Changes of calf muscle-tendon biomechanical properties induced by passive-stretching and active-movement training in children with cerebral palsy

Eight weeks of proprioceptive neuromuscular facilitation stretching and static stretching do not affect muscle-tendon properties, muscle strength, and joint function in children with spastic cerebral palsy

BACKGROUND

While the effect of static stretching for individuals with cerebral palsy is questionable, recent results suggest that the combination with activation seems promising to improve muscle-tendon properties and function. Therefore, this study analyzed the effects of 8-week proprioceptive neuromuscular facilitation stretching on the gastrocnemius medialis muscle-tendon properties, muscle strength, and the ankle joint in children with spastic cerebral palsy in comparison to static stretching.

METHODS

Initially, 24 children with spastic cerebral palsy were randomly assigned to a static stretching (10.7 ± 1.8 years) or proprioceptive neuromuscular facilitation stretching group (10.9 ± 2.6 years). Plantar flexors were manually stretched at home for 300 s and ∼ 250-270 s per day four times a week for eight weeks, respectively. Assessments of ankle joint function (e.g., range of motion), muscle-tendon properties, and isometric muscle strength were conducted using 3D motion capture, 2D ultrasound, dynamometry, and electromyography. A mixed analysis of variance was used for the statistical analysis.

FINDINGS

Stretching adherence was high in the proprioceptive neuromuscular facilitation stretching (93.1%) and static stretching group (94.4%). No significant changes (p > 0.05) were observed in ankle joint function, muscle-tendon properties, and isometric muscle strength after both interventions. Moreover, no differences (p > 0.05) were found between the stretching techniques.

INTERPRETATION

The findings support the idea that manual stretching (neither proprioceptive neuromuscular facilitation stretching nor static stretching) performed in isolation for eight weeks may not be appropriate to evoke significant changes in muscle-tendon properties, voluntary muscle strength, or joint function in children with spastic cerebral palsy.

CLINICAL TRIAL REGISTRATION NUMBER

NCT04570358.

Policy brief: adaptive cycling equipment for individuals with neurodevelopmental disabilities as durable medical equipment

- Durable medical equipment (DME) policies require that the equipment be medically necessary; however, adaptive cycling equipment (bicycles and tricycles) are usually not deemed medically necessary. - Individuals with neurodevelopmental disabilities (NDD) are at high risk for secondary conditions, both physical and mental, that can be mitigated by increasing physical activity. - Significant financial costs are associated with the management of secondary conditions. - Adaptive cycling can provide improved physical health of individuals with NDD potentially reducing costs of comorbidities. - Expanding DME policies to include adaptive cycling equipment for qualifying individuals with NDD can increase access to equipment. - Regulations to ensure eligibility, proper fitting, prescription, and training can optimize health and wellbeing. - Programs for recycling or repurposing of equipment are warranted to optimize resources.

Treatment of spasticity

Spasticity is characterized by an enhanced size and reduced threshold for activation of stretch reflexes and is associated with "positive signs" such as clonus and spasms, as well as "negative features" such as paresis and a loss of automatic postural responses. Spasticity develops over time after a lesion and can be associated with reduced speed of movement, cocontraction, abnormal synergies, and pain. Spasticity is caused by a combination of damage to descending tracts, reductions in inhibitory activity within spinal cord circuits, and adaptive changes within motoneurons. Increased tone, hypertonia, can also be caused by changes in passive stiffness due to, for example, increase in connective tissue and reduction in muscle fascicle length. Understanding the cause of hypertonia is important for determining the management strategy as nonneural, passive causes of stiffness will be more amenable to physical rather than pharmacological interventions. The management of spasticity is determined by the views and goals of the patient, family, and carers, which should be integral to the multidisciplinary assessment. An assessment, and treatment, of trigger factors such as infection and skin breakdown should be made especially in people with a recent change in tone. The choice of management strategies for an individual will vary depending on the severity of spasticity, the distribution of spasticity (i.e., whether it affects multiple muscle groups or is more prominent in one or two groups), the type of lesion, and the potential for recovery. Management options include physical therapy, oral agents; focal therapies such as botulinum injections; and peripheral nerve blocks. Intrathecal baclofen can lead to a reduction in required oral antispasticity medications. When spasticity is severe intrathecal phenol may be an option. Surgical interventions, largely used in the pediatric population, include muscle transfers and lengthening and selective dorsal root rhizotomy.

Ankle rehabilitation robot training for stroke patients with foot drop: Optimizing intensity and frequency

BACKGROUND

Robotic solutions for ankle joint physical therapy have extensively been researched. The optimal frequency and intensity of training for patients when using the ankle robot is not known which can affect rehabilitation outcome.

OBJECTIVE

To explore the optimal ankle robot training protocol on foot drop in stroke subjects.

METHODS

Subjects were randomly divided into four groups, with 9 in each group. The subjects received different intensities (low or high intensity) with frequencies (1 session/day or 2 sessions/day) of robot combination training. Each session lasted 20 minutes and all subjects were trained 5 days a week for 3 weeks.

RESULTS

After 3 weeks of treatment, all groups showed an improvement in passive and active ankle dorsiflexion range of motion (PROM and AROM) and Fugl-Meyer Assessment for lower extremity (FMA-LE) compared to pre-treatment. When training at the same level of intensity, patients who received 2 sessions/day of training had better improvement in ankle dorsiflexion PROM than those who received 1 session/day. In terms of the improvement in dorsiflexion AROM and FMA-LE, patients who received 2 sessions/day with high intensity training improved better than other protocols.

CONCLUSION

High frequency and high intensity robot training can be more effective in improving ankle dysfunction.

Mechanical and Morphological Changes of the Plantar Flexor Musculotendinous Unit in Children with Unilateral Cerebral Palsy Following 12 Weeks of Plyometric Exercise: A Randomized Controlled Trial

To investigate how plyometric exercise (PLYO-Ex) affects mechanics and morphometrics of the plantar flexor musculotendinous unit in children with unilateral cerebral palsy, 38 participants (aged 10–16 years) were allocated at random to either the PLYO-Ex group (n = 19; received 24 sessions of plyometric muscle loading, conducted 2 times a week for 3 months in succession) or the control group (n = 19; underwent traditional physical therapy for the same frequency and duration). Measurements were taken pre- and post-intervention. Standard ultrasound imaging was applied to evaluate morphometrics of the gastrocnemius muscle and Achilles tendon unit and an isokinetic dynamometer was used to evaluate maximum voluntary isometric plantar flexors contraction (IVC_max). With controlling for pre-treatment values, significant post-treatment changes favoring the PLYO-Ex group were observed for morphological (tendon (p = 0.003, η²_p = 0.23) length; belly length (p = 0.001, η²_p = 0.27); tendon thickness (p = 0.035, η²_p = 0.35); muscle thickness (p = 0.013, η²_p = 0.17); fascicle length (p = 0.009, η²_p = 0.18); pennation angle (p = 0.015, η²_p = 0.16)) and mechanical and material properties (IVC_max (p = 0.009, η²_p = 0.18); tendon’s elongation (p = 0.012, η²_p = 0.17), stiffness (p = 0.027, η²_p = 0.13); stress (p = 0.006, η²_p = 0.20); strain (p = 0.004, η²_p = 0.21)). In conclusion, plyometric exercise induces significant adaptations within the musculotendinous unit of the plantar flexors in children with unilateral cerebral palsy. These adaptations could improve muscular efficiency and consequently optimize physical/functional performance.

