nils-herrmann/clean_scirepeval huggingface dataset:
On age-dependent bone remodeling.
Venue: Journal of biomechanics

A number of previous studies have investigated the possibilities of modelling the change in density of bones. Remodeling can be formulated at the constitutive or the kinematic level. In this work we introduce a formulation for the density growth process which takes not only the mechanical stimulus into account but also the influence of age on the evolution of growth. We demonstrate the implementation in the context of the finite element method. This novel approach is illustrated for a simple uniaxial extension test and is verified against previous numerical results. Moreover, two further physiologically motivated examples are performed. The results of the proposed modified model show excellent agreement with comparable results from literature and are promising for the application to real-life problems.
A combined method for binning coupling angles to define coordination patterns.
Venue: Journal of biomechanics

The vector coding technique has been used to quantify coordination of two joints, segments, and/or planes during cyclic activities, such as walking. Coordination patterns can be identified by categorizing the tangent lines of an angle-angle plot by their direction, termed "coupling angle binning" or "phase binning". In the literature the ranges of directions, or "bins", originally divided by Chang et al. and more recently by Needham et al. have different strengths. Chang's method identifies general patterns with large bins while Needham's method identifies a dominant joint or segment in the pattern. This study created a novel method that incorporates bin categories from both methods, and therefore recognizes both general patterns and a dominant contributor when appropriate. This new method, the SRC method, as well as the two existing methods, were used to quantify knee-ankle coordination in the sagittal plane for healthy individuals and an individual with clubfoot during gait. Similarities and differences in classification between methods were compared and further investigated by interpreting the uncoupled angular data. Each method was then used to evaluate sagittal-coronal coordination of the forefoot in an individual with clubfoot during gait. This was done to demonstrate across-plane coordination analysis, to confirm that the advantages of the combined method extend to coupling pairs with like ranges of motion, and to present a clinical application. It was found that the TSRH binning methods provides a more complete description of coordination by including coordination categories defined by both the Chang and Needham method.
Impact of visual signals on axial segmental control during walking in patients with vestibular disorder and healthy persons.
Venue: Journal of biomechanics

Head and trunk control during standing in patients with vestibular disorder may depend on intact visual signal to override vestibular disturbance. It is unknown if such process during walking would change. Therefore, the aims of this study were to quantify (1) head and trunk control in healthy participants (HPs) and patients with unilateral vestibular hypofunction (UVH) during walking with and without visual manipulation; and (2) the correlation/association between vestibular function and head/trunk control during walking with visual manipulation in patients. Seventeen UVH patients and 15 HPs completed all the tests. They participated in the caloric test, which was used to examine vestibular function, and walked on a treadmill with and without visual manipulation. Head and trunk angular displacement and velocity were primary outcome measures, deviation of center of mass and step variability were secondary. Head roll angular displacement (7.38° ± 1.38 [mean ± SE] v.s. 12.95° ± 1.48, p = 0.004) and head-trunk correlation (in the pitch/sagittal plane: 0.22 ± 0.05 v.s. 0.38 ± 0.05, roll/frontal plane: 0.35 ± 0.06 v.s. 0.55 ± 0.06, p < 0.05) were significantly lower in patients compared to HPs. Head pitch angular velocity (8.58°/s ± 2.17 v.s. 14.23°/s ± 1.22, p = 0.026) and step width variability (0.075 ± 0.010 v.s. 0.083 ± 0.009, p = 0.04) increased with visual manipulation only in patients. No significant correlation/association was found between vestibular function and head/trunk control. Lower head-trunk correlation in patients suggests an independent head-trunk control strategy in response to vestibular impairment. Visual input could be used by patients to compensate for vestibular disturbance for head control and foot placement. Severe UVH may not lead to worse postural control compared to mild disorder.
What is the best way to collect maximum forward lumbar spine flexion values for normalizing posture to range of motion?
Venue: Journal of biomechanics

Spine angles are an important measure in biomechanics research and are commonly normalized to a percentage of range of motion. However, standardized methods to collect the reference posture trials for this normalization do not exist. The purpose of this study was to determine posture (seated or standing) and number of trials that should be collected and how to calculate the angle that best represents the maximum range. Forty healthy adults (22 females, 18 males) completed 12 reference trials: 1 upright standing, 5 standing flexion, and 5 seated flexion trials. The maximum lumbar angle was found for each flexion trial. Additionally, different methods to calculate the maximum were applied by taking the maximum of the 5 standing, 5 seated, and all 10 flexion trials. An interaction was found between posture, order, and trial number. 42.5% and 57.5% of participants reached their maximum angle during seated and standing flexion respectively which may be due to back- vs hip-dominant movement strategies. 85% of participants achieved their maximum at some point during the first six flexion trials. The maximum angle of all 10 flexion trials was significantly greater than the angle of the first standing or seated trial only but not significantly greater than the maximum of all seated or standing flexion trials respectively. Secondarily, no differences in the maximum lumbar angle were found between sexes. This study suggests that 6 flexion trials, involving both standing and seated flexion, should be collected to best represent the maximum end range of spine flexion.
Expressing angles relative to reference postures: A mathematical comparison of four approaches.
Venue: Journal of biomechanics

