nils-herrmann/clean_scirepeval huggingface dataset:
Walking and running with non-specific chronic low back pain: What about the lumbar lordosis angle?
Venue: Journal of biomechanics

Non-specific chronic low back pain (NSCLBP) is a major health problem, affecting about one fifth of the population worldwide. To avoid further pain or injury, patients with NSCLBP seem to adopt a stiffer movement pattern during everyday living activities. However, it remains unknown how NSCLBP affects the lumbar lordosis angle (LLA) during repetitive activities such as walking or running. This pilot study therefore aimed at exploring possible NSCLBP-related alterations in LLAs during walking and running by focusing on discrete parameters as well as continuous data. Thirteen patients with NSCLBP and 20 healthy pain-free controls were enrolled and underwent a full-body movement analysis involving various everyday living activities such as standing, walking and running. LLAs were derived from markers placed on the spinous processes of the vertebrae L1-L5 and S1. Possible group differences in discrete (average and range of motion (ROM)) and continuous LLAs were analyzed descriptively using mean differences with confidence intervals ranging from 95% to 75%. Patients with NSCLBP indicated reduced average LLAs during standing, walking and running and a tendency for lower LLA-ROM during walking. Analyses of continuous data indicated the largest group differences occurring around 25% and 70% of the walking and 25% and 75% of the running cycle. Furthermore, patients indicated a reversed movement pattern during running, with increasing instead of a decreasing LLAs after foot strike. This study provides preliminary evidence that NSCLBP might affect LLAs during walking and running. These results can be used as a basis for future large-scale investigations involving hypothesis testing.
American society of biomechanics journal of biomechanics award 2019: Circumstances of head impacts in men's university ice hockey.
Venue: Journal of biomechanics

This observational study examined the circumstances of head impacts in men's university ice hockey. Video footage was collected of 449 head impacts experienced by 37 players over 33 games. Videos were analyzed using a reliable, structured questionnaire to classify: playing zone, location on ice, puck possession, direction of gaze, object striking the head, location of head impact, trajectory of colliding players, and penalties. Generalized Linear Models were used to compare response categories for the proportion of players experiencing at least one head impact, and the number of head impacts per player. The majority of events resulting in head impact involved contact with another player (93%). Head impacts occurred most often to players who did not have puck possession, who were checked along the boards in their offensive zone. Players were just as likely to experience head impact with an environmental object, as with an opposing player's body part. Glass-to-head impacts represented 30% of cases, four times as common as board-to-head impacts. Hand-to-head impacts accounted for 23% of cases, twice as common as shoulder- or elbow-to-head impacts. In 27% of events, there were two or more successive impacts to the head (e.g., contact with shoulder and then boards). Only 16% of head impacts which involved contact with another player resulted in infractions. Our results support the need for additional research on the benefits of stricter rule enforcement, and modifications to the stiffness of glass and padding of gloves, for reducing the frequency and severity of head impacts in ice hockey.
Maxillary suture expansion: A mouse model to explore the molecular effects of mechanically-induced bone remodeling.
Venue: Journal of biomechanics

The aim of this study was to analyze the effect of rapid maxillary expansion (RME) on hard tissues. Opening loops bonded to the first and second maxillary molars on both sides were used to apply distracting forces of 0.28 N, 0.42 N and 0.56 N at the midpalatal suture for 7 and 14 days. Microcomputed tomography (MicroCT), histomorphometry and quantitative polymerase chain reaction (qPCR) analysis were performed to evaluate RME effectiveness, midpalatal suture remodeling, cell counting of osteoblasts, osteoclasts and chondrocytes and the expression of bone remodeling markers, respectively. All forces at the two different time points resulted in similar RME and enhanced of bone remodeling. Accordingly, increased number of osteoblasts and reduced chondrocytes counting and no difference in osteoclasts were seen after all RME protocols. RME yielded increased expression of bone remodeling markers as osteocalcin (Ocn), dentin matrix acidic phosphoprotein-1 (Dmp1), runt-related transcription factor 2 (Runx2), collagen type I Alpha 1 (Col1a1), alkaline phosphatase (ALP), receptor activator of nuclear factor kappa B (RANK), receptor activator of nuclear factor kappa B ligand (Rankl), osteoprotegerin (Opg), cathepsin K (Ctsk), matrix metalloproteinases 9 and 13 (Mmp9 and 13), transforming growth fator beta 1, 2 and 3 (Tgfb 1, Tgfb 2 and Tgfb3), bone morphogenetic protein 2 (Bmp-2), sclerostin (Sost), beta-catenin-like protein 1 (Ctnnbl) and Wnt signaling pathways 3, 3a and 5a (Wnt 3, Wnt 3a and Wnt 5a). These findings characterize the cellular changes and potential molecular pathways involved in RME, proving the reliability of this protocol as a model for mechanical-induced bone remodeling.
An embedded element based 2D finite element model for the strength prediction of mineralized collagen fibril using Monte-Carlo type of simulations.
Venue: Journal of biomechanics

