Ergonomic Assessment of Exiting Automobiles

1993 ◽  
Vol 37 (5) ◽  
pp. 401-405 ◽  
Author(s):  
Josef Loczi
Keyword(s):  
Kinetic Parameters ◽  
Knee Flexion ◽  
Flexion Angle ◽  
Regression Equations ◽  
Seat Height ◽  
Seat Position ◽  
Student Subjects ◽  
Screen System ◽  
Hip Flexion ◽  
High Degree

The purpose of this study was to investigate the effects of changing seat heights (51 cm, 59 cm, 67 cm), door heights (122 cm, 138 cm, 154 cm) and seat positions (27 cm and 35 cm) in automobiles on kinematic parameters (trunk rotation, trunk angle, hip flexion angle and knee flexion angle) and kinetic parameters (lumbar moment, hip moment and knee moment) while exiting automobiles. Twelve student subjects were videotaped with 2 video cameras synchronized into a split screen system. Manipulating seat height, door height and seat position resulted in 18 different testing conditions. Real time animated graphics, as well as 3-D kinematic and kinetic parameters of the movement were obtained via a video image computer capture system and newly developed 3-D digitizing software. It was determined from the study that: a) Seat and door height had significant effects on kinematic and kinetic parameters, but not seat position, b) As seat and door height increased maximum values for kinematic and kinetic parameters decreased, c) Hip and knee flexion angles seem to be an acceptable subset of variables that can be used to evaluate ease of exit, d) It seems there exists a “critical seat height” at which an equilibrium exists between the demands of maintaining balance and stability and the need to reduce stress on the lower back when exiting an automobile. e) The behavior of hip and knee flexion angles can be predicted with a high degree of confidence via regression equations.

scholarly journals Comparison of Muscle Activation and Kinematics in 6-RM Squatting With Low and High Barbell Placement

2020 ◽  
Vol 74 (1) ◽  
pp. 131-142
Author(s):  
Roland van den Tillaar ◽  
Eric Helms
Keyword(s):  
Knee Flexion ◽  
Average Velocity ◽  
Muscle Activation ◽  
Joint Kinematics ◽  
Flexion Angle ◽  
Knee Flexion Angle ◽  
Muscular Development ◽  
Hip Flexion ◽  
Maximal Capacity ◽  
Over Time

Abstract The aim of this study was to compare 6-RM muscle activation and kinematics in back squats with low and high barbell placements. Twelve resistance-trained males (23.5 ± 2.6 years, 86.8 ± 21.3 kg, 1.81 ± 0.08 m) with a minimum of 2 years of squatting experience performed a 6-RM using high and low barbell placements while muscle activation of eight muscles and joint kinematics were measured. During high barbell placement squats, lifting time was longer, with lower average velocity than low barbell placement. This was accompanied by a lesser knee flexion angle at the lowest point of the squat, and larger hip flexion angles during high, compared to low barbell squats. Furthermore, peak angular ankle, knee and hip velocities in the descending phase developed differently between conditions. No significant differences in muscle activation were found between conditions. Thus, our data suggests gross muscular adaptations between barbell placements may be similar over time, and therefore, from a muscular development standpoint, both squat styles are valid. Furthermore, unlike the low barbell placement, fatigue may manifest earlier itself in the high barbell squats during 6-RMs as sets progress toward a lifter’s maximal capacity, altering kinematics, especially in the last repetition.

Changes in Distance Running Kinematics with Fatigue

1991 ◽  
Vol 7 (2) ◽  
pp. 138-162 ◽  
Author(s):  
Keith R. Williams ◽  
Rebecca Snow ◽  
Chris Agruss
Keyword(s):  
Factor Analysis ◽  
Knee Flexion ◽  
Step Length ◽  
Analysis Procedure ◽  
Regression Equations ◽  
Knee Flexion Angle ◽  
Distance Running ◽  
Significant Difference ◽  
Individual Variables ◽  
Hip Flexion

This study investigated changes in kinematics with fatigue during intercollegiate competition, a noncompetitive track run, and a constant speed treadmill run. To account for changes in kinematics resulting from speed differences, regression equations for each individual generated from nonfatigue data were used to predict rested kinematics for speeds matching those of the fatigue conditions. A factor analysis procedure grouped 29 kinematic variables into sets of independent factors, and both factor variables and individual variables were analyzed for changes with fatigue, which were minimal. Only one significant difference was found in the factor variables between nonfatigue and fatigue states. Comparisons of specific kinematic variables showed a significant increase in step length with fatigue, an increased maximal knee flexion angle during swing, and an increased maximal thigh angle during hip flexion. While fatigue did not result in marked changes in kinematics for the group as a whole, changes for individuals were at times large.

