The Effects of Floor Incline on Lower Extremity Biomechanics During Unilateral Landing From a Jump in Dancers

2012 ◽  
Vol 28 (2) ◽  
pp. 192-199 ◽  
Author(s):  
Evangelos Pappas ◽  
Karl F. Orishimo ◽  
Ian Kremenic ◽  
Marijeanne Liederbach ◽  
Marshall Hagins
Keyword(s):  
Lower Extremity ◽  
Injury Risk ◽  
Retrospective Studies ◽  
Joint Angle ◽  
Joint Angles ◽  
Injury Rates ◽  
Inclined Surfaces ◽  
Landing Mechanics ◽  
Drop Jumps ◽  
Lower Extremity Biomechanics

Retrospective studies have suggested that dancers performing on inclined (“raked”) stages have increased injury risk. One study suggests that biomechanical differences exist between flat and inclined surfaces during bilateral landings; however, no studies have examined whether such differences exist during unilateral landings. In addition, little is known regarding potential gender differences in landing mechanics of dancers. Professional dancers (N = 41; 14 male, 27 female) performed unilateral drop jumps from a 30 cm platform onto flat and inclined surfaces while extremity joint angles and moments were identified and analyzed. There were significant joint angle and moment effects due to the inclined flooring. Women had significantly decreased peak ankle dorsiflexion and hip adduction moment compared with men. Findings of the current study suggest that unilateral landings on inclined stages create measurable changes in lower extremity biomechanical variables. These findings provide a preliminary biomechanical rationale for differences in injury rates found in observational studies of raked stages.

Preseason Injury Rates in a Division II Football Team Before and After the 2017 NCAA Practice Rule Changes

2020 ◽  
Vol 25 (1) ◽  
pp. 17-20 ◽  
Author(s):  
John J. Smith ◽  
Daniel J. Baer
Keyword(s):  
Lower Extremity ◽  
Injury Risk ◽  
Ncaa Division Ii ◽  
Practice Session ◽  
Time Loss ◽  
Injury Rates ◽  
Football Team ◽  
Before And After ◽  
Rule Changes ◽  
Division Ii

In 2017, the NCAA implemented rule changes to enhance safety in college football; however, the effect on injury risk remains unclear. The purpose of this study was to observe differences in the number and rate of injuries and time-loss injuries in an NCAA Division II football team during two consecutive preseasons, before and after the rule changes. From 2016 to 2017, we observed a decrease in lower extremity (LE) muscle strains from 1.00 injury/session to 0.55 injuries/session. We also observed a decrease in time-loss LE muscle strains from 0.52 injuries/session in 2016 to 0.20 injuries/session in 2017. After the rule changes, we observed fewer time-loss injuries (14.06% decrease), acute LE strains (45.00% decrease), and time-loss LE strains (61.54% decrease) per preseason practice session. These findings suggest that the rule changes may help reduce both the number and severity of LE muscle strains during preseason football.

scholarly journals Validation of a Bar Linkage Model for Joint Angle Estimation during Cycling

2020 ◽  
Vol 10 (15) ◽  
pp. 5104
Author(s):  
Sien Dieltiens ◽  
Kurt Claeys ◽  
Jordi D’hondt ◽  
Henri Devroey ◽  
Marc Juwet ◽  
...  
Keyword(s):  
Lower Extremity ◽  
Joint Angle ◽  
Sagittal Plane ◽  
Contact Forces ◽  
Joint Loading ◽  
Joint Angles ◽  
Special Equipment ◽  
Angle Estimation ◽  
Significant Difference

Measuring lower extremity joint angles during cycling is interesting to derive joint loading from contact forces at the pedals and to determine the cause of cycling injuries. Traditionally, joint angles are determined in a stationary setup with high-resolution cameras that track marker movement in a lab environment. Alternatively, joint angles can be estimated mathematically in-situ: the lower extremities, bicycle frame and pedal arms are presented as a 5 bar linkage system which is fully defined by the lower extremity segment lengths, seat height and pedal position. As most instrumented pedals for power measurements include pedal orientation measurements, the bar linkage system demands no special equipment to derive joint loadings from pedal loads. The aim of this study is to validate the bar linkage system for joint angle estimation in the sagittal plane during in-situ cycling. Ten subjects cycled on a stationary bike while the hip, knee and ankle angles were measured with a Vicon optoelectronic motion capture system and simultaneously calculated with the bar linkage system. The results were averaged to subject-specific and method-specific ensemble average curves in the function of the phase in the pedal cycle and compared by a correlation analysis, Bland Altman plot, and Spm1D paired T-test. The hip and knee angle estimation of the bar linkage system showed no statistically significant difference from the optoelectronic system. Moreover, the ankle showed a statistically significant difference in the last half of the recovery phase of the pedal cycle. As the difference was maximally 3°, it has no clinical significance when deriving joint loading from contact forces at the pedal.

