A Prospective Study of Two Home Based Muscle Strengthening Programs for Children With Cerebral Palsy

The aim of this randomized, stratified, single-blinded study is to compare two home based strength-training protocols (High Intensity Interval Training and Progressive Resistance Training) and their effects on muscle strength, gait and aerobic and anaerobic capacity in children with cerebral palsy.

Cerebral palsy is a common neuro-developmental disorder. Among other signs of upper motor neuron syndrome, walking pathologies and muscle weakness are leading signs of disability in children with cerebral palsy. Moreover, the gradual decline in muscle strength is part of the aging process and can be particularly devastating for people with motor disabilities. Therefore muscle-strengthening programs are indicated for children with cerebral palsy. There is evidence that lower extremity muscle strength can be increased by Progressive Resistance Training (PRT) in children with cerebral palsy. However, PRT is time consuming and therefore not always feasible for children with neurologic disorders. Moreover, it does not influence the anaerobic capacity needed for everyday activities in children. High Intensity Interval Training (HIIT) is a time efficient method, which increases both aerobic and anaerobic capacities. The aim of this randomized, stratified, single-blinded study is to compare two home based strength-training protocols (HIIT and PRT) and their effects on muscle strength, gait and aerobic and anaerobic capacity in children with cerebral palsy.

The key for the PRT is the timely progression of load, based on the child's individual level of strength, which ensures progressive overload. Every training session will consist of a warm up, progressive resistance exercises and a cool down period. During warm up and cool down periods.These exercises will be the same for both training groups. The strength training exercises have been chosen to strengthen the main lower extremity muscle groups which are important for the gait: sit-to-stand, lateral step-ups, the half knee rise, heel-rises and bridging. All these exercises are performed loaded according to the individual level. Three sets of 8 to 10 repetitions of each exercise will be practiced on 3 non-consecutive days with moderate velocity.

The High Intensity Circuit Training is a sub form of High Intensity Interval Training. The key feature is the very little rest between the exercises which causes a consistent elevation of the participant's heart rate and a short duration of the whole exercise session. Every training session consists of a warm-up, a circuit of 5 exercises (the same as these in the PRT group) and a cool-down period. The children will be asked to train 3 times a week on non-consecutive days and to perform 3 sets. Exercise workload is controlled by determination of time intervals (30 seconds). The children will be instructed to perform as many repetitions as possible during the exercise interval and to keep the rest between the exercises short (it must not exceed 30 seconds).

The 6 minute walk test is a self-paced, submaximal test that assesses functional capacity for walking a prolonged distance. The distance reached within 6 minutes of walking is evaluated.

Short-term muscle power will be measured using the mean power (in watts) derived from the Muscle Power Sprint Test. This test has been shown to be reliable in children with cerebral palsy. For the test, the children are instructed to complete six 15m runs at maximum pace. Between each run, the child is allowed a timed 10 second rest. Mean power output (in watts) is calculated based on the child's body weight and the average time taken to perform the six all-out sprints.

The test requires the children to rise from an armchair stand momentarily, walk 3 meters, return to the same seat and sit down again.

The Timed Stair Test (TST) assesses the time needed to go up and down stairs. The test is performed on a 4 or 5-step set of stairs, with handrails on both sides.

Heart rate is an accurate and convenient measure of energy expenditure during submaximal work in normally developing children and in children with cerebral palsy and other developmental disabilities.

Change in Results of Dynamometry, Ultrasound imaging, Electromyography - Analysis of the muscle-tendon unit morphology and physiology measurements of the calf muscles

After recording, the ultrasound images will be utilized to determine the muscle belly length, fascicle length, pennation angle and muscle thickness of the GM, muscle and tendon excursion, Achilles tendon length and cross-sectional-area (CSA) to calculate muscle and tendon stiffness and Young's modulus of the tendon.

Change in results of Pediatric Outcome Data Collection Instrument (PODCI) and Activity Scale for kids performance version (ASKp) questionnaires

Today three dimensional segment models allow the quantification of segment and joint motions of the lower limbs in the three major planes of movement. In addition to the joint-angle and segment-position information, kinetic parameters such as joint moments and forces can be approximated.

Inclusion Criteria: Ambulatory children with unilateral or bilateral spastic cerebral palsy Age between 8-16 years Ability to accept and follow verbal instruction Gross Motor Function Classification System (GMFCS) at level I-II Willingness to participate Exclusion Criteria: Other than spastic form of cerebral palsy (ataxia, athetoid or dystonic) Quadriplegia History of orthopaedic surgery in the last 12 months History of Botulinum Toxin A application in the last 6 months Severe mental retardation

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