下村 義弘

BACKGROUND: Surface electromyography (sEMG) is primarily used to analyze individual and neighboring muscle activity. However, using a broader approach can enable simultaneous measurement of multiple muscles, which is essential for understanding muscular coordination. Using the "bull's-eye electrode," which allows bipolar derivation without directional dependence, enables wide-area multipoint sEMG measurements. This study aims to establish a multipoint measurement system and demonstrate its effectiveness and evaluates forearm fatigue and created topographic maps during a grasping task. METHODS: Nine healthy adults with no recent arm injuries or illnesses participated in this study. They performed grasping tasks using their dominant hand, while bull's-eye electrodes recorded their muscle activity. To validate the effectiveness of the system, we calculated the root mean squares of muscle activity and entropy, an indicator of muscle activity distribution, and compared them over time. RESULTS: The entropy analysis demonstrated a significant time-course effect with increased entropy over time, suggesting increased forearm muscle uniformity, which is possibly indicative of fatigue. Topographic maps visually displayed muscle activity, revealing notable intersubject variations. DISCUSSION: Bull's-eye electrodes facilitated the capture of nine homogeneous muscle activity points, enabling the creation of topographic images. The entropy increased progressively, suggesting an adaptive muscle coordination response to fatigue. Despite some limitations, such as inadequate measurement of the forearm muscles' belly, the system is an unconventional measurement method. CONCLUSION: This study established a robust system for wide-area multipoint sEMG measurements using a bull's-eye electrode setup. This system effectively evaluates muscle fatigue and provides a comprehensive topographic view of muscle activity. These results mark a significant step towards developing a future multichannel sEMG system with enhanced measurement points and improved wearability. TRIAL REGISTRATION: This study was approved by the Ethics Committee of Chiba University Graduate School of Engineering (acceptance number: R4-12, Acceptance date: November 04, 2022).

There are limited studies on monotonous task performance and its relationship with anxiety and stress traits. This study aimed to determine if local cooling exerts physiological effects and positively affects task performance. Ten male participants performed monotonous work for 24 min under control and local cooling conditions. We measured physiological arousal and anxiety using electroencephalography and the State-Trait Anxiety Inventory, respectively. The participants rated their drowsiness, the thermal sensation of the seat and whole-body thermal sensation. Despite the lack of significant differences in physiological arousal, the state anxiety score, which reflects the current stressful situation, was significantly lower in the local cooling condition. Therefore, cooling might help relieve stress during monotonous tasks, without impairing task performance. In addition, individuals with higher state anxiety scores tended to experience a faster increase in their arousal level. Thus, individual anxiety traits may modulate attentional resources during monotonous task performance.Practitioner summary: The study on topic related to monotonous task performance and its relationship with anxiety and stress traits is novel. Minimising negative emotions is key to monotonous task execution under stress. Individual anxiety might modulate resource allocation for monotonous task execution.

Surgeons have increased physical stress during laparoscopic surgery due to operative site constraints. We developed a wearable device to reduce the physical stress on surgeons' lower extremities. The device mechanically facilitates maintaining a near-upright posture. The surgeon's knees are gently bent by a knee-joint locking mechanism, and fixing and releasing are performed independently on each side. The subjects were one female and two male surgeons, who wore the device during laparoscopic inguinal hernia repair or high anterior resection. Surface electromyogram (EMG) was conducted for both iliopsoas muscles. Control values were determined with the subject not wearing the device. Participants completed a post-procedure questionnaire. With the device, EMG activity had a tendency to decrease in the left iliopsoas muscle (P = .055), but it changed little on the right (P = .406). The post-procedure questionnaire showed an overall positive impression, although subjects reported some difficulty walking. This device decreases EMG activity and may improve a surgeon's work environment.

Different individuals respond differently to carbon dioxide (CO2) levels in the local atmosphere. We aimed to determine whether brain activity changes with various CO2 concentrations and whether this is correlated with heart rate and arterial oxygen saturation (SPO2). We used electrocardiograms, SPO2 measurements, electroencephalograms, and task performance metrics in various CO2 concentrations and studied the changes in these metrics. We found that SPO2 did not change in various CO2 conditions; elevations in CO2 up to 4000 ppm had no measurable influence on ventilation and SPO2, suggesting no effect on monotonous task performance seen in terms of the alpha wave band rate. However, heart rate increased as early as within 15 min. We found that some individuals who naturally have lower SPO2 values tended to undergo faster lowering of arousal level. Practitioner summary: SPO2 may be an individual characteristic that affects the human ability to maintain concentration in monotonous tasks in enclosed spaces, such as driving a car. This study highlights the fact that different individuals respond differently to various CO2 levels, based on SPO2 levels, as manifested by decreased concentration and brain activity. Abbreviations: CO2: carbon dioxide; SPO2: arterial oxygen saturation; HR: heart rate; PaCO2: partial pressure of carbon dioxide; EEG: electroencephalography; ECG: electrocardiography; EOG: electrooculogram; HF: high-frequency; LF: low-frequency; ANOVA: analysis of variance; RRI: R-R interval ; Type 1: sensitive group; Type 2: non-sensitised group.

