Age-Related Differences in Muscle Size and Strength between Individuals with Cerebral Palsy and Individuals with Typical Development.

AIM: Examine age-related differences in muscle size and strength of the knee extensors in individuals with cerebral palsy (CP) and individuals with typical development (TD). METHODS: 54 individuals with CP (14.5 ± 4.5 years, GMFCS I-V) and 33 individuals with TD (16.2 ± 5.5 years) were included. Relationships between rectus femoris (RF) and vastus lateralis (VL) muscle volume and isokinetic knee extensor strength with age were examined with linear regression and ANCOVA to test age-related differences between groups. RESULTS: Linear regression for muscle volume with age was statistically significant in TD (VL: r2 = 0.48, RF: r2 = 0.56, p < .05) and those with CP (VL: r = 0.36, RF: r2 = 0.27, p < .05) with no differences in regression slopes between groups (p > .05). Age-related strength differences were observed in TD (r2 = 0.66, p < .001) and those with CP (r2 = 0.096, p = .024), but the slopes were significantly different between CP and TD (p < .001). CONCLUSION: Age-related linear differences in muscle volume and strength were observed in both groups. The linear slope of the age-related differences in knee extensor muscle strength and strength-to-body mass ratio were significantly lower in individuals with CP compared to individuals with TD, suggesting that strength is insufficient to keep up with gains in body mass during growth.

Reliability, Validity and Minimal Detectable Change of a Power Leg Press Test in Individuals with Cerebral Palsy.

BACKGROUND: Lower extremity muscle power influences walking ability in individuals with Cerebral Palsy (CP). AIM: Determine the reliability, validity, and minimal detectable change (MDC) of a novel power leg press (PLP) test to measure muscle power in individuals with CP. METHODS: Individuals with spastic CP (n = 26 (10 adults, 16 children); mean (SD) age = 19.3 (7.8) years(all); 27.9 (4.89) years (adults); 13.85(2.68) years (children)) performed 2 sessions of the PLP test, 2-10 days apart. A linear position transducer and custom computer code were used to calculate mean and peak power in watts (W). Intraclass correlation coefficients (ICC), standard error of measurement, MDC, and percent change of MDC (MDC%) were calculated for 4 power measures (average and maximum of mean and peak powers) for all participants (AP) and separately for adults (A) and children (C). Validity was evaluated against isokinetic knee extensor power. RESULTS: Test-retest reliability was excellent for all measures of power (ICC = 0.94-0.99). Ranges for MDC/MDC% by the group for power measures were between 33.7-80.7W/15.5-29.4% (AP), 41.1-65.3W/10.7-22.3% (A), and 27.6-79.8W/19-34.3% (C). Correlations were good to excellent between PLP and isokinetic power at all speeds (r = 0.75-0.88, p < .001). CONCLUSIONS: The PLP test demonstrates excellent validity, reliability, and precision for measuring muscle power in those with CP.

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.

Safety and Feasibility of 1-Repetition Maximum (1-RM) Testing in Children and Adolescents With Bilateral Spastic Cerebral Palsy.

PURPOSE: The purpose of this study was to standardize 1-repetition maximum (1-RM) testing procedures and evaluate the safety and feasibility of these procedures in youth with cerebral palsy (CP). METHODS: Youth with CP completed 1-RM testing on a leg press. RESULTS: Mean absolute, adjusted, and normalized 1-RM loads were 262.4 ± 161.3 lb, 127.0 ± 80.2 lb, and 1.28 ± 0.51, respectively, and 67% were able to successfully lift the same or heavier load after a single failure. Cessation of testing after 1 failed attempt resulted in a 19.0% underestimation of the 1-RM. CONCLUSIONS: 1-RM testing in youth with CP is safe and feasible. Multiple attempts at a failed load should be provided to prevent underestimation in strength. The 1-RM test provides a more accurate strength assessment, which will improve the dosing for resistance training in youth with CP.

Research Summit V: Optimizing Transitions From Infancy to Early Adulthood in Children With Neuromotor Conditions.

