nils-herrmann/clean_scirepeval huggingface dataset:
ISB recommendations on the reporting of intersegmental forces and moments during human motion analysis.
Venue: Journal of biomechanics

The International Society of Biomechanics (ISB) has charged this committee with development of a standard similar in scope to the kinematic standard proposed in Wu et al. (2002) and Wu et al. (2005). Given the variety of purposes for which intersegmental forces and moments are used in biomechanical research, it is not possible to recommend a particular set of analysis standards that will be acceptable in all applications. Instead, it is the purpose of this paper to recommend a set of reporting standards that will result in an understanding of the differences between investigations and the ability to reproduce the research. The end products of this standard are (1) a critical checklist that can be used during submission of manuscripts and abstracts to insure adequate description of methods, and (2) a web based visualization tool that can be used to alter the coordinate system, normalization technique and internal/external perspective of intersegmental forces and moments during walking and running so that the shape and magnitude of the curves can be compared to one's own data.
Validation of a low-cost inertial motion capture system for whole-body motion analysis.
Venue: Journal of biomechanics

While some low-cost inertial motion capture (IMC) systems are now commercially available, generally, they have not been evaluated against gold standard optical motion capture (OMC). The objective was to validate the low-cost Neuron IMC system with OMC. Whole-body kinematics were recorded on five healthy subjects during manual handling of boxes for about 32 min while wearing 17 magnetic and inertial measurement units with Optotrak clusters serving as a reference. The kinematical model was calibrated anatomically for OMC and with poses for IMC. Local coordinate systems were aligned with angular velocities to dissociate differences due to technology or kinematical model. Descriptive statistics including the root mean square error (RMSE), coefficient of multiple correlation (CMC) and limits of agreement (LoA) were applied to the joint angle curves. The average technological error yielded 5.8° and 4.9° for RMSE, 0.87 and 0.96 for CMC and 0.4 ± 8.6° and -0.3 ± 6.0° for LoA about the frontal and transverse axes respectively, whereas the longitudinal axis yielded 10.5° for RMSE, 0.78 for CMC and 3.3 ± 13.1° for LoA. Differences due to technology and to the model contributed similarly to the total difference between IMC and OMC. For many joints and axes, RMSE stayed under 5°, CMC over 0.9 and LoA under 10°, especially for the transverse axis and lower limb. The Neuron low-cost IMC system showed potential for tracking complex human movements of long duration in a normal laboratory environment with a certain error level that may be suitable for many applications involving large IMC distribution.
Characterization of polyvinyl alcohol hydrogels as tissue-engineered cartilage scaffolds using a coupled finite element-optimization algorithm.
Venue: Journal of biomechanics

Mechanical strength along with high biocompatibility and water absorbing are among main characteristics of a desirable scaffold for cartilage tissue engineering. Having these properties, polyvinyl alcohol (PVA) can be a good option for constructing cartilage tissue engineering scaffolds. In this study, PVA hydrogel was produced by freeze-thaw crosslinking method, and its mechanical properties such as viscoelastic and hyperplastic behavior, which cannot be obtained analytically, was investigated with a coupled finite element (FE)-optimization algorithm and stress relaxation experimental data. To obtain isotropic hyper-viscoelastic constitutive parameters of PVA scaffolds, the Mooney-Rivlin and Neo-Hooke strain energy functions, in which shear and bulk moduli varies with time, were applied. Results showed that predicted mechanical responses of scaffolds by the Mooney-Rivlin model better fitted stress-relaxation experiments than those obtained by Neo-Hooke one. Also, the properties obtained from the finite element model, such as the bulk and the shear moduli, showed that, after successful in vitro and in vivo experiments, PVA hydrogel may be introduced as a cartilage substitute for future tissue engineering therapies.
Which is the best-suited landmark to assess the thoracic orientation?
Venue: Journal of biomechanics