A computationally efficient statistical model for the prediction of the strength of mineralized collagen fibril (a basic building block of bone) is presented by taking into account the uncertainties associated with the geometrical and material parameters of collagen and mineral phases. The mineral plates have been considered as one-dimensional bar elements embedded in the two-dimensional plane stress collagen matrix. The mineral phase is considered as linear elastic and a hyperelastic material model is adopted for the collagen phase. Further, the crack initiation and propagation in the collagen phase have been modeled using a damage plasticity approach. Different realizations of the arrangement of mineral plates have been generated to account for the associated geometrical uncertainties using an in-house MATLAB® code. Monte-Carlo type simulations have been performed on the different realizations of mineralized collagen fibril to predict its characteristic stress-strain response under tensile load. The characteristic strength of 3.64 GPa is obtained for mineralized collagen fibril using Weibull's analysis which is found to be in agreement with the molecular dynamics simulation data and numerical studies reported in the past. A parameter sensitivity analysis concluded that mineral modulus has a significant effect on the overall tangent modulus of mineralized collagen fibril in large strain regime.
An animal trial to study damage and repair in ovariectomized rabbits.
Venue: Journal of biomechanics

Microdamage accumulates in bone matrix and is repaired through bone remodeling. Conditions such as osteoporosis and treatment with antiresorptive bisphosphonates can influence this remodeling process. In order to study microdamage accrual and repair in the context of osteoporosis and osteon structures, we set out to modify the rabbit forelimb fatigue model. New Zealand White rabbits (N = 43, 10 months old) received either ovariectomy (OVX) or sham surgeries and were used for forelimb fatigue loading. OVX increased fluorochrome labeling of intracortical and periosteal bone of the ulna, without changes in bone mass. Monotonic and cyclic loading of the forelimb did not reveal any statistical differences between stiffness, ultimate force, or displacement to failure between sham and OVX rabbits. Two levels of fatigue loading, chosen to represent "low" and "moderate" fatigue (25% and 40% of total displacement to failure, respectively), were used on OVX forelimbs to examine microdamage creation. However, neither group showed increased damage burden as compared to non-loaded controls. Following fatigue loading rabbit ulnae had increased intracortical remodeling and periosteal lamellar bone formation in "moderate" fatigue limbs, although no basic multicellular units or microdamage-targeted remodeling was observed. In summary, we adapted the rabbit forelimb fatigue model to accommodate OVX animals. However, loading parameters that could induce repeatable microdamage burden were not identified. Thus, while increased intracortical remodeling and periosteal bone formation were induced by our fatigue loading regimen, this preliminary study did not establish conditions to allow future study of the interactions between microdamage accrual and repair.
Study on the bending behavior of biodegradable metal cerebral vascular stents using finite element analysis.
Venue: Journal of biomechanics

Excellent bending behavior is evaluated as the primary factor during the design of biodegradable metal cerebral vascular stents (BMCVSs), which enables vascular stents to be successfully delivered to the targeted location and avoids unnecessary damage to blood vessels. Unfortunately, this bending behavior has been barely investigated which limits the design of BMCVSs with optimal structures. Herein, six BMCVSs were designed and their bending process were simulated using finite element analysis (FEA). Then, the effects of the stent bridge connection type and structure on the bending behavior were systematically analyzed and an universal mathematical model was further established, in which the influence of the structure parameters of the stent bridge on the flexibility of stents was considered. After that, the bending mechanism of the high-stress zone of the bridge was investigated. Finally, the causes and effects of the self-contacting phenomenon as well as the inner-stent protrusion phenomenon in the bending state were analyzed theoretically, and corresponding solutions were proposed to optimize the design of stents. The numerical results show that the stents with the dislocation-line W-shaped unit have better flexibility than the other stents. The flexibility is positively correlated to the cube of the length of linear part and to the square of the curvature of curved part. The self-contacting phenomenon of the bridge during bending can constrain the formation of inner-stent protrusion, which can eliminate the negative effects of the implanted stents on the hemodynamics in blood vessels. This study is expected to provide practical guidance for the structural design of BMCVSs for clinical applications.
Peak horizontal ground reaction forces and impulse correlate with segmental energy flow in youth baseball pitchers.
Venue: Journal of biomechanics