scholarly journals Validation of a Commercially Available Markerless Motion-Capture System for Trunk and Lower Extremity Kinematics During a Jump-Landing Assessment

2021 ◽  
Vol 56 (2) ◽  
pp. 177-190
Author(s):  
Timothy C. Mauntel ◽  
Kenneth L. Cameron ◽  
Brian Pietrosimone ◽  
Stephen W. Marshall ◽  
Anthony C. Hackney ◽  
...  
Keyword(s):  
Lower Extremity ◽  
Motion Capture ◽  
Joint Angle ◽  
Sagittal Plane ◽  
Frontal Plane ◽  
Lower Extremity Injury ◽  
Joint Angles ◽  
Jump Landing ◽  
Markerless Motion Capture ◽  
Motion Capture Systems

Context Field-based, portable motion-capture systems can be used to help identify individuals at greater risk of lower extremity injury. Microsoft Kinect-based markerless motion-capture systems meet these requirements; however, until recently, these systems were generally not automated, required substantial data postprocessing, and were not commercially available. Objective To validate the kinematic measures of a commercially available markerless motion-capture system. Design Descriptive laboratory study. Setting Laboratory. Patients or Other Participants A total of 20 healthy, physically active university students (10 males, 10 females; age = 20.50 ± 2.78 years, height = 170.36 ± 9.82 cm, mass = 68.38 ± 10.07 kg, body mass index = 23.50 ± 2.40 kg/m2). Intervention(s) Participants completed 5 jump-landing trials. Kinematic data were simultaneously recorded using Kinect-based markerless and stereophotogrammetric motion-capture systems. Main Outcome Measure(s) Sagittal- and frontal-plane trunk, hip-joint, and knee-joint angles were identified at initial ground contact of the jump landing (IC), for the maximum joint angle during the landing phase of the initial landing (MAX), and for the joint-angle displacement from IC to MAX (DSP). Outliers were removed, and data were averaged across trials. We used intraclass correlation coefficients (ICCs [2,1]) to assess intersystem reliability and the paired-samples t test to examine mean differences (α ≤ .05). Results Agreement existed between the systems (ICC range = −1.52 to 0.96; ICC average = 0.58), with 75.00% (n = 24/32) of the measures being validated (P ≤ .05). Agreement was better for sagittal- (ICC average = 0.84) than frontal- (ICC average = 0.35) plane measures. Agreement was best for MAX (ICC average = 0.77) compared with IC (ICC average = 0.56) and DSP (ICC average = 0.41) measures. Pairwise comparisons identified differences for 18.75% (6/32) of the measures. Fewer differences were observed for sagittal- (0.00%; 0/15) than for frontal- (35.29%; 6/17) plane measures. Between-systems differences were equivalent for MAX (18.18%; 2/11), DSP (18.18%; 2/11), and IC (20.00%; 2/10) measures. The markerless system underestimated sagittal-plane measures (86.67%; 13/15) and overestimated frontal-plane measures (76.47%; 13/17). No trends were observed for overestimating or underestimating IC, MAX, or DSP measures. Conclusions Moderate agreement existed between markerless and stereophotogrammetric motion-capture systems. Better agreement existed for larger (eg, sagittal-plane, MAX) than for smaller (eg, frontal-plane, IC) joint angles. The DSP angles had the worst agreement. Markerless motion-capture systems may help clinicians identify individuals at greater risk of lower extremity injury.

scholarly journals Kinematic Analyses of Parkour Landings From as High as 2.7 Meters

