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There are limited reports on segment movement and their coordination pattern during gait in patients with hip osteoarthritis. To avoid the excessive stress toward the hip and relevant joints, it is important to investigate the coordination pattern between these segment movements, focusing on the time series data. This study aimed to quantify the coordination pattern of lumbar, pelvic, and thigh movements during gait in patients with hip osteoarthritis and in a control group. An inertial measurement unit was used to measure the lumbar, pelvic, and thigh angular velocities during gait of 11 patients with hip osteoarthritis and 11 controls. The vector coding technique was applied, and the coupling angle and the appearance rate of coordination pattern in each direction were calculated and compared with the control group. Compared with the control group, with respect to the lumbar/pelvic segment movements, the patients with hip osteoarthritis spent more rates in anti-phase and lower rates in in-phase lateral tilt movement. With respect to the pelvic/thigh segment movements, the patients with hip osteoarthritis spent more rates within the proximal- and in-phases for lateral tilt movement. Furthermore, patients with osteoarthritis spent lower rates in the distal-phase for anterior/posterior tilt and rotational movement. Patients with hip osteoarthritis could not move their pelvic and thigh segments separately, which indicates the stiffness of the hip joint. The rotational movement and lateral tilt movements, especially, were limited, which is known as Duchenne limp. To maintain the gait ability, it seems important to pay attention to these directional movements.

This study aimed to investigate the hip sway and the relationship between the center of pressure (CoP) and kinematic parameters regarding the time series scaling component α in patients with hip osteoarthritis (OA) during a one-leg standing task. The scaling exponent α, SD, hip sway maximal acceleration change, and balance performance, which was measured using CoP parameters, were compared between hip OA and control groups during a one-leg standing task. The relationships between balance performance with CoP parameters and kinematic parameters were investigated with the regression analysis. In the hip OA group, the scaling exponent α was smaller in the medial–lateral direction, and the SD and maximal amount of change in hip sway acceleration were larger in the anterior–posterior direction in the hip OA group. In this group, the CoP parameters were significantly associated with α in the medial–lateral direction (negatively) and in the anterior–posterior direction (positively). In the hip OA group, hip sway adaptability in the medial–lateral direction was limited, while the anterior–posterior direction showed greater movement.

Background Muscle co-contraction is the simultaneous contraction of agonist and antagonist muscles crossing a joint, and it increases with age. This study primarily aimed to clarify the difference in the effect of a light fingertip contact to stationary surface on postural sway and muscle co-contraction during single-leg standing (SLS) between young and elderly groups; the secondary aim was to reveal the quantitative difference in the muscle co-contraction of the ankle joint among the three different support structure conditions in the elderly group. Methods This study included eight young adults (age 23.4 ± 2.6 years) and nine community dwelling older adults (age 74.7 ± 3.4 years). The task was SLS under the following conditions: (1) no supporting structure, FR; (2) light index fingertip contact to a stationary supporting structure (to touch in force

Background During gait, the swing limb requires flexible control to adapt to ever changing environmental circumstances. However, few studies have focused on the mechanics of swing limb control in patients with knee osteoarthritis (OA). Investigating the variability of swing limb kinematics, which can be represented by variables such as the peak shank angular velocity during the swing phase obtained from an inertial sensor, provides insights into the adaptability of swing limb control. The purpose of this study was to investigate how patients with knee OA control the swing limb and whether the degree of impairment and disability due to knee OA affects swing limb control. Methods Twelve subjects diagnosed with knee OA and 11 healthy control subjects participated in this study. Subjects walked on a treadmill for 10 min. The mean, coefficient of variation, and fractal scaling exponent α of the peak shank angular velocity during the swing phase were calculated. Findings There were no significant differences between the groups for any of the kinematic parameters. The Knee Injury and Osteoarthritis Outcome Score (KOOS) activities of daily living (ADL) subsection correlated with the coefficient of variation ( r = −0.677, p = 0.016) and the scaling exponent α ( r = 0.604, p = 0.037) of the peak shank angular velocity. Interpretation Control of the swing limb was associated with the degree of impairment and disability. Larger and more random variability of peak shank angular velocity may indicate decreased ADL ability in patients with knee OA.