Three-dimensional joint angles are most often quantified using Euler Angles. These measures are often easier to interpret if they are reported relative to a reference posture. However, since Euler Angles are not vectors, directly subtracting their values is difficult to justify mathematically. We compared four methods for subtracting a reference posture: the Subtraction Method (SM), directly subtracting the Euler Angles; two variants on the Relative Segment Method (RSM), one aligned to global (gRSM) and one aligned to the distal segment (dRSM), which considers the relative rotation of each segment to the reference posture; and the Relative Joint Method (RJM), which considers the relative rotation of the joint coordinate systems compared to that of the reference posture. One exemplar male subject (height: 175 cm; body mass: 90 kg; age: 27) performed three trials where they extended, laterally bent to the right, and extended while returning to a neutral posture between these movements. Two reference postures were compared: a standing neutral posture, and 90 degrees of flexion. All four methods showed strong agreement when the reference posture was a neutral one (lowest R2=0.971). However, when the reference posture was 90 degrees of flexion, both the RJM and gRSM swapped their lateral bend and axial twist measures. Additionally, when the reference posture was oriented 90 degrees from the global coordinate system, the gRSM swapped flexion and lateral bending. Therefore, the RJM, dRSM, and even the SM, are more robust than the gRSM. Either the RJM or dRSM are recommended as it is a compromise between mathematical validity and interpretability, however, the RJM seems to provide more readily interpretable angular velocities. The SM is only a viable approach under very strict conditions and should be avoided.
Effects of aging and target location on reaction time and accuracy of lateral precision stepping during walking.
Venue: Journal of biomechanics

Older adults have poorer lateral balance and deficits in precision stepping accuracy, but the way these deficits manifest with lateral step distance is unclear. The purpose of this study was to investigate aging effects on lateral precision stepping performance in reaction to near and distant foot placement targets during treadmill walking. We hypothesized that older adults would step to targets later and less accurately than young adults, and that these difference would be more pronounced for distant targets. During the study, young and older adults stepped on lateral targets projected onto the surface of a treadmill one stride prior to their targeting step. We measured stepping accuracy to the target, the time when the swing foot diverged from its normal swing trajectory, and swing phase gluteus medius activity. Both groups had similar performance stepping to near targets, suggesting that giving older subjects a full stride to react to target location mitigates visuomotor processing delays that have contributed to deficits in stepping performance in prior studies. However, when stepping to distant targets, older adults had larger errors and later divergence times than young adults. This suggests that age-related deficits other than those in visuomotor processing contribute to poorer performance for more difficult stepping tasks. Furthermore, while young adults increased early swing gluteus medius activity with lateral target distance, older adults did not. This is the first study to show a potential neuromuscular basis for precision stepping deficits in older adults.
A multivariate statistical strategy to adjust musculoskeletal models.
Venue: Journal of biomechanics

In musculoskeletal modelling, adjusting model parameters is challenging. This paper proposes a multivariate statistical methodology to adjust muscle force-generating parameters optimally. Dynamic residuals are minimized as muscle force-generating parameters are varied (maximal isometric force, optimal fiber length, tendon slack length and pennation angle).First, a sensitivity and a Pareto analyses are carried out in order to sort out and screen the set of parameters having the greatest influence regarding the dynamic residuals. These parameters are then used to create a response surface following a Design of Experiments (DoE) approach. Finally, this surface is used to determine the optimum levels of the design variables (muscle force-generating parameters). The proposed methodology is illustrated by the adjustment of a three-dimensional musculoskeletal model of a sheep forelimb. After adjustment, the reserve actuator values of the elbow and wrist joints were reduced, on average, by 18%, and 16%, respectively. These results demonstrate that the use of multivariate statistical strategies is an effective way to adjust model parameters optimally while reducing dynamic inconsistencies. This study constitutes a step towards a more robust methodology in musculoskeletal modelling, focusing on muscular parameter tuning.
Whole-body dynamic stability in side cutting: Implications for markers of lower limb injury risk and change of direction performance.
Venue: Journal of biomechanics

