scholarly journals Passive knee exoskeletons in functional tasks: Biomechanical effects of a SpringExo coil-spring on squats

2021 ◽  
Vol 2 ◽  
Author(s):  
Rand Hidayah ◽  
Dongbao Sui ◽  
Kennedi A. Wade ◽  
Biing-Chwen Chang ◽  
Sunil Agrawal
Keyword(s):  
Outcome Measures ◽  
Muscle Activation ◽  
Rectus Femoris ◽  
Knee Extension ◽  
Lower Limbs ◽  
Flexion Angle ◽  
Coil Spring ◽  
Foot Pressure ◽  
Low Profile ◽  
Muscle Activations

Abstract Passive wearable exoskeletons are desirable as they can provide assistance during user movements while still maintaining a simple and low-profile design. These can be useful in industrial tasks where an ergonomic device could aid in load lifting without inconveniencing them and reducing fatigue and stress in the lower limbs. The SpringExo is a coil-spring design that aids in knee extension. In this paper, we describe the muscle activation of the knee flexors and extensors from seven healthy participants during repeated squats. The outcome measures are the timings of the key events during squat, flexion angle, muscle activation of rectus femoris and bicep femoris, and foot pressure characteristics of the participants. These outcome measures assess the possible effects of the device during lifting operations where reduced effort in the muscles is desired during ascent phase of the squat, without changing the knee and foot kinematics. The results show that the SpringExo significantly decreased rectus femoris activation during ascent (−2%) without significantly affecting either the bicep femoris or rectus femoris muscle activations in descent. This implies that the user could perform a descent without added effort and ascent with reduced effort. The exoskeleton showed other effects on the biomechanics of the user, increasing average squat time (+0.02 s) and maximum squat time (+0.1 s), and decreasing average knee flexion angle (−4°). The exoskeleton has no effect on foot loading or placement, that is, the user did not have to revise their stance while using the device.

scholarly journals Effect of Hip Flexion Angle on the Hamstring to Quadriceps Strength Ratio

Sports ◽  
2019 ◽  
Vol 7 (2) ◽  
pp. 43
Author(s):  
Eleftherios Kellis ◽  
Athanasios Ellinoudis ◽  
and Nikolaos Kofotolis
Keyword(s):  
Muscle Activation ◽  
Rectus Femoris ◽  
Biceps Femoris ◽  
Knee Extension ◽  
Quadriceps Strength ◽  
Flexion Angle ◽  
Electromyographic Activity ◽  
H:Q Ratio ◽  
Hip Flexion ◽  
Selection Of

The purpose of this study was to compare the hamstring to quadriceps ratio (H:Q) obtained from three different hip flexion angles. Seventy-three young athletes performed maximum isokinetic concentric and eccentric knee extension and flexion efforts at 60 °·s−1 and 240 °·s−1 from hip flexion angles of 90°, 60°, and 120°. The conventional (concentric to concentric), functional (eccentric to concentric) and mixed (eccentric at 30 °·s−1 to concentric torque at 240 °·s−1) H: Q torque ratios and the electromyographic activity from the rectus femoris and biceps femoris were analyzed. The conventional H:Q ratios and the functional H:Q ratios at 60 °·s−1 did not significantly differ between the three testing positions (p > 0.05). In contrast, testing from the 90° hip flexion angle showed a greater functional torque ratio at 240 °·s−1 and a mixed H:Q torque ratio compared with the other two positions (p < 0.05). The hip flexion angle did not influence the recorded muscle activation signals (p > 0.05). For the range of hip flexion angles tested, routine isokinetic assessment of conventional H:Q ratio and functional H:Q ratio at slow speed is not angle-dependent. Should assessment of the functional H:Q ratio at fast angular velocity or the mixed ratio is required, then selection of hip flexion angle is important.

scholarly journals Changes in Lower-Limb Biomechanics, Soft Tissue Vibrations, and Muscle Activation During Unanticipated Bipedal Landings

