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Muscle force production and functional performance in spastic cerebral palsy: relationship of cocontraction
D L Damiano1, T L Martellotta, D J Sullivan
1Department of Orthopaedics, University of Virginia Health System, Charlottesville, USA.
Insights
Children with spastic cerebral palsy (CP) exhibit similar muscle activation strategies. Greater muscle activity in CP patients correlated with better energy efficiency, while strength related to motor function. Further research is needed.
Area of Science:
- Neurology
- Biomedical Engineering
- Pediatric Rehabilitation
Background:
- Spastic cerebral palsy (CP) significantly impacts motor function in children.
- Understanding muscle activation patterns, like cocontraction, is crucial for assessing functional limitations.
- Quantifying the relationship between muscle strength, cocontraction, and energy expenditure in children with CP is essential for targeted interventions.
Purpose of the Study:
- To investigate the association between cocontraction, muscle strength, and motor function in children with spastic cerebral palsy.
- To explore how muscle activation strategies relate to energy efficiency during gait and strength testing.
Main Methods:
- Prospective study of 10 ambulatory children with spastic CP (ages 5-14).
- Assessed hamstring and quadriceps strength, gait using electromyography (EMG) for cocontraction analysis, Gross Motor Function Measure (GMFM), and energy expenditure index (EEI).
Main Results:
- Cocontraction patterns during strength tests mirrored those during free gait.
- Higher cocontraction and total EMG magnitude correlated with increased energy efficiency (lower EEI).
- Knee extensor strength positively associated with GMFM scores and gait velocity, but not directly with gait cocontraction.
Conclusions:
- Children with CP demonstrate consistent muscle activation strategies across different motor tasks.
- Muscle strength and cocontraction independently influence distinct aspects of motor function.
- Further investigation is required to refine the quantification of cocontraction and its relationship with muscle force in pediatric CP populations.
Objective:
To determine cocontraction's relation to strength and motor function in children with spastic cerebral palsy (CP).
Design:
Prospective evaluation with a convenience sample of 10 subjects.
Setting:
Pediatric rehabilitation center at a tertiary care hospital.
Patients:
Ten ambulatory children with spastic CP, mean age 5 to 14yrs.
Main Outcome Measures:
A single comprehensive assessment of hamstring and quadriceps muscle strength; gait analysis while monitoring electromyographic (EMG) activity in those muscles; administration of the Gross Motor Function Measure (GMFM); heart-rate monitoring during quiet rest versus gait to compute an energy expenditure index (EEI). Cocontraction ratios and magnitudes were determined for the gait and strength testing trials using the EMG data.
Results:
Cocontraction ratios during strength tests correlated directly with those during free gait. Cocontraction magnitude and total EMG magnitude had an inverse relationship to EEI; children with more muscle activity in the agonist and antagonist tended to be more energy efficient. Knee extensor muscle strength correlated positively with the GMFM and gait velocity. Neither cocontraction ratio nor magnitude during gait was related to strength.
Conclusions:
Children with CP used a similar muscle activation strategy across two different motor tasks. Strength and cocontraction were uniquely related to different aspects of motor function. Further research is needed to quantify more precisely cocontraction and force to EMG relations in this population.