Posture control depends on balancing act.Even when standing still, the human body is in constant motion. That subtle swaying causes the center of pressure under an individual's feet to shift randomly within a radius of a centimeter centimeter (sĕn`tĭmē'tər), abbr. cm, unit of length equal to 0.01 meter, the basic unit of length in the metric system. The centimeter is the unit of length in the cgs system. It is approximately equal to 0. or two.
Researchers have now shown that monitoring the path followed by the center of pressure of a quietly standing person furnishes useful information about the body's response to small impulses, or shoves. Such measurements may eventually help in diagnosing balance disorders in people, says mathematician Carson C. Chow of Boston University's Center for Biodynamics biodynamics
the scientific study of the nature and determinants of the behavior of all organisms, including humans.
biodynamics The formal study of vital forces, physiological interactions and behavior .
Chow, biomedical bi·o·med·i·cal
1. Of or relating to biomedicine.
2. Of, relating to, or involving biological, medical, and physical sciences. engineer James J. Collins, and their coworkers at the center describe their findings in the Jan. 12 Physical Review Letters Physical Review Letters is one of the most prestigious journals in physics. Since 1958, it has been published by the American Physical Society as an outgrowth of The Physical Review. .
Whether in studies of how infants learn to sit up and stand or in efforts to correct balance problems, human posture control has long been a subject of considerable interest. Although researchers sometimes measured gross characteristics of center-of-pressure fluctuations, until now they have paid little attention to the details of the overall pattern of movement.
Several years ago, Collins recognized that the location of the center of pressure, as measured on a sensitive apparatus known as a force platform, follows a specific type of random walk. Each successive step of the walk occurs in a randomly selected direction. The overall path is constrained, however, almost as if the wanderer were connected to the central point by an elastic band.
According to according to
1. As stated or indicated by; on the authority of: according to historians.
2. In keeping with: according to instructions.
3. Chow, such fluctuations can be described by simple equations that also apply to a string or polymer strand glued flat to an elastic membrane elastic membrane
A membrane formed of elastic connective tissue fibers, such as that surrounding the arteries. . As random perturbations displace the strand, the membrane pulls it back to its straight equilibrium position.
In the mathematical model
The model enables the researchers to link the body's intrinsic, random movements when standing still to its response when disturbed by a small impulse. It suggests that the same neuromuscular neuromuscular /neu·ro·mus·cu·lar/ (-mus´ku-ler) pertaining to nerves and muscles, or to the relationship between them.
1. mechanisms control posture, whether fluctuations are random and intrinsic or caused by an external, perturbing force.
This finding may greatly simplify the tests that clinicians use to determine a person's susceptibility to falling. "All you nave to do is stand on a force platform and do nothing for 30 seconds," Chow says. "By measuring the fluctuations, we can determine how you respond to perturbations."
He adds that "we want to come up with a software package that a clinician can use with a patient standing on a platform to characterize his or her body's stiffness or reaction time."