PURPOSE: The purpose of this executive summary is to review the process and outcomes of the Academy of Pediatric Physical Therapy Research Summit V, "Optimizing transitions from infancy to young adulthood in children with neuromotor disabilities: biological and environmental factors to support functional independence." SUMMARY OF KEY POINTS: An interdisciplinary group of researchers, representatives from funding agencies, and individuals with neuromotor disabilities and their parents participated in an intensive 2.5-day summit to determine research priorities to optimize life transitions for children with neuromotor disabilities. Recommended priorities for research included (1) promoting self-determination and self-efficacy of individuals with neuromotor disabilities and their families, (2) best care at the right time: evidence-based best practice care, led and navigated by families seamlessly across the lifespan, (3) strengthening connections between developmental domains to enhance function and participation, and (4) optimal dosing and timing to support adaptive bone, muscle, and brain plasticity across the lifespan.

Community-Based Upper Extremity Power Training for Youth with Cerebral Palsy: A Pilot Study.

Aim: To examine the effects of an upper-extremity, community-based, and power-training intervention.Methods: Twelve participants with cerebral palsy (CP) [8 males, 4 females; mean age 14 years 6 months (SD 5 years 4 months), range 7-24] were randomly assigned to a rest-training (RT; n = 6) or training-rest (n = 6) group in this randomized, cross-over design. Training took place in participants' home or school, three times per week for 6 weeks. We examined changes in upper extremity average power output (Pavg) in watts (W) and changes in function via the Pediatric Outcomes Data Collection Instrument (PODCI).Results: Each participant completed at least 15 of the 18 total training sessions (91.2% adherence). Pavg increased 92.2% on average among participants (p < .05). There was a significant three-way interaction among treatment, sequence, and period with the data stratified by (Bimanual Fine Motor Function [BFMF]) level on the pain subscale of the PODCI (p = 0.0118). All participants decreased pain after training with the exception of individuals with lower functioning (BFMF II-V) in the RT group.Conclusion: A community-based upper extremity power-training intervention was feasible and effective at improving power among young people with CP and has the potential to improve pain.

Caregiver-directed home-based intensive bimanual training in young children with unilateral spastic cerebral palsy: a randomized trial.

AIM: To examine the efficacy of caregiver-directed, home-based intensive bimanual training in children with unilateral spastic cerebral palsy (USCP) using a randomized control trial. METHOD: Twenty-four children (ages 2y 6mo-10y 1mo; 10 males, 14 females) performed home-based activities directed by a caregiver for 2 hours per day, 5 days per week, for 9 weeks (total=90h). Cohorts of children were age-matched into groups and randomized to receive home-based hand-arm bimanual intensive therapy (H-HABIT; n=12) or lower-limb functional intensive training (LIFT-control; n=12). Caregivers were trained before the intervention and supervised remotely via telerehabilitation. Dexterity and bimanual hand function were assessed using the Box and Blocks test (BBT) and the Assisting Hand Assessment (AHA) respectively. Caregiver perception of functional goals was measured using the Canadian Occupational Performance Measure (COPM). RESULTS: H-HABIT showed greater improvement on the BBT compared to LIFT-control and no improvement on the AHA. H-HABIT demonstrated significant improvement in COPM-Performance compared to LIFT-control and both groups showed equal improvement in COPM-Satisfaction. INTERPRETATION: H-HABIT improved dexterity and performance of functional goals, but not bimanual performance, in children with USCP compared to a control group receiving intervention of equal intensity/duration that also controlled for increased caregiver attention. Home-based models provide a valuable, family-centered approach to achieve increased treatment intensity.

A potential mechanism by which torque output is preserved in cerebral palsy during fatiguing contractions of the knee extensors.

INTRODUCTION: The purpose of this study was to compare agonist and antagonist electromyography (EMG) during an isokinetic fatigue protocol in subjects with cerebral palsy (CP) and typical development (TD). METHODS: Nine individuals with CP and 11 with TD completed 50 repetitions of maximum concentric knee extensions (KE) and flexions (KF) at 60°/second. RESULTS: Rate of decline in peak torque for KE was significantly less in CP compared with TD. Rate of decline in agonist EMG was not significantly different between groups, but the rate of decline in antagonist EMG was significantly greater in CP. There were no differences between groups for KF. CONCLUSIONS: Declining agonist EMG occurred in parallel with declining antagonist hamstring activity in CP, decreasing the relative opposing force and resulting in a lesser decline in net torque. This finding illustrates a potential mechanism by which net torque is preserved in those with CP who are inherently weaker.

