Comparative analysis of power, work and muscle activation during weight-stack and iso-inertial flywheel resistance exercise in young adults with cerebral palsy

Abstract

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. 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 22 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 weightstack), 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 isoinertial protocol for young adults with cerebral palsy.

Determinants of Frame Running Capacity in Athletes With Cerebral Palsy to Improve Training Routines and Classification Strategies

“…The relationship between muscle size and strength, 27 as well as muscle size and running capacity, 9 is well known in typically developing individuals. This association seems to be weaker in individuals with CP because of what seems to be an altered neural drive, causing muscles affected by CP to be underpowered in relation to their muscle size 28 . Notwithstanding, muscle size in individuals with CP has been found to predict maximum voluntary strength 12 and to have a greater impact on the Gross Motor Function Measure than spasticity (modified Ashworth scale rating) 26,29 .…”

“…This association seems to be weaker in individuals with CP because of what seems to be an altered neural drive, causing muscles affected by CP to be underpowered in relation to their muscle size. 28 Notwithstanding, muscle size in individuals with CP has been found to predict maximum voluntary strength 12 and to have a greater impact on the Gross Motor Function Measure than spasticity (modified Ashworth scale rating). 26,29 Supporting the studies highlighting the importance of muscle size in individuals with CP, our result showed that muscle thickness is an essential factor for FR capacity, with the thigh muscle group emerging as somewhat more important than the calf muscles.…”

Extracellular vesicle characteristics and microRNA content in cerebral palsy and typically developed individuals at rest and in response to aerobic exercise

“…Specifically, increased collagen ( Booth et al, 2001 ) and intramuscular adipose tissue content ( Noble et al, 2014 ) is believed to contribute to poor muscle function. Individuals with CP respond to exercise, although differences in performance and adaptations exist when compared with TD individuals ( Hjalmarsson et al, 2020 ; von Walden et al, 2020 ). Extracellular vesicle biology has never been investigated in individuals with CP, and it remains to be shown if the response of circulating EVs induced by exercise mimics that of TD individuals.…”