The effect of knee angle and subject position on plantar flexors isokinetic performance and muscular activity

2021 ◽  
pp. 1-9
Author(s):  
Ahmed Farrag ◽  
Moath Almusallam ◽  
Nora Almulhim ◽  
Eidan Alzahrani ◽  
Zaenab Alowa ◽  
...  
Keyword(s):  
Plantar Flexion ◽  
Muscular Activity ◽  
Subject Position ◽  
Knee Angle ◽  
Plantar Flexors ◽  
Ankle Movement ◽  
The Difference ◽  
The Moment ◽  
Isokinetic Performance ◽  
Increased Activity

BACKGROUND: Assessment of the plantar flexion (PF) isokinetic performance has been greatly diverse and based on personal preferences rather than standardized guidelines. OBJECTIVE: To examine the performance of the plantar flexors under different settings including knee joint angle and subject position. METHODS: Thirteen women and 20 men took part in this study. The isokinetic protocol (60∘/s) was set to ankle movement between 10∘ dorsiflexion to 30∘ PF. Participants performed three repetitions of concentric PF in randomly-ordered knee angles; 15∘, 45∘ and 90∘, and in seated and supine positions. Surface electromyography (EMG) data were collected from the Soleus (SOL) and Gastrocnemius. RESULTS: Knee angle impacted the PF moment (P⩽ 0.001–0.026) and work (P⩽ 0.05) measures in both genders. The moment and work measures were significantly less in the 90∘ than those in the 45∘ and 15∘ positions. The 45∘ position had the highest values, particularly in sitting in the male participants. Only the GL EMG data was significantly impacted (P= 0.017) by the subject position. However, the difference was trivial (1.6%). The SOL muscle showed a consistent pattern of increased activity when the knee was in flexion. CONCLUSION: The 45∘ position seems to be optimal for obtaining the highest isokinetic PF scores.

Ankle Angle but Not Knee Angle Influences Force Fluctuations During Plantar Flexion

2021 ◽  
Author(s):  
Georgios Trypidakis ◽  
Ioannis G. Amiridis ◽  
Roger Enoka ◽  
Irini Tsatsaki ◽  
Eleftherios Kellis ◽  
...  
Keyword(s):  
Knee Joint ◽  
Coefficient Of Variation ◽  
Discharge Rate ◽  
Dominant Role ◽  
Plantar Flexion ◽  
Motor Units ◽  
Medial Gastrocnemius ◽  
Knee Angle ◽  
Plantar Flexors ◽  
Ankle Angle

AbstractThe purpose of the study was to evaluate the influence of changes in ankle- and knee-joint angles on force steadiness and the discharge characteristics of motor units (MU) in soleus when the plantar flexors performed steady isometric contractions. Submaximal contractions (5, 10, 20, and 40% of maximum) were performed at two ankle angles (75° and 105°) and two knee angles (120° and 180°) by 14 young adults. The coefficient of variation of force decreased as the target force increased from 5 to 20% of maximal force, then remained unaltered at 40%. Independently of knee angle, the coefficient of variation for force at the ankle angle of 75° (long length) was always less (p<0.05) than that at 105° (shorter length). Mean discharge rate, discharge variability, and variability in neural activation of soleus motor units were less (p<0.05) at the 75° angle than at 105°. It was not possible to record MUs from medial gastrocnemius at the knee angle of 120° due to its minimal activation. The changes in knee-joint angle did not influence any of the outcome measures. The findings underscore the dominant role of the soleus muscle in the control of submaximal forces produced by the plantar flexor muscles.

Pointing the Foot Without Sickling: An Examination of Ankle Movement During Jumping

2015 ◽  
Vol 30 (1) ◽  
pp. 61-66 ◽  
Author(s):  
Danielle N Jarvis ◽  
Kornelia Kulig
Keyword(s):  
Plantar Flexion ◽  
Three Dimensional ◽  
Frontal Plane ◽  
Foot And Ankle ◽  
Vector Coding ◽  
Dance Training ◽  
Significant Difference ◽  
Ankle Movement ◽  
The Difference ◽  
Coordination Patterns

