Affiliations: Worcester Polytechnic Institute. Department of
Biomedical Engineering, Worcester, MA, USA | Department of Industrial Engineering and Management
Systems, University of Central Florida, Orlando, FL, USA | Department of Industrial and Manufacturing Systems
Engineering, University of Michigan-Dearborn, Dearborn, MI, USA
Note: [] Address for correspondence: Krystyna Gielo-Perczak, Worcester
Polytechnic Institute, Department of Biomedical Engineering, Goddard Hall,
Office 303A, 100 Institute Road, Worcester, MA 01609, USA. E-mail:
GieloPerczak@wpi.edu
Abstract: This study investigated the effects of width of construction beams
and single-hand load holding task conditions on nonlinear behavior of the foot
center of pressure (COP) exerted on the beam. The foot COP, defined as the
point of application of the result of vertical forces acting on the surface of
foot support, was measured in the lateral direction under simulated standing
task conditions. Twelve healthy male subjects were asked to hold a load of 6.8
kg and 11.3 kg while standing on the elevated construction beams with widths of
10 and 22.5 cm (4 and 9 inches, respectively) under low and high foot
separation (foot step). The results showed that both beam width and single-hand
load carrying conditions had significant effects on the observed nonlinearity
of the foot center of pressure exerted on the beam. Standing on the narrow beam
resulted in higher level of chaotic behavior of COP compared to the wide beam
condition. The nonlinearity of the COP exerted by the forward (left) foot was
higher for the narrow beam condition. For both beams, the nonlinearity of the
COP exerted by the forward (left) foot was consistently higher than the COP
exerted by the backward (right) foot. Furthermore, for both beams,
single-handed holding of the 11.3 kg load resulted in higher levels of COP
nonlinearity than carrying 6.8 kg or no load at all. The study results indicate
that nonlinear dynamics behavior of the forward foot under single-handed high
load holding condition may be critical to preserving lateral stability during
standing at the construction beams.
Keywords: Postural balance, center of pressure, standing on a beam, nonlinear dynamics