Acute Effects of Static and Proprioceptive Neuromuscular Facilitation Stretching of the Plantar Flexors on Ankle Range of Motion and Muscle-Tendon Behavior in Children with Spastic Cerebral Palsy-A Randomized Clinical Trial

Stretching is considered a clinically effective way to prevent muscle contracture development in children with spastic cerebral palsy (CP). Therefore, in this study, we assessed the effects of a single session of proprioceptive neuromuscular facilitation (PNF) or static stretching (SS) on ankle joint range of motion (RoM) and gastrocnemius muscle-tendon behavior in children with CP. During the SS (n = 8), the ankle joint was held in maximum dorsiflexion (30 s). During the PNF stretching (n = 10), an isometric contraction (3-5 s) was performed, followed by stretching (~25 s). Ten stretches were applied in total. We collected data via dynamometry, 3D motion capture, 2D ultrasound, and electromyography, before and after the stretching sessions. A mixed ANOVA was used for the statistical analysis. Both ankle RoM and maximum dorsiflexion increased over time (F(1,16) = 7.261, p < 0.05, η² = 0.312; and F(1,16) = 4.900, p < 0.05, η² = 0.234, respectively), without any difference between groups. An interaction effect (F(1,12) = 4.768, p = 0.05, η² = 0.284) was observed for muscle-tendon unit elongation (PNF: -8.8%; SS: +14.6%). These findings suggest a positive acute effect of stretching on ankle function. However, SS acutely increased muscle-tendon unit elongation, while this decreased after PNF stretching, indicating different effects on the spastic muscles. Whether PNF stretching has the potential to cause positive alterations in individuals with CP should be elucidated in future studies.

Effects of voluntary exercise on muscle structure and function in cerebral palsy

Skeletal muscles are required for functional movement and force production. While it is clear that cerebral palsy (CP) results in loss of muscle strength and bodily function, and that much of this loss is caused by injury to the central nervous system, muscle is a very plastic tissue that is also dramatically affected. In many studies, it is assumed that voluntary exercise will cause the muscle to respond in the same way that typically developing muscle does, but there are scarce data demonstrating that this is true. The purpose of this review is to briefly describe muscle architectural adaptation to various forms of exercise with specific reference to voluntary exercise performed in children with CP. Exercise itself is not generic but can vary by intensity, duration, and the exact nature of the muscle length change and velocity imposed during the exercise. Our goal is to stimulate discussion in this area by pointing out salient experimental variables and, ultimately, to improve activity and participation in children with CP.

Stimuli for Adaptations in Muscle Length and the Length Range of Active Force Exertion-A Narrative Review

Treatment strategies and training regimens, which induce longitudinal muscle growth and increase the muscles’ length range of active force exertion, are important to improve muscle function and to reduce muscle strain injuries in clinical populations and in athletes with limited muscle extensibility. Animal studies have shown several specific loading strategies resulting in longitudinal muscle fiber growth by addition of sarcomeres in series. Currently, such strategies are also applied to humans in order to induce similar adaptations. However, there is no clear scientific evidence that specific strategies result in longitudinal growth of human muscles. Therefore, the question remains what triggers longitudinal muscle growth in humans. The aim of this review was to identify strategies that induce longitudinal human muscle growth. For this purpose, literature was reviewed and summarized with regard to the following topics: (1) Key determinants of typical muscle length and the length range of active force exertion; (2) Information on typical muscle growth and the effects of mechanical loading on growth and adaptation of muscle and tendinous tissues in healthy animals and humans; (3) The current knowledge and research gaps on the regulation of longitudinal muscle growth; and (4) Potential strategies to induce longitudinal muscle growth. The following potential strategies and important aspects that may positively affect longitudinal muscle growth were deduced: (1) Muscle length at which the loading is performed seems to be decisive, i.e., greater elongations after active or passive mechanical loading at long muscle length are expected; (2) Concentric, isometric and eccentric exercises may induce longitudinal muscle growth by stimulating different muscular adaptations (i.e., increases in fiber cross-sectional area and/or fiber length). Mechanical loading intensity also plays an important role. All three training strategies may increase tendon stiffness, but whether and how these changes may influence muscle growth remains to be elucidated. (3) The approach to combine stretching with activation seems promising (e.g., static stretching and electrical stimulation, loaded inter-set stretching) and warrants further research. Finally, our work shows the need for detailed investigation of the mechanisms of growth of pennate muscles, as those may longitudinally grow by both trophy and addition of sarcomeres in series.

Exercise intervention protocol in children and young adults with cerebral palsy: the effects of strength, flexibility and gait training on physical performance, neuromuscular mechanisms and cardiometabolic risk factors (EXECP)

Background

Individuals with cerebral palsy (CP) have problems in everyday tasks such as walking and climbing stairs due to a combination of neuromuscular impairments such as spasticity, muscle weakness, reduced joint flexibility and poor coordination. Development of evidence-based interventions are in pivotal role in the development of better targeted rehabilitation of CP, and thus in maintaining their motor function and wellbeing. Our aim is to investigate the efficacy of an individually tailored, multifaceted exercise intervention (EXECP) in children and young adults with CP. EXECP is composed of strength, flexibility and gait training. Furthermore, this study aims to verify the short-term retention of the adaptations three months after the end of the EXECP intervention.

Methods

Twenty-four children and young adults with spastic CP will be recruited to participate in a 9-month research project with a 3-month training intervention, consisting of two to three 90-min sessions per week. In each session, strength training for the lower limbs and trunk muscles, flexibility training for the lower limbs and inclined treadmill gait training will be performed. We will evaluate muscle strength, joint flexibility, neuromuscular and cardiometabolic parameters. A nonconcurrent multiple baseline design with two pre-tests and two post-tests all interspaced by three months is used. In addition to the CP participants, 24 typically developing age and sex-matched participants will perform the two pre-tests (i.e. no intervention) to provide normative data.

Discussion

This study has a comprehensive approach examining longitudinal effects of wide variety of variables ranging from physical activity and gross motor function to sensorimotor functions of the brain and neuromuscular and cardiometabolic parameters, providing novel information about the adaptation mechanisms in cerebral palsy. To the best of our knowledge, this is the first intervention study providing supervised combined strength, flexibility and gait training for young individuals with CP.

Trial registration number

ISRCTN69044459, prospectively registered (21/04/2017).

The mechanisms of adaptation for muscle fascicle length changes with exercise: Implications for spastic muscle

We are proposing optimal training conditions that can lead to an increase in the number of serial sarcomeres (SSN) and muscle fascicle length (FL) in spastic muscles. Therapeutic interventions for increasing FL in clinical populations with neurological origin, in whom relative shortness of muscle fascicles contributed to the presentation of symptoms such as spasticity, contracture, and limited functional abilities, do not generally meet these conditions, and therefore, result in less than satisfactory outcomes. Based on a review of literature, we argue that protocols of exercise interventions that led to sarcomerogenesis, and increases in SSN and FL in healthy animal and human models satisfied three criteria: 1) all involved eccentric exercise at appropriately high velocity; 2) resulted in positive strain of muscle fascicles; and 3) momentary deactivation in the stretched muscle. Accordingly, to increase FL in spastic muscles, new exercise protocols in which the three presumed criteria are satisfied, must be developed, and long-term muscle architectural and functional adaptations to such trainings must be examined.

Changes in Ankle Range of Motion, Gait Function and Standing Balance in Children with Bilateral Spastic Cerebral Palsy after Ankle Mobilization by Manual Therapy

The aim of this study was to investigate the effect of ankle joint mobilization in children with cerebral palsy (CP) to ankle range of motion (ROM), gait, and standing balance. We recruited 32 children (spastic diplegia) diagnosed with CP and categorized them in two groups: the ankle joint mobilization (n = 16) group and sham joint mobilization (n = 16) group. Thus, following a six-week ankle joint mobilization, we examined measures such as passive ROM in ankle dorsiflexion in the sitting and supine position, center of pressure (COP) displacements (sway length, area) with eyes open (EO) and closed (EC), and a gait function test (timed up and go test (TUG) and 10-m walk test). The dorsiflexion ROM, TUG, and 10-m walk test significantly increased in the mobilization group compared to the control group. Ankle joint mobilization can be regarded as a promising method to increase dorsiflexion and improve gait in CP-suffering children.

