Pressure measurement technology can differentiate between the impact forces of a stability shoe and a flexible shoe during gait, according to a preliminary study presented in August at the annual meeting of the American Society of Biomechanics in Long Beach, CA.
Researchers from Indiana’s Valparaiso University found that walking in a flexible shoe was associated with increased duration of contact at the heel compared with a stability shoe.
“Shoes that are overly flexible in the midfoot region may delay the off-weighting or dorsiflexion of the calcaneus. This can have potential detrimental effects on foot and lower extremity function,” said Bruce Williams, DPM, one of the researchers and a podiatrist in private practice in Merrillville, IN.
The preliminary study of one 21-year-old man compared the impact force profiles produced throughout gait with two different running shoes from the same shoe company.
The flexible shoe featured flexion near the midfoot region of the shoe, while the stability shoe flexed closer to the ball of the shoe. An in-shoe pressure measurement system was used to map the force versus time profile for each shoe type as the participant walked 30 feet.
“In-shoe pressure had not been used to differentiate potential differences in function from shoes of these types and their potential effects on foot function,” Williams said.
In order to evaluate the transition between the heel and ball of the foot, force measurements were recorded for the heel, the ball, and the entire sole of the foot. Three trials for each shoe type were undertaken. To compare force profiles across trials, heel strike to toe off (one period) was truncated and normalized to the time associated with that period.
Force versus time was analyzed for the heel and the ball in order to observe slope variation and compare periods in which impact force was constant. This dwell in the gait cycle represents prolonged ground contact.
The results indicate a significantly longer dwell period in the heel region for the flexible shoe compared with the stability shoe (p < 0.05), at 0.1663 seconds compared with 0.0959 seconds. There were no significant dwell periods in the ball region for either shoe.
Prolonged pronation associated with a lack of midfoot support in the flexible shoe explains this dwell period, according to the researchers. They suggest this may be compensatory pronation in response to a lack of ankle joint dorsiflexion. Although no dwell period was evident for the ball of the foot, the researchers suggested this may not be the case in future studies with additional participants.
There is a definite clinical usage for the pressure measurement technology used in this study, said Williams. The technology holds potential for identifying effects of different shoe construction features on lower extremity mechanics and how those changes can result in pain and impaired function, he said.
The researchers plan to collect further data from a variety of subjects with varying foot types, gender, age, and weight.
“These studies may help design better shoes and help match the shoe construction to activity or foot type,” said Smita Rao, PhD, PT, assistant professor of physical therapy at New York University.
There are a number of questions that remain unanswered with regard to shoe stiffness and pressure patterns.
“Stability and flexible shoes may alter load distribution patterns. This may contribute to the user’s perceived comfort,” Rao said. “Differences in magnitude of regional loading are not discussed [in the pilot study]. It would be helpful if the authors related their findings to specific features of the shoes.”
Further trial data are being examined, said Williams. “Such data have the potential to clarify unanswered questions, such as ‘What other sporting shoe types potentially have an impact like this?’” he said.
Showing posts with label gait and walking. Show all posts
Showing posts with label gait and walking. Show all posts
Monday, January 30, 2012
Friday, August 19, 2011
Early research characterizes gait associated with autism
Results could have clinical implications
Little research has been published about gait patterns in children with autism, but that could be changing. One recently published study, although small, appears to lay the foundation for more focused research and could have clinical implications as well.
In the February issue of Clinical Biomechanics, researchers at the University of New Brunswick in Fredericton, New Brunswick, Canada, published what they describe as the first comprehensive analysis of 3-D joint and muscle gait patterns in children with autism. The study found that a group of autistic children, compared to controls, had a significantly higher cadence, increased upper flexion of the ankle in swing phase, decreased peak ankle joint angles, and significantly smaller peak plantar reflex moments.
The study included 12 children with autism, ages 5 to 9, plus 22 age-matched control participants. However, the researchers excluded toe-walkers and children with Asperger syndrome or pervasive developmental disorder not otherwise specified (who typically would fall under the definition of full autism spectrum disorder [ASD]). Many children with ASD have sensory sensitivities that make them behave less than ideally when researchers use markers, tape, and Velcro to capture patterns for wave form analysis, explained senior author Victoria Chester, PhD, associate professor of kinesiology at UNB’s Andrew and Marjorie McCain Human Performance Laboratory.
“We were successful in getting them through,” she added, probably because of the exclusion of some children from the study.
The researchers used an eight-camera motion capture system to track 3-D trajectories of reflective markers placed on the children’s skin. They used custom software to compute cadence, velocity, and percent cycle spent in single limb stance for every gait cycle. They used parameterization techniques and principal component analysis to analyze their data and then compared the two sets.
“We actually managed to get kinematic and kinetic data sets for a group of kids with autism,” Chester said. “And you really need both sets of data to get a better understanding of what their gait patterns are like. I was surprised that the children could actually be grouped this way for a study. They often appear to the naked eye to be very different from one another.”
So what do the study results mean to practitioners?