The purpose of this study was to determine associations between horizontal ground reaction force (GRF) kinetics and energy flow (EF) variables in youth baseball players. Twenty-four youth baseball players pitched fastballs in an indoor laboratory while motion capture and force plate data were collected. Horizontal GRF variables were extracted (peak GRF and GRF impulse) while EF was calculated by integrating magnitudes of mechanical powers transferred into and out of the pelvis, trunk, and arm segments via joint force power (JFP) and joint moment power (JMP) components. Peak propulsive GRF of the drive (back) leg correlated with EF into proximal segments, whereas peak braking GRF of the stride (lead) leg correlated with EF into distal segments. Furthermore, peak GRF of the drive leg and GRF impulse of both legs correlated with the JFP components of EF into the pelvis and trunk segments. In contrast, peak GRF and GRF impulse of the stride leg both correlated with the JMP components of EF into the arm segment. These results suggest that horizontal GRF impulse from the drive and stride leg contribute to EF between major segments of the lower and upper extremity. In addition, these results also suggest that propulsion kinetics of the drive leg play a role in transferring linear power via the pelvis and trunk segments in the throwing direction of the pitch, whereas braking kinetics of the stride leg play a role in creating rotational power that is transferred between the trunk and arm segment via the shoulder joint.
Computational musculoskeletal modeling of compensatory movements in the upper limb.
Venue: Journal of biomechanics

It is well documented that most upper limb amputees utilize compensatory movement strategies to accomplish everyday tasks when using a prosthetic device and that musculoskeletal complaints (MSCs) are more common in this population. However, little information is available on how the loss of distal degrees of freedom (DOFs) in the arm impact muscle force, thereby limiting our understanding of the mechanism by which these MSCs are manifesting. Knowledge of how a loss of DOFs may lead to MSCs can enable clinicians to provide more targeted guidance on how best to restore functional ability while addressing pain, and may serve as a tool for prescriptive decision-making when determining the impact of device selection on long-term clinical needs. 3D motion capture data were collected from 12 right-handed subjects with no upper limb disability using an 8-camera Vicon™ motion analysis system as they performed the targeted Box and Blocks test under normal and braced conditions to simulate a loss of DOFs in the wrist and fingers. Muscle force data were calculated using AnyBody Modeling Software™ for four different muscles: erector spinae, infraspinatus, deltoid, and trapezius. Linear mixed effects models were generated using the peak force data and mean force data for a given muscle fascicle. The fixed effect coefficient and 95% confidence intervals were reported for each muscle fascicle. Overall, a strong effect of condition on muscle force was seen for most muscles in the right side of the body (specifically deltoid and infraspinatus), with greater forces generated during the braced condition.
Hand-rung forces after a ladder climbing perturbation.
Venue: Journal of biomechanics

The hands are believed to be important for arresting falls from ladders. Yet, there is a paucity of kinetic data for the hand-handhold interface during recovery from a ladder climbing perturbation. This study quantified the hand-rung forces utilized after ladder climbing perturbations and the factors (upper body strength, fall severity, reestablished foot placement) contributing to hand-rung force. A ladder rung was released under the foot of the participants to simulate a climbing misstep perturbation. Hand-rung forces after the perturbation were quantified from load cells connected to two ladder rungs. Mean peak hand-rung force magnitudes were found to range between 46% and 84% of the climber's body weight. These magnitudes approached and, in some cases, exceeded individuals' grasping capacity. Individual upper body strength was not found to consistently contribute to hand-rung force, but increased hand-rung force was clearly linked with greater fall severity after an ascending perturbation. Individuals that reestablished foot placement after an ascending perturbation utilized lower hand-rung forces. Therefore, this study suggests hand-rung force to be dependent on circumstances of the falling event (fall severity, reestablished foot placement) as opposed to the climber's capability of producing upper body force. This knowledge highlights the importance of handhold and ladder designs for arresting a falling event, and is critical to inform ladder fall interventions such as designing handholds that resist high forces and permitting steps that enable reestablished foot placement.
Determining anatomical frames via inertial motion capture: A survey of methods.
Venue: Journal of biomechanics

Despite the exponential growth in using inertial measurement units (IMUs) for biomechanical studies, future growth in "inertial motion capture" is stymied by a fundamental challenge - how to estimate the orientation of underlying bony anatomy using skin-mounted IMUs. This challenge is of paramount importance given the need to deduce the orientation of the bony anatomy to estimate joint angles. This paper systematically surveys a large number (N = 112) of studies from 2000 to 2018 that employ four broad categories of methods to address this challenge across a range of body segments and joints. We categorize these methods as: (1) Assumed Alignment methods, (2) Functional Alignment methods, (3) Model Based methods, and (4) Augmented  Assumed Alignment methods, which are simple and commonly used, require the researcher to visually align the IMU sense axes with the underlying anatomical axes. Functional Alignment methods, also commonly used, relax the need for visual alignment but require the subject to complete prescribed movements. Model Based methods further relax the need for prescribed movements but instead assume a model for the joint. Finally, Augmented Data methods shed all of the above assumptions, but require data from additional sensors. Significantly different estimates of the underlying anatomical axes arise both across and within these categories, and to a degree that renders it difficult, if not impossible, to compare results across studies. Consequently, a significant future need remains for creating and adopting a standard for defining anatomical axes via inertial motion capture to fully realize this technology's potential for biomechanical studies.
The mechanical rower: Construction, validity, and reliability of a test rig for wind braked rowing ergometers.
Venue: Journal of biomechanics