Background Agonist and antagonist muscle co-contractions during motor tasks are greater in the elderly than in young adults. During normal walking, muscle co-contraction increases with gait speed in young adults, but not in elderly adults. However, no study has compared the effects of speed on muscle co-contraction of the ankle joint during dynamic postural control in young and elderly adults. We compared muscle co-contractions of the ankle joint between young and elderly subjects during a functional stability boundary test at different speeds. Methods Fifteen young adults and 16 community-dwelling elderly adults participated in this study. The task was functional stability boundary tests at different speeds (preferred and fast). Electromyographic evaluations of the tibialis anterior and soleus were recorded. The muscle co-contraction was evaluated using the co-contraction index (CI). Results There were no statistically significant differences in the postural sway parameters between the two age groups. Elderly subjects showed larger CI in both speed conditions than did the young subjects. CI was higher in the fast speed condition than in the preferred speed condition in the young subjects, but there was no difference in the elderly subjects. Moreover, after dividing the analytical range into phases (acceleration and deceleration phases), the CI was larger in the deceleration phase than in the acceleration phase in both groups, except for the young subjects in the fast speed conditions. Conclusions Our results showed a greater muscle co-contraction of the ankle joint during dynamic postural control in elderly subjects than in young subjects not only in the preferred speed condition but also in the fast speed condition. In addition, the young subjects showed increased muscle co-contraction in the fast speed condition compared with that in the preferred speed condition; however, the elderly subjects showed no significant difference in muscle co-contraction between the two speed conditions. This indicates that fast movements cause different influences on dynamic postural control in elderly people, particularly from the point of view of muscle activation. These findings highlight the differences in the speed effects on muscle co-contraction of the ankle joint during dynamic postural control between the two age groups.

[Purpose] The time-series waveforms of mechanical energy generation, absorption, and transfer through the joints indicate how movements are produced and controlled. Previous studies have used these waveforms to evaluate and describe the efficiency of human movements. The purpose of this study was to examine the influence of trunk flexion on mechanical energy flow in the lower extremities during gait. [Subjects and Methods] The subjects were 8 healthy young males (mean age, 21.8 ± 1.3 years, mean height, 170.5 ± 6.8 cm, and mean weight, 60.2 ± 6.8 kg). Subjects walked at a self-selected gait speed under 2 conditions: normal gait (condition N), and gait with trunk flexion formed with a brace to simulate spinal curvature (condition TF). The data collected from initial contact to the mid-stance of gait was analyzed. [Results] There were no significant differences between the 2 conditions in the mechanical energy flow in the knee joint and negative mechanical work in the knee joint. However, the positive mechanical work of the knee joint under condition TF was significantly less than that under condition N. [Conclusion] Trunk flexion led to knee flexion in a standing posture. Thus, a strategy of moving of center of mass upward by knee extension using less mechanical energy was selected during gait in the trunk flexed posture.

Background Accelerometers provide information regarding balance and gait, but they are rarely used in clinical settings for stroke patients. Clinically, balance is assessed with simple tests, but their relationships with accelerometry results after stroke are unknown. Objective We examined the relationship between accelerometry-assessed gait indices calculated from trunk acceleration and results of the Timed Up and Go (TUG) and Berg Balance Scale (BBS) tests in stroke patients. Methods Twenty-nine stroke patients completed assessments with the TUG, BBS, and trunk acceleration during walking using a tri-axial accelerometer. The root mean square (RMS), stride regularity (SR), and step symmetry (SS), which indicate gait fluctuations, regularity, and symmetry, respectively, were calculated based on trunk acceleration. These were calculated in the vertical (VT), anteroposterior, and mediolateral directions. A multiple linear regression analysis was performed to determine whether these gait indices contributed independently to TUG and BBS results. Results VT-RMS and VT-SS were significant determinants of TUG, and VT-SS, VT-RMS, and VT-SR were significant determinants of BBS. Conclusions This study suggested that the gait indices calculated from trunk acceleration that were relevant to balance were those in the VT direction. These may be useful for evaluating dynamic gait balance in patients with stroke.

Objective Sit-to-stand motion (STS) is a dynamic motion utilized in fundamental activities of daily living and requires extensive joint movement in the lower extremities and the trunk and coordination of multiple body segments. The present study aimed to investigate whether aging affects the motor coordination of joint movements required to stabilize the horizontal and vertical movement of center of mass using the uncontrolled manifold (UCM) analysis. Method We recruited 39 older adults with no musculoskeletal and/or neuromuscular conditions that affected STS, along with 21 healthy younger adults. All subjects performed five STS trials from a chair with the seat height adjusted to the length of their lower leg at a self-selected motion speed. Kinematic data were collected using a three-dimensional motion analysis system. We performed the UCM analysis to assess the effects of joint angle variance (elemental variable) to stabilize the horizontal and vertical movement of COM (performance variable) and calculated the joint angle variance that does not affect COM (VUCM), the variance that affects COM (VORT), and the synergy index (ΔV). Results ΔV values in the horizontal direction were higher in the older adults than in the younger adults, but ΔV values in the vertical direction were lower in the older adults than in the younger adults. Conclusion Older adults require increasing levels of stabilization of horizontal movement of COM after buttocks-off in the STS maneuver. As a result, variance in the joint angle of the lower extremities indicated no kinematic synergy for stabilizing the vertical movement of COM.