The sauté is a relatively simple dance jump that can be performed by both highly skilled dancers and non-dancers. However, there are characteristics of jumping unique to trained dancers, especially in terms of foot and ankle movement during flight. Dancers are trained not to “sickle,” or to avoid the anatomically coupled ankle inversion that occurs with plantar flexion, maintaining the appearance of a straight line through the lower leg and foot. The purpose of this study was to examine ankle movements in elite dancers compared to non-dancers. Twenty healthy females, 10 with no prior dance training and 10 professional dancers, performed 20 consecutive sautés while three-dimensional kinematic data were collected. Sagittal and frontal plane kinematics were calculated and vector coding methods were used to quantify coordination patterns within the ankle in the sagittal and frontal planes. This pattern was chosen for analysis to identify the avoidance of a sickled foot by trained dancers. Peak ankle positions and coordination patterns between groups were examined using independent t-tests (a<0.05). Dancers demonstrated greater peak plantar flexion (p<0.01) and less change in ankle angle during the flight phase (p=0.01), signifying holding the pointed foot position during flight. There was no statistically significant difference in sagittal and frontal plane ankle coupling (p=0.15); however, the Cohen’s d effect size for the difference in coupling was medium-to-large (0.73). Dynamic analysis of the foot and ankle during jumping demonstrates how elite dancers achieve the aesthetic requirements of dance technique.

Ankle Motion after External Fixation of Tibial Fractures

1988 ◽  
Vol 81 (1) ◽  
pp. 19-21 ◽  
Author(s):  
G J Taylor ◽  
R L Allum
Keyword(s):  
External Fixation ◽  
Plantar Flexion ◽  
Tibial Fractures ◽  
Ankle Motion ◽  
Ankle Movement ◽  
The Mean ◽  
The Difference ◽  
Tissue Trauma ◽  
Ankle Function

Loss of ankle movement is a complication of severe tibial fractures. This can be exacerbated if the foot is allowed to drop into equinus, particularly when an external fixator is employed. The range of ankle motion following external fixation of tibial fractures as compared to the opposite normal ankle was studied in 40 of 55 patients treated over a ten-year period. Nine were excluded due to other causes of ankle stiffness, leaving 31 cases for analysis. The mean follow up was 2 years 7 months (range 1 year to 8 years 3 months), and union had occurred by a mean of 35 weeks (range 9–100 weeks). The mean loss of ankle movement was 8° of plantar-flexion and 12° of dorsiflexion (overall loss 20°), the difference between the two being highly significant (P> 0.001, t test). Loss of ankle motion closely paralleled the degree of soft tissue trauma, being 6° for closed fractures and 22° for open fractures (0.05 > P> 0.02). Ankle function is therefore at risk when a severe tibial fracture is treated by external fixation, and appropriate measures should be taken to preserve movement and prevent an equinus contracture.

scholarly journals Effects of plantar flexors training (force vs. velocity) on plantar flexion and squat jump force-velocity relationships

2019 ◽  
Vol 22 (sup1) ◽  
pp. S350-S351
Author(s):  
C. Giroux ◽  
R. Hager ◽  
J. Feugray ◽  
G. Lauby ◽  
S. Dorel ◽  
...  
Keyword(s):  
Plantar Flexion ◽  
Plantar Flexors ◽  
Squat Jump ◽  
Force Velocity

scholarly journals Reliability of Bi-Axial Ankle Stiffness Measurement in Older Adults

Sensors ◽  
2021 ◽  
Vol 21 (4) ◽  
pp. 1162
Author(s):  
Hogene Kim ◽  
Sangwoo Cho ◽  
Hwiyoung Lee
Keyword(s):  
Older Adults ◽  
Range Of Motion ◽  
Angular Displacement ◽  
Plantar Flexion ◽  
Significant Negative Correlation ◽  
Talocrural Joint ◽  
Ankle Foot Orthosis ◽  
Ankle Stiffness ◽  
Ankle Movement ◽  
Test Retest Reliability

This study involves measurements of bi-axial ankle stiffness in older adults, where the ankle joint is passively moved along the talocrural and subtalar joints using a custom ankle movement trainer. A total of 15 elderly individuals participated in test–retest reliability measurements of bi-axial ankle stiffness at exactly one-week intervals for validation of the angular displacement in the device. The ankle’s range of motion was also compared, along with its stiffness. The kinematic measurements significantly corresponded to results from a marker-based motion capture system (dorsi-/plantar flexion: r = 0.996; inversion/eversion: r = 0.985). Bi-axial ankle stiffness measurements showed significant intra-class correlations (ICCs) between the two visits for all ankle movements at slower (2.14°/s, ICC = 0.712) and faster (9.77°/s, ICC = 0.879) speeds. Stiffness measurements along the talocrural joint were thus shown to have significant negative correlation with active ankle range of motion (r = −0.631, p = 0.012). The ankle movement trainer, based on anatomical characteristics, was thus used to demonstrate valid and reliable bi-axial ankle stiffness measurements for movements along the talocrural and subtalar joint axes. Reliable measurements of ankle stiffness may help clinicians and researchers when designing and fabricating ankle-foot orthosis for people with upper-motor neuron disorders, such as stroke.