2020 ◽  
Vol 72 (1) ◽  
pp. 15-28 ◽  
Author(s):  
Boyi Dai ◽  
Jacob S. Layer ◽  
Taylour J. Hinshaw ◽  
Ross F. Cook ◽  
Janet S. Dufek
Keyword(s):  
Lower Extremity ◽  
Injury Prevention ◽  
Vertical Velocity ◽  
Injury Risk ◽  
Three Dimensional ◽  
Initial Contact ◽  
Joint Angles ◽  
Performance Training ◽  
Kinematic Analyses ◽  
And Performance

AbstractDeveloping effective landing strategies has implications for both injury prevention and performance training. The purpose was to quantify the kinematics of Parkour practitioners’ landings from three heights utilizing four techniques. Seventeen male and three female Parkour practitioners landed from 0.9, 1.8, and 2.7 m utilizing the squat, forward, roll, and stiff landing techniques when three-dimensional kinematics were collected. The stiff landing demonstrated the shortest landing time, and the roll landing showed the longest landing time for 1.8 and 2.7 m. Roll landings demonstrated the greatest forward velocities at initial contact and at the end of the landing. Stiff landings showed the greatest changes in vertical velocity during the early landing, while roll landings showed the least changes for 0.9 and 1.8 m. Both roll and stiff landings generally resulted in decreased changes in horizontal velocity during the early landing compared to squat and forward landings. The four landing techniques also demonstrated different lower extremity joint angles. Stiff landings may increase injury risk because of the quick decrease of vertical velocities. Roll landings allow individuals to decrease vertical and horizontal velocities over a longer time, which is likely to decrease the peak loading imposed on the lower extremities.

Within-Session Reliability and Minimum Detectable Differences for Discrete Lower-Extremity Angles and Moments During Walking

2021 ◽  
Vol 37 (5) ◽  
pp. 477-480
Author(s):  
Jillian L. Hawkins ◽  
Clare E. Milner
Keyword(s):  
Lower Extremity ◽  
Intraclass Correlation ◽  
Three Dimensional ◽  
Correlation Coefficients ◽  
Joint Angles ◽  
Cross Sectional ◽  
Intraclass Correlation Coefficients ◽  
Walking Biomechanics ◽  
Lower Extremity Biomechanics ◽  
Better Than

Differences in walking biomechanics between groups or conditions should be greater than the measurement error to be considered meaningful. Reliability and minimum detectable differences (MDDs) have not been determined for lower-extremity angles and moments during walking within a session, as needed for interpreting differences in cross-sectional studies. Thus, the purpose of this study was to determine within-session reliability and MDDs for peak ankle, knee, and hip angles and moments during walking. Three-dimensional gait analysis was used to record walking at 1.25 m/s (±5%) in 18 men, 18–50 years of age. Peak angles and moments were calculated for 2 sets of 3 trials. Intraclass correlation coefficients (3, 3) were used to determine within-session reliability. In addition, MDDs were calculated. Within-session reliability was good to excellent for all variables. The MDDs ranged from 0.9° to 3.6° for joint angles and 0.06 to 0.15 N·m/kg for joint moments. Within-session reliability for peak ankle, knee, and hip angles and moments was better than the between-session reliability reported previously. Overall, our MDDs were similar or smaller than those previously reported for between-session reliability. The authors recommend using these MDDs to aid in the interpretation of cross-sectional comparisons of lower-extremity biomechanics during walking in healthy men.

Effect of High-Heeled Shoes on Balance and Lower-Extremity Biomechanics During Walking in Experienced and Novice High-Heeled Shoe Wearers

2020 ◽  
Vol 110 (4) ◽  
Author(s):  
Soul Lee ◽  
Miaomiao Xu ◽  
Lin Wang ◽  
Jing Xian Li
Keyword(s):  
Body Weight ◽  
Lower Extremity ◽  
Sagittal Plane ◽  
Step Length ◽  
Joint Angles ◽  
Double Support ◽  
Lower Extremity Biomechanics ◽  
Analysis System ◽  
Double Support Time ◽  
Support Time

