Ferdinand von Walden, Emma Hjalmarsson, Mikael Reimeringer, Ola Kvist, Peter C. Raffalt, Eva Pontén, Rodrigo Fernandez-Gonzalo
Women's and Children's health, Karolinska Institutet, 17177 Stockholm, Sweden. E-mail: ferdinand.von.walden@ki.se
DOI: 10.2340/16501977-2682

Introduction: The development of efficient resistance exercise protocols to counteract muscle dysfunction in cerebral palsy is warranted. Whether individuals with cerebral palsy are able to perform iso-inertial resistance (flywheel) exercise in a comparable manner to typically developed subjects has never been experimentally tested.
Design: A comparative, controlled study.
Subjects: Eight young ambulatory adults with cerebral palsy (mean age 19 years; Gross Motor Function Classification System (GMFCS) I–III) and 8 typically developed control subjects (mean age 21 years).
Methods: Subjects performed acute bouts on the weight-stack and flywheel leg-press device, respectively. Range of motion, electromyography, power, work and muscle thickness (ultrasound) data were collected.
Results: Subjects with cerebral palsy were able to produce a greater eccentric/concentric peak power ratio on the flywheel (p < 0. 05 vs ratio in weight-stack), however absolute values were lower (p < 0. 05 vs weight-stack). Typically developed subjects produced more power per mm of thigh muscle than the cerebral palsy group, independent of leg, device and action.
Discussion: Subjects with cerebral palsy could not elicit the eccentric overload seen in typically developed subjects. Furthermore, peak power production per mm muscle was markedly reduced in both legs in subjects with cerebral palsy. In conclusion, this comparative study of weight-stack and flywheel exercise does not support the implementation of the current iso-inertial protocol for young adults with cerebral palsy.

Cerebral palsy is an umbrella term for a movement disorder in children and adults, which is caused by damage to the immature, developing brain. Individuals with cerebral palsy have weaker, thinner and stiffer muscles compared with individuals without cerebral palsy. Poor muscle function makes everyday activities harder. Efficient training regimes to improve muscle function are therefore needed. This study investigated whether an alternative form of resistance exercise (iso-inertial exercise) was feasible in individuals with cerebral palsy. The results show that iso-inertial exercise was difficult for individuals with cerebral palsy to perform and is probably unsuitable for clinical practice for this specific population.

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