Joint and Muscle Assessments of the Separate Effects of Botulinum NeuroToxin-A and Lower-Leg Casting in Children With Cerebral Palsy

Botulinum NeuroToxin-A (BoNT-A) injections to the medial gastrocnemius (MG) and lower-leg casts are commonly combined to treat ankle equinus in children with spastic cerebral palsy (CP). However, the decomposed treatment effects on muscle or tendon structure, stretch reflexes, and joint are unknown. In this study, BoNT-A injections to the MG and casting of the lower legs were applied separately to gain insight into the working mechanisms of the isolated treatments on joint, muscle, and tendon levels. Thirty-one children with spastic CP (GMFCS I-III, age 7.4 ± 2.6 years) received either two weeks of lower-leg casts or MG BoNT-A injections. During full range of motion slow and fast passive ankle rotations, joint resistance and MG stretch reflexes were measured. MG muscle and tendon lengths were assessed at resting and at maximum dorsiflexion ankle angles using 3D-freehand ultrasound. Treatment effects were compared using non-parametric statistics. Associations between the effects on joint and muscle or tendon levels were performed using Spearman correlation coefficients (p < 0.05). Increased joint resistance, measured during slow ankle rotations, was not significantly reduced after either treatment. Additional joint resistance assessed during fast rotations only reduced in the BoNT-A group (-37.6%, p = 0.013, effect size = 0.47), accompanied by a reduction in MG stretch reflexes (-70.7%, p = 0.003, effect size = 0.56). BoNT-A increased the muscle length measured at the resting ankle angle (6.9%, p = 0.013, effect size = 0.53). Joint angles shifted toward greater dorsiflexion after casting (32.4%, p = 0.004, effect size = 0.56), accompanied by increases in tendon length (5.7%, p = 0.039, effect size = 0.57; r = 0.40). No associations between the changes in muscle or tendon lengths and the changes in the stretch reflexes were found. We conclude that intramuscular BoNT-A injections reduced stretch reflexes in the MG accompanied by an increase in resting muscle belly length, whereas casting resulted in increased dorsiflexion without any changes to the muscle length. This supports the need for further investigation on the effect of the combined treatments and the development of treatments that more effectively lengthen the muscle.

Stretching Interventions in Children With Cerebral Palsy: Why Are They Ineffective in Improving Muscle Function and How Can We Better Their Outcome?

Hyper-resistance at the joint is one of the most common symptoms in children with cerebral palsy (CP). Alterations to the structure and mechanical properties of the musculoskeletal system, such as a decreased muscle length and an increased joint stiffness are typically managed conservatively, by means of physiotherapy involving stretching exercises. However, the effectiveness of stretching-based interventions for improving function is poor. This may be due to the behavior of a spastic muscle during stretch, which is poorly understood. The main aim of this paper is to provide a mechanistic explanation as to why the effectiveness of stretching is limited in children with CP and consider clinically relevant means by which this shortcoming can be tackled. To do this, we review the current literature regarding muscle and tendon plasticity in response to stretching in children with CP. First, we discuss how muscle and tendon interact based on their morphology and mechanical properties to provide a certain range of motion at the joint. We then consider the effect of traditional stretching exercises on these muscle and tendon properties. Finally, we examine possible strategies to increase the effectiveness of stretching therapies and we highlight areas of further research that have the potential to improve the outcome of non-invasive interventions in children with cerebral palsy.

The Effects of Functional Progressive Strength and Power Training in Children With Unilateral Cerebral Palsy

PURPOSE

The purpose of this study was to investigate the effects of a novel functional strength and power-training program on gait and gross motor function in participants with unilateral cerebral palsy.

METHODS

This 12-week trial of functional strength and power training included 30 participants with cerebral palsy, randomly assigned to the experimental or comparison group. The primary outcomes, 1-minute walk test, muscle power, and the Gross Motor Function Measure, were assessed at baseline and 12 weeks after the intervention. Secondary outcomes included dynamic balance as measured by Timed Up and Go, muscle strength, and 1-repetition maximum measures.

RESULTS

Significantly greater improvements were seen in the experimental group for muscle power, Gross Motor Function Measure E score, and 1-minute walk test (P < .05), as well as for dynamic balance, 1-repetition maximum, and muscle strength.

CONCLUSION

Functional strength training combined with plyometric exercises improved gait and gross motor function, dynamic balance, muscle strength, and power.

VIDEO ABSTRACT

For more insights from the authors, access Supplemental Digital Content 1, available at: http://links.lww.com/PPT/A254.

Real-time ultrasound elastography evaluation of achilles tendon properties in patients with mild hemiplegic stroke after rehabilitation training

OBJECTIVE

This study aims to evaluate the Achilles tendon's properties after rehabilitation training in patients with stroke using real-time ultrasound elastography.

METHODS

A total of 24 patients with mild hemiplegic stroke in the past 6 to 12 months and unilateral lower limb movement disorder were prospectively enrolled. All patients accepted 9-week rehabilitation training with the same schema. The 2-dimensional elastography and real-time elastography findings in the impaired and contralateral normal Achilles tendon were measured at pretraining and at 3, 6, and 9 weeks after training, which included tendon length, thickness, elasticity score (grade 1-3), and strain ratio of fat to tendon. The functional properties, which include the 10-meter walk test and timed up-and-go scores, were evaluated before and after the 9-week training.

RESULTS

The impaired Achilles tendon had a longer length (P = .002), lower frequency of grade 1 (P = .012), and lower strain ratio (P = .009) than the contralateral tendon before training. The impaired tendons at the third, sixth, and ninth weeks after training were compared to ones before training, respectively, which revealed shorter length, increased frequency of grade 1, and increased strain ratio. The first statistically significant changes in the length were observed at the sixth week, while such changes in elasticity score and strain ratio were observed at the ninth week.

CONCLUSIONS

Two-dimensional elastography and real-time elastography can provide valuable imaging markers for quantitatively evaluating the Achilles tendon's properties after rehabilitation training in patients with stroke.

The Effect of Functional Home-Based Strength Training Programs on the Mechano-Morphological Properties of the Plantar Flexor Muscle-Tendon Unit in Children With Spastic Cerebral Palsy

PURPOSE

The purpose of this study was to investigate the effects of functional progressive resistance training (PRT) and high-intensity circuit training (HICT) on the mechano-morphological properties of the plantar flexor muscle-tendon unit in children with spastic cerebral palsy.

METHODS

Twenty-two children (12.8 [2.6] y old, Gross Motor Function Classification System levels I/II = 19/3) were randomly assigned to either a PRT group or an HICT group. The interventions consisted of functional lower limb exercises, which were performed at home 3 times per week for 8 weeks. Measurements at baseline, preintervention, postintervention, and follow-up were taken to assess ankle joint range of motion and the properties of the gastrocnemius medialis, vastus lateralis, rectus femoris, and Achilles tendon (eg, thickness, strength, stiffness).

RESULTS

Despite a nonsignificant increase in active torque in the HICT group, neither gastrocnemius medialis morphology nor Achilles tendon properties were significantly altered after the interventions. Vastus lateralis thickness increased following PRT only.