scholarly journals Effects of Hip Flexion on Knee Extension and Flexion Isokinetic Angle-Specific Torques and HQ-Ratios

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Christian Baumgart ◽  
Eduard Kurz ◽  
Jürgen Freiwald ◽  
Matthias Wilhelm Hoppe
Keyword(s):  
Hip Joint ◽  
Knee Flexion ◽  
Daily Life ◽  
Knee Extension ◽  
Flexion Angle ◽  
Strength Testing ◽  
Knee Strength ◽  
Sporting Activities ◽  
Torque Values ◽  
Hip Flexion

Abstract Background and Methods During isokinetic knee strength testing, the knee flexion angles that correspond to the measured torque values are rarely considered. Additionally, the hip flexion angle during seated testing diverges from that in the majority of daily life and sporting activities. Limited information concerning the influence of hip angle, muscle contraction mode, and velocity on the isokinetic knee strength over the entire range of motion (ROM) is available. Twenty recreational athletes (10 females, 10 males; 23.3 ± 3.2 years; 72.1 ± 16.5 kg; 1.78 ± 0.07 m) were tested for isokinetic knee flexion and extension at 10° and 90° hip flexion with the following conditions: (i) concentric at 60°/s, (ii) concentric at 180°/s, and (iii) eccentric at 60°/s. The effects of hip angle, contraction mode, and velocity on angle-specific torques and HQ-ratios as well as conventional parameters (peak torques, angles at peak torque, and HQ-ratios) were analyzed using statistical parametric mapping and parametric ANOVAs, respectively. Results Generally, the angle-specific and conventional torques and HQ-ratios were lower in the extended hip compared to a flexed hip joint. Thereby, in comparison to the knee extension, the torque values decreased to a greater extent during knee flexion but not consistent over the entire ROM. The torque values were greater at the lower velocity and eccentric mode, but the influence of the velocity and contraction mode were lower at shorter and greater muscle lengths, respectively. Conclusions Isokinetic knee strength is influenced by the hip flexion angle. Therefore, a seated position during testing and training is questionable, because the hip joint is rarely flexed at 90° during daily life and sporting activities. Maximum knee strength is lower in supine position, which should be considered for training and testing. The angle-specific effects cannot be mirrored by the conventional parameters. Therefore, angle-specific analyses are recommended to obtain supplemental information and consequently to improve knee strength testing.

Different squatting positions after total knee arthroplasty: a video-based observational study

2020 ◽  
Author(s):  
Jing-yang Sun ◽  
Guo-qiang Zhang ◽  
Tie-jian Li ◽  
Jun-min Shen ◽  
Yin-qiao Du ◽  
...  
Keyword(s):  
Total Knee Arthroplasty ◽  
Knee Arthroplasty ◽  
Knee Flexion ◽  
Ankle Dorsiflexion ◽  
Flexion Angle ◽  
Knee Flexion Angle ◽  
Total Knee ◽  
The Mean ◽  
Hip Flexion ◽  
Deep Squat

Abstract Aims There are no methods to assess patient’s squatting ability after TKA (total knee arthroplasty), this study aimed to evaluate the different squatting position of a series of patients who underwent primary TKA.Methods From May 2018 to October 2019, we retrospectively reviewed 154 videos recording the squattin-related motions of patients after TKA. Among the included patients, 119 were women and 35 were men. Their mean age at the index surgery was 61.4 years (range, 30 to 77). The median follow-up was 12 months (range, 6 to 156). We classified those squatting-related motions into three major variations according to squatting depth: half squat, parallel squat, and deep squat. The angle of hip flexion, knee flexion and ankle dorsiflexion were measured in the screenshots captured from the videos at the moment of squatting nadir.Results A total of 26 patients were classified as half squat, 75 as parallel squat, and 53 as deep squat. The angle of hip flexion, knee flexion and ankle dorsiflexion all differed significantly among the three squatting positions (p<0.001). In the parallel squat group, the mean knee flexion angle(°) was 116.5 (SD, 8.1; range, 97 to 137). In the deep squat group, the mean knee flexion angle(°) was 132.5 (SD, 9.3; range, 116 to 158). Among the three squatting positions, deep squat showed the highest hip, knee and ankle flexion angle. And the next was parallel squat.Conclusion Our squatting position classification offers a pragmatic approach to evaluating patient’s squatting ability after TKA. However, the relation between squatting position and daily activity requires further investigation.