手術を介助する直接介助看護師は身体的負担が大きいことから、立位姿勢を支持する近未来的ウェアラブルチェアであるアルケリスを導入し、直接介助看護師の身体的負担軽減を試みた。アルケリスを装着した直接介助看護師に、腹腔鏡下手術(n=6)/開腹手術(n=6)従事後に10項目からなるアンケート調査を行った。アルケリスの各手術下での受容性は「全体的な使用感」、「使用ニーズ」、「器械出しのし易さ」、「安定感」をVisual Analog Scaleで評価した。装着時、非装着時の身体的負担はBorgスケールで計測した。アルケリスの使用は、重量・装着時の快適性などの改善が必要であるが、腹腔鏡下手術時において相対的に直接介助看護師の受容性は高く、特に安定感の面で顕著であった。(著者抄録)

BACKGROUND: The purpose of this study was to clarify the influence of manipulation mode of chopsticks on the learning process, using assessment of task performance and electromyography, and to understand the significance of the traditional manipulation mode from the viewpoint of physiological anthropology. Previous studies have described two modes of manipulating chopsticks, the traditional pincers-pinching mode and the scissors-pinching mode. METHODS: We conducted experiments with two conditions of holding chopsticks: scissors mode and pincers mode. Eight subjects participated and were assigned to these modes, and they learned handling tasks in their assigned mode for 5 days with the non-dominant hand. We measured task execution times and conducted electromyography of the following muscles: first dorsalis interosseus, flexor pollicis brevis, flexor digiti minimi brevis, flexor digitorum superficialis, and extensor digitorum. RESULTS: The training effects were found in each mode. The pincers mode showed significantly shorter task performance times than did scissors mode. On electromyography, significant increases in activity of flexor digiti minimi brevis and tended an increase in flexor digitorum superficialis and a decrease in extensor digitorum occurred in pincers mode but not in scissors mode. CONCLUSIONS: The traditional mode of holding chopsticks was associated with not only high task performance but also an advantage in terms of learning motor control.

低侵襲手術の一つとして普及している内視鏡外科手術は、患者にとって非常にメリットの多い手技として知られているが、その普及によって、外科医の身体的負担の増加が報告されており、様々なアプローチ方法によって、その負担を軽減する取り組みが行われている。1)内視鏡外科手術の現状、2)外科医の負担軽減機器の研究開発動向、3)Surgical Assist Suitの開発、について述べた。