CONCLUSIONS

Functional home-based strength training did not lead to significant changes at the muscular level in children with cerebral palsy. We therefore assume that a more specific stimulus of higher intensity combined with a longer training duration might be necessary to evoke changes in muscles and tendons in individuals with cerebral palsy.

Resistance Training Combined With Stretching Increases Tendon Stiffness and Is More Effective Than Stretching Alone in Children With Cerebral Palsy: A Randomized Controlled Trial

Aim: Stretching is often used to increase/maintain muscle length and improve joint range of motion (ROM) in children with cerebral palsy (CP). However, outcomes at the muscle (remodeling) and resulting function appear to be highly variable and often unsatisfactory. During passive joint rotation, the Achilles tendon lengthens more than the in-series medial gastrocnemius muscle in children with CP, which might explain the limited effectiveness of stretching interventions. We aimed to ascertain whether increasing tendon stiffness, by performing resistance training, improves the effectiveness of passive stretching, indicated by an increase in medial gastrocnemius fascicle length. Methods: Sixteen children with CP (Age median [IQR]: 9.6 [8.6, 10.5]) completed the study. Children were randomly assigned to a combined intervention of stretching and strengthening of the calf muscles (n = 9) or a control (stretching-only) group (n = 7). Medial gastrocnemius fascicle length at a resting ankle angle, lengthening during passive joint rotations, and tendon stiffness were assessed by combining dynamometry and ultrasound imaging. The study was registered on clinicaltrials.gov (NCT02766491). Results: Resting fascicle length and tendon stiffness increased more in the intervention group compared to the control group (median [95% CI] increase fascicle length: 2.2 [1.3, 4.3] mm; stiffness: 13.6 [9.9, 17.7] N/mm) Maximum dorsiflexion angle increased equally in both groups. Conclusion: This study provides proof of principle that a combined resistance and stretching intervention can increase tendon stiffness and muscle fascicle length in children with CP. This demonstrates that remodeling of muscle structure is possible with non-invasive interventions in spastic CP.

Plyometric exercises: subsequent changes of weight-bearing symmetry, muscle strength and walking performance in children with unilateral cerebral palsy

OBJECTIVE

To evaluate the subsequent effects of plyometric training on weight-bearing symmetry, muscle strength, and gait performance in children with unilateral cerebral palsy.

METHODS

Thirty-nine children with spastic hemiplegia (age 8-12 years) were randomly divided into either the PLYO group (n=19, received a 30-minute plyometric exercise program plus the traditional physical rehabilitation, twice/week for eight consecutive weeks) or Non-PLYO group (n=20, received the traditional physical rehabilitation only). The weight-bearing symmetry index (WB-SI), maximum isometric muscle strength (MIMS) of quadriceps and hamstring muscles, and spatial-temporal gait parameters were assessed pre and post-intervention.

RESULTS

From pre- to post-intervention, changes of WB-SI among PLYO and Non-PLYO groups did not differ significantly (P=.81; hindfoot and P=.23; forefoot). MIMS of quadriceps and hamstring muscles at 90° knee flexion (P=.008 and .013 respectively) increased significantly in PLYO compared to Non-PLYO group. Walking speed (P=.033), stride length (P=.002), and step time (P<.001) improved markedly in PLYO group more than in Non-PLYO group. The proportion of single leg support (P=.14) among PLYO and Non-PLYO groups did not differ significantly.

CONCLUSION

Addition of plyometric exercises to the physical rehabilitation programs of children with unilateral CP could achieve greater improvement in muscles strength and walking performance, but not in WB-SI.

Muscle and tendon morphology alterations in children and adolescents with mild forms of spastic cerebral palsy

Background

Early detection of changes at the muscular level before a contracture develops is important to gain knowledge about the development of deformities in individuals with spasticity. However, little information is available about muscle morphology in children with spastic diplegic cerebral palsy (CP) without contracture or equinus gait. Therefore, the aim of this study was to compare the gastrocnemius medialis (GM) and Achilles tendon architecture of children and adolescents with spastic CP without contracture or equinus gait to that of typically developing (TD) children.

Methods

Two-dimensional ultrasonography was used to assess the morphological properties of the GM muscle and Achilles tendon in 10 children with spastic diplegic CP (Gross Motor Function Classification System level I–II) and 12 TD children (mean age 12.0 (2.8) and 11.3 (2.5) years, respectively). The children with CP were not restricted in the performance of daily tasks, and therefore had a high functional capacity. Mean muscle and tendon parameters were statistically compared (independent t-tests or Mann-Whitney U-tests).

Results

When normalized to lower leg length, muscle-tendon unit length and GM muscle belly length were found to be significantly shorter (p < 0.05, effect size (ES) = 1.00 and 0.98, respectively) in the children with spastic CP. Furthermore, there was a tendency for increased Achilles tendon length when expressed as a percentage of muscle-tendon unit length (p = 0.08, ES = − 0.80) in the individuals with CP. This group also showed shorter muscle fascicles (3.4 cm vs. 4.4 cm, p < 0.01, ES = 1.12) and increased fascicle pennation angle (21.9° vs. 18.1°, p < 0.01, ES = − 1.36, respectively). However, muscle thickness and Achilles tendon cross-sectional area did not differ between groups. Resting ankle joint angle was significantly more plantar flexed (− 26.2° vs. − 20.8°, p < 0.05, ES = 1.06) in the children with CP.

Conclusions

Morphological alterations of the plantar flexor muscle-tendon unit are also present in children and adolescents with mild forms of spastic CP. These alterations may contribute to functional deficits such as muscle weakness, and therefore have to be considered in the clinical decision-making process, as well as in the selection of therapeutic interventions.

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.

Effect on Passive Range of Motion and Functional Correlates After a Long-Term Lower Limb Self-Stretch Program in Patients With Chronic Spastic Paresis

BACKGROUND

In current health care systems, long-duration stretching, performed daily, cannot be obtained through prescriptions of physical therapy. In addition, the short-term efficacy of the various stretching techniques is disputed, and their long-term effects remain undocumented.

OBJECTIVE

To evaluate changes in extensibility in 6 lower limb muscles and in ambulation speed after a ≥1-year self-stretch program, the Guided Self-rehabilitation Contract (GSC), in individuals with chronic spastic paresis.

DESIGN

Retrospective study.

SETTING

Neurorehabilitation clinic.

PARTICIPANTS

Patients diagnosed with hemiparesis or paraparesis at least 1 year before the initiation of a GSC and who were then involved in the GSC program for at least 1 year.

INTERVENTIONS

For each patient, specific muscles were identified for intervention among the following: gluteus maximus, hamstrings, vastus, rectus femoris, soleus, and gastrocnemius. Prescriptions and training for a daily, high-load, prolonged, home self-stretching program were primarily based on the baseline coefficient of shortening, defined as C_SH = [(X_N -X_V1)/X_N] (X_V1 = PROM, passive range of motion; X_N = normally expected amplitude).

MAIN OUTCOME MEASUREMENTS

Six assessments were performed per year, measuring the Tardieu X_V1 or maximal slow stretch range of motion angle (PROM), C_SH, 10-m ambulation speed, and its functional ambulation category (Perry's classification: household, limited, or full). Changes from baseline in self-stretched and nonself-stretched muscles were compared, with meaningful X_V1 change defined as ΔX_V1 >5° for plantar flexors and >10° for proximal muscles. Correlation between the composite X_V1 (mean PROM for the 6 muscles) and ambulation speed also was evaluated.

