静止立位姿勢における足圧中心動揺の評価変数の検討 試行間信頼性と変数相互の関係の観点から

This study examined the interrelationships between various parameters evaluating body sway from the center of foot pressure (CFP) during a static standing posture, and gender difference by domain. The subjects were 220 healthy young males and females. CFP was measured 3 times with a 1 min rest, and the mean of trials 2 and 3 was used for the analysis. The measurement device was Anima's stabilometer G-5500. Data sampling frequency was 20Hz. Sixty parameters with higher reliability were selected from the following 7 domains: distance, center average, distribution of amplitude, area, velocity, power spectrum, and body sway vector.Several parameters showed a significant gender difference, but the degree was not large. The correlation coefficients between parameters in each domain of distance, center average, distribution of amplitude, area, velocity, and body sway vector were very high, and they tended to relate closely to some parameters in the other domains. Gender difference in the correlation coefficient was insignificant. Therefore, the relationship between parameters in both genders was judged to be very similar.After examining the interrelationship between parameters, 36 parameters were selected. We judged that the body sway can be synthetically evaluated by these rather than 60 parameters.

To examine the influence of alcohol intake on various parameters evaluating the change in body center of foot pressure during a static upright posture, 11 healthy young males and females gave measures of blood pressure, heart rate, whole body reaction time, standing on one leg with eyes closed, and body stability for 60 sec. in the Romberg posture (open eyes, closed feet) before and after the alcohol intake. The measurement was made with an Anima's stabilometer G5500. Data sampling frequency was 20 Hz. The subjects drank alcohol (Japanese sake 540 ml) within 10 min. After 10, 20, and 30 min. of alcohol intake, the same measurements were carried out. 24 parameters with higher trial-to-trial reliability were selected from the following 7 domains: distance, mean center of foot pressure, distribution of amplitude, area, velocity, frequency (power spectrum), and direction (vector) of body-sway and velocity. Parameters for distance, velocity, and area of body-sway significantly changed after alcohol intake, but the mean center of foot pressure and frequency of body-sway were unchanged. It was inferred that the mean center of foot pressure and frequency for body-sway did not change even if a nervous function decreased by the alcohol intake, and an upright posture was maintained by increasing the distance, area, and velocity of body-sway. Further, body-sway tends to increase in the medial/lateral direction as compared with the anterior/posterior direction.

Electromyographic (EMG) patterns of leg muscles associated with rapid body sway were studied in relation to displacement of the center of foot pressure (CFP). Standing subjects were instructed to shift the CFP by swaying their bodies, pivoting at the ankle as rapidly and accurately as possible after an auditory signal. CFP position was designated as N when the subject maintained a relaxed bending posture and as F when a maximally forward-leaning posture was maintained. A serial, stereotyped triphasic EMG pattern was observed in the rapid shift of CFP from N to F: cessation of EMG activity in the gastrocnemius (GC) muscle was followed by a burst in the tibialis anterior (TA) muscle (acceleration phase), and then resumed discharge occurred in the GC muscle with cessation of activity in the TA muscle (deceleration and stop). When the subject shifted the CFP from N to F to different degrees, the duration and amount of EMG activity in the TA muscle during acceleration and the GC muscle in deceleration were proportionate to the amount of CFP displacement associated with forward body sway. To determine the functional roles of sensory inputs from the foot on the triphasic EMG pattern, body sway was studied under the condition of sensory block in the feet induced by ischemia from tourniquets placed bilaterally just above the ankle joints. The triphasic EMG pattern persisted during ischemia. The time of GC cessation and the onset of TA burst at acceleration remained unchanged, but the times of TA cessation and resumption of GC discharge at deceleration were altered during ischemia. Moreover, subjects were unable to stop at F and eventually fell. These results indicate that both amount and duration of EMG activity associated with rapid body sway are functions of the amount of CFP displacement. Somatic sensation from the feet is important for control of burst and cessation timing and duration in leg muscle activity.

The present study examined the differences between male and female gymnasts in bipedal standing position, back standing scale, and stork standing scale testing. 29 young gymnasts (13 boys, 16 girls; ages 12 to 15 years) participated. A portable posturographic digital platform was used to record foot pressure (Foot Checker, Comex SA). Barefoot sole area (cm2), maximal pressure (kPa), center of foot pressure (CoP), sway area (mm2), and CoP linear distance displacement (mm) were analyzed in an integrated software module (Foot Checker, Version 4.0). The intra-class correlation coefficient and the coefficient of variation supported the reliability of the measurements. Results indicated no differences between boys and girls on height, weight, and Body Mass Index. Differences indicated better performance by girls compared to boys in back standing and stork standing.