2019 ◽  
Vol 67 (1) ◽  
pp. 25-35
Author(s):  
Shen Zhang ◽  
Weijie Fu ◽  
Yu Liu
Keyword(s):  
Soft Tissue ◽  
Muscle Activation ◽  
Impact Force ◽  
Rectus Femoris ◽  
Biceps Femoris ◽  
Lower Limbs ◽  
Drop Jump ◽  
Basketball Players ◽  
Drop Landing ◽  
Muscle Activations

AbstractWe aimed to explore the biomechanical differences between the anticipated drop jump and unanticipated drop landing. Twelve male collegiate basketball players completed an anticipated drop jump and unanticipated drop landing with double legs from a height of 30 cm. Kinematics, impact force, soft tissue vibrations, and electromyographic (EMG) amplitudes of the dominant leg were collected simultaneously. The anticipated drop jump showed more flexed lower limbs during landing and increased range of motion compared to the unanticipated drop landing. The anticipated drop jump also had lower impact force, lesser soft tissue vibration, and a greater damp coefficient at the thigh muscles compared with the unanticipated drop landing. Significant increases in the EMG amplitudes of the tibialis anterior, lateral gastrocnemius, rectus femoris, and biceps femoris were observed in the anticipated drop jump during the pre/post-activation and downward phases. The anticipated drop jump presented more optimized landing posture control with more joint flexion, lower impact force, less soft tissue vibrations, and full preparation of muscle activations compared with the unanticipated drop landing.

Muscle Activation in the Main Muscle Groups of the Lower Limbs in High-Level Dancesport Athletes

2018 ◽  
Vol 33 (4) ◽  
pp. 231-237
Author(s):  
Encarnación Liébana ◽  
Cristina Monleón ◽  
Raquel Morales ◽  
Carlos Pablos ◽  
Consuelo Moratal ◽  
...  
Keyword(s):  
Tibialis Anterior ◽  
Muscle Activation ◽  
Rectus Femoris ◽  
Biceps Femoris ◽  
Lower Limbs ◽  
Gastrocnemius Medialis ◽  
Leg Muscles ◽  
Relative Activation ◽  
Muscle Groups ◽  
High Level

Dancers are subjected to high-intensity workouts when they practice dancesport, and according to the literature, they are prone to injury, primarily of the lower limbs. The purpose of this study was to determine whether differences exist in relative activation amplitudes for dancers involved in dancesport due to muscle, gender, and type of dance. Measurements were carried out using surface electromyography equipment during the choreography of a performance in the following leg muscles: rectus femoris, biceps femoris, tibialis anterior, and gastrocnemius medialis. Eight couples of active dancesport athletes (aged 20.50±2.75 yrs) were analyzed. Significant gender differences were found in rumba in the tibialis anterior (p≤0.05) and gastrocnemius medialis (p≤0.05). Based on the different activations, it is possible to establish possible mechanisms of injury, as well as tools for preventing injuries and improving sports performance.

scholarly journals The Effect of Prolonged Running on the Symmetry of Biomechanical Variables of the Lower Limb Joints

Symmetry ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 720
Author(s):  
Zixiang Gao ◽  
Qichang Mei ◽  
Gusztáv Fekete ◽  
Julien S Baker ◽  
Yaodong Gu
Keyword(s):  
Lower Limb ◽  
Force Plate ◽  
Knee Extension ◽  
Lower Limbs ◽  
Flexion Angle ◽  
Camera Motion ◽  
Long Distance ◽  
Therapy Assessment ◽  
Long Distance Running ◽  
Hip Flexion