RESULTS

Twenty-seven GSC participants were identified (14 women, mean age 44 years, range 29-59): 18 with hemiparesis and 9 with paraparesis. After 1 year, 47% of self-stretched muscles showed meaningful change in PROM (ΔX_V1) versus 14% in nonself-stretched muscles (P < .0001, χ²). ΔC_SH was -31% (95% confidence interval [95% CI] -41.5 to -15.2) in self-stretched versus -7% (95% CI -11.9 to -2.1) in nonself-stretched muscles (P < .0001, t-test). Ambulation speed increased by 41% (P < .0001) from 0.81 m/s (95% CI 0.67-0.95) to 1.15 m/s (95% CI 1.01-1.29). Eight of the 12 patients (67%) who were in limited or household categories at baseline moved to a higher functional ambulation category. There was a trend for a correlation between composite X_V1 and ambulation speed (r = 0.44, P = .09) in hemiparetic patients.

CONCLUSION

Therapists should consider prescribing and monitoring a long-term lower limb self-stretch program using GSC, as this may increase muscle extensibility in adult-onset chronic paresis.

LEVEL OF EVIDENCE

III.

Outcome of medial hamstring lengthening in children with spastic paresis: A biomechanical and morphological observational study

To improve gait in children with spastic paresis due to cerebral palsy or hereditary spastic paresis, the semitendinosus muscle is frequently lengthened amongst other medial hamstring muscles by orthopaedic surgery. Side effects on gait due to weakening of the hamstring muscles and overcorrections have been reported. How these side effects relate to semitendinosus morphology is unknown. This study assessed the effects of bilateral medial hamstring lengthening as part of single-event multilevel surgery (SEMLS) on (1) knee joint mechanics (2) semitendinosus muscle morphology and (3) gait kinematics. All variables were assessed for the right side only. Six children with spastic paresis selected for surgery to counteract limited knee range of motion were measured before and about a year after surgery. After surgery, in most subjects popliteal angle decreased and knee moment-angle curves were shifted towards a more extended knee joint, semitendinosus muscle belly length was approximately 30% decreased, while at all assessed knee angles tendon length was increased by about 80%. In the majority of children muscle volume of the semitendinosus muscle decreased substantially suggesting a reduction of physiological cross-sectional area. Gait kinematics showed more knee extension during stance (mean change ± standard deviation: 34±13°), but also increased pelvic anterior tilt (mean change ± standard deviation: 23±5°). In most subjects, surgical lengthening of semitendinosus tendon contributed to more extended knee joint angle during static measurements as well as during gait, whereas extensibility of semitendinosus muscle belly was decreased. Post-surgical treatment to maintain muscle belly length and physiological cross-sectional area may improve treatment outcome of medial hamstring lengthening.

Can in Vivo Medial Gastrocnemius Muscle-Tendon Unit Lengths be Reliably Estimated by Two Ultrasonography Methods? A Within-Session Analysis

A clinically feasible method to reliably estimate muscle-tendon unit (MTU) lengths could provide essential diagnostic and treatment planning information. A 3-D freehand ultrasound (3-DfUS) method was previously validated for extracting in vivo medial gastrocnemius (MG) lengths, although the processing time can be considered substantial for the clinical environment. This investigation analyzed a quicker and simpler method using the US transducer as a spatial pointer (US-PaP), where the within-session reliability of extracting the muscle-tendon unit (MTU) and tendon lengths are estimated. MG MTU lengths were extracted in a group of 14 healthy adults using both 3-DfUS and US-PaP. Two consecutive acquisitions were performed per participant, and the data processed by two researchers independently. The intra-class correlation coefficients were above 0.97, and the standard error of measurements below 3.6 mm (1.5%). This investigation proposes that the simplified US-PaP method is a viable alternative for estimating MG MTU lengths.

Impact of ankle foot orthosis stiffness on Achilles tendon and gastrocnemius function during unimpaired gait

Ankle foot orthoses (AFOs) are designed to improve gait for individuals with neuromuscular conditions and have also been used to reduce energy costs of walking for unimpaired individuals. AFOs influence joint motion and metabolic cost, but how they impact muscle function remains unclear. This study investigated the impact of different stiffness AFOs on medial gastrocnemius muscle (MG) and Achilles tendon (AT) function during two walking speeds. We performed gait analyses for eight unimpaired individuals. Each individual walked at slow and very slow speeds with a 3D printed AFO with no resistance (free hinge condition) and four levels of ankle dorsiflexion stiffness: 0.25Nm/°, 1Nm/°, 2Nm/°, and 3.7Nm/°. Motion capture, ultrasound, and musculoskeletal modeling were used to quantify MG and AT lengths with each AFO condition. Increasing AFO stiffness increased peak AFO dorsiflexion moment with decreased peak knee extension and peak ankle dorsiflexion angles. Overall musculotendon length and peak AT length decreased, while peak MG length increased with increasing AFO stiffness. Peak MG activity, length, and velocity significantly decreased with slower walking speed. This study provides experimental evidence of the impact of AFO stiffness and walking speed on joint kinematics and musculotendon function. These methods can provide insight to improve AFO designs and optimize musculotendon function for rehabilitation, performance, or other goals.

Conservative treatment for equinus deformity in children with cerebral palsy using an adjustable splint-assisted ankle-foot orthosis

BACKGROUND

A novel splint, the assisting ankle-foot orthoses (AFO), was developed to provide adjustable sustained stretching to improve conservative treatment for equinus deformities in children with cerebral palsy (CP). The treatment effect was validated by follow-up visits.

METHODS

This study involved subjects between 2 and 12 years old, including 28 CP children treated with splint-assisted AFO correction, 30 CP children treated with static AFO correction, and 30 normal children with typical development (TD). Quantitative pedobarographic measurements were taken to evaluate the effect of splint-assisted AFO correction. The heel/forefoot ratio was introduced to indicate the degree of the equinus deformity during treatment.

RESULTS

The results showed that the heel/forefoot ratios were 1.41 ± 0.26 for the TD children; 0.65 ± 0.41, 1.02 ± 0.44, and 1.24 ± 0.51 for the splint-assisted AFO correction before and after 6-month and 12-month treatments; 0.59 ± 0.37, 0.67 ± 0.44, and 0.66 ± 0.42 for the static AFO correction before and after 6-month and 12-month treatments.

CONCLUSIONS

This study suggests that correction with the adjustable splint-assisted AFO is an effective treatment for equinus deformity in CP Children.

Relationship of medial gastrocnemius relative fascicle excursion and ankle joint power and work performance during gait in typically developing children: A cross-sectional study

Muscle fascicles lengthen in response to chronic passive stretch through in-series sarcomere addition in order to maintain an optimum sarcomere length. In turn, the muscles' force generating capacity, maximum excursion, and contraction velocity is enhanced. Thus, longer fascicles suggest a greater capacity to develop joint power and work. However, static fascicle length measurements may not be taking sarcomere length differences into account. Thus, we considered relative fascicle excursions through passive ankle dorsiflexion may better correlate with the capacity to generate joint power and work than fascicle length. Therefore, the aim of the present study was to determine if medial gastrocnemius relative fascicle excursions correlate with ankle joint power and work generation during gait in typically developing children. A sample of typically developing children (n = 10) were recruited for this study and data analysis was carried out on 20 legs. Medial gastrocnemius relative fascicle excursion from resting joint angle to maximum dorsiflexion was estimated from trigonometric relations of medial gastrocnemius pennation angle and thickness obtained from B-mode real-time ultrasonography. Furthermore, a three-dimensional motion capture system was used to obtain ankle joint work and power during the stance phase of gait. Significant correlations were found between relative fascicle excursion and peak power absorption (-) r(14) = -0.61, P = .012 accounting for 31% variability, positive work r(18) = 0.56, P = .021 accounting for 31% variability, and late stance positive work r(15) = 0.51, P = .037 accounting for 26% variability. The large unexplained variance may be attributed to mechanics of neighboring structures (e.g., soleus or Achilles tendon mechanics) and proximal joint kinetics which may also contribute to ankle joint power and work performance, and were not taken into account. Further studies are encouraged to provide greater insight on the relationship between relative fascicle excursions and joint function.

