Dynamic knee extension as model for study of isolated exercising muscle in humans

1985 ◽  
Vol 59 (5) ◽  
pp. 1647-1653 ◽  
Author(s):  
P. Andersen ◽  
R. P. Adams ◽  
G. Sjogaard ◽  
A. Thorboe ◽  
B. Saltin
Keyword(s):  
Femoral Vein ◽  
Rectus Femoris ◽  
Biceps Femoris ◽  
Knee Extension ◽  
Bicycle Ergometer ◽  
The Body ◽  
External Work ◽  
Leg Muscles ◽  
Below The Knee ◽  
The Subject

In an attempt to approach a system of isolated exercising muscle in humans, a model has been developed that enables the study of muscle activity and metabolism over the quadriceps femoris (QF) muscles while the rest of the body remains relaxed. The simplest version includes the subject sitting on a table with a rod connecting the ankle and the pedal arm of a bicycle ergometer placed behind the subject. Exercise is performed by knee extension from a knee angle of 90 to approximately 170 degrees while flywheel momentum repositions the relaxed leg during flexion. Experiments where electromyographic recordings have been taken from biceps femoris, gastrocnemius, tibialis anterior, and other muscles in addition to QF indicate that only the QF is active and that there is an equal activation of the lateral, medial, and rectus femoris heads relative to maximum. Furthermore, virtually identical pulmonary O2 uptake (Vo2) during and without application of a pressure cuff below the knee emphasizes the inactivity of the lower leg muscles. The advantages of the model are that all external work can be localized to a single muscle group suitable for taking biopsies and that the blood flow in and sampling from the femoral vein are representative of the active muscles. Thus all measurements can be closely related to changes in the working muscle. Using this model we find that a linear relationship exists between external work and pulmonary Vo2 over the submaximal range and the maximal Vo2 per kilogram of muscle may be as much as twice as high as previously estimated.

Sensorimotor State of the Contralateral Leg Affects Ipsilateral Muscle Coordination of Pedaling

1998 ◽  
Vol 80 (3) ◽  
pp. 1341-1351 ◽  
Author(s):  
Lena H. Ting ◽  
Christine C. Raasch ◽  
David A. Brown ◽  
Steven A. Kautz ◽  
Felix E. Zajac
Keyword(s):  
Rectus Femoris ◽  
Biceps Femoris ◽  
Bicycle Ergometer ◽  
Coordination Pattern ◽  
Neural Pathways ◽  
Muscle Coordination ◽  
Human Motor ◽  
The Subject ◽  
Work Done ◽  
Limb Flexion

Ting, Lena H., Christine C. Raasch, David A. Brown, Steven A. Kautz, and Felix E. Zajac. Sensorimotor state of the contralateral leg affects ipsilateral muscle coordination of pedaling. J. Neurophysiol. 80: 1341-1351, 1998. The objective of this study was to determine if independent central pattern generating elements controlling the legs in bipedal and unipedal locomotion is a viable theory for locomotor propulsion in humans. Coordinative coupling of the limbs could then be accomplished through mechanical interactions and ipsilateral feedback control rather than through central interlimb neural pathways. Pedaling was chosen as the locomotor task to study because interlimb mechanics can be significantly altered, as pedaling can be executed with the use of either one leg or two legs (cf. walking) and because the load on the limb can be well-controlled. Subjects pedaled a modified bicycle ergometer in a two-legged (bilateral) and a one-legged (unilateral) pedaling condition. The loading on the leg during unilateral pedaling was designed to be identical to the loading experienced by the leg during bilateral pedaling. This loading was achieved by having a trained human “motor” pedal along with the subject and exert on the opposite crank the torque that the subject's contralateral leg generated in bilateral pedaling. The human “motor” was successful at reproducing each subject's one-leg crank torque. The shape of the motor's torque trajectory was similar to that of subjects, and the amount of work done during extension and flexion was not significantly different. Thus the same muscle coordination pattern would allow subjects to pedal successfully in both the bilateral and unilateral conditions, and the afferent signals from the pedaling leg could be the same for both conditions. Although the overall work done by each leg did not change, an 86% decrease in retarding (negative) crank torque during limb flexion was measured in all 11 subjects during the unilateral condition. This corresponded to an increase in integrated electromyography of tibialis anterior (70%), rectus femoris (43%), and biceps femoris (59%) during flexion. Even given visual torque feedback in the unilateral condition, subjects still showed a 33% decrease in negative torque during flexion. These results are consistent with the existence of an inhibitory pathway from elements controlling extension onto contralateral flexion elements, with the pathway operating during two-legged pedaling but not during one-legged pedaling, in which case flexor activity increases. However, this centrally mediated coupling can be overcome with practice, as the human “motor” was able to effectively match the bilateral crank torque after a longer practice regimen. We conclude that the sensorimotor control of a unipedal task is affected by interlimb neural pathways. Thus a task performed unilaterally is not performed with the same muscle coordination utilized in a bipedal condition, even if such coordination would be equally effective in the execution of the unilateral task.

