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Biomechanical analysis has been one of the most used procedures when aiming to improve performance in sports and is also very relevant and decisive in the final classification of competitive events in sports such as gymnastics. Hence, this study sought to provide an overview of the number of scientific literature publications related to biomechanics research in gymnastics. The document search was completed in March 2023 and reflected a bibliometric analysis considering the published manuscripts up to 31 December 2022. Data collection was performed on the Web of Science, following the bibliometric analysis law, using Microsoft Excel and VosViewer Software (v1.6.19) for analysis and data processing. A total of 325 documents related to the topic under study were located. The results highlight that the older manuscripts date from 1980, with a growing trend of publications from that moment until now and a very visible increase in 2015, and that Sport Science is the category associated with more published manuscripts. A total of 30 manuscripts have 30 or more citations, 746 authors and co-authors are associated with the publications, and 58 co-authorships have published one or more studies. Moreover, 47 countries or regions have been associated with the topic under study, with the USA, England, and Australia being the countries with the most published articles and citations. The study also found that the highest frequency keywords are: "gymnastics" (n = 122), "biomechanics" (n = 73), "simulation" (n = 27), and "performance" (n = 25), considering the average year of publication of the documents, "balance" (n = 11), "artistic gymnastic" (n = 14) and "training" (n = 25) are the most frequently used terms. This study reveals that the topic of biomechanics in gymnastics has shown sustained growth and deserves the attention of the scientific community, but at the same time, there is still much room for research development. [ABSTRACT FROM AUTHOR]

Objective: The objective was to evaluate the effects of the configuration of endodontic cavities with parallel or divergent walls, versus traditional endodontic cavities, on stress distribution, fracture resistance, and fracture mode of maxillary premolars by using both fracture-strength and finite element tests. Method and materials: Thirty-two maxillary first premolars were divided into four groups (n = 8), according to the type of endodontic cavities: without endodontic cavities (control); conservative; conservative with diverging walls; and traditional. After performing root canal treatment and restoration, fracture resistance was evaluated by oblique compressive load. The stress distribution was evaluated by nonlinear finite element analysis by means of micro-computed tomography, operated at 50 kV and 800 mA. The fracture resistance data were analyzed by statistical software. Results: Higher stress concentration was observed on the coronal portion of the palatal cusp and the palatal root dentin. Stress concentration on the palatal root dentin was similar for all groups. The stress level on the palatal cusp and at the proximal crests was slightly increased in the traditional endodontic cavities group compared with conservative endodontic cavities. Stress distribution in restored teeth was similar to that of intact teeth. No significant differences were observed in the fracture resistance among different endodontic cavities' design (P = .32). All groups had values similar to those of the control group (P > .05). Conclusions: Regardless of the cavity design, conservative endodontic cavities that preserve marginal ridge integrity did not affect the resistance to fracture, failure mode, or stress distribution in maxillary premolars restored with composite resin. Endodontically treated teeth displayed biomechanical behavior similar to sound teeth. [ABSTRACT FROM AUTHOR]

Purpose: To compare rates of recurrent instability, revision surgery and functional outcomes following arthroscopic anterior capsulolabral repair for recurrent anterior instability using knot-tying versus knotless suture anchor techniques.Methods:  Patients who had undergone arthroscopic anterior labrum and capsular repair for recurrent anterior glenohumeral instability using knotless anchors were identified. Those with minimum 2-year follow-up were matched (1:2) to knot-tying anchor repair patients. Rates of failure and recurrent instability were compared, as well as Visual Analog Scale (VAS), Single Assessment Numeric Evaluation (SANE), Quick Disabilities of the Arm, Shoulder and Hand (QuickDASH), University of California Los Angeles (UCLA) and Rowe scores.Results: One hundred and two patients (89 males, 13 females) with a mean age of 24.3 ± 9.6 were included. Repair was performed with knotless anchors in 34 and knot-tying anchors in 68 shoulders. At mean follow-up of 4.8 ± 2.5 years, re-dislocation rates between groups were not significantly different (knotless anchor: 9% versus knot-tying group: 15%, n.s.), but the knot-tying group showed a higher re-subluxation rate (p = 0.039). 12 (18%) revisions were performed in the knot-tying group at a mean 2.9 years after surgery and 1 (3%) revision in the knotless anchors group at 1.4 years (n.s.). There was no difference in mean VAS with use (1.3 ± 1.9 versus 0.8 ± 1.5, n.s.), SANE scores (91.8 ± 12.7 versus 92.0 ± 11.0, n.s.), QuickDASH scores (4.1 ± 5.5 versus 3.0 ± 6.5, n.s.), UCLA Shoulder Score (32.5 ± 3.6 versus 33.2 ± 3.1, n.s.), or Rowe scores (90.5 ± 18.5 versus 92.2 ± 16.6, n.s.) between knotless and knot-tying groups, respectively. VAS at rest was higher in the knotless group (0.7 ± 1.5 vs 0.1 ± 0.4, p = 0.021).Conclusions: Knotless anchors demonstrated similar rates of re-dislocation and revision surgery, and lower rates of recurrent subluxation, compared to knot-tying anchors. Patients achieved good-to-excellent functional outcomes. This supports the efficacy of knotless anchors as an alternative to knot-tying anchors for arthroscopic anterior labral repair of recurrent anterior shoulder dislocation.Level Of Evidence: III. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the influence of cortical and cancellous bone structure on the biomechanical properties of all-suture and conventional anchors and compare the morphological bone damage after their failure. The hypothesis of the study is that all-suture anchor pullout is less invasive and that the pullout force is influenced by the cortical thickness.Methods: Thirty human humeri were biomechanically tested as follows: starting with a load cycle from 20 to 50 N, a stepwise increase of the upper peak force by 0.05 N for each cycle at a rate of 1 Hz was performed. Analysis included maximum pullout strength for three different anchor implantation angles (45°, 90°, 110°) of the two anchor types. After anchor pullout, every sample underwent micro-CT analysis. Bone mineral density (BMD) and cortical thickness were determined at the anchor implantation site. Furthermore, the diameter of the cortical defect and the volume of the bone cavity were identified.Results: The maximum pullout strength of all-suture anchors demonstrates a strong correlation to the adjacent cortical thickness (r = 0.82, p ≤ 0.05) with at least 0.4 mm needed to withstand 200 N. No correlation could be seen in conventional anchors. Moreover, no correlation could be detected for local BMD in both anchors. All-suture anchors show a significantly narrower cortical defect as well as a smaller bone cavity following pullout (4.3 ± 1.3 mm vs. 5.3 ± 0.9 mm, p = 0.037; 141 mm3 vs. 212 mm3; p = 0.009). The cortical defect is largest if the anchors are placed at a 45° angle.Conclusion: In contrast to conventional anchors, the pullout force of all-suture anchors depends on the thickness of the humeral cortex. Furthermore, all-suture anchors show a significantly smaller cortical defect as well as decreased bone damage in the case of pullout. Therefore, the clinical implication of this study is that all-suture anchors are advantageous due to their bone preserving ability. Also, intraoperative decortication should not be performed and cortical thickness should be preoperatively evaluated to decrease the risk of anchor failure. [ABSTRACT FROM AUTHOR]

Early stage Parkinson's disease (PD) shares certain symptoms with essential tremor (ET), which makes it difficult to differentiate between the two. We analyzed cyclical body bends to find kinematic parameters that are capable of differentiating among PD, ET and normal control (NC) subjects. A linear discriminant analysis of the joint angles showed a reliable distinction between NC and the two groups of patients, while differentiating reasonably well between PD and ET. PD patients showed difficulty performing hip segment rotation around the vertical axis, whereas ET patients demonstrated enlarged torso sway in the frontal plane. These findings suggest that kinematic parameters of body movement in the standing position are sensitive enough to serve as subclinical marks in the early diagnosis of PD and ET. [ABSTRACT FROM AUTHOR]

