Investigation of the limiting factors of shoulder joint complex motion in college baseball players: motion analysis of the humeral head and rotator cuff using ultrasound.

Background: The relationship between lower mobility, as measured by the elbow forward translation motion (T-motion) test, a new indicator of shoulder joint complex movement that measures elbow position when both dorsal hands are placed on the iliac crest while in a sitting position, and the parameters calculated by ultrasonography is unknown. The purpose of this study was to investigate the limiting factors of T-motion through motion analysis of the humeral head and rotator cuff muscles using ultrasonography in college baseball players. Methods: Thirteen college baseball players participated in this cross-sectional study. The shortest distance from the posterior edge of the glenoid to the humeral head was measured in the static and T-motion positions, and the difference was calculated as the humeral head translation. The velocity of the infraspinatus was calculated during shoulder internal/external rotation using the particle image velocimetry method. These parameters were compared between the throwing and nonthrowing sides to examine the limiting factors of T-motion. Results: This study indicated moderate-to-good reliability for the parameters calculated by ultrasonography. The mean anterior translation distance was significantly greater on the throwing side than on the nonthrowing side (r = 0.56, P = .015). The mean velocity of infraspinatus during internal rotation was significantly lower on the throwing side than on the nonthrowing side (r = 0.51, P = .028). Conclusion: Increased anterior translation of the humeral head and decreased the velocity of infraspinatus are likely correlated with reduced T-motion mobility in college baseball players. These methods showed potential for physical therapy assessment and intervention to prevent shoulder dysfunction.

Longitudinal changes in vertical stride regularity, hip flexion, and knee flexion contribute to the alteration in gait speed during hospitalization for stroke.

Changes in stride regularity and joint motion during gait appear to be related to improved gait speed in hospitalized patients with stroke. We aimed to clarify the changes in stride regularity and joint motion during gait through longitudinal observations. Furthermore, we aimed to clarify the relationship between changes in gait speed, stride regularity, and joint motion during gait. Seventeen inpatients with stroke were assessed for physical and gait functions at baseline, when they reached functional ambulation category 3, and before discharge. Physical function was assessed using the Fugl-Meyer assessment for the lower extremities and the Berg Balance Scale. Gait function was assessed on the basis of gait speed, joint motion, stride regularity, and step symmetry using inertial sensors. The correlations between the ratio of change in gait speed and each indicator from baseline to discharge were analyzed. Both physical and gait functions improved significantly during the hospital stay. The ratio of change in gait speed was significantly and positively correlated with the ratio of change in vertical stride regularity (r = 0.662), vertical step symmetry (rs = 0.627), hip flexion (rs = 0.652), knee flexion (affected side) (r = 0.611), and ankle plantarflexion (unaffected side) (rs = 0.547). Vertical stride regularity, hip flexion, and knee flexion (affected side) were significant factors in determining the ratio of changes in gait speed. Our results suggest that stride regularity, hip flexion, and knee flexion could explain the entire gait cycle and that of the affected side. These parameters can be used as indices to improve gait speed.

Effects of External Abdominal Pressure Support on Dynamic Balance: A Randomized Crossover Study.

Abdominal pressure is vital in protecting the lumbar spine and controlling postural balance. Dynamic balance is associated with movement stability, adaptation to load, and reduced injury risk. Although trunk stability has been examined using belts and braces, the effects of external abdominal pressure support (APS) on balance control remain unknown. In this study, we aimed to determine the effects of external APS on dynamic balance. Overall, 31 young adults participated in this randomized crossover study. External APS was provided using a device that could be pressurized and decompressed by inflating a cuff belt wrapped around the trunk. The modified Star Excursion Balance Test was performed under external APS and non-APS conditions. The maximum anterior, posterolateral, and posteromedial values normalized to the spinal malleolar distance and their respective composite values were compared between the two conditions with and without APS. Posterolateral, posteromedial, and composite values were significantly higher in the APS condition than in the non-APS condition (p < 0.001). The external APS was effective in immediately improving dynamic balance. Furthermore, APS was effective in dynamic balance control as it improved stability during anterior trunk tilt, which displaces the center of gravity forward.

Effect of Self-Myofascial Release of the Lower Back on Myofascial Gliding, Lumbar Flexibility, and Abdominal Trunk Muscle Strength: A Crossover Study.

