Accessible Exterior Surfaces Technical Article

COMPARISON OF OBJECTIVE MEASURES AND ENERGY COSTS

Objective measures of surface firmness and stability were compared to energy costs (energy consumption, velocity, RPE and level of difficulty) to negotiate the surfaces. All human subject measures were significantly correlated to the objective measures. All correlations were strong (>0.85; maximum 1.0 for a perfect correlation), except for the medium correlation between penetrometer firmness and velocity (r = −0.6). Velocity was inversely related to firmness and stability. All other variables were directly related to firmness and stability.

There was a strong, second order polynomial relationship between the Rotational Penetrometer stability measurements and the average energy cost for wheelchair users. As the surface became less stable (Rotational Penetrometer displacement increased), the energy cost for wheelchair users increased more dramatically than for ambulatory individuals with and without disabilities.