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Event-related Potentials During Target-response Tasks to Study Cognitive Processes of Upper Limb Use in Children with Unilateral Cerebral Palsy
Published on: January 11, 2016
Fatigue and muscle activation during submaximal elbow flexion in children with cerebral palsy
Aude-Clémence M Doix1, Anette Gulliksen, Siri M Brændvik
1Department of Human Movement Science, NTNU, Trondheim, Norway.
Insights
Children with cerebral palsy (CP) do not recruit additional motor units to compensate for muscle fatigue during sustained contractions, unlike their typically developing peers. This finding impacts understanding of motor control in CP.
Area of Science:
- Neurology
- Rehabilitation Science
- Motor Control
Background:
- Muscle fatigue is a common challenge affecting motor performance.
- Understanding compensatory mechanisms for fatigue is crucial for rehabilitation strategies.
- Cerebral palsy (CP) presents unique challenges in motor control and muscle function.
Purpose of the Study:
- To investigate if children with cerebral palsy (CP) compensate for muscle fatigue by recruiting additional motor units.
- To compare fatigue compensation strategies between children with CP and typically developing children.
- To examine motor unit recruitment during sustained submaximal contractions in CP.
Main Methods:
- Surface electromyography (EMG) of biceps brachii and triceps brachii.
- Forearm acceleration measurement using an accelerometer.
- Sustained isometric elbow flexion contraction to task failure at 25% maximal voluntary torque.
Main Results:
- No significant differences in strength or time to task failure between groups.
- Children with CP showed a lower increase in EMG amplitude during sustained contraction.
- No significant group differences in median frequency decrease or acceleration variation.
Conclusions:
- Children with CP do not appear to recruit additional motor units to compensate for muscle fatigue.
- Fatigue compensation mechanisms may differ between children with CP and typically developing peers.
- Findings suggest altered motor unit recruitment strategies in children with CP.
Abstract:
The purpose of this study was to investigate whether children with cerebral palsy (CP), like typically developing peers, would compensate for muscle fatigue by recruiting additional motor units during a sustained low force contraction until task failure. Twelve children with CP and 17 typically developing peers performed one submaximal isometric elbow flexion contraction until the task could no longer be sustained at on average 25% (range 10-35%) of their maximal voluntary torque. Meanwhile surface electromyography (EMG) was measured from the biceps brachii and triceps brachii, and acceleration variations of the forearm were detected by an accelerometer. Slopes of the change in EMG amplitude and median frequency and accelerometer variation during time normalised to their initial values were calculated. Strength and time to task failure were similar in both groups. Children with CP exhibited a lower increase in EMG amplitude of the biceps brachii and triceps brachii during the course of the sustained elbow flexion task, while there were no significant group differences in median frequency decrease or acceleration variation increase. This indicates that children with CP do not compensate muscle fatigue with recruitment of additional motor units during sustained low force contractions.
