The Impact of Spinopelvic and Hip Mobility on Passive Hip Flexion Range of Motion Assessment.

Background: Measuring passive hip flexion range of motion (ROM) is challenging due to compensatory movements. Despite the interest in using functional lateral radiographs for assessing hip mobility, the relationship with passive hip flexion ROM remains unclear. This study aims to elucidate this relationship and clarify spinopelvic parameters and mobility factors influencing variations in passive and radiographic hip flexion ROM. Methods: A retrospective cross-sectional study was conducted on 154 preoperative patients undergoing primary total hip arthroplasty. Passive and radiographic hip flexion ROM were assessed to clarify these relationships, and these differences were classified into 3 groups (O, A and U). Spinopelvic and hip parameters were assessed in standing, relaxed-seated and flexed-seated positions, as well as lumbar, pelvis, and hip mobility between each position to identify factors influencing differences. Results: There was a moderate correlation between passive and radiographic hip flexion ROM (R2 = 0.48, P < .01). A significant difference was found in pelvic and hip alignment in the flexed-seated position between all groups. In postural changes, the O group, which had more patients with relatively low hip mobility, showed greater lumbar spine and pelvic movement, while the U group, which had more patients with relatively high hip mobility, showed less lumbar spine and pelvic movement. Conclusions: This study confirmed that passive hip flexion ROM and radiographic hip flexion ROM correlate and that spinopelvic and hip alignment and mobility influence these differences. This result suggests that clinicians should consider lumbar and pelvic alignment and mobility in clinical practice to improve the accuracy of passive hip flexion ROM measurements.

A Novel Personalized Strategy for Hip Joint Flexion Assistance Based on Human Physiological State.

Soft exosuits have emerged as potent assistive tools for walking support and rehabilitation training. However, most existing soft exosuit systems rely on preset assistance modes, which may not accurately align with individual physiological states and movement requirements, leading to variable user experiences and efficacy. While existing human-in-the-loop (HIL) research predominantly focuses on optimizing metabolic cost and torque difference parameters, there is a notable absence of real-time monitoring methods that closely reflect the human body's physiological state and strategies that dynamically indicate walking efficiency. Motivated by this, we developed a novel personalized power-assist system. This system optimizes the power-assist output of the hip joint by monitoring the user's physiological and motion signals in real time, including heart rate (HR), blood oxygen saturation (SpO2), and inertial measurement unit (IMU) data, to assist hip flexion based on feedback. The findings from a metabolic expenditure trial demonstrate that the innovative soft exosuit, which is based on a Physiological State Monitoring Control (PSMC) system, achieves a reduction of 7.81% in metabolic expenditure during treadmill walking at a speed of 3.5 km/h compared to walking without the assistance of the exosuit. Additionally, during continuous exercise with varying intensities, the metabolic consumption level is reduced by 5.1%, 5.8%, and 8.2% at speeds of 2, 4, and 6 km per hour, respectively. These results support the design of a novel hip flexion-assisting soft exosuit, demonstrating that applying different assistance forces in consideration of different physiological states is a reasonable approach to reducing metabolic consumption.

Malignant Hip Flexion Failure Syndrome: An Oncologic Disease Compared to Malignant Psoas Syndrome.

Malignant psoas syndrome (MPS) causes painful hip immobilization when a malignant tumor reaches the psoas muscle. However, there exists a different condition in which a malignant tumor invades the psoas muscle, leading to hip flexion failure without painful hip immobilization. This study aimed to define malignant hip flexion failure syndrome (MHFFS) as tumors located in the upper lumbar region or at the lesser trochanter of the femur, near the origin or termination of the psoas muscle, and to compare its prevalence, characteristics, and outcomes with those of classical MPS. We analyzed 291 patients who received palliative radiotherapy (RT) in the lumbar, pelvic, and lower leg regions from 2013 to 2023. The prevalence of MPS and MHFFS, pathological features, distinctive clinical presentations, treatment modalities, and treatment outcomes have been summarized. We also defined the 'Clinical sign reported by Ishikawa and Teramura (IT sign)' to describe the characteristic action of lifting the affected lower leg with both hands in MHFFS cases and assessed its clinical significance. Among the 291 patients, 6 (2.1%) had MHFFS and 11 (3.8%) had MPS. MHFFS resulted from metastatic tumors in the 11th and 12th thoracic vertebrae, as well as the 1st and 2nd lumbar vertebrae or the lesser trochanter of the femur, and it was characterized by hip and groin pain along with hip flexion dysfunction. All cases showed a positive IT sign. The response to RT varied, with symptomatic improvement observed in 50% of the patients. MPS is characterized by tumor invasion of the psoas muscle, causing severe lumbosacral nerve pain. Strong opioids were used for pain management in all patients, and epidural anesthesia was required in some patients. The median survival time of patients with MPS and MHFFS was 13.2 months. MPS required opioids more potently than MHFFS, but MHFFS responded relatively well to early RT.

