旅行者血栓症 (いわゆるエコノミークラス症候群) 対応座席についての生理学的検討

Traveler\u27s thrombosis has posed a severe problem around the world. Much research has been conducted to find effective approaches to traveler\u27s thrombosis. We examined a proto-type ankle exerciser equipped on a plane seat in order to assess its effectiveness. The purpose of the first study is to determine a suitable exercise tempo. Three tempos of 30, 60, and 90 times per minute were examined with young male and female subjects by measuring heart rate and blood pressure during five-minute exercise. Heart rates at 90 times per minute were higher than those of other tempos. Blood pressure did not show any differences among the three tempos. We determined 60 times to be the suitable tempo because of the mildness and smoothness of the exercise. The second study is on changes of calf circumference during two-hour sitting and five-minute exercise. Calf circumference after two-hour sitting showed an increase of 1.4% in young male subjects, and 2.2% in young female subjects. The five-minute exercise made for a 0.5% decrease in men and a 1.3% decrease in women. There was a 0.9% improvement by each the exercise. Middle-aged men and women, however, did not show any improvement after exercise. The third study was on skin temperature and blood flow in the foot during two-hour sitting and five-minute exercise. Three of all six subjects showed a clear decrease in foot temperature during sitting and an increase during exercise. The results of two subjects, however, were contrary to the above-mentioned results. The temperature of another subject fluctuated up and down during sitting, and then steeply increased during exercise. Blood flow during exercise increased three to ten times in comparison with sitting. These results lead to the conclusion that the proto-type ankle exerciser connected to a plane seat might serve to prevent traveler\u27s thrombosis

筋活動等からみた水中歩行の生体負担に関する研究

本研究の目的は水中歩行の生体負担を筋電図等から検討することである。被検者は健康な男子大学生であり, 電極防水の予備実験を含めて延べ8名であったが, 本実験では2名であった。運動負荷装置としては水中トレッドミルを用いた。水中歩行時の水位は0水位も含めて7種 (水位0 (陸上), 踝の直上, 膝蓋骨の直下, 大腿の中間, 恥骨結合, 臍, 剣状突起) とした。歩行速度は0km/h (立位) を含めて6種 (0, 2, 3, 4, 5, 6km/h) とした。歩行時間は各速度につき30秒間とし, 漸増的に連続して負荷した。7箇所の被検筋 (腹直筋, 大腿直筋, 外側広筋, 大腿二頭筋, 前脛骨筋, 腓腹筋内側頭, ヒラメ筋) から表面電極を用いて筋電図を導出し, また右足踵部にフットスイッチを装着してその出力信号を記録した。表面筋電図をA/D変換して全波整流の後, 積分して筋電図積分値 (iEMG) を求め, 各パラメータを3次元表示 (水位, 歩行速度, iEMG) した。その結果, 歩数は水位が増すにつれて減少して大股歩行になることが示された。また歩行速度の増加につれてiEMGも増大した。特に, 前脛骨筋と大腿二頭筋のiEMGにおいて増大が著しかった。水位がiEMGにおよぼす影響に関しては, 上方への浮力というiEMGの軽減要因と前進に伴う水の抵抗という増大要因とが複雑に関係していて, グラフの視察だけでは明確ではなかった。しかし, 数学的手法によって, より詳細に分析すれば, その影響が明確な形で表示できる可能性は否定できないと考えられ, 今後の検討課題として残った。The purpose of the present study was to investigate the effects of both graded water immersion walking and walking speed on the electromyographic activity of lower leg muscles, as well as on walking cadence. Two healthy male university students participated in this study as subjects. They walked in water of six different water levels and six different speeds using an underwater treadmill systems. The electromyogram (EMG) was recorded by telemetry from six different muscles (m. rectus femoris, m. vastus lateralis, m. biceps femoris, m. tibialis anterior, m. gastrocnemius : caput mediale, m. soleus) of the right leg and the rectus abdominal muscle by means of surface electrodes. The raw EMG signal was sampled at 1 kHz, full-wave rectified and integrated (iEMG). The relationships among water level, walking speed and iEMG were graphically presented in three dimensions. Overall, the faster the walking speed, the larger the iEMG at each water immersion level. The highest iEMG was seen in the tibialis anterior muscle, which is related to strong dorsiflexion of the foot in water. The iEMG in the biceps femoris during water walking was more distinctive, especially at higher walking speeds, which might also be due to the intensive extension of the hip joint necessary to propel the body against the water resistance. The step frequency (SF) increased in proportion to the walking speed and in inverse proportion to the water depth. These changes in iEMG and SF imply a shift in walking style ; that is, to walking with vigorous strides. There are two factors influencing the iEMG. One is buoyancy as a factor for decrease one and the other is the depth of the water level, which causes large water resistance, as a factor for increase. We should consider these two factors in evaluating the work load from the iEMG in water walking, and may be able to express these effects clearly by applying mathematical analysis in the future