This study examined how pleasant and unpleasant emotional states influence the biomechanical organization of both forward and backward step initiation (SI). Participants (N = 31) purposely took a single step toward or away from a screen following the presentation of a pleasant (erotic), unpleasant (mutilation) or neutral (objects and landscapes) image. The main results showed that the reaction time for forward SI was shortened when individuals were exposed to pleasant pictures as compared with unpleasant pictures. The anticipatory whole-body center-of-mass velocity associated with backward SI, as well as the peak of center-of-mass velocity associated with forward SI both reached lower values when individuals were exposed to pleasant pictures as compared with neutral pictures. In contrast, unpleasant pictures did not significantly induce any change in the forward or backward SI parameters. Overall, these results obtained for whole-body approach/ avoidance-like behaviors provided mitigated support for the so-called "motivational direction hypothesis." [ABSTRACT FROM AUTHOR]

This study examined the effect of visual feedback and force level on the neural mechanisms responsible for the performance of a motor task. We used a voxel-wise fMRI approach to determine the effect of visual feedback (with and without) during a grip force task at 35% and 70% of maximum voluntary contraction. Two areas (contralateral rostral premotor cortex and putamen) displayed an interaction between force and feedback conditions. When the main effect of feedback condition was analyzed, higher activation when visual feedback was available was found in 22 of the 24 active brain areas, while the two other regions (contralateral lingual gyrus and ipsilateral precuneus) showed greater levels of activity when no visual feedback was available. The results suggest that there is a potentially confounding influence of visual feedback on brain activation during a motor task, and for some regions, this is dependent on the level of force applied. [ABSTRACT FROM AUTHOR]

Background: Decisions about the use of baby walker are in part predicated on caregivers´ beliefs about its effect on gait development. The actual effects of baby walkers, however, have not been established.Research Question: What are the effects of the use of baby walker prior to gait onset on age of acquisition of this milestone and on early walking kinematics?Methods: Thirty-two toddlers, 16 in the baby walker group (BWG) and 16 in the non-users group (BWNG), were evaluated in the week of gait acquisition and monthly up to six months after this event. Spatial and temporal gait parameters and lower limb kinematics during walking were assessed using a tridimensional motion analysis system. An independent t-test compared age of gait acquisition between groups. A mixed ANOVA examined the effects of group, moment of assessment and the group x moment of assessment interaction effect on the amplitude of joint motions during walking and on spatial and temporal gait parameters.Results: The age of gait acquisition was not different between groups. BWG had lower gait speed (specifically in the first, third, fourth, and fifth months after gait acquisition) and longer duration of stance and swing phases than BWNG. Additionally, BWG had smaller knee amplitude and greater hip amplitude in sagittal plane than BWNG in the week of gait acquisition.Significance: The results demonstrated that there is no delay in the age of gait acquisition, but there are differences in kinematics. These results can contribute to evidence-based recommendations by health care professionals about the use of baby walker by toddlers during emergence and early development of gait. [ABSTRACT FROM AUTHOR]

Background: In the immediate period following stroke, sitting balance is one of the most important predictors of functional recovery at discharge after rehabilitation. Thus, sitting balance determines the content of the early phase of stroke rehabilitation and an appropriate measurement tool is important.Research Question: The aim of this study is to investigate the concurrent validity of center of pressure (CoP) excursions of patients seated on a force plate, as well as to examine the daily variability of trunk control after stroke.Methods: Twenty stroke patients at an inpatient rehabilitation clinic underwent two assessment sessions, on average eight hours apart. Each session comprised two trials: quiet sitting for 30 s; extended reaching in forward, backward, left and right directions. The Trunk Impairment Scale (TIS) was measured during the first session. CoP excursions were measured to determine the outcomes of sway area and sway velocity during stable sitting and the maximal excursions in frontal and sagittal planes during the reaching tasks.Results: High Spearman's correlations (0.72, 0.79) were found between the TIS and the frontal and sagittal excursions. However, only low correlations between the TIS and the sway area and sway velocity were observed. Within sessions, all CoP outcomes showed high ICCs (0.73-1.00). Between sessions, high ICCs (0.86-0.93) were found except for sway velocity (ICC 0.51). Sway velocity increased significantly between sessions.Significance: Frontal and sagittal CoP excursions during reaching tasks appear to be valid measurement parameters to evaluate trunk control in patients after stroke. Only small variability was observed and no significant differences between consecutive days. [ABSTRACT FROM AUTHOR]

Background: Recovering independent walking is a priority for stroke survivors. Community walking requires speeds exceeding the average values typically achieved at discharge (0.7 m/s). To improve outcomes there is a need to clarify the factors associated with recovery of functional walking speeds.Research Question: Which biomechanical variables correlate significantly with improved walking speed following rehabilitation in acute stroke patients.Methods: The study was embedded in a larger clinical trial testing efficacy of a gait training splint. Participants, within 6 weeks of their stroke and exhibiting abnormal gait, were recruited. Using a valid and reliable video-based system, specific kinematic measures were recorded before randomisation (baseline), after a 6-week rehabilitation phase (outcome) and six months after stroke (follow-up). Measures of temporospatial symmetry, knee angular velocity and tibia to vertical angle were added to clinical measures and correlated with change in speed.Results: 23 participants were recruited, (mean age 67.7 ± 16.7 years, 19.2 ± 9.0 days after stroke and 73.9% male), with 20/23 assessed at outcome and 17/23 at follow-up. Drop out was due to withdrawal (3) and technical failure (3). Walking speed increased by 0.15 ± 0.21 m/s (outcome), and 0.21 ± 0.14 m/s (follow-up) from baseline (0.50 ± 0.20 m/s). This increase correlated with an increase in step length (r=0.88) and change in angle of tibia at initial contact (r=-0.59), foot flat (r=-0.61) and terminal contact (r=0.54).Significance: This study of gait recovery among acute stroke patients demonstrated modest improvements in walking speed. Walking speed by follow-up (0.71 m/s) classified the group as community walkers (>0.66 m/s) but still too slow to safely use a pedestrian road crossing. Change in step length and tibia to vertical angle significantly correlated with increased walking speed. This finding provides distinctive targets for therapy aimed at improving community walking among stroke survivors. This hypothesis should be tested prospectively in future studies. [ABSTRACT FROM AUTHOR]

Background: Appropriate coordination of gaze behavior and body motion is essential for navigating cluttered environments. This is often complicated by having to contend with a concurrent secondary task, like engaging in a conversation or looking for relevant landmarks. However, there is little evidence of how aging and multitasking affects how gaze is deployed during obstacle navigation to guide our movements.Research Question: How do gaze patterns differ between young and older adults when navigating around a series of obstacles under dual-task conditions?Methods: 17 young adults and 17 older adults navigated around vertically-oriented obstacles in isolation (i.e., single-task condition) and while engaging in a concurrent backward-counting or visual search task (i.e., dual-task conditions). In the visual search condition, participants had to identify the location of an object (i.e., a black shape on a tile) along the perimeter of the pathway, simulating a landmark. We quantified the spatial-temporal pattern of gaze to obstacles relative to body position, as well as the frequency and duration of gaze fixations to obstacles, route-planning features, and landmarks.Results: We found that older adults transferred gaze away from obstacles earlier and contacted obstacles more frequently than young adults. However, the proportion of fixation number and duration to obstacles did not differ between groups in any condition. In addition, older adults had to allocate gaze to landmarks to a greater extent in the visual search condition-at the expense of fixating route-planning areas-to maintain similar search performance in the dual-task condition compared to the single-task condition.Significance: Older adults use different gaze strategies and have greater difficulty under dual-tasking conditions than young adults when navigating around a series of obstacles. We suggest that deficits in visual working memory and/or divided attention may explain these results. [ABSTRACT FROM AUTHOR]