The aim of this study was to examine whether there are kinematic and kinetic differences in the lower limb and whether the symmetry of the lower extremities is different after prolonged-running. Fifteen healthy male amateur runners (age: 22 ± 1 years, height: 173 ± 8 cm, mass: 65 ± 7 kg, BMI: 21.62 ± 2 kg/m2) were recruited as participants for this study. A Vicon eight-camera motion capture system and Kistler force plate were used to collect kinematic and kinetic parameters. A motorized treadmill, 15-point Borg scale and heart rate bands were used to monitor fatigue during a running-induced fatigue protocol. Paired sample T tests were used to check statistical difference (p = 0.05) between the lower limbs and the symmetry changes in pre-fatigue and post-fatigue running sessions. The symmetry angle (SA) of the knee flexion angle, hip flexion angle and hip extension angle in post-fatigue was significantly greater than in pre-fatigue, increasing by 4.32%, 10.71%, and 23.12%, respectively. Moreover, the SA of hip flexion moment increased by 2.61%. However, the knee extension velocity and hip flexion velocity became more symmetrical than in pre-fatigue (p < 0.05), the SA decreased by 5.91% and 5.45%, respectively. Differences in limb function during post-fatigue may lead to changes of symmetry in the lower limbs. The variables of asymmetry may be used as a compensation mechanism to maintain gait stability. Physical therapy assessment of fatigue injuries and long-distance running training programs may want to consider the changes in symmetry due to limb dominance.

scholarly journals Electromyographic evaluation of the lower limbs of patients with Down syndrome in hippotherapy

2017 ◽  
Vol 39 (1) ◽  
pp. 17 ◽  
Author(s):  
Mariane Fernandes Ribeiro ◽  
Ana Paula Espindula ◽  
Alex Abadio Ferreira ◽  
Luciane Aparecida Pascucci Sande de Souza ◽  
Vicente De Paula Antunes Teixeira
Keyword(s):  
Down Syndrome ◽  
Muscle Activation ◽  
Motor Behavior ◽  
Vastus Lateralis ◽  
Rectus Femoris ◽  
Gluteus Medius ◽  
Biceps Femoris ◽  
Functional Results ◽  
Lower Limbs ◽  
Tensor Fasciae Latae

Hippotherapy is a therapeutic method that uses the horse’s movement to achieve functional results in practitioners with Down syndrome (DS), who present motor and neurophysiological changes that affect the musculoskeletal system. Evaluating the motor behavior related to the control and the improvement of muscle activation in practitioners with Down syndrome subjected to hippotherapy. 10 practitioners were divided into two groups: Down Group (DG) – practitioners with DS, and Healthy Group (HG) – practitioners with no physical impairment. The muscles gluteus medius, tensor fasciae latae, rectus femoris, vastus medialis, vastus lateralis, biceps femoris, tibialis anterior and gastrocnemius were evaluated by electromyography using gross RMS values, which correspond to muscle activation; the evaluations were performed on the 1st and 10th hippotherapy sessions (frequency: once a week), and after 2 months interval without treatment, they were performed on the 1st and 10th hippotherapy sessions (frequency: twice a week). It was noted that activation of the studied muscles increased with the passing of sessions, regardless the weekly frequency of attendance; however, the period without treatment resulted in reduction of this effect. Practitioners with DS presented satisfactory changes in muscle activation pattern, in learning and in motor behavior during hippotherapy sessions. 

scholarly journals Comparison of quadriceps muscle activation in exercises with different duration of concentric and eccentric contractions

2020 ◽  
Vol 37 (5) ◽  
pp. 291-297
Author(s):  
G Freire da Silva ◽  
F Douglas Tourino ◽  
RC Ribeiro Diniz ◽  
L Túlio de Lacerda ◽  
HC Martins Costa ◽  
...  
Keyword(s):  
Degrees Of Freedom ◽  
Muscle Activation ◽  
Vastus Lateralis ◽  
Knee Extensor ◽  
Rectus Femoris ◽  
Quadriceps Muscle ◽  
Knee Extension ◽  
Muscle Action ◽  
Emg Signal ◽  
Knee Extension Exercise