Roller massage has been recognized as an effective intervention for managing various conditions. However, data on the effects of roller massage on the dynamic mechanisms of the myofascial and soft tissues of the lower back are limited. This study aimed to examine the effect of the self-myofascial release of the lower back on myofascial gliding, lumbar flexibility, and abdominal trunk muscle strength using a roller massager. This crossover study included 24 college athletes who underwent three interventions-roller massage, static stretching, and control (rest). Before and after the intervention, lumbar and fascial gliding were evaluated using ultrasonography. Long-seat anteflexion (lumbar flexibility) and abdominal trunk muscle strength were assessed. The movement velocities of the subcutaneous tissue and the multifidus muscle over time were calculated using echo video analysis software, and gliding was estimated using the cross-correlation coefficient between the velocities. Gliding, lumbar flexibility, and abdominal trunk muscle strength showed significant intervention-by-time interactions. Roller massage significantly improved gliding, lumbar flexibility, and abdominal trunk muscle strength. The self-myofascial release of the lower back using a roller massager improved the lumbar/fascia gliding, lumbar flexibility, and abdominal trunk muscle strength compared to static stretching.

Clinical significance of the elbow forward translation motion in patients with rotator cuff tears.

Background: Range of motion (ROM) limitations can result in restricted activities of daily living (ADL) due to shoulder dysfunction, suggesting that evaluation of complex shoulder movements is necessary in clinical practice. Here, we present a new physical examination, the elbow forward translation motion (T-motion) test for measuring the position of the elbow when both dorsal hands are placed on the iliac crest in a sitting position and the elbow is moving forward. We examined the relationships between T-motion and shoulder function to identify the significance of this test in clinical practice. Methods: Preoperative patients with rotator cuff tears (RCTs) were eligible for this cross-sectional study. Active ROM and Japanese Orthopaedic Association (JOA) scores were measured as shoulder function. The degree of internal rotation was based on the Constant-Murley Score. We defined a positive T-motion test result as an elbow positioned posterior to the body on the sagittal plane. Group comparisons and logistic regression analyses were conducted to investigate the relationships between the availability of T-motion and shoulder function. Results: Sixty-six patients with RCTs participated in this cross-sectional study. The values of the JOA total score (P < .001), subscale of function and ADL (P < .001), active range of forward flexion (P = .006), abduction (P < .001), and external rotation (P < .001) were lower in the positive group than in the negative group. In addition, a significant correlation was found between the availability of T-motion and internal rotation by the chi-square test (P < .001). Logistic regression analyses showed that internal rotation (odds ratio 2.69; 95% confidence interval 1.47-4.93; P < .01) and external rotation (odds ratio 1.07; 95% confidence interval 1.00-1.14; P = .04) were related to the availability of T-motion after adjustments for covariates, and the cutoff points were 4 points for internal rotation (area under the curve 0.833, sensitivity 53.3%, specificity 86.1%, P < .001) and 35° for external rotation (area under the curve 0.788, sensitivity 60.0%, specificity 88.9%, P < .001). Conclusion: The positive T-motion group exhibited low shoulder function, including a less active ROM and JOA shoulder score. T-motion, which is a quick and simple movement, may be a new indicator for a complex shoulder motion and contribute to evaluating the decreased ADL and limited shoulder motion in patients with RCTs.

Immediate Effects of Real-Time Feedback During Overground Gait Performed Using Inertial Measurement Units on Gait Parameters in Healthy Young Participants: A Cross-Sectional Study.

This cross-sectional study examined the immediate effects of four types of real-time feedback during overground gait performed using inertial measurement units on gait kinematics in healthy young participants. Twelve healthy young participants (mean age: 27.1 years) performed 60-s gait trials with each of the following real-time feedback: walking spontaneously (no feedback trial); increasing the ankle plantar-flexion angle during the late stance (ankle trial); increasing the leg extension angle, defined the location of the ankle joint relative to the hip joint in the sagittal plane, during late stance (leg trial); and increasing the knee flexion angle during the swing phase (knee trial). Tilt angles and accelerations of the pelvis and lower limb segments were measured using seven inertial measurement units pre- and postfeedback trials. The differences in gait parameters pre- and postfeedback according to the types of feedback were compared using one-factor repeated-measures analysis of variance, Friedman test, and post hoc test. Real-time feedback in the ankle trial increased gait speed, step length, and ankle plantar-flexion angle compared to the no feedback trial (p ≤ .001). Meanwhile, real-time feedback in the leg trial increased step length and hip extension angle compared to the no feedback trial (p ≤ .001) and showed a tendency to increase gait speed and leg extension angle. Real-time feedback using inertial measurement units increased gait speed immediately with specific changes in gait kinematics in healthy participants. This study might imply the possibility of clinical application for overground gait training, and further studies are needed to clarify the effectiveness for older people.