Several skin surface-based techniques exist to non-invasively determine the spinal kinematics. However, the accuracy of these techniques is limited by soft-tissue artefacts. Furthermore, structures like the thorax are frequently assumed to be rigid but display considerable mobility within itself. This study aimed to quantify the accuracy at different thoracic landmarks for measuring mobility in healthy individuals during different activities to provide a recommendation for the best suited measurement location. The locations of 29 landmarks were continuously captured on 19 individuals (age: 25-59 years) during sitting, standing, walking, jumping, intra-thoracic motions, and different breathing depths using reflective markers. Marker triplets were used at every landmark to calculate their orientations by first backtracking the rigid-body motion (RBM) of the thorax in general, and subsequently calculating the RBM of each rigid marker triplet. Of the latter, the maximum axis angle for each exercise was statistically evaluated. Landmarks at the middle of the clavicles displayed the largest overall errors (approximately 90° during worst case scenario). However, the variability of errors among the investigated exercises was large. Landmarks at the cranial sternal region (particularly at the "Louis angle") and at the T3 spinous process showed the smallest errors for all subjects and tasks (e.g., <5° and <11°, respectively, during normal breathing). When only one sensor is to be used, it is recommended to use the cranial sternal region to assess the thoracic orientation. Study results highly sensitive to thoracic orientation should be considered with care or performed using more appropriate methods.
A novel method for measuring asymmetry in kinematic and kinetic variables: The normalized symmetry index.
Venue: Journal of biomechanics

Gait and movement asymmetries are important variables for assessing locomotor mechanics in humans and other animals and as a predictor of injury risk and success of clinical interventions. The four indices used most often to assess symmetry are not well designed for different variable types, perform poorly when presented with cases of high asymmetry or when variables are of low magnitude, and are easily influenced by small variation in the signal. The purpose of the present study was to test the performance of these indices on previously unpublished data on ACL-R patients and to propose a new index to resolve some of these limitations. The performance of four currently used indices and a new index-the Normalized Symmetry Index (NSI), which is scaled to the range of variables being tested across multiple trials-were compared using force and angular data on participants who had undergone anterior cruciate ligament reconstruction and healthy controls. The NSI performed well compared to all other indices with all variables and had the additional benefit of returning values that range from 0% (full symmetry) to ±100% (full asymmetry). Therefore, the NSI can serve as a universal index for assessing asymmetry in humans, nonhuman animal models, and in a clinical context for assessing risk for injury and clinical outcomes.
Implications of rectal preconditioning for interpretation of sensory-motor data.
Venue: Journal of biomechanics

Testing of biomechanical properties of intestine requires the tissue to be preconditioned by applying cyclic loading to obtain repeatable mechanical data. However, little is known about the mechanosensory properties during intestinal preconditioning. We aimed to study the relationship between mechanical preconditioning of the human rectum and sensory response. Three fast rectal bag distensions to the pain threshold were done in seven healthy females. A visual analog scale (VAS) was used for sensory assessment. At each distension, we determined (1) time, bag cross-sectional area (CSA), radius (r), r/r0, pressure and tension to reach VAS = 1, 3 and 5 (pain threshold); (2) the same parameters at induced contraction start; (3) CSA where the pressure started to increase (CSAP>baseline) and (4) the number of contractions. The time, CSA, r/r0 and tension to reach VAS = 1 and VAS = 3 increased from distension 1 to 3 (4.9 < F < 11.5, 0.05 > P > 0.007), primarily due to difference between the first and second distension. For VAS = 5, r/r0 was smaller in distension 3 than distension 1 (P < 0.05), whereas time, CSA and tension did not differ between distensions (P > 0.5). Compared with distension 1, CSA, r/r0 and tension at contraction start, and CSAP>baseline were bigger in distensions 2 and 3 (5.5 < F < 10.9, 0.05 > P > 0.009). The pressure to reach the VAS levels, the contraction numbers and pressure at contraction start did not differ among distensions (P > 0.6). During mechanical preconditioning, CSA, tension and deformation increased at sub-pain levels, reflecting sensory adaptation. The data point to acute remodeling of a strain-dependent mechanism in the rectal wall.
Effects of sports bra and footwear on vertebral posture during walking and running.
Venue: Journal of biomechanics

