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Bike positional configuration changes strongly affect cycling performance. While consensus has emerged on saddle height optimisation, there is none for the relationship between other bike positional variables and cycling performance. Accordingly, this systematic review examines the effect of all major positional variables on performance in cycling, assessing differences between cycling disciplines and sex where possible. The systematic review, conducted per PRISMA guidelines, searched databases including Embase, Web of Science, Medline, and CINAHL, screening 16,578 studies. Of these, 47 were fully analysed. Study quality assessment using the NIH tool revealed none rated "good", 5 "fair" and 33 "poor". The analysis involved 724 participants (90 female, 454 male, 180 sex unstated). Studies focused on trunk angle/upper body position, handlebar height, Q factor, foot position, saddle fore-aft/height, seat tube angle and crank length. Participant cycling disciplines were often unspecified and few papers address women cyclists specifically. Key findings were associated with changing saddle height, trunk angle and saddle fore-aft. For trunk angle, accounting for the biomechanical and physiological effects as well as aerodynamic changes is important. Saddle fore-aft affects the hip angle and trunk angle. There are no clear recommendations for crank length, handlebar height, Q factor or cleat position.

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PURPOSE: To assess anatomical variations in the celiac trunk (Ct) in patients with Median Arcuate Ligament Syndrome (MALS) using computed tomography (CT). The primary objectives were to investigate the celiac trunk angle (CtA), origin level, length (CtL), and their relationships with the superior mesenteric artery (SMA) in MALS patients. Additionally, the study intended to evaluate gender differences in these parameters and explore correlations between variables. METHODS: Retrospectively, reports of abdominal CT scans taken between January 2018, and Sepmtember 2021, in the hospital image archive were screened vey two observers independently for MALS diagnosis. Parameters such as CtA, CtL, Ct-SMA distance, SMA angle (SMAA), and median arcuate ligament thickness (MALT) were measured. Statistical analyses were conducted using SPSS software. RESULTS: Among the 81 patients (25 females, 56 males), significant differences were observed in MALT between genders (p = 0.001). CtA showed a negative correlation with CtL and Ct-SMA (p < 0.001), and a positive correlation was found between CtL and Ct-SMA (p = 0.002). CtL was measured as 25 mm for the all group. Origin levels of Ct and SMA were evaluated in comparison to vertebral levels. Ct-SMA distance was relatively shorter (9.19 mm) compared to the literature. SMAA findings were consistent with normal population values. CONCLUSION: This study provided valuable insights into the anatomical parameters of the Ct ans SMA in MALS patients. Despite some differences compared to normal population parameters, no evidence supported the hypothesis of a superiorly placed Ct contributing to MALS.

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Treadmill walking has been used as a surrogate for overground walking to examine how load carriage affects gait. The validity of using treadmill walking to investigate load carriage's effects on stability has not been established. Thirty young adults were randomized into 3 front-loaded groups (group 1: 0%, 2: 10%, or 3: 20% of bodyweight). Participants carried their load during overground and treadmill walking. Dynamic gait stability (primary outcome) was determined for 2 gait events (touchdown and liftoff). Secondary variables included step length, gait speed, and trunk angle. Groups 1 and 2 demonstrated similar stability between walking surfaces. Group 3 was less stable during treadmill walking than overground (P ≤ .005). Besides trunk angle, all secondary outcomes were similar between groups (P > .272) but different between surfaces (P ≤ .001). The trunk angle at both events showed significant group- and surface-related differences (P ≤ .046). Results suggested that walking with an anterior load of up to 10% bodyweight causes comparable stability between surfaces. A 20% bodyweight front load could render participants less stable on the treadmill than overground. This indicates that anteriorly loaded treadmill walking may not be interchangeable with overground walking concerning stability for anterior loads of 20% bodyweight.

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OBJECTIVES: The effect of knee position on joint moments during squats has been studied; however, the effect of trunk angle has been less well investigated. This study evaluated the effect of both trunk and knee sagittal plane position on the distribution of moments between the hip and knee extensors during the bilateral squat. DESIGN: Observational study. SETTING: Biomechanics laboratory. PARTICIPANTS: One hundred individuals performed bilateral squats. MAIN OUTCOME MEASURES: Motion and force data were collected using motion capture and force plates. Trunk and shank angles and hip and knee moments were calculated. A linear regression was used to associate the ratio between the hip and knee moments (hip-to-knee moment ratio) with the sagittal plane trunk and shank angles, while accounting for six squat depths (between 60° and 110° of knee flexion) and side. RESULTS: Trunk angle and shank angle each contributed to the hip-to-knee moment ratio (P < .001) with trunk accounting for a higher proportion of variance than the other variables. The hip-to-knee moment ratio increased with increasing trunk angle and with decreasing shank angle. CONCLUSIONS: This large cohort study supports the use of trunk position to instruct squat technique with the goal of modifying hip and knee moments.