Sex differences in age-related differences in joint motion during gait in community-dwelling middle-age and older individuals.

BACKGROUND: Walking is the most important mode of human locomotion; however, the ability to walk often decreases with age. Age-related differences in lower-limb kinematics during gait may differ depending on sex. However, the question of the compounded effects of age and sex on gait kinematics remains unsolved. RESEARCH QUESTION: The present study aimed to clarify the interaction between age and sex in differences in gait kinematics of community-dwelling middle-age and older individuals. METHODS: This study included 836 community-dwelling middle-age and older adults (61.8 % female). Joint motion during comfortable gait was measured using magnetic and inertial measurement units. Hip, knee, and ankle joint angles were calculated in the sagittal plane. Participants were divided into four groups according to age: 50-59, 60-69, 70-79, and 80-89 years. The interaction of sex and age on spatiotemporal gait parameters and the peak value of joint angles was analyzed using two-way analysis of variance (ANOVA) and Tukey's post hoc test. RESULTS: Gait speed (F = 43.92, P < 0.001), step length (F = 73.00, P < 0.001), hip extension (F = 12.89, P = 0.002), knee flexion (F = 39.99, P < 0.001), and ankle plantar flexion (F = 27.43, P < 0.001) significantly decreased with age. Significant differences according to sex were observed in all parameters except gait speed. Significant age and sex interaction effects were observed for knee flexion (F = 4.97, P = 0.002) and ankle dorsiflexion (F = 4.04, P = 0.007). SIGNIFICANCE: A significant interaction effect of age and sex was observed for peak angle of knee flexion and ankle dorsiflexion during gait. In particular, the knee flexion angle among females during gait began to decrease from 60 years of age, and the decreasing trend was faster and more prominent than that among males.

Effects of Knee Flexion Angles on the Joint Force and Muscle Force during Bridging Exercise: A Musculoskeletal Model Simulation.

Bridging exercise is commonly used to increase the strength of the hip extensor and trunk muscles in physical therapy practice. However, the effect of lower limb positioning on the joint and muscle forces during the bridging exercise has not been analyzed. The purpose of this study was to use a musculoskeletal model simulation to examine joint and muscle forces during bridging at three different knee joint angle positions. Fifteen healthy young males (average age: 23.5 ± 2.2 years) participated in this study. Muscle and joint forces of the lumbar spine and hip joint during the bridging exercise were estimated at knee flexion angles of 60°, 90°, and 120° utilizing motion capture data. The lumbar joint force and erector spinae muscle force decreased significantly as the angle of the knee joint increased. The resultant joint forces were 200.0 ± 23.2% of body weight (%BW), 174.6 ± 18.6% BW, and 150.5 ± 15.8% BW at 60°, 90°, and 120° knee flexion angles, respectively. On the other hand, the hip joint force, muscle force of the gluteus maxims, and adductor magnus tended to increase as the angle of the knee joint increased. The resultant joint forces were 274.4 ± 63.7% BW, 303.9 ± 85.8% BW, and 341.1 ± 85.7% BW at a knee flexion angle of 60°, 90°, and 120°, respectively. The muscle force of the biceps femoris decreased significantly with increased knee flexion during the bridging exercise. In conclusion, the knee flexion position during bridging exercise has different effects on the joint and muscle forces around the hip joint and lumbar spine. These findings would help clinicians prescribe an effective bridging exercise that includes optimal lower limb positioning for patients who require training of back and hip extensor muscles.

Effect of Leg Extension Angle on Knee Flexion Angle during Swing Phase in Post-Stroke Gait.