[Purpose] The strategy of trunk lean gait to reduce external knee adduction moment (KAM) may affect multi-segmental synergy control of center of mass (COM) displacement. Uncontrolled manifold (UCM) analysis is an evaluation index to understand motor variability. The purpose of this study was to investigate how motor variability is affected by using UCM analysis on adjustment of the trunk lean angle. [Subjects and Methods] Fifteen healthy young adults walked at their preferred speed under two conditions: normal and trunk lean gait. UCM analysis was performed with respect to the COM displacement during the stance phase. The KAM data were analyzed at the points of the first KAM peak during the stance phase. [Results] The KAM during trunk lean gait was smaller than during normal gait. Despite a greater segmental configuration variance with respect to mediolateral COM displacement during trunk lean gait, the synergy index was not significantly different between the two conditions. The synergy index with respect to vertical COM displacement during trunk lean gait was smaller than that during normal gait. [Conclusion] These results suggest that trunk lean gait is effective in reducing KAM; however, it may decrease multi-segmental movement coordination of COM control in the vertical direction.

The purposes of this study were to construct a real-time acceleration gait analysis system equipped with software to analyse real-time trunk acceleration during walking and to examine the intra-rater and inter-rater reliabilities of the this system.This system has been comprised of an accelerometer, an acceleration amplifier, a transmitter, two foot switches, a receiver and a personal computer installed with the real-time acceleration analysis software. The acceleration signals received were analysed using the real-time acceleration analysis software, and gait parameters were calculated. The subjects were 20 healthy individuals and two raters. The intra-rater and inter-rater reliabilities of the measurement results obtained from this system were examined by performing intraclass correlation coefficients (ICC) and Bland-Altman analysis.The intra-rater and inter-rater ICCs ranged from 0.61 to 0.92 in any gait parameters. In the Bland-Altman analysis, neither fixed nor proportional bias was found in any of the gait parameters.From the ICC and Bland-Altman analysis results, the gait measurement using this system clearly demonstrates that the intra-rater and inter-rater measurements had good reproducibility. Owing to this system, we can improve the clinical efficiency of gait analysis and gait training for physiotherapy. Implication for Rehabilitation This study focused on the advantage of a gait analysis method using an accelerometer and constructed a gait analysis system that calculates real-time gait parameters from trunk acceleration measurements during walking. The gait analysis using this system has good intra-rater and inter-rater reliabilities, and using this system can improve the clinical efficiency of gait analysis and gait training.

To explore the effects of qualitative or quantitative changes in walking on motor cortical excitability, a transcranial magnetic stimulation procedure was used to examine the alterations of motor-evoked potential (MEP) amplitude following walking. Eight healthy participants completed a series of two walking tasks on a treadmill at 2 km/h. The ratio of the left stance duration to the right stance duration was 1 : 2 in the asymmetrical walking task and 1 : 1 in the symmetrical walking task. In each task, walking for 10 min followed by MEP measurement for ∼4 min was repeated three times. MEP measurements were also performed before a walking task as a baseline and continued every 10 min for a further 30 min after the completion of the walking task. During slight voluntary contraction of the left tibialis anterior muscle, MEP measurements were conducted four times. Although a significant MEP depression was found after the asymmetrical walking task with increasing amount of walking, no significant decrease in MEP below baseline was observed after the symmetrical walking task throughout all measurement sessions. This MEP depression was the prominent response to the asymmetrical walking task compared with the symmetrical walking task. These findings indicate that the intentional control of walking pattern has both temporal and task-specific influences on excitability changes in the cerebral cortex, and suggest that motor cortical excitability may be altered by controlling the amount of central commands to the legs even during gait exercise.