scholarly journals Force Generation on the Hallux Is More Affected by the Ankle Joint Angle than the Lesser Toes: An In Vivo Human Study

Biology ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 48
Author(s):  
Junya Saeki ◽  
Soichiro Iwanuma ◽  
Suguru Torii
Keyword(s):  
Repeated Measures ◽  
Joint Angle ◽  
Plantar Flexion ◽  
Human Study ◽  
Force Generation ◽  
Functional Difference ◽  
Multiple Comparison Test ◽  
The Difference ◽  
Metatarsophalangeal Joints

The structure of the first toe is independent of that of the other toes, while the functional difference remains unclear. The purpose of this study was to investigate the difference in the force generation characteristics between the plantar-flexion of the first and second–fifth metatarsophalangeal joints (MTPJs) by comparing the maximal voluntary plantar-flexion torques (MVC torque) at different MTPJs and ankle positions. The MVC torques of the first and second–fifth MTPJs were measured at 0°, 15°, 30°, and 45° dorsiflexed positions of the MTPJs, and at 20° plantar-flexed, neutral, and 20° dorsiflexed positions of the ankle. Two-way repeated measures analyses of variance with Holm’s multiple comparison test (MTPJ position × ankle position) were performed. When the MTPJ was dorsiflexed at 0°, 15°, and 30°, the MVC torque of the first MTPJ when the ankle was dorsiflexed at 20° was higher than that when the ankle was plantar-flexed at 20°. However, the ankle position had no significant effect on the MVC torque of the second–fifth MTPJ. Thus, the MVC torque of the first MTPJ was more affected by the ankle position than the second–fifth MTPJs.

scholarly journals Elastic Simulation of Joints with Particle-Based Fluid

2021 ◽  
Vol 11 (15) ◽  
pp. 6900
Author(s):  
Su-Kyung Sung ◽  
Sang-Won Han ◽  
Byeong-Seok Shin
Keyword(s):  
Principal Stress ◽  
Human Body ◽  
Yield Condition ◽  
Maximum Principal Stress ◽  
Human Motion ◽  
The Difference ◽  
The Moment ◽  
External Forces ◽  
Physical Changes ◽  
Elastic Simulation

Skinning, which is used in skeletal simulations to express the human body, has been weighted between bones to enable muscle-like motions. Weighting is not a form of calculating the pressure and density of muscle fibers in the human body. Therefore, it is not possible to express physical changes when external forces are applied. To express a similar behavior, an animator arbitrarily customizes the weight values. In this study, we apply the kernel and pressure-dependent density variations used in particle-based fluid simulations to skinning simulations. As a result, surface tension and elasticity between particles are applied to muscles, indicating realistic human motion. We also propose a tension yield condition that reflects Tresca’s yield condition, which can be easily approximated using the difference between the maximum and minimum values of the principal stress to simulate the tension limit of the muscle fiber. The density received by particles in the kernel is assumed to be the principal stress. The difference is calculated by approximating the moment of greatest force to the maximum principal stress and the moment of least force to the minimum principal stress. When the density of a particle increases beyond the yield condition, the object is no longer subjected to force. As a result, one can express realistic muscles.

scholarly journals Loading Effect of Prosthetic Feet’s Anthropomorphicity on Transtibial Osseointegrated Implant

2021 ◽  
Vol 186 (Supplement_1) ◽  
pp. 681-687
Author(s):  
Mark Pitkin ◽  
Laurent Frossard
Keyword(s):  
Free Flow ◽  
Convex Shape ◽  
Bone Implant ◽  
Concave Shape ◽  
Early Loosening ◽  
Osseointegrated Implants ◽  
Osseointegrated Implant ◽  
Quantitative Characteristics ◽  
The Difference ◽  
The Moment

