Knee muscle strength at varying angular velocities and associations with gross motor function in ambulatory children with cerebral palsy

Selective voluntary motor control influences knee joint torque, work and power in children with spastic cerebral palsy

BACKGROUND

Children with spastic cerebral palsy (CP) have damage to the corticospinal tracts that are responsible for selective motor control (SMC). Force, velocity and timing of joint movement are related biomechanical features controlled by the corticospinal tracts (CSTs) that are important for skilled movement.

RESEARCH QUESTION

Does SMC influence knee joint biomechanics in spastic CP?

METHODS

In this prospective study, relationships between SMC and knee biomechanics (peak torque, total work, average power) across a range of velocities (0-300 deg/s) were assessed using an isokinetic dynamometer in 23 children with spastic CP. SMC was assessed using Selective Control Assessment of the Lower Extremity (SCALE). Logistic and linear regression models were used to evaluate relationships between SCALE and biomechanical measures.

RESULTS

The ability to produce knee torque diminished with increasing velocity for both Low (0-4 points) and High (5-10 points) SCALE limb score groups (p < 0.01). More knees in the High group produced extension torque at 300 deg/s (p < 0.05) and flexion torque at 30, 90,180, 240 and 300 deg/s (p < 0.05). The ability to produce torque markedly decreased above 180 deg/s for Low group flexion. For knees that produced torque, significant positive correlations between SCALE limb scores and joint torque (0 and 120 deg/s), work (120 deg/s) and power (120 deg/s) were found (p < 0.05). Greater knee torque, work and power for the High group was found for the extensors at most velocities and the flexors for up to 120 deg/s (p < 0.05). Few Low group participants generated knee flexor torque above 120 deg/s limiting comparisons.

SIGNIFICANCE

Biomechanical impairments found for children with low SMC are concerning as skilled movements during gait, play and sport activities occur at high velocities. Differences in SMC should be considered when designing individualized assessments and interventions.

Isokinetic arm and shoulder muscle torque-velocity characteristics in mobility limited children and adolescents with spina bifida

INTRODUCTION

Propulsive wheelchair capacity may be influenced by arm muscle performance.Objectives: To determine whether children and adolescent wheelchair-users with spina bifida show reduced arm muscle strength compared to their typically developing peers and to compare muscle strength data obtained by isokinetic and handheld dynamometry (HHD).

METHODS

Participants (mean age 12.5 ± 2.5 years) were assigned to spina bifida (SB; n = 11) or control (n = 22) groups. Isokinetic dynamometry was used to measure peak torque (PT) during dynamic (60°s-1 and 120°s-1) and isometric strength testing (MVIC) for shoulder and elbow flexors and extensors. HHD was used to measure MVIC of the same muscle groups.

RESULTS

SB showed reduced isokinetic PT for shoulder extensors at 60°s-1 and 120°s-1, shoulder flexor MVIC, and elbow flexors at 60°s-1 and MVIC; higher PT for shoulder flexors and elbow flexors at 120°s-1; and decreased MVIC for elbow flexors but not extensors compared to controls when assessed by HHD. The SB and control groups showed strong positive correlations between MVIC data obtained by the two devices for all muscle groups (r ≥ 0.81; p < .01), except for shoulder flexor MVIC in controls (r = 0.68; p < .01).

CONCLUSION

SB presented reduced levels of dynamic slow-speed and isometric shoulder and elbow muscle strength and greater dynamic high-speed shoulder and elbow flexor strength than controls possibly due to the exposure to self-sustained wheelchair ambulation. Exercise-based intervention protocols to increase slow-speed arm muscle strength should be considered in youth with SB. Strong positive correlations observed between muscle strength assessed by isokinetic dynamometry and HHD support the use of HHD in this clinical population.

Robotic Ankle Training Improves Sensorimotor Functions in Children with Cerebral Palsy-A Pilot Study