Fatigue Test Method to Evaluate the 50 Year Durability of Venous Stents.

OBJECTIVE: Iliofemoral venous obstructive disease can result in significant, potentially debilitating symptoms that can negatively affect quality of life. Unlike arterial disease, patients with deep venous disease have a significantly lower median age, therefore the need for long term stent patency becomes a matter of decades rather than years. Furthermore, iliofemoral lesions frequently require stent placement across the inguinal ligament. Such stents are subject to dynamic stress from leg movement and associated concerns for device fatigue, resulting in stent fracture. The aim of this study was to describe an in vitro 50 year stent fatigue test method designed to assess durability against dynamic stress induced device fracture. METHODS: Through literature review, cadaver studies, and computer modelling, the most challenging loading was confirmed to be hip flexion across the inguinal ligament. This occurs when the patient adjusts between a seated and standing position. Sit to stand hip flexion at the inguinal ligament was effectively simulated on the bench in this in vitro experimental study. RESULTS: When tested under challenge parameters, hip flexion was reliably found to cause fractures in non-venous nitinol stents. However, a dedicated self expanding nitinol venous stent, engineered for improved durability, underwent up to 50 years of simulated loading on the bench with 15% (3/20) of stents experiencing fractures at 50 years, compared with fractures in 35% (14/40) of non-venous stents tested to 1.4 years; no statistical testing was performed as durations do not match and the objective was to demonstrate the test method. CONCLUSION: The presented fatigue test method is a suitable approach for evaluating the durability of stents intended for venous use. Venous stents demonstrated superior fatigue resistance compared with non-venous stents via in vitro hip flexion testing.

The Effect of Variations in Knee and Hip Angles on Electromyographic Activity of the Hamstrings and Related Muscles During the Nordic Hamstring Exercise.

Background: The benefit of performing the Nordic Hamstring Exercise (NHE) on an inclined board has been described, however, isometric hamstring activation in different knee and hip angles has not yet been thoroughly explored. Purpose: This study investigated the effect of variations in knee and hip angles during the isometric performance of the NHE on electromyographic activity of the hamstring muscles. Study design: Crossover study. Methods: Thirteen male volunteers performed isometric contractions during the NHE with the knee (30°, 50°, 60°) and the hip (0°, 30°, and 45°) in various angles of flexion on a leg support platform which was inclined at 30°. An electrical goniometer was used to monitor the knee and hip joint angles during 5-s isometric contractions. A multivariate analysis of variance with repeated measures was used to compare normalized electromyographic values of each muscle across different knee and hip angles, followed by pairwise comparisons. Results: The electromyographic activity of the biceps femoris, semitendinosus, and semimembranosus at a knee angle of 30° and hip angle of 0° were significantly higher than those observed with a knee angle of 50° and hip angle of 0°, or a knee angle of 60° and hip angle of 0° (p<0.05). The electromyographic activity of the semimembranosus at a knee angle of 60° and hip angle of 45° was significantly higher than values obtained with knee and hip angles of 60° and 0°, respectively (p<0.05). Conclusions: The results indicate that using a knee flexion of 30° and a hip flexion of 0°, while isometrically performing the NHE on a platform inclined at 30°, may optimize electromyographic activity of the hamstrings. Level of Evidence: 3.

Recurrent Abdominal Aggressive Fibromatosis with Incapacitating Hip Contracture - A Case Report.