（緒言） 日常生活を遂行する際，手指機能は重要な要因の一つである．鎌倉^１）は手の把持把握を実用的に分類しており，物品の把持把握形態を写真の分析や16mmビデオに記録し，再生時に肉眼的観察によって分析している．その方法では把持把握形態や指関節の運動方向については分析が可能であるが定量的データとしては不十分といえる．芥川^２）は深部感覚の影響により握り潰すなどの症状のある頚髄症患者と健常人のピンチ力調整能を定量的に測定しているが，運動と感覚の連関による把持力発揮のコントロール不良は可視化しにくい．今回の研究によって各指の個別性を可視化できれば，患者が自身の把持状態が発揮過剰なのか，把持力不足なのかを理解しやすくなる．また，芥川^２）の評価システムはmmHg単位の独自システムであるため，様々な評価場面において比較しにくい現状が考えられる． 本研究では，感圧測定システムを使用し，健常人のピンチ力調整能を測定することで手の把持把握に関する患者指導への検討を行うことを目的とする． （研究方法） 被験者はリハビリテーション学科学生20名（男性10名，女性10名）で，実験前に実験に関する説明を十分に行い，実験途中での中止を求めてもよい旨説明した.同意書にて全員同意の確認を行った．また，フェイスシートにより過去の活動経験（部活動や趣味活動など）について記載を依頼した． 椅坐位にて机上での各物品の把持把握を行った．鎌倉^１）の分類では大きく分けて握力把握系・中間把握系・精密把握系としており，さらに握力把握系では標準型・鈎型・示指伸展型・伸展型・遠位型，中間把握系では側面把握・三面把握（標準型・亜型Ⅰ・亜型Ⅱ），精密把握系では並列軽屈曲把握・包囲軽屈曲把握・指尖把握・並列伸展把握としている．それぞれの把持把握に対応する物品として，包丁，金槌，うちわ，軽いかばん，編み棒，千枚通し，受け皿，裁ちばさみ，ホッチキス，鍵，鉛筆，フリクション，テーブルスプーン，箸，盃，茶筒，画鋲，輪ゴム，ハンカチを用いて，その把持把握状態を90秒間測定した．測定には感圧測定システム（KS-SYS1A-2：キャノン化成（株）製）を用いた．感圧センサーは拇指・示指・中指・環指・小指の指腹に貼付し，各指基節骨部と手関節部をベルクロにて固定した． データ解析は，ピーク値を算出し，課題による把持の違いがみられるかなど各指（母指・示指・中指・環指・小指）について男女別に分析を行った． （結果） 各物品を把持した際の値の平均は，男性・女性の順で， 握力把握系の包丁で拇指103.5・111.1， 示指113.3・155.5，中指163.9・185.9，環指169.3・215，小指92.5・78となり，男女とも中指と環指，小指で高い値となった．中間把握系の鉛筆で拇指226.8・362.8， 示指259・305.3， 中指138.6・266.2， 環指35.5・18.9，小指16.5・4.2となり，拇指・示指・中指・環指で女性の方が高い値となった．精密把握系の盃で拇指196.4・272.7， 示指148.8・162.7， 中指121.8・162.3， 環指66.4・113，小指0・0となり，男女とも拇指・示指・中指で高い値となった． （考察） 握力把握系の物品では，中指と環指，小指にてパワーを発揮する把持を行っていた．特にバドミントン経験者ではよりその傾向が強かった．一方精密把握系の物品では，拇指・示指・中指での把握により把持物を精細に操作できる把持形態となっていた． 被験者毎の把持状況より，極めて個別性が高く，平均値で結論づけることは妥当ではない．患者に対する指導においては各指の把持状況に応じ，個別性を考慮した指導が必要であると考える．本研究はそのような意味で寄与できると考えられる． （倫理規定） 本研究は，千葉県立保健医療大学研究等倫理委員会の承認を得て実施した（申請番号2018-15）．本発表内容に関連して申告すべきCOIはない．

作業療法士学生4名に体験用前腕能動義手での操作練習として立方体の連続移動を1週ごとに5分間実施し，三角筋前部線維と前鋸筋の筋音図測定によって運動学習の評価への試みを行い，従来用いられている筋電図も同時に測定した．今回の分析は4名の参加者がそれぞれの効率の良い動作の仕方を試行錯誤し，疲労に備えた筋コントロールを行っていたことを示した．さらに，筋音図の測定結果は筋負荷量が最大随意収縮の中程度であったことが推察された．パフォーマンスが向上していく中で，筋電図の中央パワー周波数の減少から徐波化がみられ，筋疲労が学習中に起こっており，三角筋前部と前鋸筋の活動割合が被験者によって異なっていた．

Background: The simultaneous exposure to blue and green light was reported to result in less melatonin suppression than monochromatic exposure to blue or green light. Here, we conducted an experiment using extremely short blue-and green-pulsed light to examine their visual and nonvisual effects on visual evoked potentials (VEPs), pupillary constriction, electroretinograms (ERGs), and subjective evaluations. Methods: Twelve adult male subjects were exposed to three light conditions: blue-pulsed light (2.5-ms pulse width), green-pulsed light (2.5-ms pulse width), and simultaneous blue-and green-pulsed light with white background light. We measured the subject's pupil diameter three times in each condition. Then, after 10 min of rest, the subject was exposed to the same three light conditions. We measured the averaged ERG and VEP during 210 pulsed-light exposures in each condition. We also determined subjective evaluations using a visual analog scale (VAS) method. Results: The pupillary constriction during the simultaneous exposure to blue-and green-pulsed light was significantly lower than that during the blue-pulsed light exposure despite the double irradiance intensity of the combination. We also found that the b/|a| wave of the ERGs during the simultaneous exposure to blue-and green-pulsed light was lower than that during the blue-pulsed light exposure. We confirmed the subadditive response to pulsed light on pupillary constriction and ERG. However, the P100 of the VEPs during the blue-pulsed light were smaller than those during the simultaneous blue-and green-pulsed light and green-pulsed light, indicating that the P100 amplitude might depend on the luminance of light. Conclusions: Our findings demonstrated the effect of the subadditive response to extremely short pulsed light on pupillary constriction and ERG responses. The effects on ipRGCs by the blue-pulsed light exposure are apparently reduced by the simultaneous irradiation of green light. The blue versus yellow (b/y) bipolar cells in the retina might be responsible for this phenomenon.