Addressing muscle performance impairments in cerebral palsy: Implications for upper extremity resistance training.

STUDY DESIGN: Case study and literature review. INTRODUCTION: Muscle performance consists of not only strength but also muscle power, rate of force development, and endurance. Therefore, resistance training programs should address not only the force-generating capacity of the muscle but also the ability to produce force quickly. PURPOSE: To discuss the National Strength and Conditioning Association's resistance training guidelines for youth as specifically related to optimal dosing for muscle strength versus muscle power. Dosing parameters of frequency, volume, intensity, duration, and velocity are discussed independently for strength and power. METHODS: We describe how resistance training principles can be applied to the upper extremity in CP through a case study. The case describes an individual with spastic CP, who has a severe motor disability and is non-ambulatory, but has been able to perform resistance training focused on speed, power, and strength. DISCUSSION: Recommendations to optimize the dosing of this individual's resistance training program are made.

Lifelong Fitness in Ambulatory Children and Adolescents with Cerebral Palsy II: Influencing the Trajectory.

Physical activity of at least moderate intensity in all children contributes to higher levels of physical and psychological health. While essential, children with cerebral palsy (CP) often lack the physical capacity, resources, and knowledge to engage in physical activity at a sufficient intensity to optimize health and well-being. Low levels of physical activity place them at risk for declining fitness and health, contributing to a sedentary lifestyle. From this perspective, we describe a framework to foster a lifelong trajectory of fitness in ambulatory children with CP (GMFCS I-III) as they progress into adolescence and adulthood, implemented in conjunction with a training program to augment bone and muscle health. First, we recommend that altering the fitness trajectory of children with CP will require the use of methods to drive behavioral change prior to adolescence. Second, to promote behavior change, we suggest embedding lifestyle intervention into fitness programming while including meaningful activities and peer socialization to foster self-directed habit formation. If the inclusion of lifestyle intervention to drive behavior change is embedded into fitness programs and found to be effective, it may guide the delivery of targeted programming and community implementation. Participation in comprehensive programming could alter the long-term trajectory of musculoskeletal health while fostering strong self-efficacy in persons with CP.

Lifelong Fitness in Ambulatory Children and Adolescents with Cerebral Palsy I: Key Ingredients for Bone and Muscle Health.

Physical activity of a sufficient amount and intensity is essential to health and the prevention of a sedentary lifestyle in all children as they transition into adolescence and adulthood. While fostering a fit lifestyle in all children can be challenging, it may be even more so for those with cerebral palsy (CP). Evidence suggests that bone and muscle health can improve with targeted exercise programs for children with CP. Yet, it is not clear how musculoskeletal improvements are sustained into adulthood. In this perspective, we introduce key ingredients and guidelines to promote bone and muscle health in ambulatory children with CP (GMFCS I-III), which could lay the foundation for sustained fitness and musculoskeletal health as they transition from childhood to adolescence and adulthood. First, one must consider crucial characteristics of the skeletal and muscular systems as well as key factors to augment bone and muscle integrity. Second, to build a better foundation, we must consider critical time periods and essential ingredients for programming. Finally, to foster the sustainability of a fit lifestyle, we must encourage commitment and self-initiated action while ensuring the attainment of skill acquisition and function. Thus, the overall objective of this perspective paper is to guide exercise programming and community implementation to truly alter lifelong fitness in persons with CP.

A comparison of 2 techniques for measuring rectus femoris muscle thickness in cerebral palsy.