The present study aimed to assess the changes in the pattern of rising from a chair and walking forward as pregnancy progressed. Twelve pregnant women and 10 nulliparous women were included in this study. Participants were videotaped with a digital video camera in the sagittal plane, and the coordinates of the markers attached to the subjects were identified using image analysis software. The peak trunk-flexion angle in pregnant women during rising was smaller, but the hip-extension angle during the stance phase was larger than in controls. Also, the peak horizontal and vertical velocities of the center of mass were lower, and appeared earlier, in pregnant women than in controls. During rising, pregnant women dampened the propulsion attributable to increased uterus volume, and they enhanced the forward propulsion at gait initiation. To ensure safe motion, pregnant women should not initiate gait until reaching a stable standing position after rising.

The biomechanical mechanism of lateral trunk lean gait employed to reduce external knee adduction moment (KAM) for knee osteoarthritis (OA) patients is not well known. This mechanism may relate to the center of mass (COM) motion. Moreover, lateral trunk lean gait may affect motor control of the COM displacement. Uncontrolled manifold (UCM) analysis is an evaluation index used to understand motor control and variability of the motor task. Here we aimed to clarify the biomechanical mechanism to reduce KAM during lateral trunk lean gait and how motor variability controls the COM displacement. Twenty knee OA patients walked under two conditions: normal and lateral trunk lean gait conditions. UCM analysis was performed with respect to the COM displacement in the frontal plane. We also determined how the variability is structured with regards to the COM displacement as a performance variable. The peak KAM under lateral trunk lean gait was lower than that under normal gait. The reduced peak KAM observed was accompanied by medially shifted knee joint center, shortened distance of the center of pressure to knee joint center, and shortened distance of the knee-ground reaction force lever arm during the stance phase. Knee OA patients with lateral trunk lean gait could maintain kinematic synergy by utilizing greater segmental configuration variance to the performance variable. However, the COM displacement variability of lateral trunk lean gait was larger than that of normal gait. Our findings may provide clinical insights to effectively evaluate and prescribe gait modification training for knee OA patients.

Lateral wedge insoles (LWIs) are prescribed for patients with medial knee osteoarthritis to reduce the external knee adduction moment (KAM). However, the biomechanical effects of LWIs are limited in some patients. The purpose of this study was to investigate whether the biomechanical effects of LWIs depend on individual foot alignment and to examine the relationship between change in KAM and changes in foot and ankle biomechanics when wearing LWIs. Twenty-one patients participated in this study. They were categorized into normal or abnormal foot groups based on the foot posture index (FPI). All patients were requested to perform a normal gait under barefoot and LWI conditions. A three-dimensional motion analysis system was used to record 1st and 2nd KAM, knee adduction angular impulse (KAAI), center of pressure displacement, and knee-ground reaction force lever arm. Furthermore, the foot and ankle frontal plane kinematic parameters were evaluated. The 1st KAM was significantly reduced under the LWI condition compared to that under the barefoot condition in the normal foot group. In contrast, there was no significant difference in 1st KAM between both conditions in the abnormal foot group. Decreased rear foot eversion strongly correlated with reduction in the 1st KAM in the normal foot group. These findings suggested that it is helpful to assess individual foot alignment to ensure adequate insole treatment for patients with medial knee osteoarthritis and that decreased rear foot eversion during the early stance phase is significantly involved in the reduction of 1st KAM when wearing LWIs with normal feet.

Objectives The purpose of this study was to investigate between movement patterns of trunk extension from full unloaded flexion and lifting techniques, which could provide valuable information to physical therapists, doctors of chiropractic, and other manual therapists. Methods A within-participant study design was used. Whole-body kinematic and kinetic data during lifting and full trunk flexion were collected from 16 healthy male participants using a 3-dimensional motion analysis system (Vicon Motion Systems). To evaluate the relationships of joint movement between lifting and full trunk flexion, Pearson correlation coefficients were calculated. Results There was no significant correlation between the amount of change in the lumbar extension angle during the first half of the lifting trials and lumbar movement during unloaded trunk flexion and extension. However, the amount of change in the lumbar extension angle during lifting was significantly negatively correlated with hip movement during unloaded trunk flexion and extension (P Conclusions The findings that the maximum hip flexion angle during full trunk flexion had a greater influence on kinematics of lumbar–hip complex during lifting provides new insight into human movement during lifting. All study participants were healthy men; thus, findings are limited to this group.

