INtroduction
Balance is essential to everyday life, but it is a luxury that is often taken
for granted. In the United States, falls are the second leading cause of
unintentional death, or accidental death, and account for approximately 8.9
million trips to the emergency room (nsc.org). According to Mary Ann Watson and
Owen Black of the Vestibular Disorders Association, balance is the ability to
maintain the body’s center of mass over its base of support, and falls occur
when the center of mass goes outside that base of support. In the body,
sensorimotor control systems are what allow for balance to be reached and
perpetuated (Watson, Black). These systems consist of a sensory input, an
integration of that sensory input, and motor output. The sensory input that
comes into the body comes from a variety of sources which include vision
(sight), auditory (sound), proprioception (touch), and the vestibular system
(motion, equilibrium, spatial orientation). From here, each of these different
inputs are received and interpreted by the brain from the nerve impulses sent
there by the sensory receptors (Watson, Black).
Each one of these sensorimotor control systems can be isolated which will provide a better understanding of how much of a key role that systems plays in balancing. In order to isolate a system, many studies may be performed in a silent environment with the test subjects eyes closed. With sight and hearing cut off, the test subject no longer has vision and auditory senses, and he or she is only left with his or her proprioceptive and vestibular systems. One study in particular that looked at how obstructed vision affected toe clearance and lead stride length was the Control of Adaptive Locomotion by Shirley Rietdyk and Chris K. Rhea. In this study, eight participants completed trials under four different visual conditions. Two of the conditions had full vision, one with object cues. Under the other two conditions, the participants wore goggles which obstructed the view of the lower limbs. There was also one goggle trial that contained object cues and one that did not. After completing the study, it was found that vision of the location of the object was more important than vision of the location of the lower limbs. This study solidified the importance of vision for crossing obstacles as previously proven by other studies.
Another study that looked into static stability was the Measures of Postural Steadiness: Differences Between Healthy Young and Elderly Adults. In this study, the center of pressure was looked at during static standing, and it was found that the center of pressure, although small, moves quite frequently in an area. The results were plotted on a graph, and it looked like a bunch of random lines that sort of formed a circle. This proved that although it may seem like you are standing completely still, your body is gently swaying in all directions and then correcting itself. This study also saw a difference in the total amount of variation found between elderly and averaged aged adults. The elderly swayed a whole lot more, which could account for much of their instability.
Although a large amount of research has been done on dynamic tasks, like walking up and down a curb, and on static stability, there is very little research on dynamic stability in healthy individuals, and there is no research available on dynamic stability during two different walking speeds. This study will investigate the center of pressure and the center of mass and their relationship to one and another in healthy individuals while walking up a curb. By having the participants complete this task at two different speeds, a correlation will hopefully be seen between the center of mass and center of pressure that will help us better understand what is necessary for dynamic stability and the prevention of falls.
By having a group of participants walk up a curb at two different paces, we expect to see an increase in the distance between the center of pressure and center of mass. We expect for the this distance to be far greater in the faster walking trials, which should result in less dynamic stability for the participants involved.
Each one of these sensorimotor control systems can be isolated which will provide a better understanding of how much of a key role that systems plays in balancing. In order to isolate a system, many studies may be performed in a silent environment with the test subjects eyes closed. With sight and hearing cut off, the test subject no longer has vision and auditory senses, and he or she is only left with his or her proprioceptive and vestibular systems. One study in particular that looked at how obstructed vision affected toe clearance and lead stride length was the Control of Adaptive Locomotion by Shirley Rietdyk and Chris K. Rhea. In this study, eight participants completed trials under four different visual conditions. Two of the conditions had full vision, one with object cues. Under the other two conditions, the participants wore goggles which obstructed the view of the lower limbs. There was also one goggle trial that contained object cues and one that did not. After completing the study, it was found that vision of the location of the object was more important than vision of the location of the lower limbs. This study solidified the importance of vision for crossing obstacles as previously proven by other studies.
Another study that looked into static stability was the Measures of Postural Steadiness: Differences Between Healthy Young and Elderly Adults. In this study, the center of pressure was looked at during static standing, and it was found that the center of pressure, although small, moves quite frequently in an area. The results were plotted on a graph, and it looked like a bunch of random lines that sort of formed a circle. This proved that although it may seem like you are standing completely still, your body is gently swaying in all directions and then correcting itself. This study also saw a difference in the total amount of variation found between elderly and averaged aged adults. The elderly swayed a whole lot more, which could account for much of their instability.
Although a large amount of research has been done on dynamic tasks, like walking up and down a curb, and on static stability, there is very little research on dynamic stability in healthy individuals, and there is no research available on dynamic stability during two different walking speeds. This study will investigate the center of pressure and the center of mass and their relationship to one and another in healthy individuals while walking up a curb. By having the participants complete this task at two different speeds, a correlation will hopefully be seen between the center of mass and center of pressure that will help us better understand what is necessary for dynamic stability and the prevention of falls.
By having a group of participants walk up a curb at two different paces, we expect to see an increase in the distance between the center of pressure and center of mass. We expect for the this distance to be far greater in the faster walking trials, which should result in less dynamic stability for the participants involved.