Background and Objectives: Leg extension angle is important for increasing the propulsion force during gait and is a meaningful indicator for evaluating gait quality in stroke patients. Although leg extension angle during late stance might potentially also affect lower limb kinematics during the swing phase, the relationship between these two remains unclear. This study aimed to investigate the relationship between leg extension angle and knee flexion angle during pre-swing and swing phase in post-stroke gait. Materials and Methods: Twenty-nine stroke patients walked along a 16 m walkway at a self-selected speed. Tilt angles and acceleration of pelvis and paretic lower limb segments were measured using inertial measurement units. Leg extension angle, consisting of a line connecting the hip joint with the ankle joint, hip and knee angles, and increments of velocity during pre-swing and swing phase were calculated. Correlation analysis was conducted to examine the relationships between these parameters. Partial correlation analysis adjusted by the Fugl-Meyer assessment-lower limb (FMA-LL) was also performed. Results: On the paretic side, leg extension angle was positively correlated with knee flexion angle during the swing phase (r = 0.721, p < 0.001) and knee flexion angle and increments of velocity during the pre-swing phase (r = 0.740-0.846, p < 0.001). Partial correlation analysis adjusted by the FMA-LL showed significant correlation between leg extension angle and knee flexion angle during the swing phase (r = 0.602, p = 0.001) and knee flexion angle and increments of velocity during the pre-swing phase (r = 0.655-0.886, p < 0.001). Conclusions: Leg extension angle affected kinematics during the swing phase in post-stroke gait regardless of the severity of paralysis, and was similar during the pre-swing phase. These results would guide the development of effective gait training programs that enable a safe and efficient gait for stroke patients.

The Relationship between Leg Extension Angle at Late Stance and Knee Flexion Angle at Swing Phase during Gait in Community-Dwelling Older Adults.

This study aimed to clarify the relationship between leg extension angle and knee flexion angle during gait in older adults. The subjects of this cross-sectional study were 588 community-dwelling older adults (74.6 ± 6.1 y). Segment angles and acceleration were measured using five inertial measurement units during comfortable gait, and bilateral knee and hip joint angles, and leg extension angle, reflecting whole lower limb extension at late stance, were calculated. Propulsion force was estimated using the increase in velocity calculated from anterior acceleration of the sacrum during late stance. Correlation analysis showed that leg extension angle was associated with knee flexion angle at swing phase and hip extension angle and increase in velocity at late stance (r = 0.444-508, p < 0.001). Multiple regression analysis showed that knee flexion angle at mid-swing was more affected by leg extension angle (ß = 0.296, p < 0.001) than by gait speed (ß = 0.219, p < 0.001) and maximum hip extension angle (ß = -0.150, p < 0.001). These findings indicate that leg extension angle may be a meaningful parameter for improving gait function in older adults due to the association with knee kinematics during swing as well as propulsion force at late stance.

Relationships between Gait Regularity and Cognitive Function, including Cognitive Domains and Mild Cognitive Impairment, in Community-Dwelling Older People.

The aim of this cross-sectional study was to examine the correlations between gait regularity, cognitive functions including cognitive domains, and the mild cognitive impairment (MCI) in community-dwelling older people. This study included 463 older adults (63.4% women, mean age: 74.1), and their step and stride regularity along the three-axis components was estimated from trunk acceleration, which was measured by inertial measurement units during a comfortable gait. Four aspects of cognitive function were assessed using a tablet computer: attention, executive function, processing speed, and memory, and participants were classified into those with or without MCI. The vertical component of stride and step regularity was associated with attention and executive function (r = -0.176--0.109, p ≤ 0.019), and processing speed (r = 0.152, p < 0.001), after it was adjusted for age and gait speed. The low vertical component of step regularity was related to the MCI after it was adjusted for covariates (OR 0.019; p = 0.016). The results revealed that cognitive function could affect gait regularity, and the vertical component of gait regularity, as measured by a wearable sensor, could play an important role in investigating cognitive decline in older people.

A self-oblique exercise that activates the coordinated activity of abdominal and hip muscles-A pilot study.

The importance of an interaction between trunk stability muscles and hip muscle function has been suggested. However, reported exercises rarely act on the trunk and hip muscles simultaneously. Here, we devised an abdominal oblique and hip muscle exercise, the Self-oblique exercise (SOE). We examined whether SOE activated abdominal and hip muscles in the supine and half-kneeling positions, compared with abdominal crunch (AC) and plank exercises; and whether participants could modulate the exercise load. Participants were 20 healthy males with some sports experience such as football and baseball on average 10.5 ± 4.0 years. Participants applied self-pressure to their right thighs using the contralateral upper limb with 40% or 70% of the maximum force in Supine SOE and Half- kneeling SOE. The following abdominal and hip muscles were measured using surface electromyography: bilateral external obliques (EO), bilateral internal obliques (IO), right rectus abdominis, right gluteus medius (GMed), and right adductor longus (ADD). All evaluated muscle groups showed significant differences between exercises (p < 0.001). Supine SOE-70% showed 80.4% maximal voluntary contraction (MVC) for left EO (p < 0.017), 61.4% MVC for right IO (p < 0.027), 24.3% MVC for GMed (p < 0.002), and 42.4% MVC for ADD (p < 0.004); these were significantly greatest among all exercises. Muscle activity during Supine SOE-70% was greater than that during Supine SOE-40%. Similarly, Half-kneeling SOE-40% promoted abdominal and hip muscle exertion, and showed more significant activity in GMed (p < 0.006) and ADD (p < 0.001) than AC and plank. SOE could activate abdominal and hip muscles depends on the pressure applied by upper limb. Also, SOE allows participants to modulate the exercise load in a self-controlled step by step manner. Modulation of the exercise load is difficult in AC or plank compared to SOE, and AC or plank cannot obtain simultaneous oblique and hip muscle activity. SOE could be practiced anywhere, in various positions, without any tools.