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PURPOSE: This study aimed to predict the ability to insert a 4-5 French (Fr) catheter insertion with a guidewire into the common hepatic artery (CHA) based on celiac trunk morphology. METHODS: This retrospective study included 64 patients who underwent balloon-occluded transcatheter arterial chemoembolization (n = 56), transcatheter arterial chemotherapy (n = 2), or were fitted with an implantable port system (n = 6) between June 2019 and December 2019 in our institution. The morphology of the celiac trunk was classified into three types (upward, horizontal, and downward) based on celiac angiography. The aortic-celiac trunk angle was measured on sagittal images of preprocedural contrast-enhanced computed tomography (CT). We reviewed whether a 4-5-Fr shepherd's hook catheter could advance beyond the CHA using a 0.035-inch guidewire (Radifocus® Guidewire M; Terumo). Three patients were diagnosed with median arcuate ligament syndrome (MALS) based on the characteristic hook shape of the celiac artery on sagittal images of contrast-enhanced CT. The predictive ability of celiac angiography and preprocedural CT for CHA insertion success was evaluated. In unsuccessful cases, the balloon anchor technique (BAT) was attempted as follows: (1) a 2.7/2.8-Fr microballoon catheter (Attendant Delta; Terumo) was placed beyond the proper hepatic artery, and (2) the balloon was inflated as an anchor for parent catheter advancement. RESULTS: Upward, horizontal, and downward celiac trunk types were noted in 42, 9, and 13 patients, respectively. The median CT angle was 122.83° (first quartile-third quartile, 102.88°-136.55°). Insertion in the CHA using the guidewire was successful in 56 of 64 patients (87.50%), and the success rate in the downward type was significantly lower than that in the upward type [42/42 (100%) vs. 7/13 (53.85%), P < 0.001]. The CT angle was significantly larger downward in the unsuccessful group than in the successful group (121.03° vs. 140.70°, P = 0.043). Celiac angiography had a significantly higher area under the curve (AUC) than preprocedural CT (AUC = 0.91 vs. AUC = 0.72, P = 0.040). All three cases of MALS showed unsuccessful CHA insertion. In all eight patients with unsuccessful insertion, the catheter could be advanced using the BAT [8/8 (100%)]. CONCLUSION: Celiac angiography and preprocedural CT could predict CHA catheter insertion using a guidewire, and celiac angiography had high predictability. CT could detect MALS, a risk factor for unsuccessful CHA insertion.

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Improper cycling posture is linked to a variety of spinal musculoskeletal diseases, including structural malformation of the spine and back discomfort. This paper presents a novel smart shirt integrated tri-axial gyroscope and accelerometer that can detect postural variation in terms of spinal curvature changes. To provide accurate feedback to the wearer and improve the wearer's correct movement, the garment is able to recognize trunk body posture. The gyroscope/accelerometer was placed around the upper and mid trunk of the user to record tri-axial angular velocity data. The device can also be used to help determine the trunk bending angle and monitor body postures in order to improve optimal orientation and position. The garment enables continuous measurement in the field at high sample rates (50 Hz), and the sensor has a large measurement range (16 g, 2000°/s). As electronic components are non-washable, instead of encapsulating them, a detachable module was created. In this, magnets are embedded in the jersey, and allow the positioning and removal of the sensor. The test results show that the average trunk-bending angle was 21.5°, and 99 percent of the observed angle fell within the standard (ranging from 8° to 35°). The findings demonstrate the feasibility of employing the smart shirt sensor to estimate trunk motions in the field on a regular basis.