“Given our small sample size, we remain fairly conservative in terms of our clinical relevance,” Chester said. “However, the findings may be important in terms of treatment planning for children with autism [plantar flexor strength training, stretching, and orthotics]. Gait analysis can provide clarification in terms of identifying gait deviations and treatment planning. The effects of treatment on gait can also be monitored. Practitioners should know that children with autism may benefit from the objective data made available from gait analyses for treatment planning. We still need to learn more about the autism spectrum and associated gait disorders, and this paper is a start in that direction.”
Whether gait pattern analysis could be used to screen for possible autism disorders is a “huge topic, very controversial,” Chester said. And while some people are looking into that possibility, it was not a focus of the UNB research, she said.
Dawn-Marie Ickes, PT, a physical therapist at Core Conditioning PT in Studio City and Burbank, CA, agreed that gait analysis screening is not close to being ready for prime time.
“I wouldn’t say it is something that is a clinically objectifiable screening program for autism. Symptoms do overlap, but not all children with sensory integration dysfunction have autism. However, it could be a predictor of other things that look like autism but aren’t,” Ickes said. “The best takeaway from this study for practitioners is that these abnormalities can pose value for predicting ASD if they’re coupled with sensory integration screening.”
Although other symptoms and aspects often are given priority when managing autism, Chester encouraged practitioners to remember that there is a physical component to autism as well, making it necessary to treat the whole child.
“A child who can’t keep up with others on the playground from a motor perspective is also affected socially,” she said.
Larger studies are now needed that include children from all autistic-related groups, Chester said, to facilitate an understanding of how gait differs across the autism spectrum
By Larry Hand
Little research has been published about gait patterns in children with autism, but that could be changing. One recently published study, although small, appears to lay the foundation for more focused research and could have clinical implications as well.
In the February issue of Clinical Biomechanics, researchers at the University of New Brunswick in Fredericton, New Brunswick, Canada, published what they describe as the first comprehensive analysis of 3-D joint and muscle gait patterns in children with autism. The study found that a group of autistic children, compared to controls, had a significantly higher cadence, increased upper flexion of the ankle in swing phase, decreased peak ankle joint angles, and significantly smaller peak plantar reflex moments.
The study included 12 children with autism, ages 5 to 9, plus 22 age-matched control participants. However, the researchers excluded toe-walkers and children with Asperger syndrome or pervasive developmental disorder not otherwise specified (who typically would fall under the definition of full autism spectrum disorder [ASD]). Many children with ASD have sensory sensitivities that make them behave less than ideally when researchers use markers, tape, and Velcro to capture patterns for wave form analysis, explained senior author Victoria Chester, PhD, associate professor of kinesiology at UNB’s Andrew and Marjorie McCain Human Performance Laboratory.
“We were successful in getting them through,” she added, probably because of the exclusion of some children from the study.
The researchers used an eight-camera motion capture system to track 3-D trajectories of reflective markers placed on the children’s skin. They used custom software to compute cadence, velocity, and percent cycle spent in single limb stance for every gait cycle. They used parameterization techniques and principal component analysis to analyze their data and then compared the two sets.
“We actually managed to get kinematic and kinetic data sets for a group of kids with autism,” Chester said. “And you really need both sets of data to get a better understanding of what their gait patterns are like. I was surprised that the children could actually be grouped this way for a study. They often appear to the naked eye to be very different from one another.”
So what do the study results mean to practitioners?
“Given our small sample size, we remain fairly conservative in terms of our clinical relevance,” Chester said. “However, the findings may be important in terms of treatment planning for children with autism [plantar flexor strength training, stretching, and orthotics]. Gait analysis can provide clarification in terms of identifying gait deviations and treatment planning. The effects of treatment on gait can also be monitored. Practitioners should know that children with autism may benefit from the objective data made available from gait analyses for treatment planning. We still need to learn more about the autism spectrum and associated gait disorders, and this paper is a start in that direction.”
Whether gait pattern analysis could be used to screen for possible autism disorders is a “huge topic, very controversial,” Chester said. And while some people are looking into that possibility, it was not a focus of the UNB research, she said.
Dawn-Marie Ickes, PT, a physical therapist at Core Conditioning PT in Studio City and Burbank, CA, agreed that gait analysis screening is not close to being ready for prime time.
“I wouldn’t say it is something that is a clinically objectifiable screening program for autism. Symptoms do overlap, but not all children with sensory integration dysfunction have autism. However, it could be a predictor of other things that look like autism but aren’t,” Ickes said. “The best takeaway from this study for practitioners is that these abnormalities can pose value for predicting ASD if they’re coupled with sensory integration screening.”
Although other symptoms and aspects often are given priority when managing autism, Chester encouraged practitioners to remember that there is a physical component to autism as well, making it necessary to treat the whole child.
“A child who can’t keep up with others on the playground from a motor perspective is also affected socially,” she said.
Larger studies are now needed that include children from all autistic-related groups, Chester said, to facilitate an understanding of how gait differs across the autism spectrum
By Larry Hand
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