Validity of two-dimensional analysis using a tablet computer for estimation of foot arch height during walking.

[Purpose] To examine the validity of two-dimensional analysis using a tablet computer for the estimation of arch height during walking by comparing it with a motion capture system and static foot alignment screenings. [Participants and Methods] Fourteen healthy males and 15 healthy females participated in this study. The arch height of the right foot while walking was simultaneously measured using a tablet computer and motion capture system. Dynamic foot alignment, including arch height, at the mid-stance and pre-swing phases was calculated from the kinematic data measured using the tablet computer and motion analysis system. Static foot alignment was also assessed by screening tests including arch height index and foot posture index. [Results] Arch height measured using a tablet computer showed a significant high correlation with that measured using the motion capture system at the mid-stance and pre-swing phases. Arch height index showed a significant moderate correlation with arch height measured using the motion capture system at the mid-stance phase. Meanwhile, foot posture index showed no relationship with arch height measured by the motion capture system. [Conclusion] These results demonstrate the high validity of dynamic foot analysis using a tablet computer for the estimation of arch height during walking. Such gait analysis can be effective for assessing dynamic foot alignment in clinical practice.

Contribution of hip and knee muscles to lateral knee stability during gait.

[Purpose] Lateral knee instability is frequently observed in patients with knee injury or risk factors associated with knee osteoarthritis. Physical exercises can strengthen muscles that stabilize the knee joint. The purpose of this study was to define the contribution of the knee and hip muscles to lateral knee stability by comparing the muscle forces, as assessed by musculoskeletal simulation using one or two degrees-of-freedom (1-DOF and 2-DOF) knee models. [Participants and Methods] We evaluated the normal gait of 15 healthy subjects. We conducted a three-dimensional gait analysis using a motion analysis system and a force plate. We considered a muscle as a lateral knee stabilizer when the calculated muscle force was greater with the 2-DOF model than with the 1-DOF model. [Results] During early and late stance, the muscle forces of the lateral knee and hip joint increased in the 2-DOF model as opposed to in the 1-DOF model. In contrast, the forces of the medial knee muscles decreased. Furthermore, hip muscle forces increased during the late stance. [Conclusion] Our results show that the lateral knee and hip muscles contribute to lateral knee stability. Thus, exercises to strengthen these muscles could improve lateral knee stability.

Accelerometer Measurement of Trunk Lateral Fluctuation During Walking Following Total Knee Arthroplasty in Patients With Osteoarthritis.

This study aimed to clarify the effect of total knee arthroplasty (TKA) on trunk fluctuation and regularity of gait in patients with knee osteoarthritis by an accelerometer. The participants included 18 patients with knee osteoarthritis undergoing TKA. The gait at a comfortable velocity was assessed pre- and post-TKA by a triaxial accelerometer attached to the neck and lumbar regions. Measurement post-TKA was performed 4 weeks after surgery. Trunk fluctuation was estimated by the root mean square (RMS) of acceleration and RMS ratio (the ratio of RMS in each direction to the total RMS). Regularity of gait was estimated using the autocorrelation function. The results showed that TKA significantly decreased the RMS ratio in mediolateral acceleration of the neck and lumbar regions and reduced gait regularity. TKA appears to reduce compensatory trunk motion through the improvement of knee function. An assessment of trunk fluctuation using an accelerometer is useful for the clinical assessment of patients with knee osteoarthritis pre- and post-TKA.

Effect of Functional Electrical Stimulation of the Gluteus Medius during Gait in Patients following a Stroke.