PURPOSE: : Precise measures of muscle size are useful when investigating weakness in children with cerebral palsy (CP). Therefore, the purpose of the study was to determine agreement between 2 muscle thickness measurements of the rectus femoris (RF) in CP. METHODS: : Measures of RF thickness in 13 youth with CP who were ambulatory (mean age: 14.4 ± 3.6 years) were obtained bilaterally using ultrasound imaging. Three measures were obtained at 50% thigh length and averaged (MT50). Maximum muscle thickness (MaxMT) was also determined through repeated measurements toward the proximal insertion of the RF. RESULTS: : The Bland-Altman plot showed that all values, except for one outlier, fell within 95% limits of agreement (-0.11 to 0.28 cm), showing excellent agreement. However, a constant bias toward higher values with MaxMT method was observed. CONCLUSION: : Given the time-consuming nature of obtaining MaxMT, the MT50 measurement may be a more feasible alternative when estimating maximum muscle thickness of the RF.

Therapeutic Lower Extremity Power Training Alters the Sensorimotor Cortical Activity of Individuals With Cerebral Palsy.

Objective: To utilize magnetoencephalographic (MEG) brain imaging to examine potential changes in sensorimotor cortical oscillations after therapeutic power training in individuals with cerebral palsy (CP). Design: Cohort. Setting: Academic medical center. Participants: Individuals with CP (N=11; age=15.9±1.1 years; Gross Motor Function Classification System I- III) and neurotypical controls (NTs; N=16; age=14.6±0.8 years). Interventions: Participants with CP underwent 24 (8 weeks; 3 days a week) sessions of high-velocity lower extremity power training on a leg press. The NTs underwent single baseline MEG assessments. Main Outcome Measures: Pre-post bilateral leg press 1-repetition maximum and peak power production were used to assess the muscular performance changes. The 10-m walk and 1-minute walk tests were used to assess mobility changes. During MEG recordings, participants used their right leg to complete a goal-directed isometric target-matching task. Advanced beamforming methods were subsequently used to image the strength of the sensorimotor beta oscillatory power. Results: Before the therapeutic power training, the participants with CP had stronger beta sensorimotor cortical oscillations compared with the NT controls. However, the beta sensorimotor cortical oscillations were weaker and approximated the controls after the participants with CP completed the therapeutic power training protocol. There also was a link between the amount of improvement in leg peak power production and the amount of reduction in sensorimotor cortical oscillations seen after therapy. Conclusions: Therapeutic power training appears to optimize the sensorimotor cortical oscillations of individuals with CP, and these neuroplastic changes partly contribute to improvements in the leg peak power production of individuals with CP. Therapeutic power training might provide the key ingredients for beneficial neuroplastic change.

Power training alters somatosensory cortical activity of youth with cerebral palsy.

OBJECTIVE: Our prior magnetoencephalographic (MEG) investigations demonstrate that persons with cerebral palsy (CP) have weaker somatosensory cortical activity than neurotypical (NT) controls, which is associated with reduced muscular strength and mobility. Power training can improve lower extremity isokinetic strength, muscular power, and walking performance of youth with CP. Potentially, these clinically relevant improvements are partially driven by changes in somatosensory processing. The objective of this investigation was to determine if power training has complementary changes in muscular function and somatosensory cortical activity in youth with CP. METHODS: A cohort of youth with CP (N = 11; age = 15.90 ± 1.1 years) and NT controls (N = 10; Age = 15.93 ± 2.48 years) participated in this investigation. Youth with CP underwent 24 power training sessions. Pre-post bilateral leg press 1-repetition maximum (1RM), peak power production, 10-m walking speed, and distance walked 1-min were used as outcome measures. MEG neuroimaging assessed the changes in somatosensory cortical activity while at rest. NT controls only underwent a baseline MEG assessment. RESULTS: Youth with CP had a 56% increase in 1RM (p < 0.001), a 33% increase in peak power production (p = 0.019), and a 4% improvement in 1-min walk (p = 0.029). Notably, there was a 46% increase in somatosensory cortical activity (p = 0.02). INTERPRETATION: These results are the first to show that power training is associated with improvements in muscular function, walking performance, and the resting somatosensory cortical activity in individuals with CP. This treatment approach might be advantageous due to the potential to promote cortical and muscular plasticity, which appear to have carryover effects for improved walking performance.

