|Budget Amount *help
¥3,700,000 (Direct Cost: ¥3,700,000)
Fiscal Year 2001: ¥1,500,000 (Direct Cost: ¥1,500,000)
Fiscal Year 2000: ¥2,200,000 (Direct Cost: ¥2,200,000)
A phenomenon due to aging is the hypofunction to walk. Hence, many studies have so far compared the walking ability between the young and aged, indicating that younger people have a higher walking ability in general5,7). The walking ability of aged people declines because their walking becomes slower such as due to narrower walking strides, slackened steps, a longer leg-supporting time, and smaller areas for motion in hip joints, knee joints, and ankles. It has also been indicated that such hypo-function is caused such as by the nerve-system's poorer regulation capacity and weakened bones as well as muscles strength2). Among them, weakened muscles strength may be mainly due to a decrease in muscle volume with aging since the strength of a muscle is proportional to its cross-sectional area.
Electromyographic studies on human walks have found that the walking ability of a human is closely associated with his or her inferior limb muscle strength. Recently, however, it is pointed out that n
ot only a group of inferior limb muscles including those in thigh and crus regions but also greater psoas muscle which participates in hip joint flection play an important role in human muscle activities at the time of walking, suggesting that review of muscle activities in thigh and crus regions alone may be insufficient for walking ability evaluation. In fact, Andersson, et al.1) reviewed how the greater psoas muscle behaved at the time of walking and found the amplitude that appeared in the electromyogram of thigh muscle at the time of walking also occurring to greater psoas muscle and, more importantly, further intensifying there with increasing speed of walk. Using 160 males and females in their 20s through 80s as MRI test subjects, we also reviewed the greater psoas muscle cross-sectional area, identifying a decrease of about 40 % for both sexes in their 70s compared with the 20s counterparts. Although preceding studies may be reviewed to take the slower speed of walk due to a decrease in muscle volume as an important factor for the aged people's poorer walking ability, none of such studies succeeded, to our best knowledge, in direct verification of the causal relationship between them.
This study was thus intended to verify a hypothesis that hip joint and egional thigh muscle cross-sectional areas would decrease with aging to result in poorer walking capability as well as concurrently review which muscle groups more strongly affected the walking ability. Less