〔博士論文概要〕

Foot characteristics and its association with balance in older adults(高齢者における足部の特性とバランス能力との関係性）

平成２６年度サカザデ

マシド（課程博士の場合は） 筑波大学大学院人間総合科学研究科体育科学専攻

Population ageing is widespread across the world and it is more in the most highly developed countries
such as Japan. With aging, balance ability is widely acknowledged to decline. Maintenance of balance
depends on the interaction of multiple sensory motor and integrative systems. Function of thesesystems declines with age and can lead to fall. Such fall incidents require medical attention and making
individuals grapple with pain and suffering as well as placing a financial burden on patience, their family
and society. All these reasons indicate that we are in dire need of protective measures in all social,economic, cultural aspects and also health care.
Most falls occur while an individual is in motion. During normal gait, the foot is the only source of directcontact with the ground. Therefore, the foot plays a considerable role in maintaining balance andstability during movement. Despite this, little is known about foot characteristics and its association withbalance in older adults. Therefore, the primary aim of this thesis was to determine whether footcharacteristics, which were foot deformity and static foot posture, associate with balance inindependently-living older adults. As the foot and toes play crucial role in safe and efficient movement,
it was hypothesised that foot deformity would be associated with poor balance. Furthermore, theassociation between balance and static foot posture, which in this study was arch height calculatedusing two different ways of measurements, was investigated. The secondary aim was identify genderdifferences in foot characteristics to design comfortable and efficient shoes in Japan which has large
elderly population.
A total of 349 older adults participated in this study conducted in the Kasama City health center. Of
these participants, we excluded some due to incomplete data, their reliance on walking sticks during themeasurement or among women because of refusing to remove their pantyhose preventing us fromcollecting foot characteristic and balance or postural sway data. We assessed foot characteristics, usingthe recently launched 3D foot scanner by Dream GP Company, Japan. Balance tests and body mass index(BMI) of participants were measured and medical histories were gathered via face-to-face interviews.
There is significant positive correlation between the first toe angle and poor balance especially inwomen. Therefore, the first toe angle is an important determinant of balance in community-dwellingolder people.
Furthermore, our study provides intriguing findings on the associations between sitting arch heightindex (AHI) and balance in both genders. Arch rigidity index (ARI) is associated with postural sway andstatic balance in women and men, respectively. Moreover, sitting navicular height (NH) and footmobility are associated with postural sway in women and with balance in men. These findings suggested
that among all those methods, sitting AHI might be better method for defining balance control in olderadults.
In addition, the current study shows evidence of difference between some of the foot characteristics
and shapes of older men and women. Gender differences in older adult’s foot shape should beconsidered when manufacturing shoes for them.