Children with cerebral palsy (CP) have sensorimotor impairments including weakness, spasticity, reduced motor control and sensory deficits. Proprioceptive dysfunction compounds the decreased motor control and mobility. The aims of this paper were to (1) examine proprioceptive deficit of lower extremities of children with CP; (2) study improvement in proprioception and clinical impairments through robotic ankle training (RAT). Eight children with CP participated in a 6-week RAT with pre and post ankle proprioception, clinical, biomechanical assessment compared to the assessment of eight typically developing children (TDC). The children with CP participated in passive stretching (20 min/session) and active movement training (20 to 30 min/session) using an ankle rehabilitation robot (3 sessions/week over 6 weeks, total of 18 sessions). Proprioceptive acuity measured as the plantar and dorsi-flexion motion at which the children recognized the movement was 3.60 ± 2.28° in dorsiflexion and -3.72 ± 2.38° in plantar flexion for the CP group, inferior to that of the TDC group's 0.94 ± 0.43° in dorsiflexion (p = 0.027) and -0.86 ± 0.48° in plantar flexion (p = 0.012). After training, ankle motor and sensory functions were improved in children with CP, with the dorsiflexion strength increased from 3.61 ± 3.75 Nm to 7.48 ± 2.75 Nm (p = 0.018) and plantar flexion strength increased from -11.89 ± 7.04 Nm to -17.61 ± 6.81 Nm after training (p = 0.043). The dorsiflexion AROM increased from 5.58 ± 13.18° to 15.97 ± 11.21° (p = 0.028). The proprioceptive acuity showed a trend of decline to 3.08 ± 2.07° in dorsiflexion and to -2.59 ± 1.94° in plantar flexion (p > 0.05). The RAT is a promising intervention for children with CP to improve sensorimotor functions of the lower extremities. It provided an interactive and motivating training to engage children with CP in rehabilitation to improve clinical and sensorimotor performance.

Development of Lower Extremity Strength in Ambulatory Children With Bilateral Spastic Cerebral Palsy in Comparison With Typically Developing Controls Using Absolute and Normalized to Body Weight Force Values

This cross-sectional study aimed to examine the development of lower limb voluntary strength in 160 ambulatory patients with bilateral spastic cerebral palsy (CP) (106 diplegics/54 quadriplegics) and 86 typically developing (TD) controls, aged 7–16 years. Handheld dynamometry was used to measure isometric strength of seven muscle groups (hip adductors and abductors, hip extensors and flexors, knee extensors and flexors, and ankle dorsiflexors); absolute force (AF) values in pounds were collected, which were then normalized to body weight (NF). AF values increased with increasing age (p < 0.001 for all muscle groups), whereas NF values decreased through adolescence (p < 0.001 for all muscle groups except for hip abduction where p = 0.022), indicating that increases in weight through adolescence led to decreases in relative force. Both AF and NF values were significantly greater in TD subjects when compared with children with CP in all muscle and all age groups (p < 0.001). Diplegics and quadriplegics demonstrated consistently lower force values than TD subjects for all muscle groups, except for the hip extensors where TD children had similar values with diplegics (p = 0.726) but higher than quadriplegics (p = 0.001). Diplegic patients also exhibited higher values than quadriplegics in all muscles, except for the knee extensors where their difference was only indicative (p = 0.056). The conversion of CP subjects' force values as a percentage of the TD subjects' mean value revealed a pattern of significant muscle strength imbalance between the CP antagonist muscles, documented from the following deficit differences for the CP muscle couples: (hip extensors 13%) / (hip flexors 32%), (adductors 27%) / (abductors 52%), and (knee extensors 37%) / (knee flexors 53%). This pattern was evident in all age groups. Similarly, significant force deficiencies were identified in GMFCS III/IV patients when compared with TD children and GMFCS I/II patients. In this study, we demonstrated that children and adolescents with bilateral CP exhibited lower strength values in lower limb muscles when compared with their TD counterparts. This difference was more prevalent in quadriplegic patients and those with a more severe impairment. An important pattern of muscle strength imbalance between the antagonist muscles of the CP subjects was revealed.

Exploring associations between neuromuscular performance, hypermobility, and children's motor competence

OBJECTIVES

To evaluate if neuromuscular performance and hypermobility are factors associated with children's motor competence.

DESIGN

Cross-sectional observation study.

METHODS

Data was collected on 60 children aged 6-12 years; motor competence was determined using the Movement Assessment Battery for Children-2 test, with children classified into 3 groups (Typically Developing n=30; 'At Risk' of low motor competence (LMC) n=9; LMC n=21). Neuromuscular performance was determined utilising the Resistance Training Skills Battery for Children (RTSBc), 5-repetition maximum (5RM) leg press and Biodex dynamometry to assess isometric and isokinetic peak torque of the knee flexors and extensors. Hypermobility was measured using the Beighton and Lower Limb Assessment Score.

RESULTS

Between-groups MANCOVA revealed typically developing children scored significantly higher on the RTSBc than those 'at risk' of LMC (p=0.021) and those in the LMC group (p<0.001). 5RM scores also differed between groups, with typically developing children achieving significantly higher scores than the LMC group. No differences were found between groups for isometric or isokinetic measures of strength. Sequential regression analysis revealed neuromuscular performance variables explained 44.7% of the variance in motor competence, with RTSBc (p<0.001) and 5RM (p=0.019) emerging as positive significant predictors. Hypermobility failed to explain significant variance in motor competence beyond that explained by neuromuscular performance.