Background: In the human retina, the contribution of intrinsically photosensitive retinal ganglion cells (ipRGCs) to the regulation of the pupillary response remains poorly understood. The objective of the current study was to determine the response dynamics of the pupillary light reflex to short, successive pulses of light. In order to better assess the roles of ipRGCs and cones, we used pulses of blue and green light. Methods: Each participant was exposed to 1-ms blue (466 nm) and/or green (527 nm) light pulses simultaneously or separately, with inter-stimulus intervals (ISIs) of 0, 250, 500, 750, or 1000 ms. Pupil diameter was measured using an infrared camera system. Results: We found that human pupillary light responses during simultaneous irradiation or successive irradiation with ISIs <= 250 ms were equivalent, though successive irradiation of blue-and green-pulsed light with ISIs >= 500 ms induced markedly increased pupillary constriction. Conclusions: We propose that this result may be related to cell hyperpolarization that occurs in the retina just after the first light stimulus is turned off, with the threshold for this effect being between 250 and 500 ms in the human retina.

[要旨] 【目的】内視鏡外科手術は，体壁に留置したトロッカーによって鉗子操作を行うため，腹腔内で術野を確保するために上腕を空中で固定するなど，不自然な姿勢で手術操作を行うため，身体的負担を来たしやすい。そこで上腕保持状態の固定を目的とした外骨格型手術支援機器（Surgical Assist Suit: SAS）を開発し，外科医の手術操作にどのような影響を与えるか，検討した。 【方法】2014年12月から2015年10月まで計6回，体重30㎏の雄家畜ブタ計6頭を全身麻酔し模擬手術実験を行った。2名の腹腔鏡下胃切除術に精通した外科医が参加し，SASを装着，非装着で腹腔鏡下幽門側胃切除の大弯側リンパ節郭清を行った。検討項目は出血量，リンパ節郭清時間，手術助手における両側三角筋の表面筋電位である。術者AはSAS装着1回，非装着一回，計2回，術者BはSAS装着2回，非装着2回，計4回，全体として計6回の動物実験データを取得した。 【結果】SAS非装着群とSAS装着群の2群比較において，模擬手術によるリンパ節郭清時間時間，出血に相違を認めず，両側三角筋%MVCに有意差を認めなかった。SAS装着群でSASを使用し上腕を固定した状態，SASを利用していない状態，SAS非装着群の三群比較において，%MVC，APDFに有意差を得られなかった。 【考察】SASによる手術手技への悪影響も指摘できなかったが，SAS装着による表面筋電位有効性は証明されなかった。しかしながら人間工学的デザインと制御機構によっては，有効性が得られる可能性もあり，ウェアラブル機器としての開発を進めていく必要があると思われる。

Background: Exposure to pulsed light results in non-visual physiological responses in humans. The present study aims to investigate whether such non-visual effects are influenced to a greater extent by the intensity of lighting or by the power (quantity) of lighting. Methods: > Twelve healthy young male participants (23 +/- 0.3 years, 21-24 age range) were recruited for the present study. Participants were exposed to light of varying levels of intensity and quantity whose frequency was held constant across the conditions, which consisted of exposure to blue (different intensity, constant quantity) and white (constant intensity, different quantity) LEDs. Pupillary constriction, electroencephalogram (EEG) alpha band ratio, subjective sleepiness, concentration and perception of blueness were measured. Results: Pupillary constriction and subjective concentration were significantly greater under the high-intensity and short pulse width (HS) condition than under the low-intensity and long pulse width (LL) conditions at three time points during exposure to high-intensity light. However, no significant differences were observed among the results at the three time points during exposure to different quantities of pulsed light. Conclusions: The results of the present study indicate that non-visual influences of pulsed light on physiological function are mainly determined not by the quantity but by the intensity of the emitted light, with relatively higher levels of intensity producing more significant physiological changes, suggesting potent excitation of intrinsically photosensitive retinal ganglion cells.

The purpose of this study was to design an endoscopic dissector handle and objectively assess its usability. The handles were designed with increased contact area between the fingers and thumb and the eye rings, and the eye rings were modified to have a more perpendicular insertion angle to the finger midline. Four different handle models were compared, including a conventional product. Subjects performed dissection, exclusion, grasping, precision manipulation and precision handling tasks. Electromyography and subjective evaluations were measured. Compared to conventional handles, the designated handle reduced the muscle load in the extensor and flexor muscles of the forearm and increased subjective stability. The activity of the first dorsal interosseous muscle was sometimes influenced by the shape of the other parts. The ergonomically designed endoscopic dissector handle used in this study achieved high usability. Medical instrument designs based on ergonomic concepts should be assessed with objective indices.