Changes in muscle activities and kinematics due to simulated leg length inequalities

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Hannah Lena Siebers ◽  
Jörg Eschweiler ◽  
Filippo Migliorini ◽  
Valentin Michael Quack ◽  
Markus Tingart ◽  
...  
Keyword(s):  
Muscle Activity ◽  
Rectus Femoris ◽  
Knee Extension ◽  
Pelvic Obliquity ◽  
Lateral Flexion ◽  
Leg Length ◽  
Joint Angles ◽  
Leg Muscles ◽  
Compensation Mechanisms ◽  
Musculoskeletal Problems

Abstract Muscle imbalances are a leading cause of musculoskeletal problems. One example are leg length inequalities (LLIs). This study aimed to analyze the effect of different (simulated) LLIs on back and leg muscles in combination with kinematic compensation mechanics. Therefore, 20 healthy volunteers were analyzed during walking with artificial LLIs (0–4 cm). The effect of different amounts of LLIs and significant differences to the reference condition without LLI were calculated of maximal joint angles, mean muscle activity, and its symmetry index. While walking, LLIs led to higher muscle activity and asymmetry of back muscles, by increased lumbar lateral flexion and pelvic obliquity. The rectus femoris showed higher values, independent of the amount of LLI, whereas the activity of the gastrocnemius on the shorter leg increased. The hip and knee flexion of the long leg increased significantly with increasing LLIs, like the knee extension and the ankle plantarflexion of the shorter leg. The described compensation mechanisms are explained by a dynamic lengthening of the short and shortening of the longer leg, which is associated with increased and asymmetrical muscle activity. Presenting this overview is important for a better understanding of the effects of LLIs to improve diagnostic and therapy in the future.

External work in level and grade walking on a motor-driven treadmill

1960 ◽  
Vol 15 (5) ◽  
pp. 759-763 ◽  
Author(s):  
J. W. Snellen
Keyword(s):  
Heat Loss ◽  
Heat Production ◽  
Total Energy Expenditure ◽  
The Body ◽  
External Work ◽  
Thermal Exchange ◽  
Level Walking ◽  
The Subject ◽  
Set Up ◽  
Physical Laws

When studying a walking subject's thermal exchange with the environment, it is essential to know whether in level walking any part of the total energy expenditure is converted into external mechanical work and whether in grade walking the amount of the external work is predictable from physical laws. For this purpose an experiment was set up in which a subject walked on a motor-driven treadmill in a climatic room. In each series of measurements a subject walked uphill for 3 hours and on the level for another hour. Metabolism was kept equal in both situations. Air and wall temperatures were adjusted to the observed weighted skin temperature in order to avoid any heat exchange by radiation and convection. Heat loss by evaporation was derived from the weight loss of the subject. All measurements were carried out in a state of thermal equilibrium. In grade walking there was a difference between heat production and heat loss by evaporation. This difference equaled the caloric equivalent of the product of body weight and gained height. In level walking the heat production equaled heat loss. Hence it was concluded that in level walking all the energy is converted into heat inside the body. Submitted on April 26, 1960

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.

The Relationship between Integrated EMG and Oxygen Uptake during Treadmill and Bicycle Exercise

1976 ◽  
Vol 20 (23) ◽  
pp. 548-551
Author(s):  
T. Fukunaga ◽  
K. Yuasa ◽  
M. Kobayashi ◽  
T. Miyagawa ◽  
H. Fujimatsu ◽  
...  
Keyword(s):  
Oxygen Uptake ◽  
Correlation Coefficient ◽  
Rectus Femoris ◽  
Biceps Femoris ◽  
Treadmill Walking ◽  
Emg Activity ◽  
Bicycle Exercise ◽  
Leg Muscles ◽  
Integrated Emg ◽  
Muscle Groups

The aim of this study is to measure the integrated EMG in relation to the oxygen uptake during submaximal treadmill and bicycle exercises. Seven healthy adult subjects performed five minute exercise at three different submaximal work intensities on the same day. The EMG activity in right thigh and leg muscles was measured from m. rectus femoris, m. biceps femoris, m. tibialis anterior and m. gastrocnemius by means of four pairs of surface electrodes sealed with collodion to the skin at a distance of 3 cm apart over the belly of muscles. The EMG activity was not likely modified by the possible fatigue during 5 minutes submaximal exercise in this experiment. In the treadmill walking, there was a rectilinear relationship between integrated EMG activity from four muscle groups and percent of VO2max. On the bicycle exercise the correlation coefficient between them was generally lower than that on the treadmill walking. The product of integrated EMG and volume of the same muscle groups was considerably linearly related to oxygen uptake during treadmill and bicycle exercise (the correlation coefficient was 0.945, p < 0.001 in treadmill and 0.710, p < 0.001 in bicycle).