• Redistribution of GRF among the sole zones at the initial stage of SF is observed. • Changes in support afferentation signals influence the coordination of natural locomotions. • Cosmonauts prefer to walk on their toes at the initial stage of SF. • The walking pattern on the first month of SF becomes heavier. • The walking pattern on the first month of SF becomes lighter. [ABSTRACT FROM AUTHOR]

Background: Observing and analyzing movement quality (MQ) in patients with non-specific low back pain (NS-LBP) is important in the clinical reasoning of primary care physiotherapists and exercise therapists. However, there is no standardized form of assessment.Research Question: which MQ domains are measured with which instruments, and which activities are relevant, appropriate and methodologically sound for assessing MQ in patients with NS-LBP?Methods: The study had three phases. In phase 1 we conducted a systematic review in PubMed, CINAHL and SPORTDiscus of literature published until October 2018. The selected studies measured MQ domains with instruments that enabled us to 1) compare MQ in self-paced dynamic activities of patients with NS-LBP and healthy controls, and/or 2) determine change over time of MQ in patients with NS-LBP. In phase 2 we established relevant dynamic activities to assess in patients with NS-LBP. In phase 3 we determined appropriateness and methodological qualities of the selected instruments.Results: Thirty cross-sectional and three pre-post-test studies were eligible. The instruments consisted of complex (n = 19) and simple (n = 7) instrumented motion analysis systems and standardized observational tests (n = 7). We identified three domains representative for MQ: range of motion (ROM), inter-segmental coordination, and whole-body movements. In these domains, patients with NS-LBP significantly differed from healthy controls, respectively 7/12, 12/13 and 13/20 studies. Moreover, ROM and whole-body movements significantly improved over time in patients with NS-LBP (3/3 studies). Based on phase 3, we concluded that none of the instruments are appropriate to assess MQ in patients with NS-LBP in primary care.Significance: Forward bending, lifting, and walking seem the most relevant activities to evaluate in patients with NS-LBP. However, we found no suitable instruments to measure ROM, inter-segmental coordination, or whole-body movements as determinants of MQ in these activities in daily practice. We therefore recommend such an instrument be developed. [ABSTRACT FROM AUTHOR]

Background: Low back pain is among the most common health problems seen in primary care. This study aimed to evaluate the effect of a corrective exercise program on GRF components, back pain, disability score, and muscle activities in back pain patients with pronated feet during walking.Research Question: What is the effect of corrective exercise program on gait kinetics, back pain, disability score, and muscle activities in back pain patients with pronated feet during walking?Methods: Thirty-six older adults with both back pain and pronated feet volunteered to participate in this study. They were randomly divided into two equal groups (experimental and control groups). Kinetic and EMG data were recorded during both pre and posttest. Visual analog pain scale and Roland-Morris disability questionnaire were used to assess back pain and disability values, respectively.Results: In the experimental group but not in the control group, walking speed was significantly increased from pre to posttest (p = 0.001). The loading rate and free moment values were similar during both the pre and posttest (p > 0.05). In the experimental group but not in the control group, the disability score, back pain, tibialis anterior activity, and rectus abdominis activity were decreased during the posttest than that in the pretest (p < 0.001).Significance: Higher walking speed, lower muscle activity and pain, lower disability score along with similar loading rate and free moments in the experimental group compared with the control group after the training protocol demonstrate the improvement of gait efficiency. [ABSTRACT FROM AUTHOR]

Background: The Wartenberg pendulum test is a common clinical test that is used to measure stiffness about the knee in persons with and without disabilities such as cerebral palsy and Down syndrome (DS). Adults and adolescents with DS show fewer number of swing cycles and a lower relaxation index than healthy controls. However, it is not clear if children with DS show a similar trend compared to typically developing (TD) children.Research Question: Was the knee joint kinematics different between children with and without DS during the pendulum test?Methods: Thirteen children with DS and 13 TD children participated in this study. There were two load conditions: no load (NL) and with ankle load (AL) equal to 2 % of the subject's body weight. Five trials of a pendulum test were collected for each condition.Results: The DS group showed a smaller first flexion excursion, a lower relaxation index, lower mean and peak velocities and accelerations during the first and second flexion and extension, and greater variability of acceleration during the first flexion than the TD group across both load conditions. This suggests that the DS group may have greater stiffness of the knee than the TD group to compensate for joint instability.Significance: The pendulum test appears to be a valid test to evaluate the passive stiffness of the knee in children with DS. The lower relaxation index in children with DS suggests that larger bursts of quadriceps may be activated during a pendulum test, particularly in the first flexion excursion, to assure the knee joint stability. [ABSTRACT FROM AUTHOR]

Background: When stepping down from a raised surface, either a toe or heel contact strategy is performed. Increased vertical momentum is likely to be experienced during a step descent, yet the extent to which these descent strategies influence the development of load at the ground and knee has not been examined.Research Question: Does descent strategy influence ground and knee joint loading? Does the contribution from leading and trailing limb joint mechanics differ between descent strategies?Methods: Twenty-two healthy male participants (age: 34.0 ± 6.5 years, height: 179 ± 6.3 cm, mass: 83.5 ± 13 kg) walked along a raised platform, stepped down from a 14 cm height utilising either a toe (n = 10) or heel (n = 12) initial contact, and continued walking. Vertical ground reaction forces and knee external adduction and flexor moments were extracted for the duration of the braking phase. Joint work was calculated for the ankle, knee, and hip in both the leading and trailing limbs.Results: Waveform analysis of the loading features indicated that a toe-contact strategy resulted in significantly reduced loading rates during early braking (1-32% of the braking phase) and significantly increased magnitude in late braking (55-96% of the braking phase). Individuals performing toe landings completed 33% greater overall work (p = 0.091) in the lead limb and utilised the lead limb ankle joint as the main shock absorber (79% of total lead limb work). Concurrently, the trailing limb performed 29% and 21% less work when lowering the centre of mass and propulsion, respectively, compared to a heel landing.Significance: A toe-contact strategy results in reduced limb and knee joint loading rates through greater utilisation of the lead limb ankle joint. A heel-contact strategy, however, can reduce loading during late braking by utilising the functionality of the trailing limb. [ABSTRACT FROM AUTHOR]

Background: Describing the response of spatiotemporal gait characteristics, and related variables such as variability and stiffness, to different stressors is important to better understand spring-mass model.Research Question: This study aimed to examine the effect of fatigue induced by a running protocol on spatiotemporal gait parameters, step variability and vertical (Kvert) and leg stiffness (Kleg) during running on a treadmill.Methods: Twenty-two trained male endurance runners performed a 60-min time trial run. An analysis of spatiotemporal parameters (contact time [CT], flight time [FT], step frequency [SF] and step length [SL]), step variability (in terms of coefficient of variation [CV]) and stiffness was conducted in two different conditions: non-fatigued (before the protocol) and fatigued (after the protocol).Results: The pairwise comparisons (i.e., non-fatigued vs. fatigued condition) indicated that temporal parameters (i.e., CT and FT) experienced significant changes (p = 0.001 and <0.001, respectively). Step variability increased in presence of fatigue, with higher CV in CT (p = 0.039), FT (p = 0.005), SF (p = 0.046) and SL (p = 0.027) after the running protocol. The Kleg experienced a reduction in the fatigued condition (p < 0.001) whereas the Kvert remained unchanged (p = 0.602).Significance: The results indicate that fatigue induced by a 60-min time trial run causes some adaptations in spatiotemporal gait characteristics and stiffness in trained endurance runners. Specifically, in the presence of fatigue, the athletes showed greater CT and shorter FT, higher step variability and lower leg stiffness. [ABSTRACT FROM AUTHOR]