In order to examine whether it is possible to activate the peripheral auditory system with high-frequency sounds around the audible area when the stimuli intensity was very low, an attempt was made to measure the auditory brainstem response (ABR). This study was intended to identify whether high-frequency low-stimulus sounds could influence cognitive processing in humans. The results showed that the potential could be evoked by a click and 4 kHz tone bursts. Additionally, a gender difference was confirmed in ABR. Finally, ABR waveforms were not observed when subjects were presented with high-frequency sounds around the audible range, suggesting that it would not affect the subsequent cognitive processes.

In the previous studies, contradictory results were reported on walking symmetry. The walking symmetry is important in the study of the evolution of bipedalism and gait therapy. This study investigated the effects of laterality and walking speed on gait symmetry during three conditions of walking on a treadmill, namely pushing while walking, walking with arm-swing, and walking while holding on a handlebar. All conditions were performed at three speeds: 1.5, 3, and 4 km/h. Symmetry was measured from bilateral gait cycle duration and cross-correlation function analysis performed in one gait cycle. Left-handers showed different characteristics from right-handers in various variables measured and not in mirror characteristics. Walking holding condition in general produced the greatest symmetry, confirmed the importance of this posture in gait therapy for improving symmetry among hemiparetic patients.

The purpose of this study is to design a new surgical scissors handle and determine its effectiveness with various usability indices. A new scissors handle was designed that retains the professional grip but has the shapes of the eye rings modified to fit the thumb and ring finger and finger rests for the index and little finger. The newly designed scissors and traditional scissors were compared by electromyography, subjective evaluation and task performance in experiments using cutting and peeling tasks. The newly designed scissors reduced muscle load in both hand during cutting by the closing action, and reduced the muscle load in the left hand during peeling by the opening action through active use of the right hand. In evaluation by surgeons, task performance improved in addition to the decrease in muscle load. The newly designed scissors used in this study demonstrated high usability.Practitioner Summary: A new scissors handle was designed that has the eye rings modified to fit the thumb and ring finger. The newly designed scissors reduced muscle load and enabled active use of the right hand. In evaluation by surgeons, task performance improved in addition to the decrease in muscle load.

Ultrasound examinations tend to put sonographers in unnatural postures, which may lead to musculoskeletal disorders. In order to address this issue, in this study, we focused on the horizontal position of the console of a diagnostic ultrasound system to quantitatively assess the influence of the work plane position on musculoskeletal stress cardiac ultrasonic diagnosis in the bed-sitting position. Five subjects were asked to simulate a scanning task that involved touching five points on the console, setting the work plane at different positions in the space. Electromyogram of each part of the body indicated that the least stressful position of the left hand was about 350 mm from the center of the trunk in the longitudinal (front-rear) direction and 100 mm left from the center of the trunk in the lateral (left-right) direction. It is necessary to rotate the console in front of the operator for this purpose.

Recently, a growing number in Japan are switching to taking baths in the morning (morning bathing). However, the effects of the morning bathing on human physiological functions and work efficiency have not yet been revealed. Then, we hypothesized that the effect of morning bathing on physiological functions would be different from those of night bathing. In this study, we measured the physiological functions and work efficiency during the day following the morning bathing (7:10-7:20) including showering, mist sauna bathing, and no bathing as a control. Ten male healthy young adults participated in this study as the subjects. We evaluated the rectal temperature (Tre), skin temperature (Tsk), heart rate (HR), heart rate variability (HRV), blood pressure (BP), the relative power density of the alpha wave (alpha-wave ratio) of electroencephalogram, alpha attenuation coefficient (AAC), and the error rate of the task performance. As a result, we found that the HR after the mist sauna bathing was significantly lower than those after no bathing rest 3 (11:00). Furthermore, we verified that the alpha-wave ratio of the Pz after the mist sauna bathing was significantly lower than those after no bathing during the task 6 (15:00). On the other hand, the alpha-wave ratio of the Pz after the mist sauna bathing was significantly higher than those after showering during the rest 3 (11:00). Tsk after the mist sauna bathing was higher than those after the showering at 9:00 and 15:00. In addition, the error rate of the task performance after the mist sauna bathing was lower than those after no bathing and showering at 14:00. This study concludes that a morning mist sauna is safe and maintains both skin temperature compared to other bathing methods. Moreover, it is presumed that the morning mist sauna bathing improves work efficiency comparing other bathing methods during the task period of the day following the morning bathing.