ABSTRACT Introduction Osseointegrated implants for direct skeletal attachment of transtibial prosthesis carry risks that are yet to be fully resolved, such as early loosening, mechanical failure of percutaneous and medullar parts of implant, periprosthetic issues, and infections. Underloading could lead to early loosening and infection. Overloading might compromise the bone–implant interface. Therefore, Goldilocks loading regimen applied by transtibial bone-anchored prostheses is critical for safe and efficient development of osseointegration around the implant during rehabilitation and beyond. We hypothesized that Goldilocks loading could be achieved when ambulating with a so-called anthropomorphic prosthetic ankle showing moment–angle relationship similar to a sound ankle. Materials and Methods Quantitative characteristics of the moment–angle curve of the sound ankle during dorsiflexion phase of a free-pace walking were extracted for 4 able-bodied participants (experiment 1). A slope of the moment–angle curve (stiffness) was calculated twice: for the first half and for the second half of the moment–angle curve. The difference of stiffnesses (those at the second half minus at the first half) was called the index of anthropomorphicity (IA). By definition, positive IA is associated with concave shape of the moment–angle curve, and the negative IA is associated with convex shape. In experiment 2, the same recordings and calculations were performed for 3 participants fitted with transtibial osseointegrated fixation during walking with their usual feet and the Free-Flow Foot (Ohio Willow Wood). The Free-Flow Foot was selected for its anthropomorphicity demonstrated in the previous studies with amputees using traditional socket attachment. Results The IA was 5.88 ± 0.93 for the able-bodied participants, indicating that the stiffness during the first part of the dorsiflexion phase was substantially fewer than during the second parts, as the calf muscles resisted to angulation in ankle substantially less than during the second part of dorsiflexion phase. For amputees fitted with Free-Flow Foot, IA was 2.68 ± 1.09 and −2.97 ± 2.37 for the same amputees fitted with their usual feet. Conclusions Indexes of anthropomorphicity, while of different magnitude, were positive in control able-bodied group and in the amputee group wearing Free-Flow Foot, which was qualitatively associated with concave shape of their moment–angle curves. The 3 usual feet worn by the participants were classified as nonanthropomorphic as their individual moment–angle curves were convex and the corresponding IAs were negative. Furthermore, this study showed that a foot with anthropomorphic characteristics tends to decrease maximal loads at the bone–implant interface as compared to the nonanthropomorphic feet and possibly may minimize the risks to compromise the integrity of this interface.

scholarly journals Design of a 2DoF Ankle Exoskeleton with a Polycentric Structure and a Bi-Directional Tendon-Driven Actuator Controlled Using a PID Neural Network

Actuators ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 9
Author(s):  
Taehoon Lee ◽  
Inwoo Kim ◽  
Yoon Su Baek
Keyword(s):  
Neural Network ◽  
Degrees Of Freedom ◽  
Plantar Flexion ◽  
Length Change ◽  
Talocrural Joint ◽  
Lower Limb Exoskeleton ◽  
Exoskeleton Robot ◽  
The Difference ◽  
Ankle Exoskeleton ◽  
The Stability

Lower limb exoskeleton robots help with walking movements through mechanical force, by identifying the wearer’s walking intention. When the exoskeleton robot is lightweight and comfortable to wear, the stability of walking increases, and energy can be used efficiently. However, because it is difficult to implement the complex anatomical movements of the human body, most are designed simply. Due to this, misalignment between the human and robot movement causes the wearer to feel uncomfortable, and the stability of walking is reduced. In this paper, we developed a two degrees of freedom (2DoF) ankle exoskeleton robot with a subtalar joint and a talocrural joint, applying a four-bar linkage to realize the anatomical movement of a simple 1DoF structure mainly used for ankles. However, bidirectional tendon-driven actuators (BTDAs) do not consider the difference in a length change of both cables due to dorsiflexion (DF) and plantar flexion (PF) during walking, causing misalignment. To solve this problem, a BTDA was developed by considering the length change of both cables. Cable-driven actuators and exoskeleton robot systems create uncertainty. Accordingly, adaptive control was performed with a proportional-integral-differential neural network (PIDNN) controller to minimize system uncertainty.

Open access to scientific information: comparative study in DOAJ

2014 ◽  
Vol 35 (4/5) ◽  
pp. 364-374 ◽  
Author(s):  
Tereza Stoyanova Trencheva ◽  
Tania Yordanova Todorova
Keyword(s):  
Open Access ◽  
Comparative Study ◽  
Scientific Information ◽  
Comparative Approach ◽  
Content Type ◽  
Open Access Journals ◽  
Global Movement ◽  
The Difference ◽  
Important Position ◽  
The Moment

Purpose – The purpose of the paper is to provide a comparative retrospective analysis of Bulgarian, Turkish and Croatian Open Access (OA) journals added in Directory of Open Access journals (DOAJ) in the period 2002-2013. Design/methodology/approach – First of all, the study is focussed on brief review of definitions and descriptions of the OA as a global movement. In the study were analyzed the three main OA initiatives and was shown the difference between Golden Road and Green Road. Second of all, the authors used the comparative approach and made a comparative study of the OA journals in Bulgaria, Turkey and Croatia and present the evaluation results and findings. Findings – Qualitative and quantitative data for the study are collected by the DOAJ. The data are analyzed in terms of quantity and period, and the results are presented graphically and tabular and finally there are made major specific conclusions and recommendations. Originality/value – The paper shows that OA in the digital space has an important position in scientific research. There are many discussion issues related to the problems of OA, but overall study of OA to scientific information, and in particular comparative study of Bulgarian, Turkish and Croatian journals in the DOAJ does not exist at the moment.

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