Aim: The objective of the present study was to compare the amplitude of the electromyographic (EMG) signal of the quadriceps muscle portions vastus medialis (VM), vastus lateralis (VL) and rectus femoris (RF) and the activation ratio (VM/VL, VM/RF and VL/RF) in protocols with different durations of concentric and eccentric muscular actions. Material and method: Twelve female volunteers performed the knee extensor exercise with two different protocols [1s for concentric muscle action and 5s for eccentric muscle action (1:5); 5s of concentric muscle action and 1s of eccentric muscle action (5:1)] and 3 sets of 6 repetitions, 180s of pause between each sets and a intensity of 50% of 1RM. The root mean square of the amplitude of the normalized EMG signal was calculated for each repetition in each series. Results: it was observed an increase in the activation of the VM and VL portions in equivalent repetitions of each series and for the VL portion, the 1: 5 protocol provided greater activation compared to the other protocol. No differences were found for muscles activation ratios VM/RF and VL/RF, being that for the VM/VL ratio there was only change at one repetition. Conclusion: The results suggest that the portions of the quadriceps muscle may present different EMG responses in similar protocols, but this fact may not interfere in the synergism between them. The reduced degrees of freedom of the knee extension exercise and the characteristics of the protocols adopted may be the elements that contributed to the limited alterations that occurred in the present study.

scholarly journals A Review on Impact of Lower Extremity Muscle Length

2021 ◽  
pp. 158-164
Author(s):  
Anushree Pawar ◽  
Pratik Phansopkar ◽  
Avanti Gachake ◽  
Komal Mandhane ◽  
Riddhi Jain ◽  
...  
Keyword(s):  
Lower Extremity ◽  
Previous History ◽  
Muscle Length ◽  
Rectus Femoris ◽  
Knee Extension ◽  
Lower Limbs ◽  
Surgical Decision ◽  
Lower Extremity Muscle ◽  
History Of ◽  
Recovery Program

Muscle length is known as the length at which muscle is able to generate the maximum amount of force. This length is determined by the joint angle corresponding to that muscle. Length of muscle is an important parameter of length-tension relationship. Muscle functions and its mechanics helps in surgical decision making, to establish primary ergonomic advice recommendations and to form a structure of recovery program using the benefits of length-tension relation. Understanding the optimal muscle length as well as its comparison between the extremities is very important as a part of examination in physiotherapy, particularly in the cases of musculoskeletal disorders. Several tests are available for testing the muscle length. However standardize and reliable tests are been chosen to prevent the error while testing as such  measurement of hamstring, iliopsoas, rectus femoris and gastrocnemius length is been acquired through standard goniometer. The methods used for the assessment comprised of; active knee extension (AKE) tests the hamstrings, Thomas and modified Thomas test to evaluate iliopsoas and rectus femoris while prone, figure-four position accompanied by dorsiflexion for gastrocnemius. Many studies have done and their results had shown that there was difference in the lengths of muscle of lower extremity which was assessed in different players along with that normative data about the length of muscle was established. However there is paucity of study on the muscle length testing of individuals who are completely normal who are not having previous history of trauma to their lower limbs and those who are not an athlete.

Hip-Muscle Activation during the Lunge, Single-Leg Squat, and Step-Up-and-Over Exercises

2009 ◽  
Vol 18 (1) ◽  
pp. 91-103 ◽  
Author(s):  
Samantha N. Boudreau ◽  
Maureen K. Dwyer ◽  
Carl G. Mattacola ◽  
Christian Lattermann ◽  
Tim L. Uhl ◽  
...  
Keyword(s):  
Lower Extremity ◽  
Outcome Measures ◽  
Muscle Activation ◽  
Gluteus Maximus ◽  
Rectus Femoris ◽  
Lower Extremity Injury ◽  
Cross Sectional ◽  
Hip Muscle ◽  
Hip Muscles ◽  
Single Leg Squat

Context:Functional exercises are often used in strengthening programs after lower extremity injury. Activation levels of the stabilizing hip muscles have not been documented.Objective:To document the progression of hip-muscle activation levels during 3 lower extremity functional exercises.Design:Cross-sectional.Setting:Laboratory.Participants:44 healthy individuals, 22 women and 22 men.Intervention:Subjects, in 1 testing session, completed 3 trials each of the lunge (LUN), single-leg squat (SLSQ), and step-up-and-over (SUO) exercise.Main Outcome Measures:Root-mean-square muscle amplitude (% reference voluntary muscle contraction) was measured for 5 muscles during the 3 exercises: rectus femoris (RF), dominant and nondominant gluteus medius (GMed_D and GMed_ND), adductor longus (ADD), and gluteus maximus (GMX).Results:The RF, GMAX, and GMed_D were activated in a progression from least to greatest during the SUO, LUN, and SLSQ. The progression for the GMed_ND activation was from least to greatest during the SLSQ, SUO, and then LUN. Activation levels of the ADD showed no progression.Conclusion:Progressive activation levels were documented for muscles acting on the hip joint during 3 functional lower extremity exercises. The authors recommend using this exercise progression when targeting the hip muscles during lower extremity strengthening.