CONCLUSIONS

Neuromuscular performance of children varies according to levels of motor competence, with those with LMC performing poorly on tasks requiring multi-joint movement. Furthermore, neuromuscular performance predicted almost half the variance observed in motor competence and highlights a novel intervention strategy.

Do functional hamstring to quadriceps ratio differ between men and women with and without stroke?

BACKGROUND

The functional hamstrings/quadriceps ratio (FH/Q) is useful to detect muscle imbalances after stroke. However, is necessary to investigate possible differences between men and women affected by stroke and controls.

OBJECTIVES

To compare the FH/Q between men and women with stroke and matched controls.

METHOD

Cross-sectional study. Fifty-six participants (10 men - MSTK and 18 women - WSTK with stroke; and 10 men - MCONT and 18 women - WCONT, matched controls) were recruited. The concentric knee extension (conc) and eccentric flexion exercises (ecc) were performed, and peak torque (PT) was used to calculate the FH/Q. Comparisons of PT between sexes (MSTK vs WSTK; MCONT vs WCONT) and comparisons of FH/Q between sexes and groups (MSTK vs MCONT; WSTK vs WCONT), considering dominant vs non-paretic side and non-dominant vs paretic side were performed by ANOVA and Kruskal-Wallis test, when applicable.

RESULTS

No significant FH/Q differences were found between STK vs CONT and sexes (non-paretic vs dominant). The paretic FH/Q was significantly higher than the non-dominant (CONT), for both sexes. PTconc and PTecc were significant higher for men, considering limbs comparisons. No significant PTecc an PTconc differences were found between STK vs CONT, for men's non-paretic and paretic limb's. However, men's non-dominant limb presented a higher PTconc compared to men's paretic limbs.

CONCLUSIONS

Our study demonstrated that individuals affected by stroke had a higher FH/Q in the paretic limb compared to the non-dominant limb of the control group, for both men and women. One interesting finding was the absence of significant FH/Q differences between men and women with stroke.

Running in people with cerebral palsy: A systematic review

BACKGROUND

Running is a fundamental motor skill which is important for participation in recreational activities throughout the lifespan.

AIM

To identify, appraise, and synthesize the evidence related to running in people with cerebral palsy (CP).

METHOD

A search of electronic databases was conducted in April 2016. Articles were reviewed by two assessors and had to meet the following criteria: 1) population included people with CP; and 2) included information about running. Articles were assessed for quality using the Checklist for Measuring Study Quality by Downs and Black.

RESULTS

Of 2607 articles initially identified, 56 underwent full-text review and 17 were included. Quantitative analysis was not possible. The quality of descriptive studies was fair-good, while intervention studies scored poor-good. Four of the 12 descriptive studies reported kinematic and kinetic data. Five intervention studies included running as an outcome measure, although running was not the focus of intervention. A few studies showed that sprint speed, agility, and running efficiency are impaired in people with CP, but mechanisms underlying these impairments have yet to be reported.

INTERPRETATION

Research on running in people with CP is limited, methodology and findings are inconsistent and studies are generally fair quality. Further investigation is warranted.

Relative appendicular skeletal muscle mass is associated with isokinetic muscle strength and balance in healthy collegiate men

There are few studies on the relationship between skeletal muscle mass and balance in the young ages. We investigated the relationship between appendicular skeletal muscle mass, isokinetic muscle strength of lower extremity, and balance among healthy young men using relative skeletal muscle index. Thirty men were grouped according to relative appendicular skeletal muscle mass index: higher skeletal muscle group (n = 15) and lower skeletal muscle group (n = 15). Static and dynamic balance abilities were measured using the following: a test where participants stood on one leg with eyes closed, a modified Clinical Test of Sensory Interaction on Balance (mCTSIB) with eyes open and eyes closed, a stability test, and limits of stability test. The muscle strength of lower extremities was measured with an isokinetic analyser in hip, knee, and ankle joints. Participants with higher appendicular skeletal muscle mass were significantly more stable in maintaining dynamic balance than those with lower appendicular skeletal muscle mass. Moreover, appendicular skeletal muscle mass index was positively correlated with dynamic balance ability. Participants with higher appendicular skeletal muscle mass had stronger strength in the lower extremity, and there were significant differences in the isokinetic torque ratios between groups. From these results, it can be inferred that higher appendicular skeletal muscle mass relates to muscle strength and the alteration in the peak torque ratio of the lower extremity, contributing to the maintenance of balance.

The scope of pediatric physical therapy practice in health promotion and fitness for youth with disabilities

PURPOSE

The purpose of this report is to discuss the scope of pediatric physical therapy practice in health promotion and fitness for youth with disabilities.