本研究では転倒防止に重要なステッピング反応に着目し、身体重心動揺と下肢関節モーメント、それらの関係性から後方へのステップ着地時に不安定性を呈する高齢者の特性を明らかにすることを目的とした。対象は健常高齢者19名とし、外乱負荷時の反応からsingle step群とmulti step群に選別した。動作解析装置と床反力計を用いて、ステップ着地時における身体重心動揺と関節モーメントを計測し両群間で比較した。結果、multi step群では着地時に発揮する足関節底屈・外がえしモーメントが有意に低値を示し、左右方向への身体重心動揺は高値を示した。ステップ着地時に不安定性を認める高齢者の特性として、着地時での左右方向への身体重心動揺を制御する能力が低下しており、その要因の一つとして足関節の底屈モーメントを適切に発揮できていないことが明らかとなった。(著者抄録)

The purpose of this study was to examine the perception of visual motion stimulation in the peripheral vision during eye fixation. Fourteen subjects participated in the study, and they were instructed to observe twelve white circles in their peripheral vision. The subjects were asked which circle wasvibrating. These results showed that rods cells adjusted to vibrations that were slower than 1 Hz, and that the vibration frequencies that humans can perceive in their peripheral vision depends on critical flicker fusion values. Moreover, these results suggested that the lower visual field was better able to perceive low-frequency stimulations.

To assess the physiological responses of subjects with differing personality traits to the artificial lighting environments, we examined the effects of four lighting conditions on cognition taste thresholds and saliva secretion in relation to subjects' personality types (Type A vs. B behavior pattern and the State-Trait Anxiety Inventory) in 40 healthy men. The physiological responses to light differed between the Type A and Type B subjects and among the high-, middle- and low-scorers on a trait anxiety test. We next studied the nonvisual effects of blue-pulsed light, and we observed that the nonvisual effect of pupillary constriction (miosis) occurred even during blue-pulsed light irradiation at very short pulse widths. When the product of irradiance intensity and the pulse width were equal, the condition of high irradiance and short pulse width was shown to produce marked miosis.

This study investigated laterality of manual pushing during a gait cycle by measuring pushing force, muscular activation and foot pressure. Subjects were 17 healthy young adult males; (11 right-handed [RH], and 6 left-handed [LH]). They pushed a force plate while walking on a treadmill at 1.5, 3, and 4 km/h. Electromyogram (EMG) data were collected bilaterally from the tibialis anterior, soleus, lumbar erector spinae and triceps brachii. To measure foot pressure, ten pressure sensors were attached bilaterally on five points of the sole. Symmetry assessment was performed by comparing bilateral data and cross-correlation function (CCF). Gait cycle duration was found to be symmetrical in all conditions. LH subjects demonstrated asymmetry in calcaneus contact duration to control ankle flexion, whereas RH were symmetrical. Velocity affected tibialis anterior muscle time lag and soleus muscle CCF coefficients, mainly in LH. We found that triceps brachii muscle CCF coefficients in LH subjects were affected by increasing velocity. Results indicated that LH and RH did not mirror each other, since both had distinct characteristics. Furthermore these asymmetries were not strictly associated with the preferred side, indicating that generalisation of preferred side to whole-body coordination should be avoided, since we could not separate one side from the other.

Ultrasound examinations may require sonographers to adopt unnatural postures, which can lead to musculoskeletal disorders. We previously assessed the effect of a vertical operation panel on muscular stress. In this study, we focused on the horizontal positioning of the control panel of a diagnostic ultrasound system to quantitatively assess the influence of work plane position on musculoskeletal stress during scanning. Five subjects were asked to perform a simulated scanning task that involved touching five points on the control panel, with the work plane set at different positions in space. Electromyograms of each part of the body and wrist joint angles indicated that the least stressful position of the left hand was about 350 mm from the center of the trunk in the longitudinal (front-back) direction and 100 mm left of the center of the trunk in the lateral (right-left) direction.

We evaluated and compared different methods of normalizing and analyzing electromyogram (EMG) data during short-term lightweight activity to identify the most suitable methodology. Surface EMG was obtained in five regions of the upper limbs in 10 elderly women (70-79 yrs old) and 10 young women (21-23 yrs old) during activities of daily living (ADL) such as skincare, eating, etc. The results suggested that %MVE (Maximal Voluntary Electrical activity) or %RVE (Reference Voluntary Electrical activity) is more sensitive for identifying differences in short-term, lightweight activity compared to %MVC (Maximal Voluntary Contraction). The results also clarified that exposure variation analysis (EVA) was the most suitable method to characterize the EMG obtained during ADL because EVA provided various types of muscle activity information.