scholarly journals Influence of Hip-Flexion Angle on Hamstrings Isokinetic Activity in Sprinters

2012 ◽  
Vol 47 (4) ◽  
pp. 390-395 ◽  
Author(s):  
Kenny Guex ◽  
Boris Gojanovic ◽  
Grégoire P. Millet
Keyword(s):  
Root Mean Square ◽  
Knee Flexion ◽  
National Level ◽  
Peak Torque ◽  
Muscular Contraction ◽  
Flexion Angle ◽  
Mean Square ◽  
Resistance Training Program ◽  
The Right ◽  
Hip Flexion

Context: Hamstrings strains are common and debilitating injuries in many sports. Most hamstrings exercises are performed at an inadequately low hip-flexion angle because this angle surpasses 70° at the end of the sprinting leg's swing phase, when most injuries occur. Objective: To evaluate the influence of various hip-flexion angles on peak torques of knee flexors in isometric, concentric, and eccentric contractions and on the hamstrings-to-quadriceps ratio. Design: Descriptive laboratory study. Setting: Research laboratory. Patients and Other Participants Ten national-level sprinters (5 men, 5 women; age = 21.2 ± 3.6 years, height = 175 ± 6 cm, mass = 63.8 ± 9.9 kg). Intervention(s): For each hip position (0°, 30°, 60°, and 90° of flexion), participants used the right leg to perform (1) 5 seconds of maximal isometric hamstrings contraction at 45° of knee flexion, (2) 5 maximal concentric knee flexion-extensions at 60° per second, (3) 5 maximal eccentric knee flexion-extensions at 60° per second, and (4) 5 maximal eccentric knee flexion-extensions at 150° per second. Main Outcome Measure(s): Hamstrings and quadriceps peak torque, hamstrings-to-quadriceps ratio, lateral and medial hamstrings root mean square. Results: We found no difference in quadriceps peak torque for any condition across all hip-flexion angles, whereas hamstrings peak torque was lower at 0° of hip flexion than at any other angle (P &lt; .001) and greater at 90° of hip flexion than at 30° and 60° (P &lt; .05), especially in eccentric conditions. As hip flexion increased, the hamstrings-to-quadriceps ratio increased. No difference in lateral or medial hamstrings root mean square was found for any condition across all hip-flexion angles (P &gt; .05). Conclusions: Hip-flexion angle influenced hamstrings peak torque in all muscular contraction types; as hip flexion increased, hamstrings peak torque increased. Researchers should investigate further whether an eccentric resistance training program at sprint-specific hip-flexion angles (70° to 80°) could help prevent hamstrings injuries in sprinters. Moreover, hamstrings-to-quadriceps ratio assessment should be standardized at 80° of hip flexion.

scholarly journals Single-Leg Landings Following a Volleyball Spike May Increase the Risk of Anterior Cruciate Ligament Injury More Than Landing on Both-Legs

2020 ◽  
Vol 11 (1) ◽  
pp. 130
Author(s):  
Datao Xu ◽  
Xinyan Jiang ◽  
Xuanzhen Cen ◽  
Julien S. Baker ◽  
Yaodong Gu
Keyword(s):  
Anterior Cruciate Ligament ◽  
Knee Flexion ◽  
Sagittal Plane ◽  
Cruciate Ligament ◽  
Flexion Angle ◽  
Ligament Injury ◽  
Time Range ◽  
Acl Injuries ◽  
Volleyball Players ◽  
Anterior Cruciate

Volleyball players often land on a single leg following a spike shot due to a shift in the center of gravity and loss of balance. Landing on a single leg following a spike may increase the probability of non-contact anterior cruciate ligament (ACL) injuries. The purpose of this study was to compare and analyze the kinematics and kinetics differences during the landing phase of volleyball players using a single leg (SL) and double-leg landing (DL) following a spike shot. The data for vertical ground reaction forces (VGRF) and sagittal plane were collected. SPM analysis revealed that SL depicted a smaller knee flexion angle (about 13.8°) and hip flexion angle (about 10.8°) during the whole landing phase, a greater knee and hip power during the 16.83–20.45% (p = 0.006) and 13.01–16.26% (p = 0.008) landing phase, a greater ankle plantarflexion angle and moment during the 0–41.07% (p < 0.001) and 2.76–79.45% (p < 0.001) landing phase, a greater VGRF during the 5.87–8.25% (p = 0.029), 19.75–24.14% (p = 0.003) landing phase when compared to DL. Most of these differences fall within the time range of ACL injury (30–50 milliseconds after landing). To reduce non-contact ACL injuries, a landing strategy of consciously increasing the hip and knee flexion, and plantarflexion of the ankle should be considered by volleyball players.