Background Wearing high-heeled shoes and carrying asymmetrical loads are common in ladies. However, knowledge of the effects of wearing high-heeled shoes on balance and lower-extremity biomechanics in experienced and novice high-heeled shoe wearers is lacking. The study aims to examine the effects of high-heeled shoes and asymmetrical load carrying on joint kinematics and kinetics of the lower extremity during walking as well as balance in experienced and novice high-heeled shoe wearers. Methods Fifteen experienced and 15 novice high-heeled shoes wearers participated in this study. Using a motion analysis system, kinematic and kinetic data were collected while participants walked at their preferred speed in six conditions created from two types of shoes (9-cm high-heeled shoes and flat-heeled shoes) and three weights of symmetrical load (0%, 5%, and 10% of body weight). Stride time and length, step length, double support time, peak joint angles, and joint moments in a sagittal plane were analyzed. Single-leg and tandem-leg stance tests were performed in each condition. Results Compared with experienced high-heeled shoe wearers, novice high-heeled shoe wearers had longer double support time and shorter stride length during 10% of body weight asymmetrical load walking; walked with greater knee flexion angle, smaller knee range of motion, and smaller ankle dorsiflexor moment; and scored lower in the single-leg and tandem-leg stance tests. Conclusions Novice high-heeled shoe wearers need to alter their lower-limb joint angles and moments to adjust to high-heeled shoes to achieve balance during gait while carrying an asymmetrical load.

Ankle Dorsiflexion Affects Hip and Knee Biomechanics During Landing

2021 ◽  
pp. 194173812110196
Author(s):  
Jeffrey B. Taylor ◽  
Elena S. Wright ◽  
Justin P. Waxman ◽  
Randy J. Schmitz ◽  
James D. Groves ◽  
...  
Keyword(s):  
Lower Extremity ◽  
Knee Flexion ◽  
Injury Risk ◽  
Female Athletes ◽  
Knee Extensor ◽  
Ankle Dorsiflexion ◽  
Level Of Evidence ◽  
Peak Knee ◽  
Knee Abduction ◽  
Lower Extremity Biomechanics

Background: Restricted ankle dorsiflexion range of motion (DFROM) has been linked to lower extremity biomechanics that place an athlete at higher risk for injury. Whether reduced DFROM during dynamic movements is due to restrictions in joint motion or underutilization of available ankle DFROM motion is unclear. Hypothesis: We hypothesized that both lesser total ankle DFROM and underutilization of available motion would lead to high-risk biomechanics (ie, greater knee abduction, reduced knee flexion). Study Design: Cross-sectional study. Level of Evidence: Level 3. Methods: Nineteen active female athletes (age, 20.0 ± 1.3 years; height, 1.61 ± 0.06 m; mass, 67.0 ± 10.7 kg) participated. Maximal ankle DFROM (clinical measure of ankle DFROM [DF-CLIN]) was measured in a weightbearing position with the knee flexed. Lower extremity biomechanics were measured during a drop vertical jump with 3-dimensional motion and force plate analysis. The percent of available DFROM used during landing (DF-%USED) was calculated as the peak DFROM observed during landing divided by DF-CLIN. Univariate linear regressions were performed to identify whether DF-CLIN or DF-%USED predicted knee and hip biomechanics commonly associated with injury risk. Results: For every 1.0° less of DF-CLIN, there was a 1.0° decrease in hip flexion excursion ( r2 = 0.21, P = 0.05), 1.2° decrease in peak knee flexion angles ( r2 = 0.37, P = 0.01), 0.9° decrease in knee flexion excursion ( r2 = 0.40, P = 0.004), 0.002 N·m·N−1·cm−1 decrease in hip extensor work ( r2 = 0.28, P = 0.02), and 0.001 N·m·N−1·cm−1 decrease in knee extensor work ( r2 = 0.21, P = 0.05). For every 10% less of DF-%USED, there was a 3.2° increase in peak knee abduction angles ( r2 = 0.26, P = 0.03) and 0.01 N·m·N−1·cm−1 lesser knee extensor work ( r2 = 0.25, P = 0.03). Conclusion: Lower levels of both ankle DFROM and DF-%USED are associated with biomechanics that are considered to be associated with a higher risk of sustaining injury. Clinical Relevance: While total ankle DFROM can predict some aberrant movement patterns, underutilization of available ankle DFROM can also lead to higher risk movement strategies. In addition to joint specific mobility training, clinicians should incorporate biomechanical interventions and technique feedback to promote the utilization of available motion.

scholarly journals Genome-Wide Association Studies Based on Equine Joint Angle Measurements Reveal New QTL Affecting the Conformation of Horses