Background: Knee osteoarthritis is a disease of the joint causing decreased function and pain. Currently, treatments range from medication to surgery, with the use of different insoles and footwear recommended. These methods are effective by either correcting the position of the knee or providing shock absorption. However, there is little understanding of the effective characteristics of these devices.Research Question: This paper aims to investigate this question and provide future areas of research to help better define treatment guidelines. Foot orthoses are an example of non-pharmacological conservative treatments mentioned in National Institute for Health and Care Excellence (NICE) guidelines to treat knee osteoarthritis (OA). These include lateral wedge insoles (LWI), developed with the intention of load reduction of the knee. Different footwear has also been shown to affect pain, biomechanical and functional outcomes in knee OA patients.Methods: To address what features of LWIs and footwear make them effective in the treatment of knee OA, scientific databases were used to search for papers on this topic and then selected to be included based on pre-defined criteria. Data were extracted and analysed from these studies to provide a basis for possible areas for future development of these foot orthoses, and research required to improve clinical treatment guidelines. Databases used were PubMed, Scopus and Web of Science.Results and Significance: Thirty-four out of 226 papers were included after application of inclusion and exclusion criteria. Regarding LWIs, the characteristics showing the most beneficial effect on either biomechanical, functional or pain outcomes were customisation, full-length, 5° elevation, shock absorption and arch support. For footwear, barefoot mimicking soles produced the most favourable biomechanics. Results also showed that insoles work in correcting the position of the knee, but it may or may not affect patients' pain and function. [ABSTRACT FROM AUTHOR]

Background: Anterior cruciate ligament (ACL) injury often occurs during deceleration maneuvers in sports. Combined knee valgus and tibial internal rotation (VL + IR) moments have been recognized as a risk leading to ACL injury; however, it is unknown how the foot strike pattern (forefoot or rearfoot strike) affects the occurrence rate of the aforementioned combined knee moments during cutting maneuvers.Research Question: To test the hypothesis that rearfoot strikes rather than forefoot strikes show a significantly higher occurrence rate of the combined VL + IR moments during the early stance phase of a cutting maneuver.Methods: Twenty-four females performed 60° cutting maneuvers under rearfoot and forefoot strike conditions. Positional data of lower limb markers and ground reaction force (GRF) were collected. Knee varus/valgus and tibial internal/external rotation moments due to GRF were calculated and time-normalized (0-100 %) to the stance phase. The occurrence rates of combined VL + IR moments were compared between rearfoot and forefoot strike conditions throughout the stance (chi-squared test, p < 0.01). Furthermore, the time patterns of the two knee moments and the position of the GRF acting point were compared using the statistical parametric mapping paired t-test (p < 0.0125).Results: Rearfoot strikes more frequently produced combined VL + IR moments than forefoot strikes (maximum occurrence rates: 73.5 % vs. 27.8 %, p < 0.01) during the first 0-40 % of the stance. Both foot strikes consistently showed an increase in knee valgus moment soon after foot impact; however, rearfoot and forefoot strikes respectively applied opposite internal and external rotation moments during the first 0-7 % of stance (p < 0.0125), indicating that the GRF vector that generated knee valgus moment further applied tibial internal rotation moment when it acted posterior to the tibial rotation axis.Significance: The current results suggest that rearfoot strike in cuttings elevates the probability of ACL injury via combined VL + IR moments. [ABSTRACT FROM AUTHOR]

Background: Naturally aligned toes, particularly hallux, have reported with gripping functions during locomotion, thus expanding the forefoot loading area.Research Question: The purpose of this study was aimed to investigate the influence of hallux abduction manipulation on the foot plantar pressure distribution and inter-segment kinematic alterations.Methods: Thirteen subjects participated in this toe manipulation study. A Footscan® pressure plate and Vicon motion capture system were utilized for the measurement of plantar pressure distribution and lower extremity and foot inter-segment kinematics during walking and running. Paired-sample t-test from statistical parametric mapping 1d was used to check the kinematic significance.Results: Peak pressure in third metatarsal (M3) increased significantly during walking under manipulation. Contact area increased in second metatarsal (M2) with manipulation during running. Peak pressure and pressure-time integral illustrated significant increases in M3, and the maximum force and impulse in fourth metatarsal (M4) increased significantly. Arch height index increased while walking with toe manipulation. The foot progression angle in the frontal plane showed significant decrease in mid-swing phase during walking and significant increase in mid-stance phase during running. The hallux relative to forefoot angles presented higher axial rotation in the frontal plane.Significance: Findings form this study showed centrally and laterally redistributed foot loadings and increased forefoot inter-segment flexibility with manipulation, which may be used as baseline to evaluate toe-manipulation interventions in foot disorders, specifically hallux valgus deformity. [ABSTRACT FROM AUTHOR]

Background: Individuals with neck pain have different movement and muscular activation (collectively termed as biomechanical variables) patterns compared to healthy individuals. Incorporating biomechanical variables as covariates into prognostic models is challenging due to the high dimensionality of the data.Research Question: What is the classification performance of neck pain status of a statistical model which uses both scalar and functional biomechanical covariates?Methods: Motion capture with electromyography assessment on the sternocleidomastoid, splenius cervicis, erector spinae, was performed on 21 healthy and 26 individuals with neck pain during walking over three gait conditions (rectilinear, curvilinear clockwise (CW) and counterclockwise (CCW)). After removing highly collinear variables, 94 covariates across the three conditions were used to classify neck pain status using functional data boosting (FDboost).Results: Two functional covariates trunk lateral flexion angle during CCW gait, and trunk flexion angle during CW gait; and a scalar covariate, hip jerk index during CCW gait were selected. The model achieved an estimated AUC of 80.8 %. For hip jerk index, an increase in hip jerk index by one unit increased the log odds of being in the neck pain group by 0.37. A 1° increase in trunk lateral flexion angle throughout gait alone reduced the probability of being in the neck pain group from 0.5 to 0.15. A 1° increase in trunk flexion angle throughout gait alone increased the probability of being in the neck pain group from 0.5 to 0.9.Significance: Interpreting the physiological significance of the extracted covariates, with other biomechanical variables, suggests that individuals with neck pain performed curvilinear walking using a stiffer strategy, compared to controls; and this increased the risk of being in the neck pain group. FDboost can produce clinically interpretable models with complex high dimensional data and could be used in future prognostic modelling studies in neck pain research. [ABSTRACT FROM AUTHOR]