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 Stumbling Over Obstacles in Older Adults Compared to Young Adults

2005 ◽  
Vol 94 (2) ◽  
pp. 1158-1168 ◽  
Author(s):  
A. M. Schillings ◽  
Th. Mulder ◽  
J. Duysens
Keyword(s):  
Older Adults ◽  
Young Adults ◽  
Age Groups ◽  
Rectus Femoris ◽  
Biceps Femoris ◽  
Risk Of Falling ◽  
Leg Muscles ◽  
Long Latency Responses ◽  
Long Latency ◽  
Movement Strategies

Falls are a major problem in older adults. Many falls occur because of stumbling. The aim of the present study is to investigate stumbling reactions of older adults and to compare them with young adults. While subjects walked on a treadmill, a rigid obstacle unexpectedly obstructed the forward sway of the foot. In general, older adults used the same movement strategies as young adults (“elevating” and “lowering”). The electromyographic responses were categorized according to latencies: short-latency (about 45 ms, RP1), medium-latency (about 80 ms, RP2), and long-latency responses (about 110 ms, RP3; about 160 ms, RP4). Latencies of RP1 responses increased by about 6 ms and of RP2 by 10–19 ms in older adults compared with the young. Amplitudes of RP1 were similar for both age groups, whereas amplitudes of RP2–RP4 could differ. In the early-swing elevating strategy (perturbed foot directly lifted over the obstacle) older adults showed smaller responses in ipsilateral upper-leg muscles (biceps femoris and rectus femoris). This was related to shorter swing durations, more shortened step distances, and more failures in clearing the obstacle. In parallel, RP4 activity in the contralateral biceps femoris was enhanced, possibly pointing to a higher demand for trunk stabilization. In the late-swing lowering strategy (foot placed on the treadmill before clearing the obstacle) older adults showed lower RP2–RP3 responses in most muscles measured. However, kinematic responses were similar to those of the young. It is concluded that the changes in muscular responses in older adults induce a greater risk of falling after tripping, especially in early swing.

scholarly journals Interlimb communication following unexpected changes in treadmill velocity during human walking

2015 ◽  
Vol 113 (9) ◽  
pp. 3151-3158 ◽  
Author(s):  
Andrew J. T. Stevenson ◽  
Svend S. Geertsen ◽  
Thomas Sinkjær ◽  
Jens B. Nielsen ◽  
Natalie Mrachacz-Kersting
Keyword(s):  
Dynamic Stability ◽  
Stance Phase ◽  
Biceps Femoris ◽  
The Body ◽  
Context Dependency ◽  
Human Walking ◽  
Human Gait ◽  
Velocity Change ◽  
Leg Muscles ◽  
Interlimb Reflex

Interlimb reflexes play an important role in human walking, particularly when dynamic stability is threatened by external perturbations or changes in the walking surface. Interlimb reflexes have recently been demonstrated in the contralateral biceps femoris (cBF) following knee joint rotations applied to the ipsilateral leg (iKnee) during the late stance phase of human gait (Stevenson AJ, Geertsen SS, Andersen JB, Sinkjær T, Nielsen JB, Mrachacz-Kersting N. J Physiol 591: 4921–4935, 2013). This interlimb reflex likely acts to slow the forward progression of the body to maintain dynamic stability following the perturbations. We examined this hypothesis by unexpectedly increasing or decreasing the velocity of the treadmill before (−100 and −50 ms), at the same time, or following (+50 ms) the onset of iKnee perturbations in 12 healthy volunteers. We quantified the cBF reflex amplitude when the iKnee perturbation was delivered alone, the treadmill velocity change was delivered alone, or when the two perturbations were combined. When the treadmill velocity was suddenly increased (or decreased) 100 or 50 ms before the iKnee perturbations, the combined cBF reflex was significantly larger (or smaller) than the algebraic sum of the two perturbations delivered separately. Furthermore, unexpected changes in treadmill velocity increased the incidence of reflexes in other contralateral leg muscles when the iKnee perturbations were elicited alone. These results suggest a context dependency for interlimb reflexes. They also show that the cBF reflex changed in a predictable manner to slow the forward progression of the body and maintaining dynamic stability during walking, thus signifying a functional role for interlimb reflexes.

scholarly journals Characterization of kinesiological patterns of the frontal kick, mae-geri, in karate experts and non-karate practitioners