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Although interventional studies have suggested that dance-based training may reduce fall risk for older adults based on unperturbed assessments, it remains unknown whether dance (particularly ballet) enhances recovery from an external perturbation. This preliminary study sought to test if and how ballet dancers respond differently to a novel standing-slip perturbation relative to non-dancers. Ten young professional ballet dancers and 10 age/sex-matched non-dancers were exposed to an unannounced slip while standing on the treadmill. Their reactions to the slip, characterized by dynamic gait stability (primary outcome), and the recovery stepping and trunk movements (secondary outcomes), were compared between groups. No significant group difference in dynamic gait stability was found at slip onset and recovery step liftoff, but dancers were more stable than non-dancers at touchdown (p = 0.046). Compared to non-dancers, dancers took a longer (p = 0.049) and faster (p = 0.007) backward recovery step and exhibited a less backward leaned trunk at all instants (p ≤ 0.026). Our study suggests that professional ballet dancers are more stable after a novel standing-slip than non-dancers. This better slip-related fall resistance among dancers could result from their more effective recovery stepping strategy and better trunk movement control after the slip. Both reactions may be attributed to ballet training, which requires frequent backward stepping and an upright trunk. Our findings could potentially provide preliminary evidence for applying ballet training to reduce balance losses and falls in people at a high fall risk. More studies are needed to examine ballet training's effects among other populations with elevated fall risk in real-life situations.

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BACKGROUND: Anteriorly-loaded walking is common in many occupations and may increase fall risk. Dynamic gait stability, defined by the Feasible Stability Region (FSR) theory, quantifies the kinematic relationship between the body's center of mass (COM) and base of support (BOS). FSR-based dynamic gait stability has been used to evaluate the fall risk. RESEARCH QUESTION: How does front load carriage affect dynamic gait stability, step length, and trunk angle among young adults during treadmill walking? METHODS: In this between-subject design study, 30 healthy young adults were evenly randomized into three load groups (0%, 10%, or 20% of body weight). Participants carried their assigned load while walking on a treadmill at a speed of 1.2 m/s. Body kinematics were collected during treadmill walking. Dynamic gait stability (the primary variable) was calculated for two gait events: touchdown and liftoff. Step length and trunk angle were measured as secondary variables. One-way analysis of variance was conducted to detect any group-related differences for all variables. Post-hoc analysis with Bonferroni correction was performed when main group differences were found. RESULTS: No significant differences but medium to large effect sizes were found between groups for dynamic gait stability at touchdown (p = 0.194, η2 = 0.114) and liftoff (p = 0.122, η2 = 0.139). Trunk angle significantly increased (indicating backward lean) with the front load at touchdown (p < 0.001, η2 = 0.648) and liftoff (p < 0.001, η2 = 0.543). No significant between-group difference was found related to the step length (p = 0.344, η2 = 0.076). SIGNIFICANCE: Carrying a front load during walking significantly alters the trunk orientation and may change the COM-BOS kinematic relationship and, therefore, fall risk. The findings could inform the design of future studies focusing on the impact of anterior load carriage on fall risk during different locomotion.

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Whole-body models are historically developed for traffic injury prevention, and they are positioned accordingly in the standing or sitting configuration representing pedestrian or occupant postures. Those configurations are appropriate for vehicle accidents or pedestrian-vehicle accidents; however, they are uncommon body posture during a fall accident to the ground. This study aims to investigate the influence of trunk and pelvis angles on the proximal femur forces during sideways falls. For this purpose, a previously developed whole-body model was positioned into different fall configurations varying the trunk and pelvis angles. The trunk angle was varied in steps of 10° from 10 to 80°, and the pelvis rotation was changed every 5° from -20° (rotation toward posterior) to +20° (rotation toward anterior). The simulations were performed on a medium-size male (177 cm, 76 kg) and a small-size female (156 cm, 55 kg), representative for elderly men and women, respectively. The results demonstrated that the highest proximal femur force measured on the femoral head was reached when either male or female model had a 10-degree trunk angle and +10° anterior pelvis rotation.

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Occupational Abstract The aim of this project was to develop and test an application capable of quickly and repeatedly measuring trunk flexion angles during sagittal plane lifting tasks. The developed application uses the built-in accelerometer in mobile devices to approximate trunk flexion angle, as the user follows an operator as they perform a lift. A black line is superimposed over the camera feed, allowing the user to approximate the angle of inclination of a line connecting the operator's seventh cervical and first sacral vertebrae-thereby estimating the trunk flexion angle. The magnitude of this angle and its velocity have been linked to the development of occupational low back pain; thus the application provides ergonomists a more refined means of screening tasks beyond currently available survey tools.