Background: Pregnant women experience numerous physiological and biomechanical alterations which may be associated with their increased risk of experiencing a fall. Gait alterations in other populations who fall include increased step width and mediolateral trunk motion. It is not known if pregnant women who have fallen exhibit these alterations.Research Question: Our purpose was to examine torso kinematics and step width during gait in pregnant fallers, pregnant non-fallers and non-pregnant controls. We also examined trunk anthropometry in the pregnant groups to determine if pregnant fallers have different trunk physiques than pregnant non-fallers.Methods: 3D kinematic data were collected on 14 pregnant fallers, 15 pregnant non-fallers and 40 non-pregnant controls. Pregnant women were in their second or third trimester of pregnancy. Frontal plane translations of C7 and L4, step width, stride length, walking velocity, and 3D thoracic and pelvic kinematics were determined. Anthropometric torso measurements were obtained on the pregnant women. A series of MANCOVAs was performed (covariate: walking velocity, α = 0.05) to compare the dependent variables between pregnant fallers, pregnant non-fallers, and controls. Tukey post-hoc analyses were performed when appropriate (α = 0.05). A MANOVA compared anthropometric variables between pregnant fallers and non-fallers (α = 0.05).Results: Pregnant non-fallers exhibited greater step width and frontal and transverse plane angles at heel contact and range of motion over the gait cycle when compared to the fallers. Trunk anthropometry did not differ between pregnant fallers and non-fallers.Significance: Pregnancy-associated gait alterations differed between fallers and non-fallers. Greater step width of the pregnant non-fallers increased the base of support, thus increasing stability. Exercise participation may allow pregnant women to better adapt to their altered physiques and be more able to prevent a fall should a trip or slip occur. [ABSTRACT FROM AUTHOR]

Background: Abnormalities in gait kinetics in patients with Parkinson's disease (PD) who have suffer from gait impairment have been noted using a conventional inverse dynamic analysis derived by marker-based motion capture system and force plate, which are typically mounted in the laboratory floor. Despite the high accuracy of this approach in tracking markers' trajectories and acquiring ground reaction forces (GRFs), its dependence on laboratory-mounted equipment restricts its potential use in wider variety of clinical applications.Research Question: Would a full-body musculoskeletal model driven by a single depth sensor data only produce comparable gait kinetic parameters, including GRFs and lower extremity joints moments, for elderly participants, both healthy and those diagnosed with PD?Methods: Nine patients diagnosed with PD and 11 healthy age-matched control participants performed three over-ground gait trials. Full-body kinematic data were collected using a depth sensor and a musculoskeletal model have been constructed using AnyBody musculoskeletal modeling system to predict the three-dimensional GRFs and lower extremity joint moments. Predicted kinetic parameters for both PD and control groups were compared during the braking and propulsive phases of the gait cycle. In addition, ensemble curve analysis with 90% confidence intervals were constructed to compare between group differences across the stance phase of the gait cycle.Results: The findings of this study showed that the PD exhibited a significantly lower braking peak vertical GRF and propulsion peak horizontal GRF while no significant between-group differences were found in peak lower extremity joint moments. However, the PD showed significant alterations in lower extremity joint moments during the early and late phases of stance, which indicate a difference in ambulation strategy.Significance: The proposed method adopting full-body musculoskeletal model driven by a depth sensor data proves that it has the potential to be a portable and cost-effective gait analysis tool in the clinical setting. [ABSTRACT FROM AUTHOR]

Background: Prosthetic alignment directly affects the biomechanical loading in individuals with lower-limb amputation, and improper alignment may be contribute to the high incidence of hip and knee osteoarthritis (OA). The biomechanical changes caused by different alignments should be considered in prosthetic fitting. However, the quantitative effect of alignment on the kinetic features of individuals with transfemoral amputation remains unclear.Research Question: As important kinetics indexes, how are the hip and knee joint moments affected by prosthetic alignment in individuals with transfemoral amputation?Methods: Gait tests of ten individuals with transfemoral amputation and fifteen individuals without amputation (control group) were performed. Several prosthetic alignment conditions were used, including the so-called "initial" alignment and eight malalignments. The hip and knee joint moments of the individuals with amputation under various alignments were analysed and compared with those of the control group. Statistical analyses were performed by one-way ANOVA, repeated measure multivariate ANOVA, and paired t tests.Results: The peaks and impulses of the hip abductor and external rotator moments on the residual side were significantly smaller than those of the control group (P < 0.0056). The peaks of the hip extensor, adductor and external rotator moments on the intact side were significantly larger than those on the residual side (P < 0.05). Alignment significantly affected the intact hip and knee joint moments for each individual with amputation (P < 0.00625), but there was no consistent effect among individuals.Significance: The significantly larger hip joint moment on the intact side of individuals with transfemoral amputation may be associated with the higher incidence of hip OA on the intact side. Alignment significantly affects the hip and knee joint moments of each individual with transfemoral amputation, but the individual responses to alignment changes are different. This situation may imply that the method for optimizing alignment should be personalized. [ABSTRACT FROM AUTHOR]

Background: Sex and obesity may influence knee biomechanics associated with poor outcomes following primary total knee arthroplasty (TKA) however their long-term impact has not been investigated.Research Question: Does sex and/or pre-operative obesity influence change in gait biomechanics from pre-TKA to two-years after TKA, and do knee biomechanics return to normal two-years after TKA?Methods: In this longitudinal study, gait analysis was performed on 78 patients undergoing TKA for knee osteoarthritis prior to surgery (baseline), and on 66 (85 %) of these who returned at the two year follow-up. Gait biomechanics were also collected on a reference sample of 40 asymptomatic participants. Knee variables were analyzed according to time (pre- and post-TKA), sex (men and women), pre-operative obesity (obese vs non-obese), and group (TKA vs reference). Mixed linear regression models were used to examine the effects of TKA, obesity status, gender and all interactions.Results: There were two-year reductions in peak knee frontal plane angle (mean difference -7.21°; 95% confidence intervals -9.37 to -5.05), peak knee adduction moment (KAM) (-17.64Nm; -23.04 to -12.24) and KAM impulse (-9.40Nm.s; -12.04 to -6.77) in males. These and other variables were unchanged in women. At two years, men exhibited a greater varus-valgus thrust excursion (4.9°; 2.7-7.2), and a lower peak knee frontal plane angle (-4.4°; -7.1 to -1.7) and peak KAM (-13.1Nm; -20.9 to -5.4), compared to the reference sample. Biomechanics at two years did not differ between pre-operative obesity subgroups, or between female TKA patients and the reference sample.Significance: Changes in gait biomechanics two years after TKA are influenced by sex but not obesity. Men but not women showed altered knee biomechanics two years following TKR and compared to a reference sample. It is unknown whether these altered biomechanics in men impact longer term clinical outcomes and satisfaction following surgery. [ABSTRACT FROM AUTHOR]

Background: Posterior tibial tendon dysfunction (PTTD) is a common and debilitating tendinopathy that can lead to a profound decrease in gait function. While the clinical diagnosis and treatment of this disorder are well described, the pathomechanics have not been adequately characterized. The purpose of this systematic review and meta-analysis is to compare foot/ankle kinematics and kinetics in patients with PTTD with healthy controls during gait.Methods: Relevant articles were selected thought Medline (Pubmed), Scopus, CINAHL, and Web of Science. Studies focused on foot/ankle kinematics and kinetics in patients with PTTD were involved. Articles were included if they: 1) compared patients with PTTD to healthy controls, 2) utilized kinematics or kinetics as the primary outcome measure, 3) evaluated gait tasks, and 4) were written in English.Results: Eleven articles were included in this systematic review, and 8 studies were synthesized and analyzed. Our meta-analyses indicated increased dorsiflexion and abduction of the forefoot, as well as increased plantarflexion and eversion of hindfoot for patients with PTTD during stance of walking.Conclusion: Our results from the meta-analysis showed more conclusive changes in the forefoot (increased dorsiflexion and abduction) and hindfoot (increased plantarflexion and eversion) kinematics during stance of walking, which may be associated with a pathological process of PTTD. This review provides an improved understanding of gait function in patients with PTTD and preliminary knowledge for future research. [ABSTRACT FROM AUTHOR]

