Limited interlimb transfer of locomotor adaptations to a velocity-dependent force field during unipedal walking

2012 ◽  
Vol 108 (3) ◽  
pp. 943-952 ◽  
Author(s):  
Adina Houldin ◽  
Romeo Chua ◽  
Mark G. Carpenter ◽  
Tania Lam
Keyword(s):  
Force Field ◽  
Lower Limb ◽  
Maximum Voluntary Contraction ◽  
Voluntary Contraction ◽  
Task Environment ◽  
Locomotor Adaptation ◽  
The Right ◽  
Hip Flexion ◽  
Locomotor Adaptations ◽  
Kinematic Errors

Several studies have demonstrated that motor adaptations to a novel task environment can be transferred between limbs. Such interlimb transfer of motor commands is consistent with the notion of centrally driven strategies that can be generalized across different frames of reference. So far, studies of interlimb transfer of locomotor adaptations have yielded disparate results. Here we sought to determine whether locomotor adaptations in one (trained) leg show transfer to the other (test) leg during a unipedal walking task. We hypothesized that adaptation in the test leg to a velocity-dependent force field previously experienced by the trained leg will be faster, as revealed by faster recovery of kinematic errors and earlier onset of aftereffects. Twenty able-bodied adults walked unipedally in the Lokomat robotic gait orthosis, which applied velocity-dependent resistance to the legs. The amount of resistance was scaled to 10% of each individual's maximum voluntary contraction of the hip flexors. Electromyography and kinematics of the lower limb were recorded. All subjects were right-leg dominant and were tested for transfer of motor adaptations from the right leg to the left leg. Catch trials, consisting of unexpected removal of resistance, were presented after the first step with resistance and after a period of adaptation to test for aftereffects. We found no significant differences in the sizes of the aftereffects between the two legs, except for peak hip flexion during swing, or in the rate at which peak hip flexion adapted during steps against resistance between the two legs. Our results indicate that interlimb transfer of these types of locomotor adaptation is not a robust phenomenon. These findings add to our current understanding of motor adaptations and provide further evidence that generalization of adaptations may be dependent on the movement task.

Effects of contraction force and frequency on postexercise hyperemia in human calf muscles

1980 ◽  
Vol 49 (4) ◽  
pp. 649-654 ◽  
Author(s):  
D. Richardson ◽  
R. Shewchuk
Keyword(s):  
Blood Flow ◽  
Muscle Blood Flow ◽  
Maximum Voluntary Contraction ◽  
Voluntary Contraction ◽  
Calf Muscle ◽  
Contraction Force ◽  
A Value ◽  
True Blood ◽  
The Right ◽  
Human Calf

The purpose of this study was to examine the separate effects of contraction force and frequency on postexercise hyperemia in the human calf muscle. Nine male subjects were used. Each was seated in a chair with the right foot on a pedal coupled to a load cell and the knee secured. Calf muscle blood flow, measured by a Whitney gauge, was determined before and periodically after 3-pmin bouts of rhythmic isometric plantar-flexor exercise. The contraction frequency was graded from 20 to 50 to 80 contractions/min. The force per contraction was graded from 7.5 to 15 to 30% of maximum voluntary contraction (MVC) of the calf muscle. The average MCV was 502 lb. Peak postexercise blood flow (PBF) increased with either increasing frequency at a given force or increasing force at a given frequency. However, at the higher levels of exercise, PBF tended to plateau at a value of about 50 ml.min-1.100 ml-1. The plateau phase of PBF was associated with a substantial increase in the total volume of postexercise hyperemia. This appeared to be well above any repayment of a blood flow deficit. However, it is not certain that the extra volume represented the repayment of a true blood flow debt.

scholarly journals El impacto inicial con antepié incrementa la actividad muscular del gastrocnemios durante la carrera. Un estudio cuantitativo de actividad electromiográfica (The initial impact with forefoot increases the muscular activity of gastrocnemius during running)

Retos ◽  
2020 ◽  
pp. 271-275
Author(s):  
Oscar Valencia ◽  
Iver Cristi ◽  
Dario Ahumada ◽  
Keiny Meza ◽  
Rodrigo Salas ◽  
...  
Keyword(s):  
Lower Limb ◽  
Stance Phase ◽  
Maximum Voluntary Contraction ◽  
Neuromuscular Control ◽  
Voluntary Contraction ◽  
Medial Gastrocnemius ◽  
Emg Activity ◽  
Myoelectric Activity ◽  
Initial Contact ◽  
Limb Injuries