Coupling Timing of Interventions With Dose to Optimize Plasticity and Participation in Pediatric Neurologic Populations

PURPOSE

The purpose of this article is to propose that coupling of timing of interventions with dosing of interventions optimizes plasticity and participation in pediatric neurologic conditions, specifically cerebral palsy. Dosing includes frequency, intensity, time per session, and type of intervention. Interventions focus on body structures and function and activity and participation, and both are explored. Known parameters for promoting bone, muscle, and brain plasticity and evidence supporting critical periods of growth during development are reviewed. Although parameters for dosing participation are not yet established, emerging evidence suggests that participation at high intensities has the potential for change. Participation interventions may provide an additional avenue to promote change through the life span. Recommendations for research and clinical practice are presented to stimulate discussions and innovations in research and practice.

Gastrocnemius operating length with ankle foot orthoses in cerebral palsy

BACKGROUND

Many individuals with cerebral palsy wear ankle foot orthoses during daily life. Orthoses influence joint motion, but how they impact muscle remains unclear. In particular, the gastrocnemius is commonly stiff in cerebral palsy. Understanding whether orthoses stretch or shorten this muscle during daily life may inform orthosis design and rehabilitation.

OBJECTIVES

This study investigated the impact of different ankle foot orthoses on gastrocnemius operating length during walking in children with cerebral palsy.

STUDY DESIGN

Case series, within subject comparison of gastrocnemius operating length while walking barefoot and with two types of ankle foot orthoses.

METHODS

We performed gait analyses for 11 children with cerebral palsy. Each child was fit with two types of orthoses: a dynamic ankle foot orthosis (Cascade dynamic ankle foot orthosis) and an adjustable dynamic response ankle foot orthosis (Ultraflex ankle foot orthosis). Musculoskeletal modeling was used to quantify gastrocnemius musculotendon operating length and velocity with each orthosis.

RESULTS

Walking with ankle foot orthoses could stretch the gastrocnemius more than barefoot walking for some individuals; however, there was significant variability between participants and orthoses. At least one type of orthosis stretched the gastrocnemius during walking for 4/6 and 3/5 of the Gross Motor Functional Classification System Level I and III participants, respectively. AFOs also reduced peak gastrocnemius lengthening velocity compared to barefoot walking for some participants, with greater reductions among the Gross Motor Functional Classification System Level III participants. Changes in gastrocnemius operating length and lengthening velocity were related to changes in ankle and knee kinematics during gait.

CONCLUSION

Ankle foot orthoses impact gastrocnemius operating length during walking and, with proper design, may assist with stretching tight muscles in daily life. Clinical relevance Determining whether ankle foot orthoses stretch tight muscles can inform future orthotic design and potentially provide a platform for integrating therapy into daily life. However, stretching tight muscles must be balanced with other goals of orthoses such as improving gait and preventing bone deformities.

Skeletal muscle water T2 as a biomarker of disease status and exercise effects in patients with Duchenne muscular dystrophy

The purpose of this study was to examine exercise effects on muscle water T₂ in patients with Duchenne muscular dystrophy (DMD). In 12 DMD subjects and 19 controls, lower leg muscle fat (%) was measured by Dixon and muscle water T₂ and R₂ (1/T₂) by the tri-exponential model. Muscle water R₂ was measured again at 3 hours after an ankle dorsiflexion exercise. The muscle fat fraction was higher in DMD participants than in controls (p < .001) except in the tibialis posterior muscle. Muscle water T₂ was measured independent of the degree of fatty degeneration in DMD muscle. At baseline, muscle water T₂ was higher in all but the extensor digitorum longus muscles of DMD participants than controls (p < .001). DMD participants had a lower muscle torque (p < .001) and exerted less power (p < .01) during exercise than controls. Nevertheless, muscle water R₂ decreased (T₂ increased) after exercise from baseline in DMD subjects and controls with greater changes in the target muscles of the exercise than in ankle plantarflexor muscles. Skeletal muscle water T₂ is a sensitive biomarker of the disease status in DMD and of the exercise response in DMD patients and controls.

Influence of "J"-Curve Spring Stiffness on Running Speeds of Segmented Legs during High-Speed Locomotion

Both the linear leg spring model and the two-segment leg model with constant spring stiffness have been broadly used as template models to investigate bouncing gaits for legged robots with compliant legs. In addition to these two models, the other stiffness leg spring models developed using inspiration from biological characteristic have the potential to improve high-speed running capacity of spring-legged robots. In this paper, we investigate the effects of "J"-curve spring stiffness inspired by biological materials on running speeds of segmented legs during high-speed locomotion. Mathematical formulation of the relationship between the virtual leg force and the virtual leg compression is established. When the SLIP model and the two-segment leg model with constant spring stiffness and with "J"-curve spring stiffness have the same dimensionless reference stiffness, the two-segment leg model with "J"-curve spring stiffness reveals that (1) both the largest tolerated range of running speeds and the tolerated maximum running speed are found and (2) at fast running speed from 25 to 40/92 m s-1 both the tolerated range of landing angle and the stability region are the largest. It is suggested that the two-segment leg model with "J"-curve spring stiffness is more advantageous for high-speed running compared with the SLIP model and with constant spring stiffness.

Effects of Plantar Flexor Muscle Static Stretching Alone and Combined With Massage on Postural Balance

OBJECTIVE

To evaluate and compare the effects of stretching and combined therapy (stretching and massage) on postural balance in people aged 50 to 65 years.

METHODS

Twenty-three subjects participated in this nonrandomized clinical trial study. Each participant randomly received plantar flexor muscle stretching (3 cycles of 45 seconds with a 30-second recovery period between cycles) alone and in combination with deep stroking massage (an interval of at least 30 minutes separated the two interventions). The data were recorded with a force platform immediately after each condition with eyes open and closed. The center of pressure displacement and velocity along the mediolateral and anteroposterior axes were calculated under each condition. The data were analyzed with multiple-pair t-tests.

RESULTS

The center of pressure displacement and velocity along the mediolateral axis increased after both stretching and the combined intervention. There were significant differences in both values between participants in the stretching and combined interventions (p<0.05).

CONCLUSION

Plantar flexor muscle stretching (for 45 seconds) combined with deep stroking massage may have more detrimental effects on postural balance than stretching alone because each intervention can intensify the effects of the other.

Real-time feedback of dynamic foot pressure index for gait training of toe-walking children with spastic diplegia

PURPOSE

The aim of this study was to determine whether and how real-time feedback of dynamic foot pressure index (DFPI) could be used to correct toe-walking gait in spastic diplegic children with dynamic equinus.

METHODS

Thirteen spastic diplegic children with dynamic equinus were asked to wear a monitoring device to record their ambulation during daily gait, conventional training gait, and feedback training gait. Parameters based on their DFPI and stride duration were compared among the three test conditions.

RESULTS

The results with feedback training were significantly better for all DFPI parameters in comparison to patients' daily gait and showed significant improvements in DFPI for toe-walking gait and percentage of normal gait in comparison to conventional training methods. Moreover, stride duration under two training gaits was longer than patient's daily gait, but there was no significant difference between the two training gaits.