Background: Pedobarography is a commonly used testing procedure in clinical gait analysis, yet has limited roles in quantification for treatment planning, outcome assessment, and classification. Spatial registration between plantar pressure and motion capture data allows for accurate quantitative assessment and metric development based on a typically developing cohort.Research Question: This study assesses the validity of new center of pressure based metrics of anatomically registered pedobarography data by evaluating kinematic relationships over a broad spectrum of feet and by evaluating the sensitivity of these metrics to pathologies, interventions, and outcomes in two common clinical foot pathologies.Methods: 3D trajectories from retroreflective markers were recorded to establish a single foot axis simultaneous with plantar pressure mat data spatially calibrated to a global coordinate system. Indices for clinical populations were determined as mediolateral (MLI, |MLI|, MFI) and anteroposterior (API, |API|) deviations of center of pressure excursions from typically developing feet. 198 feet were retrospectively identified to evaluate relationships between mediolateral (ML) indices and foot kinematics over a spectrum of foot pathologies. Additional feet from two broad pathologic foot types, planovalgus (PV) and cavovarus (CV), were assessed pre and post-surgery to determine sensitivity to pathology, surgical intervention, and outcomes.Results: ML indices and supination were highly correlated (r2 > 0.5). Two mediolateral indices (MLI, MFI) and one anteroposterior index (|API|) demonstrated significant differences between typical and PV feet, with the MFI index also exhibiting significant improvement with surgery. All three mediolateral indices and |API| demonstrated differences between typical and cavovarus feet, with |API| significantly improving with surgery. Changes in API also correlated with patient goals.Significance: Spatial registration between plantar pressure center of pressure and motion capture data allows calculation of indices that reflect foot function and are sensitive to foot pathologies and treatment outcomes. [ABSTRACT FROM AUTHOR]

Assessing movement skills is a fundamental issue in motor development. Current process-oriented assessments, such as developmental sequences, are based on subjective judgments; if paired with quantitative assessments, a better understanding of movement performance and developmental change could be obtained. Our purpose was to examine the use of inertial sensors to evaluate developmental differences in hopping over distance. Forty children executed the task wearing the inertial sensor and relevant time durations and 3D accelerations were obtained. Subjects were also categorized in different developmental levels according to the hopping developmental sequence. Results indicated that some time and kinematic parameters changed with some developmental levels, possibly as a function of anthropometry and previous motor experience. We concluded that, since inertial sensors were suitable in describing hopping performance and sensitive to developmental changes, this technology is promising as an in-field and user-independent motor development assessment tool. [ABSTRACT FROM AUTHOR]

The purpose of this study was to examine the effects of interpersonal synchronization of stepping on stride interval dynamics during over-ground walking. Twenty-seven footswitch instrumented subjects walked under three conditions: independent (SOLO), alongside a partner (PAIRED), and side by side with intentional synchronization (FORCED). A subset of subjects also synchronized stepping to a metronome (MET). Stride time power spectral density and detrended fluctuation analysis revealed that the rate of autocorrelation decay in stride time was similar for both the SOLO and PAIRED conditions, but was significantly reduced during the FORCED and MET conditions (p=0.03 & 0.002). Stride time variability was also significantly increased for the FORCED and MET conditions (p<0.001). These data suggest that forced synchronization of stepping results in altered stride interval dynamics, likely through increased active control by the CNS. Passive side by side stepping, where synchronization is subconscious, does not appreciably alter stepping in this manner. [ABSTRACT FROM AUTHOR]

This study investigated the nature of the structural variations found in the motor output of individuals with Parkinson's disease (PD). Young (n = 21; 19.9 ± 1.3 yrs.), aged (n = 9; 74.8 ± 6.8 yrs.) and individuals with PD (n = 9; 73.4 ± 6.6 yrs.) swung their leg at a pendular frequency and frequencies that were 20% faster and slower. This study had three key findings. First, individuals with PD have greater variability in the leg swing angular kinematics and swing times. These variations appear to be related to the 0-15 Hz band of the of angular displacement power spectrum. Second, changes in the structural variations appear to not be derived from a stochastic source. Third, the magnitude of the variations and the structure of the variations are influenced by the frequency that the leg is swung. These results are consistent with the viewpoint that changes in the magnitude of the variations and the regularity of the structural variations are dependent upon health and adaptability to the task dynamics. [ABSTRACT FROM AUTHOR]

Previous studies on sequential effects of human grasping behavior were restricted to binary grasp type selection. We asked whether two established motor control strategies, the end-state comfort effect and the hysteresis effect, would hold for sequential motor tasks with continuous solutions. To this end, participants were tested in a sequential (predictable) and a randomized (nonpredictable) perceptual-motor task, which offered a continuous range of posture solutions for each movement trial. Both the end-state comfort effect and the hysteresis effect were reproduced under predictable, continuous conditions, but only the end-state comfort effect was present under nonpredictable conditions. Experimental results further revealed a work range restriction effect, which was reproduced for the dominant and the nondominant hand. [ABSTRACT FROM AUTHOR]

On the basis of simulations carried out with a finite element biomechanical model of the face, the influence of the muscle stress stiffening effect was studied for the protrusion/rounding of the lips produced with the Orbicularis Oris (OO). It is shown that the stress stiffening effect influences lip shape. When stress stiffening is modeled, the variation in the crucial geometrical characteristics of the lips shows a clear saturation effect as the OO activation level increases. Similarly, for a sufficient amount of OO activation, a saturation effect is observed when stiffening increases. In both cases, differences in lip shaping associated with the absence or presence of stiffening have consequences for the spectral characteristics of the speech signal obtained for the French vowel /u/. These results are interpreted in terms of their consequences for the motor control strategies underlying the protrusion/ rounding gesture in speech production. [ABSTRACT FROM AUTHOR]

This paper presents a comparative conceptual review of speech and limb motor control. Speech is essentially cognitive in nature and constrained by the rules of language, while limb movement is often oriented to physical objects. We discuss the issue of intrinsic vs. extrinsic variables underlying the representations of motor goals as well as whether motor goals specify terminal postures or entire trajectories. Timing and coordination is recognized as an area of strong interchange between the two domains. Although coordination among different motor acts within a sequence and coarticulation are central to speech motor control, they have received only limited attention in manipulatory movements. The biomechanics of speech production is characterized by the presence of soft tissue, a variable number of degrees of freedom, and the challenges of high rates of production, while limb movements deal more typically with inertial constraints from manipulated objects. This comparative review thus leads us to identify many strands of thinking that are shared across the two domains, but also points us to issues on which approaches in the two domains differ. We conclude that conceptual interchange between the fields of limb and speech motor control has been useful in the past and promises continued benefit. [ABSTRACT FROM AUTHOR]