Lateral wedge insoles (LWIs) reduce the peak external knee adduction moment (KAM). However, the efficacy of LWIs is limited in certain individuals for whom they fail to decrease KAM. Possible explanations for a lack of desired LWI response are variations in foot alignments. The purpose of this study was to evaluate whether the immediate biomechanical effects of LWIs depend on individual foot alignments during gait. Fifteen healthy adults participated in this study. Their feet were categorized as normal, pronated, and supinated using the foot posture index. All subjects were subsequently requested to perform a normal gait under barefoot and LWI conditions. A three-dimensional motion analysis system was used to record the kinematic and kinetic data, included peak KAM, KAM impulse (KAAI), center of pressure displacement, and knee-ground reaction force lever arm (KLA). Furthermore, lower limb frontal plane kinematic parameters at the rear foot, ankle, knee, and hip were evaluated. Among all feet, there was no significant difference in the peak KAM and KAAI between the conditions. In contrast, the peak KAM was significantly reduced under the LWI condition relative to the barefoot condition in the normal foot group. Reductions in the peak KAM were correlated with a more lateral center of pressure and reduced KLA. In addition, a reduced KLA was correlated with decreased hip adduction. LWIs significantly reduced the peak KAM in normal feet, indicating that biomechanical effects of LWIs vary between individual foot alignments. Our findings suggest that it is helpful to assess individual foot alignment to ensure adequate insole treatment for patients with knee osteoarthritis.

〔目的〕本研究は，歩行分析における最適な加速度計装着部位を同定することを目的とした．〔対象〕健常成人男性15名とした．〔方法〕快適歩行にて鉛直・前後・左右成分の体幹加速度と床反力を同時に測定した．加速度計は第10胸椎（Th10），第3腰椎（L3），第2仙椎（S2）に装着した．左右下肢合成床反力と加速度より算出した床反力推定値との一致度の指標として，3つの装着部位での相互相関係数（CC）により比較した．〔結果〕鉛直・前後成分のCCはL3にて最も高く，左右成分のCCはいずれも低かった．〔結語〕歩行分析では加速度計をL3に装着することにより，鉛直・前後成分では実際の床反力に近似した波形パターンを得られることが示された．

〔目的〕本研究は，椅子からの立ち上がり動作（sit-to-stand，以下STS）における体幹運動への加齢及び動作スピードの影響を調べることを目的として行った。〔対象〕被験者は若年者19名と高齢者21名であった。〔方法〕快適および最大スピード条件でのSTSを三次元動作解析装置と床反力計を用いて計測した。身体重心（center of mass，以下COM）速度，COM座標-踵間距離，体幹角度と股関節角度の最大値，下肢関節モーメントを若年群と高齢群とで比較した。〔結果〕最大スピード条件での離臀時のCOM速度とCOM-踵間距離，体幹の屈曲最大値，最大スピード条件での股関節モーメントにおいて，高齢群は若年群より有意に小さかった。〔結語〕STSでは加齢により体幹屈伸運動は小さくなり，体幹運動がSTSにおける運動量の産生と制御に関与していることが示唆された。

〔目的〕本研究は，体幹および下肢の運動連鎖の観点から変形性膝関節症（膝OA）の発症・進行に関与する機能障害を明らかにするために，膝OA患者における椅子からの立ち上がり動作（STS）の運動学的分析を行った。〔対象〕膝OAと診断された女性17名の膝OA群と膝関節痛を有さない女性16名の対照群とした。〔方法〕課題動作は座面高が下腿長の高さの椅子からのSTSとした。3次元動作解析システムKinema Tracer（キッセイコムテック社製）を用いて各体節および下肢関節の角度を求めた。〔結果〕身体重心（COM）前方移動期における各体節の角速度の平均値には有意差が認められなかったが，COM上方移動期における膝関節伸展，足関節底屈の角速度平均値は対照群に比し，膝OA群が有意に小さかった。〔結語〕膝OA群のSTSにおいて，臀部離床後に体幹前傾で得られた速度を下肢に伝えることができず，適切な膝関節の関節運動および肢節のアライメント保持が難しくなっていることが示唆された。

〔目的〕本研究は，膝OAの歩き始めに生じる膝関節のメカニカルストレスを解明することを目的とし，歩き始めを捉えるうえで，外部膝関節内反モーメントが重要な指標であることを明らかにすることである。〔対象〕対象者は変形性膝関節症の女性10名と健常中年者の女性9名であった。〔方法〕課題動作は歩き始めと定常歩行とし，各動作は3次元動作解析装置と床反力計を用いて立脚肢の外部膝関節内反モーメントを算出した。そして，変形性膝関節症者と健常者における歩き始めと定常歩行時の立脚肢の外部膝関節内反モーメントの差を比較することとした。〔結果〕外部膝関節内反モーメントは二元配置分散分析の結果，群の主効果のみに有意差が認められ，課題動作の主効果には有意差は認められなかった。〔結語〕膝OAは健常者より外部膝関節内反モーメントが増大しており，歩き始めと定常歩行とでは同程度の外部膝関節内反モーメントの大きさであった。膝OAの歩き始めを捉えるうえで，外部膝関節内反モーメントは膝関節のメカニカルストレスを反映する重要な指標であると考えられる。

