cerebral palsy from Shengjing Hospital, China were also enrolled in this experiment. Standard data were collected by simultaneously recording gait information from two digital cameras. DVracker was used to analyze the standard data. The children with hemiplegic cerebral palsy had a longer gait cycle, slower walking speed, and longer support phase than did the healthy children. The support phase was longer than the swing phase in the children with hemiplegic cerebral palsy. There were significant differences in the angles of the hip, knee, and ankle joint between children with cerebral palsy and healthy children at the moment of touching the ground and buffering, and during pedal extension. Children with hemiplegic cerebral palsy had poor motor coordination during walking, which basically resulted in a short stride, high stride frequency to maintain speed, more obvious swing, and poor stability.

Gait training facilitates central drive to ankle dorsiflexors in children with cerebral palsy

Foot drop and toe walking are frequent concerns in children with cerebral palsy. The main underlying cause of these problems is early damage and lack of maturation of the corticospinal tract. In the present study we investigated whether 4 weeks of daily treadmill training with an incline may facilitate corticospinal transmission and improve the control of the ankle joint in children with cerebral palsy. Sixteen children with cerebral palsy (Gross Motor Classification System I:6, II:6, III:4) aged 5-14 years old, were recruited for the study. Evaluation of gait ability and intramuscular coherence was made twice before and twice after training with an interval of 1 month. Gait kinematics were recorded by 3D video analysis during treadmill walking with a velocity chosen by the child at the first evaluation. Foot pressure was measured by force sensitive foot soles during treadmill and over ground walking. EMG-EMG coherence was calculated from two separate electrode recordings placed over the tibialis anterior muscle. Training involved 30 min of walking daily on a treadmill with an incline for 30 days. Gait training was accompanied by significant increases in gait speed, incline on the treadmill, the maximal voluntary dorsiflexion torque, the number and amplitude of toe lifts late in the swing phase during gait and the weight exerted on the heel during the early stance phase of the gait cycle. EMG-EMG coherence in the beta and gamma frequency bands recorded from tibialis anterior muscle increased significantly when compared to coherence before training. The largest changes in coherence with training were observed for children <10 years of age. Importantly, in contrast to training-induced EMG increases, the increase in coherence was maintained at the follow-up measurement 1 month after training. Changes in the strength of coherence in the beta and gamma band were positively correlated with improvements in the subjects' ability to lift the toes in the swing phase. These data show that daily intensive gait training increases beta and gamma oscillatory drive to ankle dorsiflexor motor neurons and that it improves toe lift and heel strike in children with cerebral palsy. We propose that intensive gait training may produce plastic changes in the corticospinal tract, which are responsible for improvements in gait function.

Correlation between architectural variables and torque in the erector spinae muscle during maximal isometric contraction

This study analysed whether a significant relationship exists between the torque and muscle thickness and pennation angle of the erector spinae muscle during a maximal isometric lumbar extension with the lumbar spine in neutral position. This was a cross-sectional study in which 46 healthy adults performed three repetitions for 5 s of maximal isometric lumbar extension with rests of 90 s. During the lumbar extensions, bilateral ultrasound images of the erector spinae muscle (to measure pennation angle and muscle thickness) and torque were acquired. Reliability test analysis calculating the internal consistency (Cronbach's alpha) of the measure, correlation between pennation angle, muscle thickness and torque extensions were examined. Through a linear regression the contribution of each independent variable (muscle thickness and pennation angle) to the variation of the dependent variable (torque) was calculated. The results of the reliability test were: 0.976-0.979 (pennation angle), 0.980-0.980 (muscle thickness) and 0.994 (torque). The results show that pennation angle and muscle thickness were significantly related to each other with a range between 0.295 and 0.762. In addition, multiple regression analysis showed that the two variables considered in this study explained 68% of the variance in the torque. Pennation angle and muscle thickness have a moderate impact on the variance exerted on the torque during a maximal isometric lumbar extension with the lumbar spine in neutral position.

Relationship of moderate and low isometric lumbar extension through architectural and muscular activity variables: a cross sectional study

BACKGROUND

No study relating the changes obtained in the architecture of erector spinae (ES) muscle were registered with ultrasound and different intensities of muscle contraction recorded by surface EMG (electromyography) on the ES muscle was found. The aim of this study was analyse the relationship in the response of the ES muscle during isometric moderate and light lumbar isometric extension considering architecture and functional muscle variables.

METHODS

Cross-sectional study. 46 subjects (52% men) with a group mean age of 30.4 (±7.78). The participants developed isometric lumbar extension while performing moderate and low isometric trunk and hip extension in a sitting position with hips flexed 90 degrees and the lumbar spine in neutral position. During these measurements, electromyography recordings and ultrasound images were taken bilaterally. Bilaterally pennation angle, muscle thickness, torque and muscle activation were measured. This study was developed at the human movement analysis laboratory of the Health Science Faculty of the University of Malaga (Spain).

RESULTS

Strong and moderate correlations were found at moderate and low intensities contraction between the variable of the same intensity, with correlation values ranging from 0.726 (Torque Moderate - EMG Left Moderate) to 0.923 (Angle Left Light - Angle Right Light) (p < 0.001). This correlation is observed between the variables that describe the same intensity of contraction, showing a poor correlation between variables of different intensities.

CONCLUSION

There is a strong relationship between architecture and function variables of ES muscle when describe an isometric lumbar extension at light or moderate intensity.

Muscle plasticity and ankle control after repetitive use of a functional electrical stimulation device for foot drop in cerebral palsy

BACKGROUND/OBJECTIVES

The primary goal was to determine whether repetitive functional electrical stimulation (FES) for unilateral foot drop increases tibialis anterior (TA) muscle size compared with an untreated baseline and the contralateral side in cerebral palsy (CP). Secondary goals were to determine whether positive changes in muscle size and gait, if found, accumulated during the 3 intervals during which participants used the device. FES devices differ from traditional orthoses that often restrict muscle activation and may exacerbate weakness, promote continued dependence on orthoses, or precipitate functional decline.

METHODS

Participants were 14 independent ambulators with inadequate dorsiflexion in swing, with a mean age of 13.1 years, evaluated before and after the 3-month baseline, 1-month device accommodation, 3-month primary intervention, and 3-month follow-up phases. The FES device (WalkAide) stimulated the common fibular nerve to dorsiflex the ankle and evert the foot while monitoring use. TA muscle ultrasound, gait velocity, and ankle kinematic data for barefoot and device conditions are reported.

RESULTS

Ultrasound measures of TA anatomic cross-sectional area and muscle thickness increased in the intervention compared with baseline and with the contralateral side and were maintained at follow-up. Maximum ankle dorsiflexion decreased at baseline but improved or was maintained during the intervention phase with and without the device, respectively. Muscle size gains were preserved at follow-up, but barefoot ankle motion returned to baseline values.

CONCLUSIONS

This FES device produced evidence of use-dependent muscle plasticity in CP. Permanent improvements in voluntary ankle control after repetitive stimulation were not demonstrated.