Control of the centre of mass (CoM) whilst minimising the use of unnecessary movements is imperative for successful performance of dynamic sports tasks, and may indicate the condition of whole-body dynamic stability. The aims of this study were to express movement strategies that represent whole-body dynamic stability, and to explore their association with potentially injurious joint mechanics and side cutting performance. Twenty recreational soccer players completed 45° unanticipated side cutting. Five distinct whole-body dynamic stability movement strategies were identified, based on factors that influence the medial ground reaction force (GRF) vector during ground contact in the side cutting manoeuvre. Using Statistical Parametric Mapping, the movement strategies were linearly regressed against selected performance outcomes and peak knee abduction moment (peak KAM). Significant relationships were found between each movement strategy and at least one selected performance outcome or peak KAM. Our results suggest excessive medial GRFs were generated through sagittal plane movement strategies, and despite being beneficial for performance aspects, poor sagittal plane efficiency may destabilise control of the CoM. Frontal plane hip acceleration is the key non-sagittal plane movement strategy used in a corrective capacity to moderate excessive medial forces. However, whilst this movement strategy offered a way to retrieve control of the CoM, mitigating reduced whole-body dynamic stability, it also coincided with increased peak KAM. Overall, whole-body dynamic stability movement strategies helped explain the delicate interplay between the mechanics of changing direction and undesirable joint moments, providing insights that might support development of future intervention strategies.
Reliability and sensitivity of an instrument for measuring the midfoot passive mechanical properties.
Venue: Journal of biomechanics

To assess the test - retest reliability and sensitivity of an instrument developed to measure the passive mechanical properties of the midfoot joint complex (MFJC), nine female and three male healthy young adults were evaluated in two different days by two experienced examiners. After proper participant positioning on the instrument, the left forefoot was passively moved from eversion (20°) to inversion (45°) at 2°/s, while the rearfoot and shank were kept immobile. From the instrument's sensing units (torque meter and potentiometer at 100 Hz), passive torque and angle data were registered. Passive stiffness was calculated as the instantaneous slope of the torque vs. angle curve. Therefore, the variables analyzed were resting angle, passive torques and stiffnesses during inversion and eversion through the intraclass correlation coefficient (ICC3,3), standard error of measurement (SEM) and minimal detectable change (MDC95). For the resting angle, ICC3,3 ranged from 0.85 to 0.91, SEM ranged from 1.54° to 1.95° and MDC95 ranged from 4.26° to 5.41°. For the torques, ICC3,3 ranged from 0.85 to 0.97, SEM ranged from 0.09Nm to 0.42Nm and MDC95 ranged from 0.26Nm to 1.16Nm. Finally, for the stiffnesses, ICC3,3 ranged from 0.79 to 0.98, SEM ranged from 0.01Nm/° to 0.04Nm/° and MDC95 ranged from 0.01Nm/° to 0.10 Nm/°. It can be concluded that most of the measurements presented good to excellent reliability with low measurement error. Hence, clinicians and researchers may benefit from the reliable and stable measures provided by the Foot Torsimeter when assessing patients and planning interventions.
Effect of testing temperature on the nanostructural response of tendon to tensile mechanical overload.
Venue: Journal of biomechanics

Despite many in vitro mechanical experiments of tendon being conducted at room temperature, few assessments have been made to determine how the structural response of tendon to mechanical overload may vary with ambient temperature. We explored whether damage to the collagen nanostructure of tendon resulting from tensile rupture varies with temperature. Use of bovine tail tendons in combination with NaBH4 crosslink stabilization treatment allowed us to probe the mechanisms underlying the observed changes. Untreated tendons and NaBH4-stabilized tendons were pulled to rupture at temperatures of 24, 37, and 55 °C. Of nine mechanical parameters measured from the resulting stress-strain curves, only yield stress differed between the tendons tested at 37 and 24 °C. When tested at 55 °C, untreated tendons showed large reductions in ultimate strength and toughness, while NaBH4-stabilized tendons showed smaller reductions. Differential scanning calorimetry was used to assess damage to the collagen fibril nanostructure of tendons resulting from rupture, with samples from the ruptured tendons compared to samples from the same tendons removed prior to loading. While there was indication that overload-induced molecular packing disruption to collagen fibrils may be heightened at 37 °C, statistical increases in damage compared to that occurring at 24 °C were only seen when testing was conducted at 55 °C. The results show that the temperature sensitivity of tendon to ramp loading depends on crosslinking within the tissue. In poorly crosslinked tissues, collagen may be more susceptible to mechanical damage when tested at physiologic temperature compared to room temperature. For tendons with a high density of thermally stable crosslinks, such as the human Achilles or patellar tendons, testing at room temperature should produce comparable results to testing at physiologic temperature.
The effects of fatigue on synergy of selected lower limb muscles during running.
Venue: Journal of biomechanics