2014 ◽  
Vol 9 (1) ◽  
pp. 20 ◽  
Author(s):  
António M. VencesBrito ◽  
Marco A. Colaço Branco ◽  
Renato M. Cordeiro Fernandes ◽  
Mário A. Rodrigues Ferreira ◽  
Orlando J. S. M. Fernandes ◽  
...  
Keyword(s):  
Muscle Activity ◽  
Vastus Lateralis ◽  
Plantar Flexion ◽  
Neuromuscular Control ◽  
Rectus Femoris ◽  
Biceps Femoris ◽  
Knee Extension ◽  
Maximum Speed ◽  
Ballistic Performance ◽  
The Impact

Presently, coaches and researchers need to have a better comprehension of the kinesiological parameters that should be an important tool to support teaching methodologies and to improve skills performance in sports. The aim of this study was to (i) identify the kinematic and neuromuscular control patterns of the front kick (<em>mae-geri</em>) to a fixed target performed by 14 experienced karate practitioners, and (ii) compare it with the execution of 16 participants without any karate experience, allowing the use of those references in the analysis of the training and learning process. Results showed that the kinematic and neuromuscular activity during the kick performance occurs within 600 ms. Muscle activity and kinematic analysis demonstrated a sequence of activation bracing a proximal-to-distal direction, with the muscles presenting two distinct periods of activity (1, 2), where the karateka group has a greater intensity of activation – root mean square (RMS) and electromyography (EMG) peak – in the first period on <em>Rectus Femoris</em> (RF1) and  <em>Vastus Lateralis</em> (VL1) and a lower duration of co-contraction in both periods on <em>Rectus Femoris</em>-<em>Biceps Femoris</em> and <em>Vastus Lateralis</em>-<em>Biceps Femoris</em> (RF-BF; VL-BF). In the skill performance, the hip flexion, the knee extension and the ankle plantar flexion movements were executed with smaller difference in the range of action (ROA) in the karateka group, reflecting different positions of the segments. In conclusion, it was observed a general kinesiological pattern, which was similar in karateka and non-karateka practitioners. However, in the karateka group, the training induces a specialization in the muscle activity reflected in EMG and kinematic data, which leads to a better ballistic performance in the execution of the <em>mae-geri</em> kick, associated with a maximum speed of the distal segments, reached closer to the impact moment, possibly representing more power in the contact.

scholarly journals The Effect of Step Width on Muscle Contributions to Body Mass Center Acceleration During the First Stance of Sprinting

2021 ◽  
Vol 9 ◽  
Author(s):  
Ruoli Wang ◽  
Laura Martín de Azcárate ◽  
Paul Sandamas ◽  
Anton Arndt ◽  
Elena M. Gutierrez-Farewik
Keyword(s):  
Lower Limb ◽  
Sagittal Plane ◽  
Center Of Mass ◽  
Gluteus Maximus ◽  
Rectus Femoris ◽  
Gluteus Medius ◽  
Biceps Femoris ◽  
The Body ◽  
Step Width ◽  
Acceleration Analysis

BackgroundAt the beginning of a sprint, the acceleration of the body center of mass (COM) is driven mostly forward and vertically in order to move from an initial crouched position to a more forward-leaning position. Individual muscle contributions to COM accelerations have not been previously studied in a sprint with induced acceleration analysis, nor have muscle contributions to the mediolateral COM accelerations received much attention. This study aimed to analyze major lower-limb muscle contributions to the body COM in the three global planes during the first step of a sprint start. We also investigated the influence of step width on muscle contributions in both naturally wide sprint starts (natural trials) and in sprint starts in which the step width was restricted (narrow trials).MethodMotion data from four competitive sprinters (2 male and 2 female) were collected in their natural sprint style and in trials with a restricted step width. An induced acceleration analysis was performed to study the contribution from eight major lower limb muscles (soleus, gastrocnemius, rectus femoris, vasti, gluteus maximus, gluteus medius, biceps femoris, and adductors) to acceleration of the body COM.ResultsIn natural trials, soleus was the main contributor to forward (propulsion) and vertical (support) COM acceleration and the three vasti (vastus intermedius, lateralis and medialis) were the main contributors to medial COM acceleration. In the narrow trials, soleus was still the major contributor to COM propulsion, though its contribution was considerably decreased. Likewise, the three vasti were still the main contributors to support and to medial COM acceleration, though their contribution was lower than in the natural trials. Overall, most muscle contributions to COM acceleration in the sagittal plane were reduced. At the joint level, muscles contributed overall more to COM support than to propulsion in the first step of sprinting. In the narrow trials, reduced COM propulsion and particularly support were observed compared to the natural trials.ConclusionThe natural wide steps provide a preferable body configuration to propel and support the COM in the sprint starts. No advantage in muscular contributions to support or propel the COM was found in narrower step widths.

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