Little attention has been given to factors which affects women running, such as proper footwear and breast support and their effects on spine. The objective of study was to analyse the influence of different breast support and footwear on vertebral posture during walking and running. Seventeen women (x¯ = 23.51; SD = 3.70 years) performed a treadmill walking (5 km/h) and running (7 and 10 km/h) with different footwear (barefoot, minimalist and traditional) and breast support (bare breast, everyday bra and sports bra) conditions. Spine movements were analyzed using three cameras in grayscale video mode, positioned behind the participant to register reflective markers fixed in the vertebrae. From the 3D coordinates of the trunk markers we computed, for the whole gait cycle (C) and for the average gait posture (neutral curve-NC) the maximal (M) thoracic (T) kyphosis and lateral flexion, and the maximal lumbar (L) lordosis and lateral flexion. Frontal plane: bare breast presented higher lumbar NC than the everyday bra and sports bra, higher MLC than the sports bra and lower MTC than the everyday bra and sports bra. Barefoot presented higher MTC than minimalist. Sagittal plane: bare breast presented lower MTC than the sports bra. Barefoot presented higher lumbar NC than the minimalist and traditional footwear and higher MLC than the minimalist and traditional ones. The sports bra increased curvatures in the thoracic spine that were rectified during bare breast conditions. In addition, both footwears were able to maintain the natural curvatures of the spine in the lumbar.
Thickness, cross-sectional area, and stiffness of intrinsic foot muscles affect performance in single-leg stance balance tests in healthy sedentary young females.
Venue: Journal of biomechanics

The purpose of this study was to investigate the effect of thickness, cross-sectional area and stiffness of intrinsic foot muscles on performance in single-leg stance balance tasks in healthy sedentary young females. This study included a total of 40 healthy sedentary young females between the ages of 19 and 35 years. Single-leg stance balance assessments were carried out using Biodex Balance Systems (Biodex Medical Systems, Shirley, NY, USA). Performance in the single-leg stance balance tests was assessed using the overall stability index (OSI), mediolateral stability index (MLSI) and the anteroposterior stability index (APSI). Lower scores indicated better postural stability. Stiffness, thickness and cross-sectional area measurements of the abductor hallucis (AbH), flexor digitorum brevis (FDB) and flexor hallucis brevis (FHB) muscles were performed using an ultrasonography device. Larger AbH and FHB muscles were correlated with higher OSI, APSI, and MLSI (r = 0.31-0.46, p < 0.05), whereas larger FDB muscle was correlated with higher OSI and MLSI (r = 0.28-0.38, p < 0.05). Higher stiffness of the AbH and FHB muscles were correlated with lower OSI, APSI, and MLSI (r = -0.32 to 0.58, p < 0.05), but stiffness of the FDB muscle was not significantly correlated with OSI, APSI, and MLSI (r = 0.03-0.22, p ˃ 0.05). These results suggest that larger AbH, FDB and FHB muscles are related to reduced performance in single-leg stance balance tests, whereas higher AbH and FHB stiffness are related to better performance in single-leg stance balance tests in healthy sedentary young females.
The ability of surface electromyography to represent supraspinatus anterior and posterior partition activity depends on elevation angle, hand load and plane of elevation.
Venue: Journal of biomechanics