This study explored the functional movement task of stepping up and over an obstacle in individuals with Parkinson's disease to their aged-matched controls. Ten participants with Parkinson's disease and 10 aged matched participants were assessed on the Step Up/Over task completed on a NeuroCom EquiTest long force-plate and analyzed using Group MANOVAs. The results indicate that individuals with Parkinson's disease produce less lifting force and exhibited an increased time to complete the task of stepping up and over an object when compared with their aged matched peers. Considering the substantial risk of falls demonstrated in this population these preliminary finding demonstrate the need for interventions aimed at improving this component of function. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study was to analyze and compare the implant-bone interface stresses in anisotropic three-dimensional finite element models of an osseointegrated implant with platform switching and a conventional matching-diameter implant platform and abutment in the posterior maxilla. Materials and Methods: Three-dimensional finite element models were created of a first molar section of the maxilla and embedded with a single endosseous implant (4.1 × 10 mm). One model simulated a 4.1-mm-diameter abutment connection and the other was a narrower 3.4-mm-diameter abutment connection, ie, simulating a platform-switching configuration. A gold alloy crown with 2-mm occlusal thickness was applied over the titanium abutment. Material properties of compact and cancellous bone were modeled as fully orthotropic and transversely isotropic, respectively. Oblique (200-N vertical and 40-N horizontal) occlusal loads were applied and perfect bonding was assumed at all interfaces. Results: Maximum von Mises, compressive, and tensile stresses in compact bone were lower in the platform-switching model than in the conventional model. However, the maximum von Mises stress in cancellous bone was higher in the platform-switching model than in the conventional model. Conclusion: The platform-switching technique reduced the stress concentration in the area of compact bone and shifted it to the area of cancellous bone during oblique loading. [ABSTRACT FROM AUTHOR]

Purpose: To investigate the influence of framework materials with different elasticity moduli on the biomechanical performance of fixed partial dentures (FPDs).Materials and Methods: A tooth-anchored three-unit FPD and surrounding tissues were modeled in two variants (veneered/full anatomical FPD) and loaded on the central unit. Three different framework materials (titanium, zirconia, high-performance polymer) were simulated.Results: The polymer framework resulted in reduced framework stresses and increased veneering stresses. Varying the framework material had minimal influence on the loading of surrounding tissue.Conclusions: Using soft, novel materials as framework for dental FPDs does not negatively influence biomechanical loading of the involved biologic structures. [ABSTRACT FROM AUTHOR]

Purpose: The objective of this study was to investigate the time-dependent biomechanics of marginal bone around osseointegrated dental implants within physiologic loading conditions. Materials and Methods: The remodeling of marginal bone around a 4.1-mm-diameter, 10-mm-long implant was studied by implementing the Stanford theory into axisymmetric mathematical models simulating different bone support at the implant neck: 1-mm-thick cortical bone (model 1), 0.5-mm-thick cortical bone (model 2), absence of cortical bone (model 3), and absence of cortical bone with 0.5 mm of resorption of marginal trabecular bone (model 4). The results were examined separately for all models at five time intervals: the first loading after osseointegration and 3, 6, 9, and 12 months after osseointegration. Minimum principal stress, maximum principal stress, strain energy, total equivalent strain, displacement, average elastic modulus, and bone density were evaluated. Results: In models 1 and 2, the magnitude of the stresses increased during the 1-year period. The distributions of stresses in models 3 and 4 were less variable and lower than models with cortical bone. The region of high stresses enlarged during the first 3 months and then decreased over time. There was a time-dependent increase in strain energy density around the neck of the implant in models 1 and 2. The time-dependent displacement values of implants were almost constant over time (maximum 1 μm change). The lowest implant displacement values were observed in model 1. There was a slight increase in the elastic modulus of cortical bone and a decrease in trabecular bone (maximum 1% change). Conclusion: The time-dependent increase in stresses in the marginal zone of the implants with cortical bone support was higher than that of the implants supported solely by trabecular bone in the first year of function. Higher strain energy density around the implants with cortical bone support might indicate apposition and increase in interface stiffness, whereas lower strain energy density around implants supported solely by trabecular bone could be associated with skeletal tissue loss. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study was to investigate the physiological demands of field players in international women's water polo match play. Methods: Video footage was collected at the 13th FINA Women's Water Polo World Cup in Perth in 2002. Video recordings were analyzed using a simple hand-based notation system to record predefined activity durations, frequencies, and corresponding subjective intensities. Results: Average exercise bout duration was 7.4 ± 2.5 s and exercise to rest ratio within play 1:1.6 ± 0.6. The average pattern of exercise was represented by 64.0 ± 15.3% swimming, 13.1 ± 9.2% contested swimming, 14.0 ± 11.6% wrestling, and 8.9 ± 7.1% holding position. Significant differences existed between outside and center players for percentage time swimming (67.5 ± 14.0% vs 60.2 ± 13.3%, P = .002) and wrestling (9.9 ± 9.3% vs 18.4 ± 11.1%, P = .000). A significant difference was found in the number (P = .017) and duration (P = .010) of high-intensity activity (HIA) bouts performed each quarter for outside (1.8 ± 2.2 bouts, 7.0 ± 3.4 s) and center players (1.2 ± 1.5 bouts, 5.2 ± 3.4 s). Positional differences in HIA were the result of a significant difference (P = .000) in the number of maximal/near maximal swims (outside 1.2 ± 1.5 and center 0.5 ± 0.9 per quarter). Conclusions: This study characterizes international women's water polo match play as a highly intermittent activity. Swimming, particularly high intensity, has greater significance to outside players, whereas wrestling has greater significance to center players. [ABSTRACT FROM AUTHOR]

Ground reaction force patterns during walking were observed in 18 children 3 and 4 years of age. The children walked barefoot at a self-chosen walking pace. Selected variables representing the vertical, anteroposterior, and mediolateral force components were evaluated. The results indicated that children in this age range contact the ground with greater vertical force measures relative to body mass than do adults. In addition, the minimum vertical force was lower, the transition from braking to propulsion occurred earlier, and the mediolateral force excursions were higher than typically found in adults. When the children were divided into groups on the basis of sex, differences were observed between those groups. The boys exhibited a greater difference in he vertical peak forces, a lower minimum force, a greater braking force, and a higher mediolateral force excursion value. The results indicated that children display a different ground reaction force pattern than do adults and that differences between boys and girls may be observed as early as ages 3 and 4 years. [ABSTRACT FROM AUTHOR]

A review of wheelchair research within the scope of the wheelchair as a means of daily ambulation is presented. The relevance of a combined biomechanical and physiological research approach is advocated for enhancing the body of knowledge of wheelchair ergonomics, that is, the wheelchair/user interaction in relation to aspects of vehicle mechanics and the user's physical condition. Results of experiments regarding variations in the wheelchair/user interface stress the possibilities of optimization in terms of wheelchair dimensions and user characteristics. Analysis of propulsion technique is aimed at the within cycle characteristics and the time-dependent organization of technique. [ABSTRACT FROM AUTHOR]

In a previous paper (Neptune & Hull. 1995), a new video-based method (ASIS) for locating the hip joint center (HJC) in seated cycling was shown to be more accurate than tracking a marker placed over the superior aspect of the greater trochanter (TRO). The main goal of the present study was to see if the conclusions presented in Neptune and Hull (1995) may be applied to other cyclists. Lower limb kinematic and pedal force data were collected from 7 cyclists at nine combinations of pedaling rate and work rate. ASIS produced significantly different hip joint movement patterns than TRO, which resulted in significantly different power and work calculations developed by the intersegmental hip joint force, at all combinations except one. A significant quadratic trend was evident as a function of pedaling rate, and a significant linear trend was evident for work rate. At naturally preferred pedaling rates (~90 rpm) and lower work rates (<225 W). the hip joint movement was minimum. Under these conditions, the fixed hip assumption is least prone to error. [ABSTRACT FROM AUTHOR]