SUMMARY OF KEY POINTS

Evidence is provided that supports integration of health promotion and fitness strategies in physical therapy clinical management. Physical therapists' roles in community-based adapted sports and fitness interventions and reimbursement considerations are discussed.

CONCLUSIONS

Physical therapists are in a unique position to provide expertise in the design and implementation of health promotion and fitness programs for youth with disabilities. These programs are important to promote active, healthy lifestyles and reduce comorbidities associated with sedentary behaviors and unhealthy weight, which are often seen in youth with disabilities.

RECOMMENDATIONS FOR CLINICAL PRACTICE

Pediatric physical therapists should incorporate health promotion and fitness strategies into practice.

Meta-analysis of the effect of strengthening interventions in individuals with cerebral palsy

This study aimed to investigate the evidence that strengthening interventions can improve muscle strength and activity in individuals with cerebral palsy. The search focused on studies that employed strength training for children with cerebral palsy for which six electronic databases were used to extract literature published from 2001 to 2012. The key terms used in these searches were combined strength training, strengthening, weight training, weight lifting, resistance, and cerebral palsy. The quality of each study was assessed using the PEDro (Physiotherapy Evidence Database) scale. Thirteen randomized controlled trial studies were selected and divided into categories according to program type, mode, and outcome measures. The overall effect sizes of each study and types of strengthening were large. Strengthening exercise improved muscle strength to a greater degree, when practiced 3 times per week in 40-50 min sessions than in other categories of session length, and greater improvement was observed in younger children than in older. The effect size of the activities and variables related to gait, except for gait endurance, were medium to large. The effect size of individual muscles was large, but the effect sizes for ankle plantar flexor, hip abductor/adductor, and extensor were insignificant. Strengthening interventions are useful for increasing muscle strength in individuals with cerebral palsy, specifically in youth and children, and optimal exercise consisted of 40- to 50-min sessions performed 3 times per week. Although strengthening interventions may improve activities, including gait, more studies that are rigorous are needed to determine the contributions to gross motor function.

Predictors for changes in various developmental outcomes of children with cerebral palsy--a longitudinal study

We aimed to identify predictors for the changes of various developmental outcomes in preschool children with cerebral palsy (CP). Participants were 78 children (49 boys, 29 girls) with CP (mean age: 3 years, 8 months; SD: 1 year, 7 months; range: 1 year to 5 years, 6 months). We examined eight potential predictors: age, sex, CP subtype, Gross Motor Function Classification System (GMFCS) level, selective motor control, Modified Ashworth Scale, and the spinal alignment (SA) and range of motion subscales of the Spinal Alignment and Range of Motion Measure (SAROMM). Developmental outcomes for cognition, language, self-help, and social and motor functions were measured at baseline and a 6-month follow-up with the Comprehensive Developmental Inventory for Infants and Toddlers. Regression model showed GMFCS level was a negative predictor for change of language (adjusted r(2)=0.30, p<.001), motor function (adjusted r(2)=0.26, p<.001), social function (adjusted r(2)=0.07, p=0.014), and self-help (adjusted r(2)=0.26, p<.001). Age was a negative predictor for change of cognition (adjusted r(2)=0.21, p<.001) and language functions (adjusted r(2)=0.26, p<.001). SAROMM-SA was a negative predictor for cognitive change (adjusted r(2)=0.30, p<.001). The GMFCS levels and age are robust negative predictors for change of most developmental domains in these children.

Test-retest reliabilities of hand-held dynamometer for lower-limb muscle strength in intellectual disabilities

The primary purpose of this study was to investigate the test-retest reliabilities of hand-held dynamometer (HDD) for measuring lower-limb muscle strength in intellectual disabilities (ID). The other purposes were to: (1) compare the lower-limb muscle strength between children with and without ID; (2) probe the relationship between the muscle forces and agility performance in ID; and (3) explore the factors associated with muscle strength in ID. Sixty-one participants (30 boys and 31 girls; mean age=14.1 ± 3.3 year) were assessed by the HDD using a "make" test. The comparative group consisted of 63 typically developing children (33 boys and 30 girls; mean age=14.9 ± 2.1 year). The ID group demonstrated lower muscle groups than in typically developing group. Except for the ankle plantarflexors (ICC=0.69, SEM=0.72), test-retest analysis showed good intrarater reliability with ICC ranging from 0.81 to 0.96, and intrarater SEM values ranged from 0.40 to 0.57. The HDD has the potential to be a reliable tool for strength measurement in ID. Muscle strength was positively related to agility performance. Regression analysis indicated that height, weight, BMI, and activity level were significant predictors of muscle strength in ID.