This study aimed to examine the effects of open/ closed eyes and age difference on Center of Foot Pressure (COP) sway during stepping. The subjects were 87 healthy males aged 10 - 80 years. COP was measured 20 times when subjects stepped on two force plates (left and right) at a rate of 60 steps/min. The evaluation parameters selected were: total trace length, velocity, circumference, rectangular area，left-right width, and front-back width. The former four of these parameters were found to be significantly lower with eyes open than eyes closed in 80-year-old subjects, while the last parameter was significantly lower with eyes open in 10-year-old subjects. In 70- and 80-year-old subjects with eyes open, circumference was greater than that in 10- and 40 - 60-year-old subjects; their rectangular area was greater than that in 50- and 60-year-old subjects; and, their front-back width was greater than that in 10- and 30 - 60-year-old subjects. With eyes closed, circumference, rectangular area, left-right width, and front-back width in 80-year- old subjects, were greater than those in 10 - 70- year-old subjects. The front-back width during stepping with eyes closed was greater in 70- and 80-year-old subjects than in 30 - 50-year-old subjects. The Romberg quotient for all COP sway parameters revealed no significant age-related differences. From our findings, a difference in body sway was observed in 80-year-old subjects (with eyes open/closed) when compared with the other age groups. In addition, the extent of sway varied little among 80 year-old- subjects have greater body sway during stepping, particularly with eyes closed.

Seiza is one of the most commonly used sitting postures in various enrichment lessons of Japanese origin. It is reported that Seiza with large knee flexion produces harmful effects on the cartilage of knee joints and hemodynamics of the lower legs. This study aimed at examining the influence of Seiza on tissue oxygenation kinetics of the lower limbs, plantar somatic and cutaneous sensation, and the center of foot pressure (COP) sway using 10 young adults. COP sway was measured for 1 min just after sitting on a chair for 10 min (pre-test), after 30-min Seiza (post-test 1), and 5 min after Seiza (post-test 2). To evaluate the COP sway, we used 4 body sway factors; unit time sway factor (F1), front-back sway factor (F2), left-right sway factor (F3) and high frequency band power spectrum factor (F4). Physiological parameters (i.e., tissue oxygenation kinetics in the lower legs and sensation on the sole) were measured during 30-min Seiza (continuously on tissue oxygenation, and at 1 min intervals on sensation), and for 1 min just before each COP test (pre-test, post-test 1 and 2). Oxygenated hemoglobin/myoglobin (Hb/Mb) concentration decreased markedly and deoxygenated Hb/Mb concentration increased markedly, resulting in reaching a plateau state at around 7 min. Tissue Hb/Mb index changed little during Seiza. Proprioceptive perception thresholds increased rapidly about 17 min after Starting Seiza. Means of 3 COP sway factors of F1, F2 and F4 were significantly higher in post-test 1 than in pre-test and post-test 2. In conclusion, a marked decrease in tissue oxygen concentration of the lower legs within 4-5 min, and an increase of proprioceptive perception thresholds in the sole at about 17 min are induced by Seiza. Although wiggle and quick body sway in the antero-posterior axis increases markedly in an upright posture just after maintaining Seiza for 30 min, sway recovers after sitting on a chair for 5 min.

Vestibular deficit patients have an increased fall risk and fear of falling. Postural threat, known to increase balance-related fear and anxiety, influences vestibular gains during quiet standing in young healthy adults. The current study examined whether there is a similar relationship for peripheral unilateral vestibular loss (UVL) patients in comparison to age-matched healthy controls (HC). University laboratory. Prospective laboratory study. Eleven UVL patients, nine with vestibular neurectomy. Eleven aged-matched HCs. Subjects stood on a hydraulic lift placed at two heights: low (0.8 m, away from the edge) and high (3.2 m, at the edge). Amplitude (root mean square), mean power frequency (MPF), and mean position were analyzed for center of foot pressure (COP) and 90% ranges for angle amplitude and velocity for trunk sway. Group interactions were strongest for anterior-posterior (AP) COP and trunk pitch angle. AP lean away from the edge was greater in HCs than UVLs. HCs, but not UVLs had a decrease in root mean square AP COP with height. Trunk pitch sway was changed similarly. Both groups had increased trunk pitch velocity at height. Changes with height were less for roll: MPF of lateral COP increased with height for UVLs with no changes for HCs, and trunk roll amplitude decreased for both groups. This report provides evidence for a differential effect of height induced postural threat on balance control between UVLs and HCs presumably due to the reduced vestibular-spinal gain in UVL subjects.

Alterations of body sway caused by isometric contractions of the jaw muscles have been reported previously. The objective of this study was to test if motor tasks of the masticatory system with different control demands affect body posture differently during quiet stance. Position and sway displacements of the center of foot pressure (COP) were measured for 20 healthy subjects who either kept the mandible at rest or performed unilateral and bilateral maximum voluntary teeth clenching, feedback-controlled biting tasks at submaximum bite forces, or unilateral chewing. Two weeks later the measurements were repeated. Compared with quiet stance, the COP results revealed significant changes during the feedback-controlled biting tasks. Robust sway reduction and anterior displacement of the COP were observed under these conditions. Body oscillations were not significantly affected by maximum bites or by unilateral chewing. For most of the variables investigated there were no significant differences between unilateral and bilateral biting. Robust sway reduction during feedback-controlled biting tasks in healthy subjects involved a stiffening phenomenon that was attributed to the common physiological repertoire of posture control, and might optimize the stability of posture under these conditions.