Introduction: Aggressive fibromatosis (AF) is a fibroblastic locally aggressive neoplasm arising from the musculoaponeurotic stroma and has no metastatic potential. The high tendency of recurrence despite complete surgical resections makes the management of the condition onerous. It can result in significant morbidity with major functional loss due to the destruction of adjacent vital structures and organs. AF with hip flexion contracture is a very rare occurrence. Case Report: A 20-year-old male presented with recurrent abdominal AF with severe hip flexion contracture and an unresectable tumor. He underwent deformity correction and he maintains the full correction achieved along with very good functional improvement at the end of 4 years. Conclusion: This case demonstrates that in a case of AF with an unresectable tumor, good functional outcome can be obtained; it can be maintained over the short term following contracture release with soft-tissue coverage surgery along with chemotherapy with sorafenib.

A single center prospective study: Influences of different hip flexion angles on the measurement of lumbar spine bone mineral density by dual energy X-ray absorptiometry.

To investigate whether there is an influence on the results of lumbar spine bone mineral density (BMD) measured by dual-energy X-ray absorptiometry (DXA) under three different hip flexion angles (90°, 45°, 0° of hip flexion). We collected a total of 60 outpatients, including 44 females (56.4 ± 5.7 years) and 16 males (50.2 ± 13.7 years). The DXA results of the lumbar spine were scanned and analyzed in three different positions with hip flexion of 90°, 45°, and 0°. We found that there was no significant difference in the area of interest, bone mineral content, BMD, and vertebral body height of the lumbar vertebral body measured by DXA in three hip flexion positions of 90°, 45°, and 0°; Pearson's correlation analysis showed that lumbar BMD in hip flexion 90° was correlated with it in hip flexion 45° (r = 0.998, P＜0.01) and in hip flexion 0° (r = 0.996, P＜0.01) respectively. There was no statistically significant difference in the diagnosis of BMD between 90° and 45° hip flexion (P = 0.903), which was the same as 90° and 0° hip flexion (P = 0.822). Therefore, we conclude that different hip flexion angles can be used in lumbar BMD detection by DXA, which is beneficial to patients who have difficulty in hip flexion, especially for elderly patients with osteoporosis.

The Effect of the Hip Flexion Angle in Osteonecrosis of the Femoral Head Based on China-Japan Friendship Hospital Classification - A Finite Element Study.

OBJECTIVE: The alteration in the mechanical environment of the necrotic area is the primary cause of the collapse observed in osteonecrosis of the femoral head (ONFH). This study aims to evaluate the biomechanical implications of the China-Japan Friendship Hospital (CJFH) classification system and hip flexion angles on the necrotic area in ONFH using finite element analysis (FEA). The goal is to provide valuable guidance for hip preservation treatments and serve as a reference for clinical diagnosis and therapeutic interventions. METHODS: Hip tomography CT scan data from a healthy volunteer was used to create a 3D model of the left hip. The model was preprocessed and imported into Solidworks 2018, based on the CJFH classification. Material parameters and boundary conditions were applied to each fractal model in ANSYS 21.0. Von Mises stresses were calculated, and maximum deformation values were obtained to evaluate the biomechanical effects of the load on the necrotic area and post-necrotic femur, as well as assess each fractal model's collapse risk. RESULTS: (1) At the same hip flexion angle, maximum deformation followed this order: M Type < C Type < L Type. The L3 type necrotic area experienced the most significant deformation at 0, 60, and 110° angles (1.121, 1.7913, and 1.8239 mm respectively). (2) Under the same CJFH classification, maximum deformation values increased with hip flexion angle (0 < 60 < 110°), suggesting a higher risk of collapse at larger angles. (3) Von Mises stress results showed that the maximum stress was not located in the necrotic area but near the inner and outer edge of the femoral neck, indicating decreased stiffness and strength of the subchondral bone after osteonecrosis. CONCLUSION: The study found that femoral head collapse risk was higher when the necrotic area was located in the lateral column under the same stress load and flexion angle. Mechanical properties of the necrotic area changed, resulting in decreased bone strength and stiffness. Large-angle hip flexion is more likely to cause excessive deformation of the necrotic area; thus, ONFH patients should reduce or avoid large-angle hip flexion during weight-bearing training in rehabilitation activities.

Stent deformations in the common iliac and iliofemoral veins as a result of hip flexion and extension.