CONCLUSIONS

Although the stride duration for the two training gaits was similar, gait training with real-time feedback of DFPI did produce noticeably superior results by increasing heel-loading impulse of toe-walking gait and percentage of normal gait in comparison to convention training methods. However, its effectiveness was still impacted by the motion limitations of diplegic children. Implications for Rehabilitation The DFPI-based gait training feedback system introduced in this study was shown to be more effective at toe-walking gait rehabilitation training over conventional training methods. The feedback system accomplished superior improvement in correcting toe-walking gait, but its effectiveness in an increasing heel-loading impulse in normal gait was still limited by the motion limitations of diplegic children. Stride duration of normal gait and toe-walking gait was similar under conventional and feedback gait training.

Neuro-musculoskeletal simulation of instrumented contracture and spasticity assessment in children with cerebral palsy

Background

Increased resistance in muscles and joints is an important phenomenon in patients with cerebral palsy (CP), and is caused by a combination of neural (e.g. spasticity) and non-neural (e.g. contracture) components. The aim of this study was to simulate instrumented, clinical assessment of the hamstring muscles in CP using a conceptual model of contracture and spasticity, and to determine to what extent contracture can be explained by altered passive muscle stiffness, and spasticity by (purely) velocity-dependent stretch reflex.

Methods

Instrumented hamstrings spasticity assessment was performed on 11 children with CP and 9 typically developing children. In this test, the knee was passively stretched at slow and fast speed, and knee angle, applied forces and EMG were measured. A dedicated OpenSim model was created with motion and muscles around the knee only. Contracture was modeled by optimizing the passive muscle stiffness parameters of vasti and hamstrings, based on slow stretch data. Spasticity was modeled using a velocity-dependent feedback controller, with threshold values derived from experimental data and gain values optimized for individual subjects. Forward dynamic simulations were performed to predict muscle behavior during slow and fast passive stretches.

Results

Both slow and fast stretch data could be successfully simulated by including subject-specific levels of contracture and, for CP fast stretches, spasticity. The RMS errors of predicted knee motion in CP were 1.1 ± 0.9° for slow and 5.9 ± 2.1° for fast stretches. CP hamstrings were found to be stiffer compared with TD, and both hamstrings and vasti were more compliant than the original generic model, except for the CP hamstrings. The purely velocity-dependent spasticity model could predict response during fast passive stretch in terms of predicted knee angle, muscle activity, and fiber length and velocity. Only sustained muscle activity, independent of velocity, was not predicted by our model.

Conclusion

The presented individually tunable, conceptual model for contracture and spasticity could explain most of the hamstring muscle behavior during slow and fast passive stretch. Future research should attempt to apply the model to study the effects of spasticity and contracture during dynamic tasks such as gait.

Electronic supplementary material

The online version of this article (doi:10.1186/s12984-016-0170-5) contains supplementary material, which is available to authorized users.

Effects of ankle-foot braces on medial gastrocnemius morphometrics and gait in children with cerebral palsy

PURPOSE

In children with cerebral palsy (CP), braces are used to counteract progressive joint and muscle contracture and improve function. We examined the effects of positional ankle-foot braces on contracture of the medial gastrocnemius (MG) and gait in children with CP while referencing to typically developing children.

METHODS

Seventeen independently ambulant children with CP and calf muscle contracture (age 10.4 ± 3.0y) and 17 untreated typically developing peers (age 9.5 ± 2.6y) participated. Children with CP were analysed before and 16 ± 4 weeks after ankle-foot bracing. MG muscle belly length and thickness, tendon and fascicle length, as well as their extensibility were captured by 2D ultrasound and 3D motion capturing during passive, manually applied stretches. In addition, 3D gait analysis was conducted.

RESULTS

Prior to bracing, the MG muscle-tendon unit in children with CP was 22 % less extensible. At matched amounts of muscle-tendon unit stretch, the muscle belly and fascicles in CP were 7 % and 14 % shorter while the tendon was 11 % longer. Spastic fascicles displayed 32 % less extensibility than controls. Brace wear increased passive dorsiflexion primarily with the knees flexed. During gait, children walked faster and foot lift in swing improved. MG muscle belly and tendon length showed little change, but fascicles further shortened (-11 %) and muscle thickness (-8 %) decreased.

CONCLUSIONS

Use of ankle-foot braces improves function but may lead to a loss of sarcomeres in series, which could explain the shortened fascicles. To potentially induce gastrocnemius muscle growth, braces may also need to extend the knee or complementary training may be necessary to offset the immobilizing effects of braces.

Concurrent deficits of soleus and gastrocnemius muscle fascicles and Achilles tendon post stroke

Calf muscles and Achilles tendon play important roles in functional activities. However, it is not clear how biomechanical properties of the uniarticular soleus (SOL) and biarticular gastrocnemius muscle and Achilles tendon, including the fascicle length, pennation angle, and stiffness, change concurrently post stroke. Biomechanical properties of the medial gastrocnemius (GM) and soleus muscles were evaluated bilaterally in 10 hemiparetic stroke survivors using combined ultrasonography-biomechanical measurements. Biomechanical properties of the Achilles tendon including the length, cross-sectional area (CSA), stiffness, and Young's modulus were evaluated, together with calf muscle biomechanical properties. Gastrocnemius and SOL contributions were separated using flexed and extended knee positions. The impaired side showed decreased fascicle length (GM: 6%, P = 0.002 and SOL: 9%, P = 0.03, at full knee extension and 0° ankle dorsiflexion) and increased fascicular stiffness (GM: 64%, P = 0.005 and SOL: 19%, P = 0.012, at a common 50 N force level). In contrast, Achilles tendon on the impaired side showed changes in the opposite direction as the muscle fascicles with increased tendon length (5%, P < 0.001), decreased tendon CSA (5%, P = 0.04), decreased tendon stiffness (42%, P < 0.001) and Young's modulus (30%, P < 0.001) compared with the unimpaired side. The fascicle and tendon stiffness changes were correlated negatively to the corresponding fascicle and tendon length changes, and decrease in Achilles tendon stiffness was correlated to the increases of SOL and GM fascicular stiffness (P < 0.05). Characterizations of calf muscle fascicles and Achilles tendon biomechanical properties help us better understand concurrent changes of fascicles and tendon as part of the calf muscle-tendon unit and facilitate development of more effective treatments.

The effect of training in an interactive dynamic stander on ankle dorsiflexion and gross motor function in children with cerebral palsy

OBJECTIVE

To study the effect of active stretching of ankle plantarflexors using an interactive dynamic stander in children with cerebral palsy (CP).

METHODS

Six children in Gross Motor Function Classification System classes I-III, aged 4-10 years, trained intensive active dorsiflexion in an interactive dynamic stander using ankle movement to play custom computer games following a 10-week control period. Gross Motor Function Measure Item Set, gait performance and passive and active dorsiflexion with extended and flexed knee were chosen as outcome parameters.

RESULTS

Median active and passive ankle dorsiflexion increased significantly (5 and 10 degrees, respectively) with extended knee. There was a small but clinically significant increase in gross motor function. The intervention had no effect on temporospatial gait parameters.

CONCLUSION

In spite of the low number of participants, these results may indicate that intensive active stretching in an interactive dynamic stander could be an effective new conservative clinical treatment of ankle plantarflexor contracture in children with CP.

Effects of short duration static stretching on jump performance, maximum voluntary contraction, and various mechanical and morphological parameters of the muscle-tendon unit of the lower extremities

Purpose

Static stretching is used in sport practice but it has been associated with decrements in force and performance. Therefore, we examined the effect of short duration static stretch on the mechano-morphological properties of the m. vastus lateralis (VL) muscle tendon unit (MTU) and on the jumping performance.