For some people with leg disorders, the alternative to becoming bedridden is sitting in a wheelchair for long periods of time. The purpose of this study was to investigate the relation between the backrest of a chair and the position of the pelvis on the maximum pressure at the ischium and the estimated shear force encountered while sitting in a chair.Ten healthy males aged 22.4 +/- 2.3 years without pathologies in the leg and/or trunk participated in this study. The subjects were instructed to sit in a chair and the pressure and shear forces were measured under three sitting conditions: In the standard position, a 5 cm forward position and a 10 cm forward position. The effects of the positions of the pelvis on the maximum pressure at the ischium were measured by an instrument for measuring pressure distribution and the shear forces were estimated using an experimental model proposed by us.Comparisons were made among the three sitting positions; the range of displacement of the maximum pressure point was not significant. The estimated shear force on the seat was 15.5 +/- 12.4 N in the standard position, 34.4 +/- 8.5 N in the 5-cm forward position, and 53.2 +/- 16.7 N in the 10 cm forward position. There were significant differences among the three values (p0.01).Displacing the pelvis forward and leaning against the backrest tends to increase the shear force and raise the risk of decubitus ulcers.

〔目的〕本研究は，背もたれの高さが安楽座位時の臀部ずれ力に及ぼす影響を検討することを目的として行った。〔対象〕対象は，健常成人男性13名（年齢：21.3±2.4歳）であった。〔方法〕床反力計を用いて座位時に臀部にかかるずれ力を測定した。形態学的な影響を考慮し，測定したずれ力を各対象者の体重で除した値を採用した。測定肢位は，床反力計上に殿部，床反力計外に下肢を置いた長座位とした。背もたれの代わりとして床反力計上に接しないように横方向に設置した平行棒にもたれさせた。実験は，背もたれ（平行棒）の高さを調節した2条件（床面から46 cmと49 cm）で行った。〔結果〕結果を背もたれ高別にみると，46 cmでは0.83±0.27 [N/kg]，49 cmでは0.71±0.25 [N/kg]であり，2条件間に有意差が認められた（p=0.014）。〔結語〕本研究結果から，背もたれの高さが高い方が臀部ずれ力は小さくなることが示された。

This study was done to investigate whether cushion thickness affected elderly people during the sit-to-stand motion (STS motion). Fourteen elderly subjects aged 79 or over were recruited from the out-patients at a rehabilitation clinic. Their STS motions were evaluated and analyzed using a digital video camera and analyzing software. As the thickness of the cushion increased, it was difficult to identify the pelvic movement during STS motion, although the trunk was inclined more anteriorily and the load to the knee extensors was greater. Furthermore, three of the fourteen subjects had difficulties performing STS motion when the pelvis was contoured by a thick cushion. These results suggests that if an older person has a knee extensor strength below an appropriate level and/or the cushion thickness is enough large to contour the subject's pelvis, the risk of falling during STS motion is higher.

[Purpose] The purpose of this study was to clarify the difference in sit-to-walk (STW) motion between young adults (YG) and an elderly persons (EG). [Subjects and Methods] Twenty-seven subjects (9 in YG and 18 in EG) were instructed to perform STW and to walk 3 m at a comfortable speed and at maximal speed. Data were obtained using a 3D motion capture system for kinematic data, and two force plates for kinetic data. [Results] The time required for STW was similar for both groups at both comfortable and maximal speeds, but the forward velocity of the center of gravity of the whole body (COG-WB) was higher for YG, and upward COG-WB at the time of the first heel contact was faster for YG. Ground reaction force analyses showed many differences between the groups. For YG, COG-WB moved forward and the first swing side was longer than for EG. [Conclusion] Forward and lateral COG-WB movements before the toe-off generate a progressive force. We suggest that YG subjects may have sufficient muscle power in their lower extremity to bear the progressive force, or that EG subjects may have learned anticipatory postural control which has shorter forward movement due to aging and declining physical function.