OBJECTIVE: In the present study, we characterized deformations of venous stents implanted into common iliac veins for nonthrombotic iliac vein lesions and iliofemoral veins for deep vein thrombosis due to hip movements commensurate with everyday activities such as walking, sitting, and stair climbing. METHODS: Patients treated with iliofemoral venous stents were recruited from three centers and underwent imaging with two orthogonal two-dimensional projection radiographs. Stents in the common iliac veins and iliofemoral veins crossing the hip joint were imaged with the hip in 0°, 30°, 90° and -15°, 0°, and 30° positions, respectively. Using the radiographs, the three-dimensional geometries of the stents were constructed for each hip position, and the diametric and bending deformations between those positions were quantified. RESULTS: Twelve patients were included, and the findings showed that the common iliac vein stents experienced approximately twofold more local diametric compression with 90° hip flexion compared with 30° flexion. Also, iliofemoral vein stents crossing the hip joint experienced significant bending with hip hyperextension (-15°) but not with hip flexion. In both anatomic locations, maximum local diametric and bending deformations were in proximity with each other. CONCLUSIONS: Stents implanted in the common iliac and iliofemoral veins exhibit greater deformation during high hip flexion and hyperextension, respectively, and iliofemoral venous stents interact with the superior ramus of the pubis during hyperextension. These findings suggest that device fatigue could be influenced by the type and level of patient physical activity, in addition to anatomic positioning, opening up the potential benefit of activity modification and the use of a careful implantation strategy. The proximity of maximum diametric and bending deformations means that simultaneous multimodal deformations should be considered for device design and evaluation.

Measurement of the normal contralateral hip flexion angle and posterior pelvic tilt angle using a pelvic guide pin in total hip arthroplasty.

BACKGROUND: We aimed to measure the posterior pelvic tilt angle at maximum hip flexion and hip flexion range of motion at the femoroacetabular joint using a pelvic guide pin and to examine the difference in flexion range of motion when determined by a physical therapist and under anesthesia. METHODS: Data of 83 consecutive patients undergoing primary unilateral total hip arthroplasty were assessed. Using a pin inserted into the iliac crest to define the cup placement angle under anesthesia before and after total hip arthroplasty, the posterior pelvic tilt angle was determined as the change in pin tilt from the supine position to maximum hip flexion. Flexion range of motion under anesthesia was calculated as the difference in the angle between the trunk and thigh at maximum flexion and the posterior pelvic tilt angle. Flexion range of motion with a fixed pelvis measured preoperatively by a physical therapist was compared to that under anesthesia. A goniometer was used for all measurements and the number of measurements was one. FINDINGS: Mean posterior pelvic tilt angle of the pin inserted into the pelvis under anesthesia was 15.8° ± 5.3° (3°-26°) preoperatively and 12.1° ± 4.9° (3°-26°) postoperatively. Mean flexion range of motion under anesthesia was 109.4° ± 6.9° (88°-126°) and that measured by a physical therapist was 101.1° ± 8.2° (80°-120°); the difference was significant (9.7°; p < 0.01). INTERPRETATION: These results highlight the difficulty in accurately determining hip flexion angles without the use of special devices and may help surgeons and physical therapists recognize and address this issue.

The energetic effect of hip flexion and retraction in walking at different speeds: a modeling study.

In human walking, power for propulsion is generated primarily via ankle and hip muscles. The addition of a 'passive' hip spring to simple bipedal models appears more efficient than using only push-off impulse, at least, when hip spring associated energetic costs are not considered. Hip flexion and retraction torques, however, are not 'free', as they are produced by muscles demanding metabolic energy. Studies evaluating the inclusion of hip actuation costs, especially during the swing phase, and the hip actuation's energetic benefits are few and far between. It is also unknown whether these possible benefits/effects may depend on speed. We simulated a planar flat-feet model walking stably over a range of speeds. We asked whether the addition of independent hip flexion and retraction remains energetically beneficial when considering work-based metabolic cost of transport (MCOT) with different efficiencies of doing positive and negative work. We found asymmetric hip actuation can reduce the estimated MCOT relative to ankle actuation by up to 6%, but only at medium speeds. The corresponding optimal strategy is zero hip flexion and some hip retraction actuation. The reason for this reduced MCOT is that the decrease in collision loss is larger than the associated increase in hip negative work. This leads to a reduction in total positive mechanical work, which results in an overall lower MCOT. Our study shows how ankle actuation, hip flexion, and retraction actuation can be coordinated to reduce MCOT.

