Obese children often face a Catch-22.
Research has found that the pressure sensors in human feet that contribute to balance become desensitized when a person is obese, which might contribute to obese people having poorer balance than healthy weight people.
However, "for children with obesity, the intervention is usually physical activity," said Dr. Toyin Ajisafe, assistant professor of Kinesiology. "Children with obesity also tend to fall more. The problem is that if you aren't used to activity and don't feel stable, you're not likely to venture into learning new movements."
Ajisafe's research aims to break the cycle of childhood obesity by using pressure sensors inserted in shoes to determine whether the feet can be trained to increase sensation.
To understand this concept, it helps to step back and consider the role of the feet in balance. When humans stand, they sway slightly, often almost unnoticeably. As a person's position shifts, receptors in the plantar (foot) surface sense small changes in pressure at different locations. The sensations transmit to the brain, which sends signals to muscles throughout the body to make micro adjustments in posture to maintain balance. When plantar sensitivity decreases, the delicate interaction between the senses and muscles becomes muted, and balance suffers.
Previous research has found that vibration increases the skin's sensitivity, so Ajisafe worked with engineers to configure a sensor that can deliver targeted vibration within the wearer's shoe. Ajisafe and team will test the intervention by icing research participants' feet to simulate descreased plantar sensitivity, then testing sensitivity before and after vibration using aesthesiometry, a measure of tactile sensitivity. This portion of the study will take place with college-aged participants, but the results can inform work with children.
Improving postural control may reduce the risk of fall-related injuries, decrease excessive foot loading, and encourage children who are overweight and obese to be more physically active.
The same shoe sensor technology will later be applied to study whether children who take part in a free group program designed to teach physical activity and healthy habits remain physically active after the program's conclusion.
Dr. Toyin Ajisafe, Department of Kinesiology
$20,000, Texas Comprehensive Research Fund
$19,330, Blue Cross Blue Shield of Texas
Quantitative study with experimental design
Addressing cutaneous sensation and associated movement impediments in children overweight or obese:
This research takes a 2-part approach. The first strategy aims to establish a basis and need for a vibration intervention that may improve postural control challenges associated with decreased plantar cutaneous sensation in children who are overweight and obese. Due to potential comorbidities, including sensory processing disorder, especially in children with obesity, and other motor systems maturational factors in children, the actual relationships between decreased plantar sensation, decreased postural control, increased foot loading, and a vibration-based intervention may be masked. Therefore, it is important to establish these potential relationships in a population that is devoid of comorbidities or potentially immature motor systems.
The second part of the study simulates decreased plantar sensation in healthy young adults by icing their feet (following established protocols) and evaluating the relationships between the foregoing factors. This strategy aims to identify the effects of vibration signal delivered via an ad hoc insole on postural control deficits and excessive foot loading following decreased plantar sensation.
Below: Ajisafe demonstrates aesthesiometry. In this study, a monofilament fiber is applied to different regions of a participant's foot until the filament bends. The participant is scored based on the number of applications he or she can feel. The test begins with a thin filament, and if the participant can not feel that, the filament size is gradually increased until the participant can detect it.