# Body-weight support is the primary driver of elevated walking cost in cerebral palsy

## TL;DR

Children with cerebral palsy use more energy to walk, mainly due to the need for extra body-weight support, which can be significantly reduced with assistance.

## Contribution

This study identifies body-weight support as the primary biomechanical factor driving elevated walking costs in cerebral palsy.

## Key findings

- Body-weight support reduced walking energy expenditure by 41% in children with cerebral palsy.
- Mediolateral stabilization had negligible effects on energetic cost in both cerebral palsy and typically developing children.
- Higher baseline energy cost and greater knee flexion predicted larger reductions in energy expenditure with body-weight support.

## Abstract

Children with cerebral palsy (CP) exhibit substantially elevated energetic costs of walking, yet the biomechanical origins of this excessive cost remain unclear, limiting the effectiveness of current interventions.

We tested the hypothesis that elevated energetic cost of walking in CP arises primarily from increased demands for body-weight support and lateral stabilization. Using a custom mechatronic system, we independently applied controlled vertical body-weight support (1–60% body weight) and mediolateral stabilization stiffness (50–1500 N/m) while children with CP and typically developing (TD) peers walked on a treadmill at a fixed nondimensional speed. We quantified steady-state energetic cost using indirect calorimetry and used linear regression models to determine energetic responses to each intervention.

Providing body-weight support significantly reduced net energetic cost in both groups, with a 3.5-fold greater effect in children with CP (n = 23) compared to TD peers (n = 10). Across the 1–60% support range, energetic cost decreased by 41% in CP, normalizing walking energy expenditure to TD levels. Higher baseline energetic cost of walking and greater knee flexion during stance were associated with larger energetic reductions (p < 0.01). In contrast, mediolateral stabilization produced negligible energetic effects in both CP (n = 14) and TD groups, with no demographic or biomechanical predictors of response.

Body-weight support is the dominant contributor to elevated energetic cost of walking in children with CP, whereas lateral stabilization contributes minimally under the conditions tested. These findings identify gravitational support as a key biomechanical target for energy-focused rehabilitation and assistive technology interventions.

Providing body-weight support reduced the energetic cost of walking in children with cerebral palsy to levels similar to those of typically developing peers.