Femoral impingement in maximal hip flexion is anterior-inferior distal to the cam deformity in femoroacetabular impingement patients with femoral retroversion : implications for hip arthroscopy.

AIMS: Femoroacetabular impingement (FAI) patients report exacerbation of hip pain in deep flexion. However, the exact impingement location in deep flexion is unknown. The aim was to investigate impingement-free maximal flexion, impingement location, and if cam deformity causes hip impingement in flexion in FAI patients. METHODS: A retrospective study involving 24 patients (37 hips) with FAI and femoral retroversion (femoral version (FV) < 5° per Murphy method) was performed. All patients were symptomatic (mean age 28 years (SD 9)) and had anterior hip/groin pain and a positive anterior impingement test. Cam- and pincer-type subgroups were analyzed. Patients were compared to an asymptomatic control group (26 hips). All patients underwent pelvic CT scans to generate personalized CT-based 3D models and validated software for patient-specific impingement simulation (equidistant method). RESULTS: Mean impingement-free flexion of patients with mixed-type FAI (110° (SD 8°)) and patients with pincer-type FAI (112° (SD 8°)) was significantly (p < 0.001) lower compared to the control group (125° (SD 13°)). The frequency of extra-articular subspine impingement was significantly (p < 0.001) increased in patients with pincer-type FAI (57%) compared to cam-type FAI (22%) in 125° flexion. Bony impingement in maximal flexion was located anterior-inferior at femoral four and five o'clock position in patients with cam-type FAI (63% (10 of 16 hips) and 37% (6 of 10 hips)), and did not involve the cam deformity. The cam deformity did not cause impingement in maximal flexion. CONCLUSION: Femoral impingement in maximal flexion was located anterior-inferior distal to the cam deformity. This differs to previous studies, a finding which could be important for FAI patients in order to avoid exacerbation of hip pain in deep flexion (e.g. during squats) and for hip arthroscopy (hip-preservation surgery) for planning of bone resection. Hip impingement in flexion has implications for daily activities (e.g. putting on shoes), sports, and sex.Cite this article: Bone Joint Res 2023;12(1):22-32.

Effect of hip flexion contracture on the pelvic sagittal tilt in the supine position: A retrospective case-series study.

OBJECTIVES: The functional pelvic plane, which adopts the natural pelvic sagittal tilt in the supine position, is a good reference for determining the cup angle in total hip arthroplasty. However, hip flexion contracture may change pelvic tilt postoperatively by the release of contracture. This study investigated the influence of hip flexion contracture on pelvic sagittal tilt in the supine position. METHODS: This study included 300 patients who underwent primary unilateral total hip arthroplasty. We divided the participants into two groups: with a preoperative hip extension angle of <0° (hip flexion contracture group) and without (non-contracture group). The pelvic sagittal tilt and femoral flexion angle were investigated using computed tomography or pelvic radiographs performed preoperatively and postoperatively. RESULTS: The femoral flexion angle had significantly reduced postoperatively in the hip flexion contracture group but remained unchanged in the non-contracture group. The preoperative and postoperative pelvic sagittal tilt showed no significant differences between the two groups up to 1 year postoperatively. CONCLUSIONS: The influence of hip flexion contracture on the pelvic sagittal tilt in the supine position was minimal. The functional pelvic plane in the supine position could be a good reference to ascertain the cup orientation, even in hip flexion contracture cases.

Instrument-Assisted Soft Tissue Mobilization Increased Hamstring Mobility.