〔目的〕本研究は足踏み動作時の外部膝関節内反モーメントを内側型変形性膝関節症(膝OA)群と健常群で比較した。さらに膝OA群の外部膝関節内反モーメントと疼痛，身体機能との関係を明らかにすることを目的とした。〔対象〕被験者は内側型変形性膝関節症と診断された女性30名（膝OA群），健常女性18名（対照群）であった。〔方法〕動作課題とした足踏み動作を，3次元動作解析装置と床反力計を用いて計測した。疼痛と身体機能に関してはWOMACを用いて評価した。〔結果〕外部股関節内転モーメント，外部膝関節内反モーメントは膝OA群と対照群で有意な差はなかった。外部膝関節内反モーメント比率は，片脚起立期では膝OA群は対照群より有意に大きかった。片脚起立期の外部膝関節内反モーメントは，疼痛に影響を与える要因である可能性が示唆された。疼痛は身体機能に影響を与える要因であった。〔結論〕膝OAの理学療法では外部膝関節内反モーメントを減少させる治療戦略が重要であることが示唆された。

It is important to clarify the normal biomechanical characteristics of the sit-to-walk (STW) series of motions clear for healthy elderly people. Clarifying the biomechanical characteristics of normal motions is necessary to be able to develop an appropriate intervention to improve physical functions. Eight healthy elderly people performed STW motion at the two patterns of speeds: a fast condition and a slow condition. Kinematic and kinetic data were obtained. Maximal anterior ground reaction force was significantly larger in the fast speed condition. In the fast speed condition, the subjects initiated gait with the hip and knee more flexed. And the center of pressure (COP) moved forward gradually constraining the forward movement of the center of the gravity (COG). In the slow speed condition, the COG movement was slower, so the COP moved backward in order to induce a forward COG movement. In the fast motion it is important to accelerate and control the forward movement of the body.

The purpose of this study was to investigate the effects of cognitive and visuomotor tasks on gait control in terms of the magnitude and temporal structure of the variability in stride time and lower-limb kinematics measured using inertial sensors. Fourteen healthy young subjects walked on a treadmill for 15min at a self-selected gait speed in the three conditions: normal walking without a concurrent task; walking while performing a cognitive task; and walking while performing a visuomotor task. The time series data of stride time and peak shank angular velocity were generated from acceleration and angular velocity data recorded from both shanks. The mean, coefficient of variation, and fractal scaling exponent α of the time series of these variables and the standard deviation of shank angular velocity over the entire stride cycle were calculated. The cognitive task had an effect on long-range correlations in stride time but not on lower-limb kinematics. The temporal structure of variability in stride time became more random in the cognitive task. The visuomotor task had an effect on lower-limb kinematics. Subjects controlled their swing limb with greater variability and had a more complex adaptive lower-limb movement pattern in the visuomotor task. The effects of the dual tasks on gait control were different for stride time and lower-limb kinematics. These findings suggest that the temporal structure of variability and lower-limb kinematics are useful parameters to detect a change in gait pattern and provide further insight into gait control.

There are few papers about the biomechanical characteristics of sit-to-walk motion, although many researchers have written about the biomechanical analyses of sit-to-stand motion or gait initiation. The purpose of this study was to compare the biomechanics of sit-to-walk motion with sit-to-stand motion or gait initiation. The subjects were 9 healthy young men, who were instructed to perform sit-to-walk motion, sit-to-stand motion, and gait initiation. Kinematics and kinetics data were obtained using a 3D motion capture system and two force plates. The coordinates of reflective markers (RM)s, the coordinates and velocity of the center of gravity of the whole body (COG), the coordinates and velocity of the center of gravity of the head, arm and trunk (COG of HAT), each joint angle, and the ground reaction forces (GRFs) were calculated from the data. We found that the maximal horizontal velocity of HAT occurred later in a sit-to-walk motion than in sit-to-stand (p