The purpose of this study was to investigate the relationship between the shape of the spinal column and the deflection in the segmental and body center of mass during quiet standing in elderly individuals. Sixteen elderly individuals were recruited in this study. Their thoracic kyphosis and lumbar lordosis angles were measured using a spinal column-measuring instrument. Further, we determined the deflection characteristics of the segmental center of mass at the landing phase by using a three-dimensional motion analysis system. A significant positive correlation was observed between the thoracic kyphosis angle and the velocity of anteroposterior deflection in the center of mass of the whole body and head. These results suggest that increase in the thoracic kyphosis angle is associated with the deflection characteristics of the whole-body and head centers of mass during quiet standing.

磁気による3次元計測システムを用いて、顎および口腔ケア用具に関する運動解析方法を開発した。有効性を示すため、歯ブラシの先端部分の寸法がブラッシング行動に与える影響を検討した。第3大臼歯を有する健常成人8例を対象とした。ヘッド先端が最後臼歯周辺で小刻みな運動をしている様子を観察した。開口量には条件の有意な主効果は認めなかった。到達度と開口量は有意な正の相関関係があった。散布図の全体の傾向としては開口するほど奥行度も高くなるが、ヘッドやネックが大きいものほどその影響が顕著であり、小さいものでは開口度によらず奥行度が高い様子が示唆された。

Ultrasound examinations tend to put sonographers in unnatural postures, which may lead to musculoskeletal disorders. In this study, we focused on the height of the operation panel of the diagnostic ultrasound system to quantitatively assess the effects of panel height (work plane height) on musculoskeletal stress during scanning in a sitting position. Eight subjects were asked to perform a simulated scanning task that involved touching nine points on the operation panel at four different panel heights. Electromyogram, left wrist joint angle, and subjective evaluation on ease of manipulation, etc., indicated that the optimum height of the operation panel during scanning in a sitting position is elbow height. © 2012 The Japan Society of Ultrasonics in Medicine.

Physiological anthropology presently covers a very broad range of human knowledge and engineering technologies. This study reviews scientific inconsistencies within a variety of areas: sitting posture; negative air ions; oxygen inhalation; alpha brain waves induced by music and ultrasound; 1/f fluctuations; the evaluation of feelings using surface electroencephalography; Kansei; universal design; and anti-stress issues. We found that the inconsistencies within these areas indicate the importance of integrative thinking and the need to maintain the perspective on the biological benefit to humanity. Analytical science divides human physiological functions into discrete details, although individuals comprise a unified collection of whole-body functions. Such disparate considerations contribute to the misunderstanding of physiological functions and the misevaluation of positive and negative values for humankind. Research related to human health will, in future, depend on the concept of maintaining physiological functions based on consistent science and on sustaining human health to maintain biological welfare in future generations.

Background: It has been assumed that light with a higher irradiance of pulsed blue light has a much greater influence than that of light with a lower irradiance of steady blue light, although they have the same multiplication value of irradiance and duration. We examined the non-visual physiological effects of blue pulsed light, and determined whether it is sensed visually as being blue. Findings: Seven young male volunteers participated in the study. We placed a circular screen (diameter 500 mm) in front of the participants and irradiated it using blue and/or white light-emitting diodes (LEDs), and we used halogen lamps as a standard illuminant. We applied three steady light conditions of white LED (F0), blue LED + white LED (F10), and blue LED (F100), and a blue pulsed light condition of a 100-mu s pulse width with a 10% duty ratio (P10). The irradiance of all four conditions at the participant's eye level was almost the same, at around 12 mu W/cm(2). We measured their pupil diameter, recorded electroencephalogram readings and Kwansei Gakuin Sleepiness Scale score, and collected subjective evaluations. The subjective bluish score under the F100 condition was significantly higher than those under other conditions. Even under the P10 condition with a 10% duty ratio of blue pulsed light and the F10 condition, the participant did not perceive the light as bluish. Pupillary light response under the P10 pulsed light condition was significantly greater than under the F10 condition, even though the two conditions had equal blue light components. Conclusions: The pupil constricted under the blue pulsed light condition, indicating a non-visual effect of the lighting, even though the participants did not perceive the light as bluish.

Background: Recently, mist saunas have been used in the home as a new bathing style in Japan. However, there are still few reports on the effects of bathing methods on recovery from muscle fatigue. Furthermore, the effect of mist sauna bathing on human physiological function has not yet been revealed. Therefore, we measured the physiological effects of bathing methods including the mist sauna on recovery from muscle fatigue. Methods: The bathing methods studied included four conditions: full immersion bath, shower, mist sauna, and no bathing as a control. Ten men participated in this study. The participants completed four consecutive sessions: a 30-min rest period, a 10-min all out elbow flexion task period, a 10-min bathing period, and a 10-min recovery period. We evaluated the mean power frequency (MNF) of the electromyogram (EMG), rectal temperature (Tre), skin temperature (Tsk), skin blood flow (SBF), concentration of oxygenated hemoglobin (O2Hb), and subjective evaluation. Results: We found that the MNF under the full immersion bath condition was significantly higher than those under the other conditions. Furthermore, Tre, SBF, and O2Hb under the full immersion bath condition were significantly higher than under the other conditions. Conclusions: Following the results for the full immersion bath condition, the SBF and O2Hb of the mist sauna condition were significantly higher than those for the shower and no bathing conditions. These results suggest that full immersion bath and mist sauna are effective in facilitating recovery from muscle fatigue.