TECHNICAL ABSTRACT Background The majority of quantitative postural analysis tools used in biomechanics laboratories are either infeasible or impractical for applied ergonomic field use. Survey tools do exist but are subjective in nature. Purpose To develop an application for handheld mobile devices that can quickly, reliably, and accurately measure the trunk flexion angle in order to afford more detailed and objective ergonomic analyses. Methods The application, Trunk Angle Goniometer (TAG), was programed using Xcode (Apple Inc. Cupertino, CA). Sixteen participants measured the trunk angle of lifts in the sagittal plane using TAG installed on an iPad (Apple Inc., Cupertino, CA). To establish the accuracy of the application, comparisons were made to gold standard (manual anatomical landmark digitization) measures of maximum trunk angle, maximum trunk velocity, and the root-mean square (RMS) difference between trunk angle time histories. Precision was also assessed between raters (inter-rater reliability), between trials assessing the same lift (intra-rater reliability) and between trials assessing similar lifts (test-retest reliability). Results TAG generally underestimated the true magnitude of trunk flexion by 5 ° to 15 °, and overestimated flexion velocity by approximately 10 °/sec. RMS errors were between 8.6 ° and 13.4 °. Performance measures showed fair to good test-retest reliability between 0.631 and 0.709. Overall the application had an excellent inter-rater reliability above 0.95 for all measures; however, suffered from low intra-rater reliability (0.381 to 0.520) but these dramatically increased when averages were taken across multiple trials (from 0.739 to 0.838). Conclusions TAG performed well for quantifying angles in the sagittal plane. The approach has the added benefit of being able to assess lifting tasks in real time, combined with its relatively cheap cost, the approach shows promise for field-work and assessments.

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This study sought to investigate the effects of obesity on falls and dynamic stability control in young adults when subject to a standardized treadmill-induced gait-slip. Forty-four young adults (21 normal-weight and 23 obese) participated in this study. After their muscle strength was assessed at the right knee under maximum voluntary isometric (flexion and extension) contractions, participants were moved to an ActiveStep treadmill. Following 5 normal walking trials on the treadmill, all participants encountered an identical and unexpected slip defined as a perturbation in the anterior direction with the magnitude of 24-cm slip distance and 2.4-m/s peak slip velocity. The trials were categorized as a fall or recovery based on the reliance of the subject on external support following the slip. Compared with the normal-weight group, the obese group demonstrated less relative muscle strength and fell more responding to the slip (78.3% vs. 40.0%, p=0.009). After adjusting the body height and gender, the results indicated that the obese group was 19.1-time (95% confidence interval: [2.06, 177.36]) more prone to a fall than the normal-weight group when experiencing the same treadmill-induced slip. The obese group showed significantly impaired dynamic stability after slip possibly due to the inability of controlling the trunk segment׳s backward lean movement. Obesity measurements explained more slip outcome variance than did the strength measurements (53.4% vs. 18.1%). This study indicates that obesity most likely influences the ability to recover from slip perturbations. It is important to develop interventions to improve the capability of balance recovery among individuals with obesity.

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BACKGROUND: The flexion-relaxation phenomenon (FRP) in standing is a specific and sensitive diagnostic tool for low back pain. Seated flexion as an alternative could be beneficial for certain populations, yet the behavior of the trunk extensors during seated maximum flexion compared to standing flexion remains unclear. OBJECTIVE: Compare FRP occurrences and spine angles between seated and standing flexion postures in three levels of the erector spinae muscles. METHODS: Thirty-one participants free of back pain performed seated and standing maximum trunk flexion. Electromyographical signals were recorded from the bilateral lumbar (L3), lower-thoracic (T9), and upper-thoracic (T4) erector spinae and assessed for the occurrence of FRP. Spine angles corresponding to FRP onset and cessation were determined, and FRP occurrences and angles were compared between posture and muscle. RESULTS: FRP occurrence was similar in standing and seated maximum flexion across all muscles, with the lumbar muscles showing the greatest consistency. Standing FRP onset and cessation angles were consistently greater than the corresponding seated FRP angles. CONCLUSION: Considering the similar number of FRP occurrences, seated maximum flexion may constitute an objective criterion for low back pain diagnosis. Future work should seek to confirm the utility of this test in individuals with low back pain.

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The purpose of this study was to evaluate changes in movement patterns during a sit-to-stand (STS) task before and after total hip arthroplasty (THA), and to compare biomechanical outcomes after THA to a control group. Forty-five subjects who underwent THA and twenty-three healthy control subjects participated in three-dimensional motion analysis. Pre-operatively, subjects exhibited inter-limb movement asymmetries with lower vertical ground reaction force (VGRF) and smaller moments on the operated limb. Although there were significant improvements in movement symmetry 3 months after THA, patients continued to demonstrate lower VGRF and smaller moments on the operated limb compared to non-operated and to control limbs. Future studies should identify the contributions of physical impairments and the influence of surgical approach on STS biomechanics.

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