This study examined relationships between electromyography recorded from indwelling electrodes of the anterior and posterior supraspinatus and a surface supraspinatus electrode. Twenty male and twenty female participants completed full range humeral elevations in three planes of elevation (0/40/90°) and three hand loads (unloaded/20%/40% of maximal elevation strength). EMG activation was combined with motion capture to determine activation at instantaneous activation angles, and linear regressions of anterior and posterior indwelling electrodes relative to the surface electrode determined relationships between these signals. Regressions between surface and indwelling signals were affected by plane of elevation, elevation angle, load intensity and participant sex, but no interactions existed. Surface signals underestimated activation at low elevation angles for both regions, and up to 45% in the anterior supraspinatus (p < 0.01), then overestimated activation at higher elevation angles. Surface EMG underestimated indwelling signals by up to 15% in unloaded conditions, while overestimating the posterior region by up to 17% in the 40% load condition (p < 0.01). Sex effects showed increased overestimation by surface signals in the posterior region in males by 21% (p < 0.01). Better agreement existed for the anterior region than the posterior region across postures, but postural relationships should be considered when choosing electrodes for this muscle.
Mechanical characterization of an in-body tissue-engineered autologous collagenous sheet for application as an aortic valve reconstruction material.
Venue: Journal of biomechanics

The reconstruction of the aortic valve using glutaraldehyde-treated autologous pericardium is known as "aortic valve neo-cuspidization" (AVNeo). In-body tissue architecture (iBTA), a cell-free, in vivo tissue-engineering technology that can form autologous implantable tissues of the desired shape by subcutaneous embedding specially designed molds, was used to prepare sheet-like collagenous tissues called "Biosheets". Cylindrical molds with several line slits arranged in an alternating (n = 30) or parallel (n = 36) pattern were subcutaneously embedded in goats (n = 12) for 2 or 3 months. The tubular tissues formed in the molds were dried and then cut in the longitudinal direction, thus obtaining Biosheets (5 × 7 cm). The success rate was 97.6% when using the alternating-pattern molds and 97.2% for the parallel molds. Thickness mapping of the Biosheets showed that their entire surface, except for the line-projection portions, was smooth without any defects. The average wall thickness could be controlled over a range of ca. 0.2-0.5 mm by changing the size of the gap (0.75-1.5 mm) in the molds. The alternating slit-patterned Biosheets were found to be almost isotropic in their mechanical properties (ultimate tensile strength, fracture strain, and Young's modulus). Although the composition of the Biosheet wall was heterogeneous in terms of its density (which varied with the thickness), the breaking strength of all the alternating-patterned Biosheets increased almost linearly with the thickness within the range of the thickness of clinically used glutaraldehyde-treated pericardium as a control, and was larger than that of human aortic valve leaflets. Therefore, the alternating-patterned Biosheets have potential for use in an alternative aortic leaflet material in AVNeo.
The effects of upper airway tissue motion on airflow dynamics.
Venue: Journal of biomechanics

The human upper airway is not only geometrically complex, but it can also deform dynamically as a result of active muscle contraction and motility during respiration. How the active transformation of the airway geometry affects airflow dynamics during respiration is not well understood despite the importance of this knowledge towards improving current understanding of particle transport and deposition. In this study, particle imaging velocimetry (PIV) measurements of the fluid dynamics are presented in a physiologically realistic human upper airway replica for (i) the undeformed case and (ii) the case where realistic soft tissue motion during breathing is emulated. Results from this study show that extrathoracic wall motion alters the flow field significantly such that the fluid dynamics is distinctly different from the undeformed airway. Distinctive flow field patterns in the physiologically realistic airway include (i) fluid recirculation at the back of the tongue and cranial to the tip of the epiglottis during mid-inspiration, (ii) horizontal and posteriorly directed flow at the back of tongue at the peak of inspiration and (iii) a more homogeneous flow across the airway downstream from the epiglottis. These findings suggest that the active deformation of the human upper airway may potentially influence particle transport and deposition at the back of the tongue and therefore, highlights the importance of considering extrathoracic wall motion in future airway flow studies.
Do gait and muscle activation patterns change at middle-age during split-belt adaptation?
Venue: Journal of biomechanics