Genes ◽  
2019 ◽  
Vol 10 (5) ◽  
pp. 370 ◽  
Author(s):  
Annik Imogen Gmel ◽  
Thomas Druml ◽  
Rudolf von Niederhäusern ◽  
Tosso Leeb ◽  
Markus Neuditschko
Keyword(s):  
Joint Angle ◽  
Association Studies ◽  
Genome Wide Association ◽  
Cranial Morphology ◽  
Genome Wide Association Studies ◽  
Joint Angles ◽  
Mineral Density ◽  
Mixed Effect ◽  
Stifle Joint ◽  
Genome Wide

The evaluation of conformation traits is an important part of selection for breeding stallions and mares. Some of these judged conformation traits involve joint angles that are associated with performance, health, and longevity. To improve our understanding of the genetic background of joint angles in horses, we have objectively measured the angles of the poll, elbow, carpal, fetlock (front and hind), hip, stifle, and hock joints based on one photograph of each of the 300 Franches-Montagnes (FM) and 224 Lipizzan (LIP) horses. After quality control, genome-wide association studies (GWASs) for these traits were performed on 495 horses, using 374,070 genome-wide single nucleotide polymorphisms (SNPs) in a mixed-effect model. We identified two significant quantitative trait loci (QTL) for the poll angle on ECA28 (p = 1.36 × 10−7), 50 kb downstream of the ALX1 gene, involved in cranial morphology, and for the elbow joint on ECA29 (p = 1.69 × 10−7), 49 kb downstream of the RSU1 gene, and 75 kb upstream of the PTER gene. Both genes are associated with bone mineral density in humans. Furthermore, we identified other suggestive QTL associated with the stifle joint on ECA8 (p = 3.10 × 10−7); the poll on ECA1 (p = 6.83 × 10−7); the fetlock joint of the hind limb on ECA27 (p = 5.42 × 10−7); and the carpal joint angle on ECA3 (p = 6.24 × 10−7), ECA4 (p = 6.07 × 10−7), and ECA7 (p = 8.83 × 10−7). The application of angular measurements in genetic studies may increase our understanding of the underlying genetic effects of important traits in equine breeding.

scholarly journals Experimental and Numerical Study of Fracture Behavior of Rock-Like Material Specimens with Single Pre-Set Joint under Dynamic Loading

Materials ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2690
Author(s):  
Bo Pan ◽  
Xuguang Wang ◽  
Zhenyang Xu ◽  
Lianjun Guo ◽  
Xuesong Wang
Keyword(s):  
Crack Initiation ◽  
Crack Propagation ◽  
Joint Angle ◽  
Simulation Software ◽  
Dissipated Energy ◽  
Energy Structure ◽  
Joint Angles ◽  
Crack Penetration ◽  
Before And After ◽  
The Impact

The Split Hopkinson Pressure Bar (SHPB) is an apparatus for testing the dynamic stress-strain response of the cement mortar specimen with pre-set joints at different angles to explore the influence of joint attitudes of underground rock engineering on the failure characteristics of rock mass structure. The nuclear magnetic resonance (NMR) has also been used to measure the pore distribution and internal cracks of the specimen before and after the testing. In combination with numerical analysis, the paper systematically discusses the influence of joint angles on the failure mode of rock-like materials from three aspects of energy dissipation, microscopic damage, and stress field characteristics. The result indicates that the impact energy structure of the SHPB is greatly affected by the pre-set joint angle of the specimen. With the joint angle increasing, the proportion of reflected energy moves in fluctuation, while the ratio of transmitted energy to dissipated energy varies from one to the other. NMR analysis reveals the structural variation of the pores in those cement specimens before and after the impact. Crack propagation direction is correlated with pre-set joint angles of the specimens. With the increase of the pre-set joint angles, the crack initiation angle decreases gradually. When the joint angles are around 30°–75°, the specimens develop obvious cracks. The crushing process of the specimens is simulated by LS-DYNA software. It is concluded that the stresses at the crack initiation time are concentrated between 20 and 40 MPa. The instantaneous stress curve first increases and then decreases with crack propagation, peaking at different times under various joint angles; but most of them occur when the crack penetration ratio reaches 80–90%. With the increment of joint angles in specimens through the simulation software, the changing trend of peak stress is consistent with the test results.

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