Many stroke patients rely on cane or ankle-foot orthosis during gait rehabilitation. The purpose of this study was to investigate the immediate effect of functional electrical stimulation (FES) to the gluteus medius (GMed) and tibialis anterior (TA) on gait performance in stroke patients, including those who needed assistive devices. Fourteen stroke patients were enrolled in this study (mean poststroke duration: 194.9 ± 189.6 d; mean age: 72.8 ± 10.7 y). Participants walked 14 m at a comfortable velocity with and without FES to the GMed and TA. After an adaptation period, lower-limb motion was measured using magnetic inertial measurement units attached to the pelvis and the lower limb of the affected side. Motion range of angle of the affected thigh and shank segments in the sagittal plane, motion range of the affected hip and knee extension-flexion angle, step time, and stride time were calculated from inertial measurement units during the middle ten walking strides. Gait velocity, cadence, and stride length were also calculated. These gait indicators, both with and without FES, were compared. Gait velocity was significantly faster with FES (p = 0.035). Similarly, stride length and motion range of the shank of the affected side were significantly greater with FES (stride length: p = 0.018; motion range of the shank: p = 0.026). Meanwhile, cadence showed no significant difference (p = 0.238) in gait with or without FES. Similarly, range of motion of the affected hip joint, knee joint, and thigh did not differ significantly depending on FES condition (p = 0.115-0.529). FES to the GMed and TA during gait produced an improvement in gait velocity, stride length, and motion range of the shank. Our results will allow therapists to use FES on stroke patients with varying conditions.

Trunk muscle activity during trunk stabilizing exercise with isometric hip rotation using electromyography and ultrasound.

INTRODUCTION: The purpose of this study was to clarify the muscle activation during trunk stabilizing exercise with isometric hip rotation in healthy males by comparing that with abdominal crunch (AC) and active straight leg raise (ASLR). Electromyography and ultrasound imaging were used to simultaneously measure muscle activity and thickness of the internal oblique (IO), the external oblique (EO), transverse abdominis (TrA) and multifidus (MF) on the right side during exercise. METHODS: Twenty healthy participants performed the following exercises in supine position: isometric right or left hip internal/external rotation, AC, and ASLR. Muscle activity was normalized to maximum voluntary contraction (MVC), and muscle thickness was normalized to resting muscle thickness. RESULTS: Muscle activation and thickness of IO, MF and TrA increased significantly during the isometric hip rotation compared with other exercises. Muscle activation during the trunk stabilizing exercise with ipsilateral isometric hip internal rotation was 21% in IO, 26% in MF, and with ipsilateral hip external rotation was 12% of MVC in EO. CONCLUSION: These findings suggest that trunk stabilizing exercise with isometric hip rotation exercise may be a more safe and effective exercise to promote trunk muscle activity than AC and ASLR. These findings would be beneficial for therapists engaged in prevention and treatment of low back pain.

Validity of Measurement for Trailing Limb Angle and Propulsion Force during Gait Using a Magnetic Inertial Measurement Unit.

Propulsion force and trailing limb angle (TLA) are meaningful indicators for evaluating quality of gait. This study examined the validity of measurement for TLA and propulsion force during various gait conditions using magnetic inertial measurement units (IMU), based on measurements using a three-dimensional motion analysis system and a force platform. Eighteen healthy males (mean age 25.2 ± 3.2 years, body height 1.70 ± 0.06 m) walked with and without trunk fluctuation at preferred, slow, and fast velocities. IMU were fixed on the thorax, lumbar spine, and right thigh and shank. IMU calculated the acceleration and tilt angles in a global coordinate system. TLA, consisting of a line connecting the hip joint with the ankle joint, and the laboratory's vertical axis at late stance in the sagittal plane, was calculated from thigh and shank segment angles obtained by IMU, and coordinate data from the motion analysis system. Propulsion force was estimated by the increment of velocity calculated from anterior acceleration measured by IMU fixed on the thorax and lumbar spine, and normalized impulse of the anterior component of ground reaction force (AGRF) during late stance. Similarity of TLA measured by IMU and the motion analysis system was tested by the coefficient of multiple correlation (CMC), intraclass correlation coefficient (ICC), and root mean square (RMS) of measurement error. Relationships between normalized impulse of AGRF and increments of velocity, as measured by IMU, were tested using correlation analysis. CMC of TLA was 0.956-0.959. ICC between peak TLAs was 0.831-0.876 (p < 0.001), and RMS of error was 1.42°-1.92°. Velocity increment calculated from acceleration on the lumbar region showed strong correlations with normalized impulse of AGRF (r = 0.755-0.892, p < 0.001). These results indicated a high validity of estimation of TLA and propulsion force by IMU during various gait conditions; these methods would be useful for best clinical practice.