Effects of Optimization Technique on Simulated Muscle Activations and Forces

2020 ◽  
Vol 36 (4) ◽  
pp. 259-278
Author(s):  
Sarah A. Roelker ◽  
Elena J. Caruthers ◽  
Rachel K. Hall ◽  
Nicholas C. Pelz ◽  
Ajit M.W. Chaudhari ◽  
...  
Keyword(s):  
Muscle Function ◽  
Muscle Activation ◽  
Optimization Technique ◽  
Knee Extension ◽  
Optimization Techniques ◽  
Model Choice ◽  
Muscle Forces ◽  
Joint Torques ◽  
Muscle Activations ◽  
Proportional Derivative Controller

Two optimization techniques, static optimization (SO) and computed muscle control (CMC), are often used in OpenSim to estimate the muscle activations and forces responsible for movement. Although differences between SO and CMC muscle function have been reported, the accuracy of each technique and the combined effect of optimization and model choice on simulated muscle function is unclear. The purpose of this study was to quantitatively compare the SO and CMC estimates of muscle activations and forces during gait with the experimental data in the Gait2392 and Full Body Running models. In OpenSim (version 3.1), muscle function during gait was estimated using SO and CMC in 6 subjects in each model and validated against experimental muscle activations and joint torques. Experimental and simulated activation agreement was sensitive to optimization technique for the soleus and tibialis anterior. Knee extension torque error was greater with CMC than SO. Muscle forces, activations, and co-contraction indices tended to be higher with CMC and more sensitive to model choice. CMC’s inclusion of passive muscle forces, muscle activation-contraction dynamics, and a proportional-derivative controller to track kinematics contributes to these differences. Model and optimization technique choices should be validated using experimental activations collected simultaneously with the data used to generate the simulation.

scholarly journals Static vs. Dynamic Acute Stretching Effect on Quadriceps Muscle Activity during Soccer Instep Kicking

2013 ◽  
Vol 39 (1) ◽  
pp. 37-47 ◽  
Author(s):  
Mohammadtaghi Amiri-Khorasani ◽  
Eleftherios Kellis
Keyword(s):  
Angular Velocity ◽  
Muscle Activity ◽  
High Speed ◽  
Muscle Activation ◽  
Body Height ◽  
Rectus Femoris ◽  
Quadriceps Muscle ◽  
Knee Extension ◽  
Emg Activity ◽  
Dynamic Stretching

Abstract The purpose of this study was to compare the effects of static and dynamic stretching on quadriceps muscle activation during maximal soccer instep kicking. The kicking motion of twelve male college soccer players (body height: 174.66 ± 5.01 cm; body mass: 72.83 ± 4.83 kg; age: 18.83 ± 0.75 years) was captured using six synchronized high-speed infra-red cameras whilst electromyography (EMG) signals from vastus medialis (VM), lateralis (VL) and rectus femoris (RF) were recorded before and after static or dynamic stretching. Analysis of variance designs showed a higher increase in knee extension angular velocity (9.65% vs. -1.45%, p < 0.001), RF (37.5% vs. -8.33%, p < 0.001), VM (12% vs. - 12%, p < 0.018), and VL EMG activity (20% vs. -6.67%, p < 0.001) after dynamic stretching exercises. Based on these results, it could be suggested that dynamic stretching is probably more effective in increasing quadriceps muscle activity and knee extension angular velocity during the final swing phase of a maximal soccer instep kick than static stretching.

Sign in / Sign up

Export Citation Format

Share Document