Plantar flexor muscle weakness and fatigue in spastic cerebral palsy patients.
Young adults with CP have weak calf muscles that tire slowly because they can’t fully activate them.
01Research in Context
What this study did
Neyroud et al. (2017) tested young adults with spastic cerebral palsy in a lab.
They compared calf-muscle strength and fatigue to healthy peers during hard foot presses.
What they found
The CP group was weaker but lasted longer before the muscle gave out.
They could not fully switch on their calf muscles, so the muscle tired more slowly.
How this fits with other research
Keawutan et al. (2014) saw the same group pattern in kids: weaker CP muscles linked to less daily movement.
Goodwin et al. (2012) also used lab gait tests and found weaker CP children showed faster EMG bursts—different method, same weak-muscle story.
Verschuren et al. (2010) found lower aerobic capacity in CP youth; Daria now shows the power side of that coin.
Why it matters
When you plan gait or standing programs, expect weak but fatigue-resistant calf muscles in CP clients.
Use shorter, high-effort bursts instead of long endurance sets.
Track fatigue by how fast force drops, not just how long they keep going.
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02At a glance
03Original abstract
BACKGROUND: Patients with cerebral palsy develop an important muscle weakness which might affect the aetiology and extent of exercise-induced neuromuscular fatigue. AIM: This study evaluated the aetiology and extent of plantar flexor neuromuscular fatigue in patients with cerebral palsy. METHODS: Ten patients with cerebral palsy and 10 age- and sex-matched healthy individuals (∼20 years old, 6 females) performed four 30-s maximal isometric plantar flexions interspaced by a resting period of 2-3s to elicit a resting twitch. Maximal voluntary contraction force, voluntary activation level and peak twitch were quantified before and immediately after the fatiguing task. RESULTS: Before fatigue, patients with cerebral palsy were weaker than healthy individuals (341±134N vs. 858±151N, p<0.05) and presented lower voluntary activation (73±19% vs. 90±9%, p<0.05) and peak twitch (100±28N vs. 199±33N, p<0.05). Maximal voluntary contraction force was not significantly reduced in patients with cerebral palsy following the fatiguing task (-10±23%, p>0.05), whereas it decreased by 30±12% (p<0.05) in healthy individuals. CONCLUSIONS: Plantar flexor muscles of patients with cerebral palsy were weaker than their healthy peers but showed greater fatigue resistance. WHAT THIS PAPER ADDS: Cerebral palsy is a widely defined pathology that is known to result in muscle weakness. The extent and origin of muscle weakness were the topic of several previous investigations; however some discrepant results were reported in the literature regarding how it might affect the development of exercise-induced neuromuscular fatigue. Importantly, most of the studies interested in the assessment of fatigue in patients with cerebral palsy did so with general questionnaires and reported increased levels of fatigue. Yet, exercise-induced neuromuscular fatigue was quantified in just a few studies and it was found that young patients with cerebral palsy might be more fatigue resistant that their peers. Thus, it appears that (i) conflicting results exist regarding objectively-evaluated fatigue in patients with cerebral palsy and (ii) the mechanisms underlying this muscle fatigue - in comparison to those of healthy peers - remain poorly understood. The present study adds important knowledge to the field as it shows that when young adults with cerebral palsy perform sustained maximal isometric plantar flexions, they appear less fatigable than healthy peers. This difference can be ascribed to a better preservation of the neural drive to the muscle. We suggest that the inability to drive their muscles maximally accounts for the lower extent of exercise-induced neuromuscular fatigue in patients with cerebral palsy.
Research in developmental disabilities, 2017 · doi:10.1016/j.ridd.2016.12.015