The purpose of this study was to investigate the effect of fatigue on selected lower extremity muscles synergy during running using non-negative matrix factorization algorithm method. Sixteen male recreational runners participated in this study. The surface electromyographic activity of rectus femoris (RF), vastus lateralis (VL), vastus medialis (VM), biceps femoris (BF), semitendinosus, gastrocnemius medialis (GM), soleus (SO) and tibialis anterior (TA) were recorded on treadmill at 3.3 m s-1 before and after the fatigue protocol. Synergy pattern and relative muscle weight were calculated by non-negative matrix factorization (NNMF) algorithm method. The results showed that using the VAF method, five muscle synergies were extracted from the emg data during running. After the fatigue, the number of muscular synergies did not show a change, but relative weight of the muscles changed. Fatigue did not have any effect on the structure of muscular synergy, but changed the relative weight of muscles. These changes could be the strategy of the central nervous system to maintain optimal function of the motor system.
Impact of sleeping position, gravitational force & effective tissue stiffness on obstructive sleep apnoea.
Venue: Journal of biomechanics

Accurate prediction of deformation and collapse of the upper airway during breathing is required for effective and personalised treatment of obstructive sleep apnoea (OSA). While numerical modelling techniques such as fluid-structure interaction (FSI) are promising, an outstanding challenge is to accurately predict the deformation of the airway during breathing and thus the occurrence of OSA. These difficulties arise because the effective stiffness of the soft tissue in the human upper airway varies due to neuromuscular effects on the stiffness of the underlying muscles. In addition, both the elasticity and anisotropy of the soft tissues along the upper airway are poorly characterised. Finally, gravitational effects on anatomic features are yet to be considered. In this study, a validated FSI technique is introduced that allows prediction of the extent and position of the major deformation in the upper airway. This technique is used to analyse the behaviour of the upper airway in the two most common sleeping positions and for a range of effective tissue stiffnesses. The results demonstrate that sleeping position, gravity and soft tissue stiffness (used here as a proxy for neuromuscular effects) are the main factors that affect upper airway collapse. Therefore, this study provides new insights into the mechanisms of OSA and a new methodology that significantly advances the patient-specific treatment of OSA.
Relevance of sex, age and gait kinematics when predicting fall-risk and mortality in older adults.
Venue: Journal of biomechanics

Approximately one-third of elderly people fall each year with severe consequences, including death. The aim of this study was to identify the most relevant features to be considered to maximize the accuracy of a logistic regression model designed for prediction of fall/mortality risk among older people. This study included 261 adults, aged over 65 years. Men and women were analyzed separately because sex stratification was revealed as being essential for our purposes of feature ranking and selection. Participants completed a 3-m walk test at their own gait velocity. An inertial sensor attached to their lumbar spine was used to record acceleration data in the three spatial directions. Signal processing techniques allowed the extraction of 21 features representative of gait kinematics, to be used as predictors to train and test the model. Age and gait speed data were also considered as predictors. A set of 23 features was considered. These features demonstrate to be more or less relevant depending on the sex of the cohort under analysis and the classification label (risk of falls and mortality). In each case, the minimum size subset of relevant features is provided to show the maximum accuracy prediction capability. Gait speed has been largely used as the single feature for the prediction fall risk among older adults. Nevertheless, prediction accuracy can be substantially improved, reaching 70% in some cases, if the task of training and testing the model takes into account some other features, namely, sex, age and gait kinematic parameters. Therefore we recommend considering sex, age and step regularity to predict fall-risk.
Incorporation of vasculature in a head injury model lowers local mechanical strains in dynamic impact.
Venue: Journal of biomechanics

Cerebral vasculature is several orders of magnitude stiffer than the brain tissue. However, only a handful of studies have investigated its potential stiffening effect on dynamic brain strains; yet, they report contradictory findings. Here, we reanalyze the cerebrovascular stiffening effect by incorporating vasculature derived from the latest neuroimaging atlases into a re-meshed Worcester Head Injury Model using an embedded element method. Regional brain strains with and without vasculature were simulated using a reconstructed, predominantly sagittal head impact. Using the two previously adopted linear or non-linear vessel material models, we reproduced the earlier conflicting results (~40% vs. ~1-6% in regional strain reductions). Nevertheless, with refitted non-linear material models chosen to represent the average dynamic tension behaviors of arteries and veins, respectively, inclusion of vasculature reduced regional brain strains by ~13-36% relative to the baselines without vasculature. Compared to the whole brain baseline response, inclusion of vasculature led to an element-wise linear regression slope of 0.8 and a Pearson correlation coefficient of 0.8. The vascular stiffening effect appears mild for the whole brain but more significant locally, which should not be ignored in head injury models. Nevertheless, more work is necessary to investigate the cerebrovascular mechanical behaviors and loading environment to allow for more biofidelic modeling of the brain in the future.