scholarly journals A high degree of knee flexion after TKA promotes the ability to perform high-flexion activities and patient satisfaction in Asian population

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Hyuk-Soo Han ◽  
Jong Seop Kim ◽  
Bora Lee ◽  
Sungho Won ◽  
Myung Chul Lee
Keyword(s):  
Quality Of Life ◽  
Patient Satisfaction ◽  
Clinical Data ◽  
Knee Flexion ◽  
Male Gender ◽  
Flexion Angle ◽  
Knee Flexion Angle ◽  
High Flexion ◽  
Standing Up

Abstract Background This study investigated whether achieving a higher degree of knee flexion after TKA promoted the ability to perform high-flexion activities, as well as patient satisfaction and quality of life. Methods Clinical data on 912 consecutive primary TKA cases involving a single high-flexion posterior stabilized fixed-bearing prosthesis were retrospectively analyzed. Demographic and clinical data were collected, including knee flexion angle, the ability to perform high-flexion activities, and patient satisfaction and quality of life. Results Of the cases, 619 (68%) achieved > 130° of knee flexion after TKA (high flexion group). Knee flexion angle and clinical scores showed significant annual changes, with the maximum improvement seen at 5 years and slight deterioration observed at 10 years postoperatively. In the high flexion group, more than 50% of the patients could not kneel or squat, and 35% could not stand up from on the floor. Multivariate analysis revealed that > 130° of knee flexion, the ability to perform high-flexion activities (sitting cross-legged and standing up from the floor), male gender, and bilateral TKA were significantly associated with patient satisfaction after TKA, while the ability to perform high-flexion activities (sitting cross-legged and standing up from the floor), male gender, and bilateral TKA were significantly associated with patient quality of life after TKA. Conclusions High knee flexion angle (> 130°) after TKA increased the ease of high-flexion activities and patient satisfaction. The ease of high-flexion activities also increased quality of life after TKA in our Asian patients, who frequently engage in these activities in daily life.

scholarly journals Kinematic Comparison between Medially Congruent and Posterior-Stabilized Third-Generation TKA Designs

2021 ◽  
Vol 6 (1) ◽  
pp. 27
Author(s):  
Stefano Ghirardelli ◽  
Jessica L. Asay ◽  
Erika A. Leonardi ◽  
Tommaso Amoroso ◽  
Thomas P. Andriacchi ◽  
...  
Keyword(s):  
Knee Flexion ◽  
Knee Kinematics ◽  
Primary Total Knee Arthroplasty ◽  
Flexion Angle ◽  
Heel Strike ◽  
Third Generation ◽  
Knee Flexion Angle ◽  
Posterior Stabilized ◽  
Rotational Angle ◽  
Peak Knee

Background: This study compares knee kinematics in two groups of patients who have undergone primary total knee arthroplasty (TKA) using two different modern designs: medially congruent (MC) and posterior-stabilized (PS). The aim of the study is to demonstrate only minimal differences between the groups. Methods: Ten TKA patients (4 PS, 6 MC) with successful clinical outcomes were evaluated through 3D knee kinematics analysis performed using a multicamera optoelectronic system and a force platform. Extracted kinematic data included knee flexion angle at heel-strike (KFH), peak midstance knee flexion angle (MSKFA), maximum and minimum knee adduction angle (KAA), and knee rotational angle at heel-strike. Data were compared with a group of healthy controls. Results: There were no differences in preferred walking speed between MC and PS groups, but we found consistent differences in knee function. At heel-strike, the knee tended to be more flexed in the PS group compared to the MC group; the MSKFA tended to be higher in the PS group compared to the MC group. There was a significant fluctuation in KAA during the swing phase in the PS group compared to the MC group, PS patients showed a higher peak knee flexion moment compared to MC patients, and the PS group had significantly less peak internal rotation moments than the MC group. Conclusions: Modern, third-generation TKA designs failed to reproduce normal knee kinematics. MC knees tended to reproduce a more natural kinematic pattern at heel-strike and during axial rotation, while PS knees showed better kinematics during mid-flexion.

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