In vivo muscle architecture and size of the rectus femoris and vastus lateralis in children and adolescents with cerebral palsy.

AIM: Our aim was to investigate muscle architecture and size of the rectus femoris (RF) and vastus lateralis (VL) in children and adolescents with cerebral palsy (CP) compared with age-matched typically developing participants. METHOD: Muscle architecture and size were measured with ultrasound imaging in 18 participants with spastic CP (9 females, 9 males; age range 7.5-19 y; mean age 12 y [SD 3 y 2 mo]) within Gross Motor Function Classification System levels I (n=4), II (n=2), III (n=9), and IV (n=3) and 12 typically developing participants (10 females, 2 males; age range 7-20 y; mean age 12 y 4 mo [SD 3 y 11 mo]). Exclusion criteria were orthopedic surgery or neurosurgery within 6 months before testing or botulinum toxin injections to the quadriceps within 3 months before testing. RESULTS: RF cross-sectional area was significantly lower (48%), RF and VL muscle thickness 30% lower, RF fascicle length 27% lower, and VL fascicle angle 3 degrees less in participants with CP compared to the typically developing participants (p<0.05). Intraclass correlation coefficients were >or=0.93 (CP) and >or= 0.88 (typical development), indicating excellent reliability. INTERPRETATION: These results provide the first evidence of altered muscle architecture and size of the RF and VL in CP, similar to patterns observed with disuse and aging. These alterations may play a significant role in the decreased capacity for force generation as well as decreased shortening velocity and range of motion over which the quadriceps can act.

Effectiveness of Lower-Extremity Functional Training (LIFT) in Young Children With Unilateral Spastic Cerebral Palsy: A Randomized Controlled Trial.

Background. Children with unilateral spastic cerebral palsy (USCP) have strength, coordination, and balance deficits affecting gross motor skills, such as walking, running, and jumping. However, there is a paucity of evidence for effective treatments for lower-extremity (LE) function in children with USCP. Objective. To determine the effectiveness of LE intensive functional training (LIFT) compared with an attention control group receiving upper-extremity bimanual training (Hand-Arm Bimanual Intensive Therapy [H-HABIT]). Methods. A total of 24 children with USCP were randomized to receive 90 hours of LIFT (5.8 [2.3] years) or an equivalent dosage of H-HABIT (5.1 [2.6] years) delivered 2 h/d, 5 d/wk for 9 weeks. Caregivers were trained to administer the intervention in the home setting. Progress and skill progression were monitored, and supervision was provided via weekly telerehabilitation. The primary outcome was the 1-minute walk test (1MWT). Secondary outcomes included self-selected and fast walking speeds, ABILOCO-kids, 30-s chair rise test, and single-leg stance. Results. LIFT showed greater improvement for the 1MWT (P = .017) and ABILOCO-kids (P = .008) compared with controls. The other secondary outcomes were not different between groups. Conclusions. The administration of LE intensive interventions in the home setting by caregivers was shown to be an effective and novel mode of delivery for improving gait capacity and performance. LIFT delivered in the home setting using telerehabilitation for monitoring resulted in improvements in ambulation distance and overall walking ability as compared to an intervention of equal intensity and duration that also controlled for the increased social interaction and attention between caregiver and child.

Fatigue resistance during a voluntary performance task is associated with lower levels of mobility in cerebral palsy.

OBJECTIVES: To investigate muscle fatigue of the knee flexors and extensors in people with cerebral palsy (CP) compared with those without motor disability during performance of a voluntary fatigue protocol and to investigate the relationship with functional mobility. DESIGN: A case-control study. SETTING: A biomechanics laboratory. PARTICIPANTS: Ambulatory subjects with CP (n=18; mean age, 17.5 y) in Gross Motor Function Classification System (GMFCS) levels I, II, and III and a comparison group of age-matched subjects (n=16) without motor disability (mean age, 16.6 y). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: The voluntary muscle fatigue protocol consisted of concentric knee flexion and extension at 60 degrees a second for 35 repetitions on an isokinetic dynamometer. Peak torque for each repetition was normalized by the maximum peak torque value. Muscle fatigue was calculated as the rate of decline in normalized peak torque across all repetitions, represented by the slope of the linear regression. Self-selected and fast gait velocities were measured as well as the Pediatric Outcomes Data Collection Instrument (PODCI). RESULTS: Greater fatigability (slope) was observed in the comparison group for both knee flexors and extensors than in the group with CP. Within CP, lower knee extensor fatigue (slope) was associated with lower functioning GMFCS levels and lower levels of activity and participation as measured by the PODCI transfers and basic mobility. CONCLUSIONS: Even after adjusting for maximum peak torque, the knee flexors and extensors of participants with CP were observed to be less fatigable than age-matched peers without motor disability. The lower rate of muscle fatigue was also associated with lower functional mobility in CP. These results may be related to strength or activation differences and/or muscle property alterations. Future investigations are warranted.