Methods

Eight males and three females (mean ± SD, 25.5 ± 3.1 years) stretched their lower legs for a 15 or 60 s duration or acted as their own control without stretching in a randomized order. In a pre-post design, a passive movement (5°/s) and a maximum voluntary knee extension contraction (MVC) were performed on dynamometer while the VL tendon and aponeurosis was observed via ultrasound. Furthermore, the participants performed countermovement (CMJ) and squat jumps (SJ).

Results

Repeated measures ANOVA did not show significant differences in MVC, active and passive strain, stiffness, elongation, knee joint angle range, and jump performance between and within groups.

Conclusions

The applied stretch stimuli (15 or 60 s) were not sufficient to trigger adaptations in the mechano-morphological properties of the lower extremities MTU which therefore did neither affect jump performance nor MVC. As a possible mechanism, we hypothesized that the dose-time dependency effect of static stretch might have important implications when measuring functional parameters of the MTU and performance. Further examination is necessary to elucidate its impact in the examination of the MTU mechano-morphological properties.

Clinical application of a robotic ankle training program for cerebral palsy compared to the research laboratory application: does it translate to practice?

OBJECTIVE

To determine the clinical efficacy of an ankle robotic rehabilitation protocol for patients with cerebral palsy.

DESIGN

The clinic cohort was identified from a retrospective chart review in a before-after intervention trial design and compared with a previously published prospective research cohort.

SETTING

Rehabilitation hospital.

PARTICIPANTS

Children (N=28; mean age, 8.2±3.62 y) with Gross Motor Function Classification System levels I, II, or III who were referred for ankle stretching and strengthening used a robotic ankle device in a clinic setting. Clinic results were compared with a previously published cohort of participants (N=12; mean age, 7.8±2.91 y) seen in a research laboratory-based intervention protocol.

INTERVENTIONS

Patients in the clinic cohort were seen 2 times per week for 75-minute sessions for a total of 6 weeks. The first 30 minutes of the session were spent using the robotic ankle device for ankle stretching and strengthening, and the remaining 45 minutes were spent on functional movement activities. There was no control group.

MAIN OUTCOME MEASURES

We compared pre- and postintervention measures of plantarflexor and dorsiflexor range of motion, strength, spasticity, mobility (Timed Up and Go test, 6-minute walk test, 10-m walk test), balance (Pediatric Balance Scale), Selective Control Assessment of the Lower Extremity (SCALE), and gross motor function measure (GMFM).

RESULTS

Significant improvements were found for the clinic cohort in all main outcome measures except for the GMFM. These improvements were equivalent to those reported in the research cohort, except for larger SCALE test changes in the research cohort.

CONCLUSIONS

These findings suggest that translation of repetitive, goal-directed biofeedback training into the clinic setting is both feasible and beneficial for patients with cerebral palsy.

A path model for evaluating dosing parameters for children with cerebral palsy

Dosing of pediatric rehabilitation services for children with cerebral palsy (CP) has been identified as a national priority. Establishing dosing parameters for pediatric physical therapy interventions is critical for informing clinical decision making, health policy, and guidelines for reimbursement. The purpose of this perspective article is to describe a path model for evaluating dosing parameters of interventions for children with CP. The model is intended for dose-related and effectiveness studies of pediatric physical therapy interventions. The premise of the model is: Intervention type (focus on body structures, activity, or the environment) acts on a child first through the family, then through the dose (frequency, intensity, time), to yield structural and behavioral changes. As a result, these changes are linked to improvements in functional independence. Community factors affect dose as well as functional independence (performance and capacity), influencing the relationships between type of intervention and intervention responses. The constructs of family characteristics; child characteristics (eg, age, level of severity, comorbidities, readiness to change, preferences); plastic changes in bone, muscle, and brain; motor skill acquisition; and community access warrant consideration from researchers who are designing intervention studies. Multiple knowledge gaps are identified, and a framework is provided for conceptualizing dosing parameters for children with CP.

Lower-limb multi-joint stiffness of knee and ankle

Lower-limb multi-joint (knee and ankle) stiffness may play an important role in functional activities such as walking, and may be significantly altered post stroke. Thus, determination of lower-limb multi joint stiffness matrix is important for better understanding of gait and of pathological changes post stroke. In this study, using novel dynamics decomposition, the knee and ankle joint stiffness matrix including cross-coupled stiffness terms between the two joints were determined and reported ever first. The determined stiffness matrix may be useful for gait studies, and can be served as a baseline for studying pathophysiological changes post stroke.

Plyometric training: effectiveness and optimal duration for children with unilateral cerebral palsy

PURPOSE

To evaluate the optimal duration and effects of plyometric training on the gross motor abilities of 3 boys with unilateral spastic cerebral palsy (9 years 11 months, 10 years, and 8 years 9 months).

METHODS

This was a multiple-baseline, multiple-probe, single-subject experiment. The intervention followed the National Strength and Conditioning Association's guidelines for youth. The Gross Motor Function Measure 66, 10×5-m sprint, 20-m run, throw ball, broad jump, and vertical jump tests were used to evaluate gross motor abilities, agility, running speed, and power.

RESULTS

Improvements were found in upper extremity power, Gross Motor Function Measure 66 scores, and agility. Findings for lower extremity power and running speed were inconsistent. Training duration ranged from 8 to 14 weeks.

CONCLUSIONS

This study suggests that plyometric training improves gross motor ability, agility, and upper extremity power in boys with unilateral cerebral palsy. Treatment duration should be determined by an individual's capacity, the task, and the outcome measure.

Movement within foot and ankle joint in children with spastic cerebral palsy: a 3-dimensional ultrasound analysis of medial gastrocnemius length with correction for effects of foot deformation

Background

In spastic cerebral palsy (SCP), a limited range of motion of the foot (ROM), limits gait and other activities. Assessment of this limitation of ROM and knowledge of active mechanisms is of crucial importance for clinical treatment.

Methods

For a comparison between spastic cerebral palsy (SCP) children and typically developing children (TD), medial gastrocnemius muscle-tendon complex length was assessed using 3-D ultrasound imaging techniques, while exerting externally standardized moments via a hand-held dynamometer. Exemplary X-ray imaging of ankle and foot was used to confirm possible TD-SCP differences in foot deformation.

Results

SCP and TD did not differ in normalized level of excitation (EMG) of muscles studied. For given moments exerted in SCP, foot plate angles were all more towards plantar flexion than in TD. However, foot plate angle proved to be an invalid estimator of talocrural joint angle, since at equal foot plate angles, GM muscle-tendon complex was shorter in SCP (corresponding to an equivalent of 1 cm). A substantial difference remained even after normalizing for individual differences in tibia length. X-ray imaging of ankle and foot of one SCP child and two typically developed adults, confirmed that in SCP that of total footplate angle changes (0-4 Nm: 15°), the contribution of foot deformation to changes in foot plate angle (8) were as big as the contribution of dorsal flexion at the talocrural joint (7°). In typically developed individuals there were relatively smaller contributions (10 -11%) by foot deformation to changes in foot plate angle, indicating that the contribution of talocrural angle changes was most important.

Using a new estimate for position at the talocrural joint (the difference between GM muscle–tendon complex length and tibia length, GM relative length) removed this effect, thus allowing more fair comparison of SCP and TD data. On the basis of analysis of foot plate angle and GM relative length as a function of externally applied moments, it is concluded that foot plate angle measurements underestimate angular changes at the talocrural joint when moving in dorsal flexion direction and overestimate them when moving in plantar flexion direction, with concomitant effects on triceps surae lengths.

Conclusions

In SCP children diagnosed with decreased dorsal ROM of the ankle joint, the commonly used measure (i.e. range of foot plate angle), is not a good estimate of rotation at the talocrural joint. since a sizable part of the movement of the foot (or foot plate) derives from internal deformation of the foot.