The reproducibility of 99m Tc-pertechnetate single photon emission computed tomography (SPECT) for measurement of gastric accommodation in healthy humans: Evaluation of the test results performed at the same time and different time of the day (

An experimental study is performed to determine flow instability in the diverging-flow region with flip-flop phenomenon inside diamond-shaped cylinder bundles. Both two-dimensional particle imaging velocimetry (PIV) and two-dimensional laser Doppler velocimery (LDV) are employed to visualize and monitor flow phenomena. The study leads to the following disclosures in the diverging region with flip-flop phenomenon: (i) Velocity distribution can be expressed three-dimensionally and longitudinal vortices (migrating helically) appear in the secondary flow resulting from separation of the main stream. (ii) Power spectrum distribution with identical dominant frequency prevails in every row, indicating flow oscillations propagate over the entire passage. At the third row, the magnitude of power spectra reaches maximum near the “energy supply point” but subsequently diminishes to the minimum value at the apex of the succeeding cylinder where micro vortices alternately shedding on each of the downstream surface. (iii) The flow exhibits the characteristics of a jet tone.

Objective To establish a way to measure the injury severity of articular surface due to posterior malleolus fracture and investigate its clinical significance based on three-dimensional reconstruction technique. Methods Between May 2009 and March 2014, 138 cases of peri-ankle injury combined with posterior malleolus fracture were treated. Lateral radiographs were reviewed to measure the ratio of posterior fragment area to distal tibial plafond area using the common method. Three-dimensional CT images were examined to measure ratio of the area of injury using the three-dimensional measuring method. Statistical comparison was made using the t-test and intraclass correlation coefficient (ICC). Results Measurement failed on 33 lateral radiographs and 13 three-dimensional CT images. Six cases cannot be measured by both imaging technology, so results of 98 cases were compared. Ratio of posterior fragment area to tibial plafond area was (16.2±7.2)% measured by radiographs and was (29.6±10.1)% by three-dimensional CT scans (P<0.05). Three-dimensional CT measurements showed higher intra and inter-observer agreement (ICC of 0.973 to 0.942) than that in radiographic measurements (ICC of 0.875 to 0.860). Conclusion Three-dimension CT assessment of the extent of injury to articular surface because of posterior malleolus fracture is reliable and reproducible, but radiographic assessment may underestimate the injury and influence the choice of surgical indications. Key words: Ankle injuries; Imaging, three-dimensional; Tomography, X-ray computed

Introduction: Electromyography (EMG) normalization often relies on maximum voluntary isometric contraction (MVIC), which may not be suitable for knee osteoarthritis (KOA) patients due to difficulties in generating maximum joint torques caused by pain. This study aims to assess the reliability of standard isometric contraction (SIC) for EMG normalization in older adults with KOA, comparing it with MVIC. Methods: We recruited thirty-five older adults with KOA and collected root mean square EMG amplitudes from seven muscles in the affected limb during level walking, SIC, and MVIC tests. EMG data during level walking were normalized using both SIC and MVIC methods. This process was repeated after at least 1week. We calculated intra-class correlation coefficients (ICCs) with 95% confidence intervals to evaluate between- and within-day reliabilities. Results: SIC tests showed higher between- (ICC: 0.75-0.86) and within-day (ICC: 0.84-0.95) ICCs across all seven muscles compared to MVIC tests. When normalized with SIC, all seven muscles exhibited higher between- (ICC: 0.67-0.85) and within-day (ICC: 0.88-0.99) ICCs compared to MVIC normalization. Conclusion: This study suggests that SIC may offer superior movement consistency and reliability compared to MVIC for EMG normalization during level walking in older adults with KOA.

This study was done to examine age-stage (preschool children, young adults, and elderly people) differences in the center-of-pressure sway using body-sway factors (unit-time sway, front-back sway, left-right sway, and high frequency-band power), power-spectrum distribution, and relative accumulation of power frequency (25%, 50%, and 75% RAPF) of the center-of-pressure spectrum. The center-of-pressure movement for 1 min. was measured twice using Anima's stabilometer. Data-sampling frequency was set at 20 Hz. Significant age-stage differences were found for 3 factors except for left-right sway, which was larger for preschool children and elderly than for young adults. The power spectrum of body sway in any age-stage was noted mainly in low frequency bands. A marked age-stage difference was found at 75% RAPF. Body-sway characteristics in each age-stage differ, and differences of postural-sway frequency are marked in the low frequency bands.

Time course of stabilometric changes after a strenuous treadmill exercise

Curved walking in hemiparetic patients