Effectiveness of Rehabilitation Interventions to Improve Gait Speed in Children With Cerebral Palsy: Systematic Review and Meta-analysis.

BACKGROUND: Children with cerebral palsy (CP) have decreased gait speeds, which can negatively affect their community participation and quality of life. However, evidence for effective rehabilitation interventions to improve gait speed remains unclear. PURPOSE: The purpose of this study was to determine the effectiveness of interventions for improving gait speed in ambulatory children with CP. DATA SOURCES: MEDLINE/PubMed, CINAHL, ERIC, and PEDro were searched from inception through April 2014. STUDY SELECTION: The selected studies were randomized controlled trials or had experimental designs with a comparison group, included a physical therapy or rehabilitation intervention for children with CP, and reported gait speed as an outcome measure. DATA EXTRACTION: Methodological quality was assessed by PEDro scores. Means, standard deviations, and change scores for gait speed were extracted. General study information and dosing parameters (frequency, duration, intensity, and volume) of the intervention were recorded. DATA SYNTHESIS: Twenty-four studies were included. Three categories of interventions were identified: gait training (n=8), resistance training (n=9), and miscellaneous (n=7). Meta-analysis showed that gait training was effective in increasing gait speed, with a standardized effect size of 0.92 (95% confidence interval=0.19, 1.66; P=.01), whereas resistance training was shown to have a negligible effect (effect size=0.06; 95% confidence interval=-0.12, 0.25; P=.51). Effect sizes from negative to large were reported for studies in the miscellaneous category. LIMITATIONS: Gait speed was the only outcome measure analyzed. CONCLUSIONS: Gait training was the most effective intervention in improving gait speed for ambulatory children with CP. Strength training, even if properly dosed, was not shown to be effective in improving gait speed. Velocity training, electromyographic biofeedback training, and whole-body vibration were effective in improving gait speed in individual studies and warrant further investigation.

Kinematic measurement of 12-week head control correlates with 12-month neurodevelopment in preterm infants.

BACKGROUND: Although new interventions treating neonatal brain injury show great promise, our current ability to predict clinical functional outcomes is poor. Quantitative biomarkers of long-term neurodevelopmental outcome are critically needed to gauge treatment efficacy. Kinematic measures derived from commonly used developmental tasks may serve as early objective markers of future motor outcomes. AIM: To develop reliable kinematic markers of head control at 12week corrected gestational age (CGA) from two motor tasks: head lifting in prone and pull-to-sit. STUDY DESIGN AND SUBJECTS: Prospective observational study of 22 preterm infants born between 24 and 34weeks of gestation. OUTCOME MEASURES: Bayley Scales of Infant Development III (Bayley) motor scores. RESULTS: Intrarater and interrater reliability of prone head lift angles and pull-to-sit head angles were excellent. Prone head lift angles at 12week CGA correlated with white matter NAA/Cho, concurrent Test of Infant Motor Performance (TIMP) scores, and 12-month Bayley motor scores. Head angles during pull-to-sit at 12-week CGA correlated with TIMP scores. CONCLUSIONS: Poor ability to lift the head in prone and an inability to align the head with the trunk during the pull-to-sit task were associated with poorer future motor outcome scores. Kinematic measurements of head control in early infancy may serve as reliable objective quantitative markers of future motor impairment and neurodevelopmental outcome.