In this paper a new method for the registration of trunk movements is presented. With this method, called the Ponable Posture Registration Set (PPRS), movements can be recorded continuously over a long period of time. The purpose of this study was to test whether the PPRS can be applied in golf. A pilot study using 4 male golfers demonstrated that qualitative and quantitative data on trunk movements in golf can be collected with the PPRS. The inclination of the trunk proved to be large (40-45°) in all swings tested, resulting in a considerable load on the back. The contribution of torsion to the spinal load was relatively small, especially in the putt, which showed very little movement in the transverse and frontal planes. However, putting accounted for most of the total spinal load in playing a course. Even when playing a round of 18 holes, subjects did not experience any hindrance or discomfort from the sensors or the recorder. This method seems to offer new possibilities in the biomechanical study of trunk movement in golf. [ABSTRACT FROM AUTHOR]

Olympic skiers in the women's 30-km race were analyzed as they double poled on a moderate downhill slope. Movement patterns of 20 skiers were analyzed, 10 from a top finishing group and 10 from slower finishers in the bottom third of the field. Skiers in the faster group not only were faster overall in the race but were faster as they double poled through the site (6.75 vs. 6.43 m/s). Cycle length was significantly correlated with cycle velocity (r = .81). Trunk flexion and shoulder extension during poling were similar between groups; however, considerable variability of shoulder positioning was noted for both groups of skiers. Distinct shoulder-elbow-pole positioning differences were noted among skiers. Disadvantageous positioning of the shoulder at the beginning of poling was related to poorer pole inclination during elbow extension. While many skiers in both fast and slow groups double poled with good positioning, others would benefit from greater shoulder flexion to maximize double poling performance. [ABSTRACT FROM AUTHOR]

An experimental study was undertaken to optimize the placement of boxes on the shelves in a food product warehouse by minimizing joint loadings on the shoulders and on the lower back as criteria. A dynamic sagittal plane model was used to estimate net muscular moments on the shoulders, and a model of internal forces was used to estimate compression forces on the L5/S1 intervertebral disk. Lifting boxes of 6.4 kg or more produced compression forces at L5/S1 above the "action limit" of the National Institute for Occupational Safety and Health (NIOSH, 1981). Regression methods were then used to estimate joint loadings for each product at each working height and for each task. Optimizing the placement of products by minimizing loadings on the lower back reduced overall loadings by as much as 15% for certain racks. For minimizing loadings on the shoulders, results indicated that this variable was not sensitive to different placements of boxes on the shelves. [ABSTRACT FROM AUTHOR]

The purpose of this investigation was to determine the relationship between isometric measures of muscular function at two different joint angles and dynamic performance. Thirteen experienced weight trainers performed two isometric tests in a bench press position, at elbow angles of 90 and 120°. Performance was assessed by a one repetition maximum (1-RM) bench press and a series of upper body bench press throws at loads of 15, 30, and 60% of the 1-RM load. The results clearly show that changing the joint angle from 120 to 90° improved the relationship between most of the tests and performance by more than 100%, possibly due to differences in motor unit recruitment patterns and differing muscle mechanics (e.g. length-tension). at varying joint angles. It was suggested that the best angle at which to assess isometric function may be the joint angle at which peak force is developed in the performance of interest. [ABSTRACT FROM AUTHOR]

The maximum cantilever length-anterior-posterior spread (CL-AP) ratio is often used as an indication of the ability to cantilever in completely implant-supported prostheses. The CL-AP ratios were determined assuming that failure occurs when the prosthesis retaining screw-prosthesis joint was compromised by either compressive (exceeding the pretorque value) or tensile (opening of the joint via plastic deformation) vertical forces using the Skalak model. Geometric arrangements of three, four, five, and six implants were analyzed. Force variables were 143, 200, and 400 N for the applied force, the pretorque value, and the joint tensile yield strength, respectively. The pretorque value was always exceeded before the yield strength. Allowable CL-AP ratios were (1) lower than those previously reported and (2) found to be 0.5 to 1.8, 0.7 to 1.6, 1.1 to 1.7, and 1.8 for three, four, five, and six implants, respectively. Although implant distributions with the highest AP often provide adequate occlusion, the results of this study indicate that the use of a single CL-AP ratio alone is not necessarily a good indicator of the ability to cantilever. [ABSTRACT FROM AUTHOR]

Purpose: We aimed to biomechanically evaluate the effect of the supraspinatus tendon on tuberosity stability using two different reverse shoulder arthroplasty (RSA) models for complex proximal humeral fractures (PHFs).Methods: Four-part proximal humeral fractures were simulated in 20 cadaveric shoulders. Two different RSA designs were implemented: a glenosphere-medialized model and a glenosphere-lateralized model. Tuberosities were reconstructed, and displacement of bony fragments was measured (mm) by placing three sensors: in the humeral diaphysis (D), in the greater tuberosity (GT), and in the lesser tuberosity (LT). Axial forces were induced and measured in Newton (N). The test was performed twice in each specimen, with and without the supraspinatus tendon. The regression line (RL) was measured in mm/N.Results: In the medialized model, the GT-D displacement was greater in the supraspinatus preserving model than that in the tendon excision model (p < 0.001), as well as for the LT-D displacement (p < 0.001). In the lateralized model, GT-D displacement and GT-LT distance were greater in the preserving model than that in the excision model (p < 0.001, p = 0.04).Conclusion: The supraspinatus tendon resection leads to a more biomechanically stable tuberosity construct when performing RSA for PHFs, while the rest of the rotator cuff tendons (infraspinatus and teres minor) are retained in the greater tuberosity.Level Of Evidence: Basic science study. Cadaveric study. [ABSTRACT FROM AUTHOR]

Functional electrical stimulation of lower limb muscles during rowing provides a means for the cardiovascular conditioning in paraplegia. The possibility of shaping stimulation profiles according to changes in knee angle, so far conceived as changes in seat position, may help circumventing open issues associated with muscle fatigue and movement coordination. Here, we present a subject-specific biomechanical model for the estimation of knee joint angle during indoor rowing. Anthropometric measurements and foot and seat positions are inputs to the model. We tested our model on two samples of elite rowers; 15 able-bodied, and 11 participants in the Rio 2016 Paralympic games. Paralympic rowers presented minor physical disabilities (LTA-PD classification), enabling them to perform the full rowing cycle (with legs, trunks, and arms). Knee angle was estimated from the rowing machine seat position, measured with a linear encoder, and transmitted wirelessly to a computer. Key results indicate the root mean square error (RMSE) between estimated and measured angles did not depend on group and stroke rate (${p} > \textsf {0.267}$). Significantly greater RMSE values were observed, however, within the rowing cycle (${p} < \textsf {0.001}$), reaching on average 8 deg in the mid-recovery phase. Differences between estimated and measured knee angle values resulted in slightly earlier (5%) detection of knee flexion, regardless of the group and stroke rate considered. Offset of knee extension, knee angle at catch and range of knee motion were identified equally well with our model and with inertial sensors. These results suggest our model describes accurately the movement of knee joint during indoor rowing. [ABSTRACT FROM AUTHOR]

Imaging Genetics (IG) integrates neuroimaging and genomic data from the same individual, deepening our knowledge of the biological mechanisms behind neurodevelopmental domains and neurological disorders. Although the literature on IG has exponentially grown over the past years, the majority of studies have mainly analyzed associations between candidate brain regions and individual genetic variants. However, this strategy is not designed to deal with the complexity of neurobiological mechanisms underlying behavioral and neurodevelopmental domains. Moreover, larger sample sizes and increased multidimensionality of this type of data represents a challenge for standardizing modeling procedures in IG research. This review provides a systematic update of the methods and strategies currently used in IG studies, and serves as an analytical framework for researchers working in this field. To complement the functionalities of the Neuroconductor framework, we also describe existing R packages that implement these methodologies. In addition, we present an overview of how these methodological approaches are applied in integrating neuroimaging and genetic data. [ABSTRACT FROM AUTHOR]