Electromyographic (EMG) analysis of quadriceps muscle fatigue in children with cerebral palsy during a sustained isometric contraction.

The purpose of this investigation was to determine whether changes in surface electromyography (EMG) data during an isometric muscle protocol, in combination with maximal voluntary isometric force, provide information on fatigue occurrence and exercise limitation in children with cerebral palsy. Twelve children with cerebral palsy and 10 age-matched controls completed an assessment of quadriceps muscle fatigue on an isokinetic device with surface EMG measurements, during a sustained isometric contraction at 50% of the maximal voluntary isometric force. The EMG data collected in participants with cerebral palsy suggest that muscle fatigue occurred sooner in children with cerebral palsy relative to the age-matched controls. However, the results demonstrate that no difference was found in time to exhaustion between the able-bodied and participants with cerebral palsy. These contrasting results may be the result of spasticity and co-contraction during maximal testing, which may play an important role in exercise limitation in children with cerebral palsy.