CONTEXT: Limited research reveals that the use of different soft tissue mobilization techniques increases tissue mobility in different regions of the body. OBJECTIVE: The purpose of this study was to determine whether there is a difference between administering instrument-assisted soft tissue mobilization (IASTM) and therapeutic cupping (TC) on hamstring tightness. DESIGN: Subjects attended one session wherein treatment and leg order were randomized before attending the session. A statistical analysis was completed using a 2 (intervention) × 2 (time) repeated-measures analysis of variance at α level ≤ .05. PARTICIPANTS: Thirty-three subjects between the age of 18-35 years old with bilateral hamstring tightness participated in this study. INTERVENTIONS: The IASTM and TC were administered on different legs for 5 minutes and over the entire area of the hamstring muscles. One TC was moved over the entire treatment area in a similar fashion as the IASTM. MAIN OUTCOME MEASURES: The intervention measurements included soreness numeric rating scale, Sit-n-Reach (single leg for side being tested), goniometric measurement for straight-leg hip-flexion motion, and superficial skin temperature. The timeline for data collection included: (1) intervention measurements for the first randomized leg, (2) 5-minute treatment with the first intervention treatment, (3) intervention measurements repeated for postintervention outcomes, and (4) repeat the same steps for 1 to 3 with the contralateral leg and the other intervention. RESULTS: There was a main effect over time for Sit-n-Reach, measurement (pre-IASTM-29.50 [8.54], post-IASTM-32.11 [8.31] and pre-TC-29.67 [8.21], post-TC-32.05 [8.25]) and goniometric measurement (pre-IASTM-83.45 [13.86], post-IASTM-92.73 [13.20] and pre-TC-83.76 [11.97], post-TC-93.67 [12.15]; P < .05). CONCLUSION: Both IASTM and TC impacted hamstring mobility during a single treatment using only an instrument-assisted soft tissue mobilization technique without any additional therapeutic intervention.

Association between interindividual variability in training volume and strength gain.

This study aimed to examine the association between interindividual variability in strength changes and in training volume. A total of 26 untrained men completed 4-weeks of isometric knee extension (KE group, n = 12) and hip flexion (HF group, n = 14) training. Each training session comprised four sets of ten isometric contractions, 3-s contractions every 20 s. Training volume, which was defined as impulse during contractions, and maximal voluntary contraction (MVC) torque during KE and HF were evaluated. Based on the magnitude of MVC torque changes, the participants were divided into the high and low responders (n = 13; KE = 6 and HF = 7 per responders). The MVC torque changes (KE, 20.8%; HF, 22.4%) and total training volume did not significantly differ between the two groups. A higher training volume was demonstrated in the low responders than the high responders. The total training volume was positively associated with the MVC torque changes in low responders (r = 0.869%, 95% confidence interval [0.610, 0.960], p < 0.001), but not in high responders [r = 0.229, 95% confidence interval (-0.368, 0.693), p = 0.451], KE or HF group. Results showed that training volume was an important factor in determining the magnitude of strength gains in low responders, and MVC torque could improve by approximately 20% with the use of the study protocol regardless of joint actions involved during training.

Kinetic and kinematic comparisons in high school pitchers with low and high pitch location consistency.

BACKGROUND: Although ball velocity has often been associated with increased kinetics at the upper extremity and risk of injury in youth and adolescent pitchers, it is unclear if the performance metric pitch location consistency has any positive or negative associations with pitching kinetics. METHODS: High school pitchers (n = 59) pitched 8-12 fastballs using 3D motion capture (480 Hz). Pitchers were divided into high-consistency (HiCon) and low-consistency (LoCon) groups based on the absolute center deviation of each pitcher's pitch to the center of the pitcher's mean pitch location. Ninety-five percent confidence ellipses with major and minor radii were constructed, and kinematics and kinetics were compared between groups. RESULTS: Compared with LoCon pitchers, HiCon pitchers had decreased lead hip flexion at elbow extension (40° ± 12° vs. 52° ± 13°, respectively, P = .008), and at foot contact, decreased back hip extension (-1° ± 10° vs. -10° ± 13°, respectively, P = .038) and increased back hip internal rotation (9° ± 15° vs. -2° ± 15°, respectively, P = .043). LoCon pitchers achieved maximum lead hip flexion earlier in the pitch (61.3% ± 23.2% vs. 75.8% ± 15.1%, respectively, P = .039). A multiregression model predicted 0.49 of variance in pitch location consistency using kinematic inputs. DISCUSSSION AND CONCLUSION: Pitchers who differ in pitch location consistency outcomes do not appear to demonstrate physiologically unsafe kinematics. High school pitchers who strive for improved pitch consistency can consider adjusting parameters of hip kinematics during early portions of the pitch.

A Portable Waist-Loaded Soft Exosuit for Hip Flexion Assistance with Running.

