Running capacity in children with bilateral cerebral palsy: What are the biomechanical and neuromotor differences between runners and walkers?

Background: Running is a high-level locomotor activity requiring more from joints, muscles and a more complex interaction of the neuromuscular system than walking. High-level locomotor activity has the potential to shed light on motor function deficits that lower-level activity does not reveal. Therefore, the study aimed to compare biomechanical and neuromotor function between a group of children with bilateral cerebral palsy who are able and unable to run.

Methods: Retrospectively, children with bilateral cerebral palsy aged between 6 and 18 years who completed a clinical gait analysis between 2006 and 2019 were included. Participants were categorized as walkers or runners based on the presence of a double floating phase. Spasticity, selectivity, muscle weakness, and passive range of motion of the lower limbs were measured and dichotomized as «normal» or «abnormal» based on reference values. Functional tasks reflecting balance (standing on one leg) and power (single leg and two-legged jumps) were realized and evaluated as failure or success.

Findings: 75 children with bilateral cerebral palsy (53 runners/22 walkers) were included. Children classified as runners were stronger (hip flexors, p = 0.006; hip abductors, p = 0.022; knee flexors, p = 0.001; dorsiflexors, p = 0.014), had greater selectivity (hip flexors, p = 0.011; dorsiflexors, p = 0.001; plantiflexors, p = 0.043) and lower spasticity at the knee extensors (p = 0.045). No differences were observed in the passive range of motion between the two groups. Children classified as runners performed better at all tasks of balance and power (p < 0.05).

Interpretation: Flexors muscles strength and selectivity and knee extensor spasticity are key points for running ability in children with bilateral cerebral palsy.