Wind braked rowing ergometers are used worldwide for training and testing of rowers, but data on validity and reliability of the calculated mechanical power output are scarce. Studies published so far are based on data generated by human rowers, inevitably adding biological variability without any option to clamp particular variables like stroke structure or force. To this end, we developed a test rig for rowing ergometers aiming to generate valid and reliable stroke structures (i.e. force-displacement curves). Briefly, the rig consists out of a frame connected to the ergometer. The handlebar of the rowing ergometer is attached to a sledge that can be displaced on a linear drive by a motor that is controlled by torque curves which are derived from elite rowers. A load cell between handlebar and chain and an incremental linear transducer allow criterion measures of force and distance of displacement to calculate mechanical power output. To evaluate the validity of the machine generated force-displacement curves, three different stroke structures were compared to the respective human reference curves. To evaluate reliability, series of 50 consecutive strokes were performed for 10 times. Validity of the curves was indicated by small differences in stroke-force, -distance, and -work (≤ |-7.8|%) between machine generated and human generated curves. Mean power output of the test series was 445 ± 1 W with a coefficient of variation of 0.53% between series. Hence, the test rig allows to generate valid and reliable rowing strokes on wind braked rowing ergometers.
Effects of shelf bar assistance on kinetic control during sit-to-stand in healthy young and elderly subjects.
Venue: Journal of biomechanics

This study aimed to determine the kinetic effects of using unilateral shelf bar, vertical grab bar (GB), and horizontal GB during sit-to-stand (STS) in young and elderly subjects. Twenty young adults aged 20-40 years and eighteen healthy elderly people aged ≥ 65 years old were recruited. The subjects performed STS with and without using the three types of bars. Bar reaction force (BRF) and maximum power (MP) defined as the maximal product calculated by multiplying the GRF and the velocity of the center of mass in each direction were measured using three-dimensional motion analysis, two load sensors of GB, and four force plates. The use of the shelf bar generated a significantly larger BRF in the vertical direction than the other bars (p < 0.05) and lower MP in the vertical direction than the horizontal bar (p < 0.05) and no bar (p < 0.05). In the younger subjects, only the use of the vertical bar generated a significantly larger BRF (p < 0.05) and negative MP (p < 0.05) in the forward direction than those in elderly subjects. The use of the shelf bar may assist the decreased MP in the vertical direction during STS in elderly people, resulting in decrease of failed STS in daily living. In contrast, the use of the vertical bar in the elderly may not generate sufficient BRF in the forward direction because of lack of eccentric control in the whole body in the forward direction during STS.
Adapting a fatigue model for shoulder flexion fatigue: Enhancing recovery rate during intermittent rest intervals.
Venue: Journal of biomechanics

Although the rotator cuff muscles are susceptible to fatigue, shoulder fatigue studies reporting torque decline during intermittent tasks are relatively uncommon in the literature. A previous modification to the three-compartment controller (3CC) fatigue model incorporated a rest recovery multiplier (3CC-r model) to represent augmented blood flow to muscle during rest intervals (Looft et al., 2018). A rest recovery value of r = 15 was optimal for ankle, knee, and elbow joint regions, whereas r = 30 was better for hand/grip muscles. However, shoulder torque decline data was unavailable in the literature for comparison. Thus, the purpose of this study was to collect fatigue data for two different intermittent, isometric shoulder flexion fatiguing tasks and assess the 3CC-r model with r = 15 or 30 compared to the original 3CC model. Twenty healthy participants (9 M) completed two fatigue tasks: 50% maximum voluntary contraction (MVC) with 50% duty cycle (DC) and 70% MVC with 70% DC. MVCs were assessed at discrete time points (1, 3, 5, 10, and 15 min) until endurance time (MET). Mean observed percent torque decline (%TD) for the two tasks were compared to three model estimates: 3CC-r (using r = 15 and r = 30) and 3CC. Using these data, we confirmed that the addition of a rest multiplier (r = 15 somewhat better than r = 30) substantially improved predictions of shoulder fatigue using a previously validated analytical fatigue model (3CC). The relatively large reduction in model errors over the original model suggests the importance of representing augmented recovery during rest periods.