高齢者における足関節底屈機能と歩行機能への加齢の影響

本研究の目的は，高齢者を対象に足闘節の筋－神経系機能，歩行機能を測定し，前期高齢者と後期高齢者の比較から高齢者の関節の筋－神経系機能，歩行機能の特性を明らかにすることである。被験者は，健康な女性高齢者25名(平均年齢75.2:±5.6歳)を対象とし，その中から前期高齢者13名(70.0±2.2歳)と後期高齢者12名(80.0±4.3歳)に振り分け分析・検討を行った。足関節底屈の筋反応時間，筋出力の測定は筋力測定装置(KinCom500H)を使用し伸張性筋活動時の条件下において行った。また，その際の反応刺激は，足関節底屈部の固有受容器反応にて実施した。歩行機能は，側方より2次元撮影により5mの区間の測定を行った。主な結果として，最大歩行速度(前期高齢:1.91±0.5m/s，後期高齢者:1.5±1.4m/s)とストライド(前期高齢者:69.3±5.3cm，後期高齢者:60.5±6.0m/s)においては，前期高齢者より後期高齢者の値が有意に劣っていた(最大歩行速度:p<O.OO1，ストライド:p<O.O1)。Electromechanical delayにおいては，前期高齢者より後期高齢者の値が5%水準で、有意に劣っていた(前期高齢者:65.6±9.1msec，後期高齢:73.8±9.3msec)。同様にPre-motor reaction timeも，前期高齢者より後期高齢者の値が5%水準で有意に劣っていた(前期高齢者:210.9±23.9msec，後期高齢者:252.7±53.5msec)。ピークトノレク値においては，前期高齢者(55.5±18.0Nm)に対して後期高齢者(40.4士12.4mse)が5%水準で、有意に劣っていた。これらの結果，加齢に伴い足関節底屈機能は低下することが明らかになり，この機能的低下は高齢者の歩行機能に影響を及ぼす可能性が示唆された。これらの機能改善にはカーフレイズなどのエクササイズが有効的であることが示唆された。

Ankle plantar flexion is important in the mid-stance and terminal stance pheses in walking. Therefore，if the function of ankle plantar flexion decreases，it influences walking. PURPOSE: The purpose of this study is, by measuring electromechanical delay and strength in ankle plantar flexion of older adults，to investigate the characteristics of older adults' electromechanical delay (EMD) and muscle strength in comparison between 60 to 70 year-old subjects and those over the agc of 70 METHOD. A group of 25 healthy older female (mean age: 75.2±5.6years)subjects gave informed consent for participating in this experiment. In addition，we classified the older women into two groups: the ones who were “yaung-old” (n=13，mean age: 70.0±2.2 years) and the ones who old-old (n-12，mean age:80.0±4.3years) .The measurements of EMD and muscle strength in ankle plantar flexion were performed by using a dynamometer (KinCom 500H). Moreover，the measurements were performed under the condition of eccentric muscle action. The initial reaction in measurement of EMD was performed on the proprioceptor response of the plantar. RESULTS: The main results were as follows: Maximal walking velocity (“youg-old”: 1.91±O.5m/s，“old-old”: 1.5±1.4m/s) andl stride (“youg-old” :69.3±5.3cm,“old-old”:60.5±6.0m/s) concerning the walking capabilities of the“old-old”were significantly worse (Maximal walking velocity: p<O.OO1, stride: p<O.O1) than those of the“young-old”. In the EMD of the old-old，there was significantly longer time spent (p<0.05) than by the“young-old”(“youg-old": 65.6:±9.1msec，“old-old”:73.8±9.3msec).Similarly，in pre-motor reaction time (“ young-old": 210.9±23.9msec，“old-old”:252.7土53.5msec)and peak torque value (“ young-old: 55. 5±18.0Nm，“old-old”:40.4±12.4Nm) these were significantly worse (p<0.05) than those of the“young-old”. CONCLUSION: These results suggest the following: According to age，the function of plantar flexion clearly decreases. This decrease was considered to affect the ability of the elderly to walk. Therefore，the calf raise exercise intervention was considered to be effective in the elderly.

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