The soft exosuit is an emerging robotics, which has been proven to considerably reduce the metabolic consumption of human walking and running. However, compared to walking, relatively few soft exosuits have been studied for running. Many soft exosuits used for running are worn on the back and with a heavy weight load, which may cause instability while running and potentially increase metabolic consumption. Therefore, reducing the weight of the whole soft exosuit system as much as possible and keeping the soft exosuit close to the center of gravity, may improve running stability and further reduce metabolic consumption. In this paper, a portable waist-loaded soft exosuit, the weight of which is almost entirely concentrated at the waist, is shown to assist hip flexion during running, and justifies choosing to assist hip flexion while running. As indicated by the experiments of motion flexibility, wearing the waist-loaded soft exosuit can assist in performing many common and complex motions. The metabolic consumption experiments proved that the portable waist-loaded soft exosuit reduces the metabolic consumption rate of wearers when jogging on the treadmill at 6 km per hour by 7.79% compared with locomotion without the exosuit. Additionally, at the running speed of 8 km per hour, using the waist-loaded soft exosuit can reduce metabolic consumption rate by 4.74%. Similarly, at the running speed of 10 km per hour, it also can be reduced by 6.12%. It is demonstrated that assisting hip flexion for running is also a reasonable method, and wearing the waist-loaded soft exosuit can keep human motion flexibility and reduce metabolic consumption.

The influence of hip flexion mobility and lumbar spine extensor strength on lumbar spine flexion during a squat lift.

STUDY DESIGN: Cross-sectional; Controlled laboratory study. OBJECTIVE: To examine the associations among available hip flexion motion, lumbar extensor strength and peak lumbar flexion during a squat lift task. SUMMARY OF BACKGROUND DATA: Lumbar spine flexion during lifting can result in increased strain on spinal structures. Although decreased available hip flexion motion and reduced strength of the lumbar extensor muscles has been proposed to contribute to greater lumbar flexion during lifting, direct relationships have not been explored. METHODS: Fifty healthy young adults participated (23 males and 27 females). Strength of the lumbar extensors was measured using a motor-driven dynamometer. Available hip flexion was assessed using 3D motion capture. Peak lumbar spine flexion and hip flexion were quantified during the descent phase of the squat lifting task. RESULTS: There was a significant negative association between available hip flexion and peak lumbar spine flexion during squat lifting in females (r = -0.407, p = 0.035) but not males (r = -0.341, p = 0.120). Similarly, peak lumbar spine flexion was negatively associated with lumbar extensor strength in females (r = -0.398, p = 0.040) but not males (r = -0.310, p = 0.161). During the squat lift, peak hip motion was positively associated with available hip flexion for both males and females combined (r = 0.774, p < 0.001). CONCLUSION: Females with less available hip flexion and lower lumbar extensor strength exhibit greater lumbar flexion when performing a lifting task. Clinicians should be aware of the potential contributions of such impairments when instructing patients into various lifting strategies.

Effect of Home-Based Tele-Pilates Intervention on Pregnant Women: A Pilot Study.

Pilates is effective for training the core muscles and stabilizing the hip joints, which provides relief from pelvic pain and low back pain during pregnancy. However, there are no specific guidelines on appropriate physical exercises for pregnant women due to the current pandemic. We aimed to apply the exercise standard proposed by the American College of Obstetricians and Gynecologists to home-based tele-Pilates exercise (HTPE), to determine its effect on the physical and mental health of pregnant women. We randomly divided the subjects into the following two groups who completed 8 weeks of HTPE (50 min/day, 2 days/week): (a) Pilates exercise (PE, n = 7) and (B) non-Pilates exercise (CON, n = 7). HTPE was performed by adjusting the program every 3 weeks, based on pain and physical fitness levels. We measured body composition, muscles of the hip joint, pelvic tilt, Oswestry Disability Index (ODI), and Pittsburgh Sleep Quality Index (PSQI), before and after HTPE. Following HTPE, while the percentage of body fat and body mass index had significantly decreased, the body fat mass did not change in the PE group (p < 0.05). The PE group showed an increase in strength of the left and right hip flexion and hip abduction, compared to the CON group (p < 0.01). The ODI and PSQI were significantly decreased in the PE group (p < 0.05). Therefore, the 8-week HTPE program is an effective exercise for pregnant woman that reduces body fat metabolism and strengthens muscles of the hip joint, thus alleviating pregnancy-induced low back pain and insomnia.