スキンケア用コットンの持ち方を「はさむ」と「つまむ」２つの姿勢に分けた。「はさむ」は手指を伸展させ、指と指の間にコットンをはさむ姿勢であり、「つまむ」は拇指とそれに対向する複数の指でコットンをつまむ姿勢であった。本実験のタスクは化粧水を顔にコットンでなじませる動作であり、18プロセスから成っていた。被験者は30代の社会人女性15名と高齢女性11名であった。測定項目は上肢の筋電図および関節角度であった。結果、「はさむ」場合、コットンを手と顔面の相対的な角度と位置に合わせて幅広く移動させるため、手指と掌についての力および姿勢の変化は大きく、手関節の姿勢変化は小さいことがわかった。「つまむ」場合、手指の力および姿勢は一定であるため、コットンを顔面に移動させるのに、手関節の姿勢変化が大きいことがわかった。<br>コットンの持ち方に関わらず、高齢者の化粧対象部位間の筋活動と関節運動の違いが若年者より小さかった。このことより、高齢者は若年者のように力と姿勢の調整が上手にできず、運動学的により狭くかつ低い活動度であることが示唆された。

In recent years, parametric speakers have been used in various circumstances. In our previous studies, we verified that the physiological burden of the sound of parametric speaker set at 2.6 m from the subjects was lower than that of the general speaker. However, nothing has yet been demonstrated about the effects of the sound of a parametric speaker at the shorter distance between parametric speakers the human body. Therefore, we studied this effect on physiological functions and task performance. Nine male subjects participated in this study. They completed three consecutive sessions: a 20-minute quiet period as a baseline, a 30-minute mental task period with general speakers or parametric speakers, and a 20-minute recovery period. We measured electrocardiogram (ECG) photoplethysmogram (PTG), electroencephalogram (EEG), systolic and diastolic blood pressure. Four experiments, one with a speaker condition (general speaker and parametric speaker), the other with a distance condition (0.3 m and 1.0 m), were conducted respectively at the same time of day on separate days. To examine the effects of the speaker and distance, three-way repeated measures ANOVA (speaker factor x distance factor x time factor) were conducted. In conclusion, we found that the physiological responses were not significantly different between the speaker condition and the distance condition. Meanwhile, it was shown that the physiological burdens increased with progress in time independently of speaker condition and distance condition. In summary, the effects of the parametric speaker at the 2.6 m distance were not obtained at the distance of 1 m or less.

使いやすさの視点から製品の設計や評価を行う際に、生体負担の指標として、表面筋電図がしばしば使われる。しかし迅速さが要求される開発環境で筋電図を導入することは、今も簡単ではない。本研究では、現場でのユーザビリティ評価に特化した表面筋電図の測定デバイスを開発した。本デバイスはアナログ増幅部とデジタル処理部、LED表示部からなった。増幅率のアナログ調整、包絡線処理による較正方法を電極上に実装した。較正方法は、最大随意収縮（MVC）、ある条件を基準とする相対化、上下の 2値による直線較正の 3つであった。ボトルの把持性に関する実験を行った結果、本デバイスの出力と主観評価との間に相関関係が認められた。本デバイスは効率的で高精度な人間工学的プロトタイピングを可能にし、開発現場への筋電図の導入に貢献する。

低栄養患者に対して栄養サポートチーム（NST）によるチーム医療が展開されている．NST介入の必要性を判断するための標準的な方法として，MNA（Mini Nutritional Assessment）が用いられる．MNAに含まれる指標である下腿周囲長（Calf Circumference；CC）について，計測誤差やデバイスのデザインについての検討は皆無であった．本研究では，CC計測用メジャーテープを人間工学的に設計・製作した．設計の主眼は，下腿の長軸に対する直交性，メジャーを引く力の統制，重力に対するテープのたわみにくさと最大周径の狙いやすさ，であった．24名の被験者によって従来製品と新案の比較実験を行った．その結果，新案において個人内・個人間誤差は30～40％程度減少し，測定に要する時間は平均17.4秒から10.3秒に減少した．主観評価も含めて新案は総合的に高いユーザビリティを示した．人間工学的デザインは栄養アセスメントに一層の信頼性をもたらすだろう．