Our previous single-pulse transcranial magnetic stimulation (TMS) study revealed that excitability in the motor cortex can be altered by conscious control of walking relative to less conscious normal walking. However, substantial elements and underlying mechanisms for inducing walking-related cortical plasticity are still unknown. Hence, in this study we aimed to examine the characteristics of electromyographic (EMG) recordings obtained during different walking conditions, namely, symmetrical walking (SW), asymmetrical walking 1 (AW1), and asymmetrical walking 2 (AW2), with left to right stance duration ratios of 1:1, 1:2, and 2:1, respectively. Furthermore, we investigated the influence of three types of walking control on subsequent changes in the intracortical neural circuits. Prior to each type of 7-min walking task, EMG analyses of the left tibialis anterior (TA) and soleus (SOL) muscles during walking were performed following approximately 3 min of preparative walking. Paired-pulse TMS was used to measure short-interval intracortical inhibition (SICI) and intracortical facilitation (ICF) in the left TA and SOL at baseline, immediately after the 7-min walking task, and 30 min post-task. EMG activity in the TA was significantly increased during AW1 and AW2 compared to during SW, whereas a significant difference in EMG activity of the SOL was observed only between AW1 and AW2. As for intracortical excitability, there was a significant alteration in SICI in the TA between SW and AW1, but not between SW and AW2. For the same amount of walking exercise, we found that the different methods used to control walking patterns induced different excitability changes in SICI. Our research shows that activation patterns associated with controlled leg muscles can alter post-exercise excitability in intracortical circuits. Therefore, how leg muscles are activated in a clinical setting could influence the outcome of walking in patients with stroke.

The sit-to-stand motion (STS) is a frequently executed activity that is affected by weakness in the quadriceps femoris muscle and knee joint pain in patients with knee osteoarthritis (OA). We investigated whether patients with knee OA can efficiently perform STS through mechanical energy transfer assessments. Participants were 20 women with knee OA and 17 age-matched asymptomatic controls. The center of mass (COM), segment angles, joint moments, and powers during STS were measured. The negative mechanical work in the proximal portion of the shank, negative mean powers in the distal portion of the pelvis and proximal portion of the shank, and the positive mean power in the proximal and distal portions of the thigh were significantly lower in the knee OA group than in the control group. Patients with knee OA primarily performed thoracic forward lean movement, shifting their COM closer to the base of support provided by the feet alone, in an attempt to achieve stability at and after buttocks-off. However, control ability, which generates and absorbs kinetic energy quickly, was not enhanced in these patients, and their motion was unable to increase absorption of the mechanical energy in hip extensors and reduce the load on knee extensors. Furthermore, STS in patients with knee OA had reduced energy absorption in the knee extensors from the shank forward lean movement after buttocks-off, had reduced knee extensor efficiency, and made greater use of physiological energy. These findings suggest that, from the standpoint of mechanical energy transfer, patients with knee OA do not perform STS efficiently.

The purpose of this study was to examine the moisture permeability properties of materials used for total surface bearing (TSB) socket with a silicone liner, a combination of Silicone Suction Socket or Icelandic Roll-On Silicone Socket (ICEROSS) and an acrylic plastic sheet (Degaplast), patella-tendon bearing (PTB) socket, a combination of Pe-Lite and Degaplast, and wooden socket made of poplar. Moisture permeability of the socket materials was measured as the diminution of water in a container after 12 hours in a climatic chamber. Eight containers with their open, top side were uncovered (no material) or sealed with one of the socket materials; the experiment was repeated four times. One-way analysis of variance followed by Bonferroni's test was applied to examine the differences in moisture permeability. Moisture permeability levels were as follows: no material, 85.9 +/- 1.3 g; poplar, 4.3 +/- 0.4 g; Silicone Suction Socket, 1.1 +/- 0.2 g; ICEROSS, 1.0 +/- 0.2 g; Pe-Lite, 0.8 +/- 0.1 g; 3S + Degaplast, 0.8 +/- 0.1 g; ICEROSS + Degaplast, 0.8 +/- 0.2 g; and Pe-Lite + Degaplast, 0.8 +/- 0.1 g. There were significant differences between the uncovered container and the others, and between poplar and the others (P < 0.05). We concluded that the TSB socket with a silicone liner is not superior to the PTB socket with regard to moisture permeability, and that it is necessary to develop a new prosthetic socket that allows heat release and drainage of sweat.

This paper presents a phase plane analysis of the motion of the CG (center of gravity) of the human body during the sit-to-stand movement. The time history of the joint angles of the ankle, knee and hip were measured by optical position sensors during the motion. The experimental data when combined with human morphology, such as mass and length of each part of the body, allows the tracking of the CG position. Experiments were done on four healthy young men. Analysis shows that the motion of the CG can be clearly recognized as three motion modes:an acceleration mode and two convergent modes to an origin of the phase plane and to an equilibrium state of the standing state. Furthermore, it is suggested that the elderly usually use a spiral trajectory to the equilibrium state in the sit-to-stand movement, which is observed when a system is close to an unstable state.