Effects of Different Shoes on Balance and Stability
Shoe wear can be an extremely important item of clothing in the older adult. Studies show that almost half of all falls are linked with the type of shoes worn at the time of the fall. Slippers and heels double the risk of falling in older people. Even younger adults are at risk of fractures from shoes with a high or narrow heel. And walking barefoot isn't any better. The risk of falling also increases with bare feet (and especially wearing just socks).
In this study, investigators looked at specific shoe features and how they affect walking and balance. Young adults in their early-to-mid twenties were compared with older adults (over 65). Everyone was tested on a flat surface and again on an uneven surface wearing shoes with different heels, soles, tread, and collar.
A standard shoe was defined as an Oxford-style lace-up shoe with a low heel collar, square heel, and smooth sole. Five other shoe designs were included: high-collar shoe, elevated heel shoe, tread sole shoe, soft sole shoe, and hard sole shoe. An orthopedic boot maker made all the shoes and fit them to each participant.
Before starting the walking part of the study, each person was tested for sensation, balance control, and strength. Then they completed three walking trials wearing each of the different shoes on a level flat floor and on an uneven walkway. Special motion detector equipment recorded three-dimensional (3-D) movement data of the entire body.
Center-of-mass (COM) and ground reaction forces were calculated. Each person also rated their own sense of stability on a scale from one (most unstable) to five (most stable). Level of comfort was also rated using a similar scale (one to five for least comfortable to most comfortable).
The researchers pointed out that maintaining stability when walking requires control of the center of mass as the person's base of support (BOS) changes. As a person's balance is challenged, the center-of-mass expands and reaches the edges of the base-of-support. The difference between these two measures is referred to as COM-BOS margin.
They used this study to find out if shoe wear could improve center of mass, stability, and comfort. The hope was to find a shoe that would enhance balance and improve an older adult's ability to respond when suddenly off balance.
The authors looked at four areas and compared them between the two groups. These four areas were: 1) age-related effects, 2) surface-related effects, 3) shoe condition effects, and 4) shoe comfort and stability.
First, they found many differences based on age. Older adults had poorer visual contrast sensitivity (seeing differences or changes in floor/surface color or design). They also had less sensitivity on the bottom of their feet and decreased knee strength compared to younger adults. Older adults were more likely to take shorter steps, walk slower, and spend more time with both feet on the ground at the same time.
The response to the uneven surface was the same between the two groups. Everyone took wider steps, walked more slowly, and expanded their center of balance to the edge of their base of support. Both groups were able to walk faster and take longer steps when wearing a tread shoe on an even surface. Soft-soled shoes also allowed a faster pace.
Shoes with an elevated heel or hard soles resulted in smaller step width. Subjects kept both feet on the ground for longer time than with the standard shoe. When wearing the soft soled shoes or shoes with a high collar, adults in both groups had a larger shift in their center-of-mass and base-of-support (from side to side). Some of the shoe types (hard sole, elevated heel, high collar) also reduced the margins between center-of-mass and base-of-support from front to back.
In the final category of outcome measures (shoe comfort and stability), everyone felt the elevated heel shoes were less comfortable and more unstable. The younger adults felt that the soft sole shoes were less stable than the standard shoes. Older adults with less sensitivity on the bottom surface of the feet did not notice the difference between soft, standard, and hard soles.
In summary, this was the first study to look at the effects of specific shoe features on walking stability in young and older adults. As might be expected, uneven surfaces did challenge balance control. COM-BOS margins were less when there was an unstable surface or shoe type such as the elevated heel shoes.
Soft sole shoes offer less mechanical support while tread sole shoes and the standard shoe allowed people to walk faster and take a longer stride length. Anyone with balance problems, or decreased sensation in the feet should beware of soft sole shoes. This type of footwear is considered a potential hazard.
For the older adult, an increased shoe heel height is a risk factor for loss of balance. It appears that the optimal shoe type is a low heeled, low collar, lace-up Oxford with or without tread. They may not be the height of fashion, but they will reduce the risk of falls and disabling fractures in anyone 65 or older.
Jasmine C. Menant, BSc, et al. Effects of Shoe Characteristics on Dynamic Stability When Walking on Even and Uneven Surfaces in Young and Older People. In Archives of Physical Medicine and Rehabilitation. October 2008. Vol. 89. No. 10.