Advancing age affects gait adaptability, but it is unclear if such adaptations to split-belt perturbations are already affected at middle-age. Changes in neuromuscular control, that already start at middle-age, may underlie the age-related changes in gait adaptation. Thus, we examined the effects of age on adaptations in gait and muscle activation patterns during split-belt walking in healthy young and middle-aged adults. Young (23.3 ± 3.13 years) and middle-aged adults (55.3 ± 2.91 years) walked on an instrumented split-belt treadmill. Both age groups adapted similarly by reducing asymmetry in step length and double support time. Surface EMG was recorded from eight leg muscles bilaterally. Principal Component Analysis (PCA) was applied to the EMG data of all subjects, for the fast and slow leg separately, to identify muscle activation patterns. The principal components consisted of i.e. temporal projections that were analyzed with Statistical Parametric Mapping (SPM). The functional muscle groups, identified by PCA, increased activation during early adaptation and post-adaptation, and decreased activation over time similarly in both age groups. Extra activation peaks of the plantar- and dorsiflexors suggest a role in gait modulation during split-belt walking. Both young and middle-aged adults re-established gait symmetry and showed adaptation effects in the muscle activation patterns. Since the adaptation of muscle activation patterns parallels adaptation of gait symmetry, changes in muscle activation likely underlie the changes in step parameters during split-belt adaptation. In conclusion, split-belt adaptation, in terms of gait and muscle activation patterns, is still preserved at middle-age, suggesting that age-related differences occur later in the lifespan.
Characterizing the shoe-rung friction requirements during ladder climbing.
Venue: Journal of biomechanics

Ladder slip and falls cause negative financial and health impacts due to their severity and frequency. However, frictional requirements of climbing, which presumably influence slip risk, are unknown. The purpose of this study was to quantify frictional requirements during climbing at different ladder angles. The required coefficient of friction (RCOF) was calculated during ladder climbing and assessed for three ladder angles (75.5°, 82.8°, and 90°). Data was collected from 10 participants at each angle. Kinetic data and kinematic data of the climber's shoe was collected and used to map friction and normal forces to the shoe. These forces were then used to calculate the RCOF. The RCOF and friction force at 90° was higher than at lower angles (75.5° and 82.8°). RCOF was correlated with shoe angle and body angle supporting both the relevance of shoe orientation and body position to slip risk. This study suggests that frictional requirements of ladder climbing are dependent on ladder angle, shoe orientation, and body angle.
Biomechanists can revolutionize the STEM pipeline by engaging youth athletes in sports-science based STEM outreach.
Venue: Journal of biomechanics

Increasing diversity in the STEM (Science, Technology, Engineering, and Math) fields has become imperative to ensure equitable access to economic opportunity and to provide the technologically adept workforce of the future. The present STEM pipeline preferentially engages youth who are, not only aware of and interested in STEM, but also, can see themselves on a path to a STEM career. The present pipeline fails to capture youth for whom STEM remains remote and outside their current experience. Interest in sports casts a wider net and includes populations currently underrepresented in the STEM pipeline and in STEM careers. To engage these young people in STEM, it is necessary to incorporate STEM into activities they enjoy and already participate in, such as sports. Sports engage millions of youth who are intrinsically motivated to grow and improve as athletes. Biomechanical experiments and activities can build a bridge between young people's interest in sport activities to awareness and interest in STEM. This connection between science and sports is reinforced by the growing use of sports-science as a tool for elite athletic performance at the highest levels. The potential of sports-science to provide diverse youth with access to the STEM Pipeline is extraordinarily promising. Biomechanics researchers are uniquely positioned to deliver on the promise of sport-science based STEM outreach due to the applicability of biomechanical analysis to sports-science analysis. Historically, and not without resistance and great effort, participation in sports has broken barriers of cultural and racial discrimination within broader society. Through sports-science infused STEM outreach, biomechanists have potential to jumpstart the same process within the STEM career fields.