Un importante porcentaje de las lesiones de miembros inferiores ha sido vinculado a la técnica de carrera, en particular, al contacto inicial con retropié (RP) o antepié (AP). Sin embargo, existe limitada evidencia de la actividad electromiográfica (EMG) para ambas condiciones. El objetivo de este estudio fue comparar la amplitud EMG en miembros inferiores al utilizar técnicas de RP vs AP durante la carrera. Trece corredores fueron evaluado a una velocidad de trote autoseleccionada en dos condiciones: contacto inicial con RP y AP. Se registró la actividad mioeléctrica del recto femoral (RF), bíceps femoral (BF), tibial anterior (TA), gastrocnemio medial (GM) y lateral (GL). Se consideró la amplitud promedio de la EMG en 10 ciclos de carrera, normalizados a la contracción voluntaria máxima. Los resultados destacan una mayor activación significativa de los músculos GM y GL en el contacto AP durante la fase de apoyo, balanceo y en todo el ciclo de carrera. Adicionalmente, el TA presentó una mayor activación durante la fase de vuelo y el 100% del ciclo de carrera para la condición RP. No se encontraron otras diferencias significativas. En conclusión, el uso de la técnica AP incrementa la actividad muscular de GM y GL, posiblemente asociado a una mayor absorción del impacto durante la fase de apoyo. Por otro lado, el TA incrementa su actividad con RP, lo que podría implicar un mayor control previo al contacto inicial. La técnica de carrera se presenta como una condición modificable según situaciones de rendimiento o patología.Abstract. Running technique has an impact on lower limb injuries, particularly the initial contact pattern such as rearfoot (RF) or forefoot (FF). However, there is limited evidence of the electromyographic (EMG) activity for both conditions. The aim of this study was to compare the lower limb muscles EMG amplitude between RF and FF techniques during running. Thirteen runners were evaluated at a self-selected running speed under two conditions: initial contact with RF and FF. The myoelectric activity of the rectus femoris (RE), biceps femoris (BF), tibialis anterior (TA), medial gastrocnemius (GM) and lateral (GL) were analysed. The EMG amplitudes of 10 running cycles were averaged and normalized to the maximum voluntary contraction. The results included a significantly higher activation of GM and GL muscles for the FF condition during the stance phase, balance and the entire running cycle. In addition, TA showed higher activation during the swing phase and the 100% running cycle for the RP condition. No other significant differences were found. In conclusion, FF technique increases GM and GL myoelectric activity, possibly associated with a higher impact absorption during the stance phase. On the other hand, TA increases its activity for RF condition which may imply a greater neuromuscular control prior to initial contact. Finally, the running technique is presented as a modifiable condition which can be changed to enhance performance or in pathologic circumstances.

Muscle Strength Assessment from the EMG Frequency Spectrum

1987 ◽  
Vol 31 (3) ◽  
pp. 310-314 ◽  
Author(s):  
Eui S. Jung
Keyword(s):  
Biceps Brachii ◽  
Muscle Tension ◽  
Maximum Voluntary Contraction ◽  
Power Spectra ◽  
Voluntary Contraction ◽  
The Other ◽  
Mean Power ◽  
Mean Power Frequency ◽  
Strength Assessment ◽  
The Right

Assessment of a worker's strength is of great interest when evaluating the worker's ability to safely perform a job. Many previous studies have shown that surface electromyogram EMG amplitudes correlate well with muscle force. The present study furthered this concept by using EMG power spectra to achieve a quantified representation of true strength capability. Two groups of male subjects performed isometric elbow flexions while EMG was obtained from the right belly of biceps brachii. One group exercised their arms regularly while the other not. Six different levels of graded maximum voluntary contraction (%MVC) were selected to examine the relations between muscle tension and the mean power frequency (MPF) resulting from EMG power spectra. Resultant MPF's ranged between 50Hz and 70Hz in agreement with previous research results. Two-way ANOVA showed that, in the trained group, a significant increase in the MPF was found at near maximum contractions, whereas the other group failed to show any difference. Further analysis revealed that this increase in MPF was mainly caused by the power increase in the higher bandwidth (70—100Hz). A significant variation between subjects in both groups was also observed.

Two heads are better than one: both complementary and synchronous strategies facilitate joint action

2013 ◽  
Vol 109 (5) ◽  
pp. 1307-1314 ◽  
Author(s):  
Junya Masumoto ◽  
Nobuyuki Inui
Keyword(s):  
Joint Action ◽  
Maximum Voluntary Contraction ◽  
Absolute Error ◽  
Voluntary Contraction ◽  
Phase Region ◽  
Total Force ◽  
Individual Action ◽  
New Findings ◽  
The Individual ◽  
The Right

If two people lift and carry an object, they not only produce complementary forces on the object but also walk in synchrony. Previous studies have not examined how two types of coordination strategy are adopted simultaneously. The present study thus tested the hypothesis that complementary and synchronous strategies simultaneously facilitate the action coordination performed by two people. Ten pairs of participants produced periodic isometric forces such that the sum of forces they produced was the target force cycling between 5% and 10% of maximum voluntary contraction with an interval of 1,000 ms (joint action), while individuals alone produced the same target forces with the right hand (individual action). The correlation between forces produced by two participants was highly negative when the total force was visible, indicating that the two participants produced complementary forces. When the image of the total or partner force was presented, the coherence between force-time series produced by two participants was highest at 1 Hz. The relative phase angles were also distributed at the 0–20° phase region. These innovative findings indicate that two participants simultaneously adopted both complementary and temporal synchronous strategies exclusively when the total force was visible. With the vision of total force, surprisingly, while the joint action exhibited a less variable force than the individual action, the joint action exhibited a smaller absolute error of forces than the individual action. These new findings indicated that the joint action controlled force more accurately than the individual action.

Skin Cooling Alters the Activation Patterns of Different Heads of the Quadriceps

2005 ◽  
Vol 30 (2) ◽  
pp. 127-139 ◽  
Author(s):  
Ryuta Kinugasa ◽  
Kazumasa Yoshida ◽  
Takayuki Watanabe ◽  
Kousuke Kuchiki ◽  
Akira Horii
Keyword(s):  
Isometric Force ◽  
Vastus Lateralis ◽  
Maximum Voluntary Contraction ◽  
Force Production ◽  
Transverse Relaxation Time ◽  
Knee Extension ◽  
Voluntary Contraction ◽  
Activation Patterns ◽  
Skin Cooling ◽  
The Right

The purpose of this study was to examine the effect of selective skin cooling over m. vastus lateralis (VL) on the activation patterns of quadriceps femoris muscle during knee extension exercise (KEE) using muscle function magnetic resonance imaging (mfMRI). The isometric force production of the right thigh was tested in 7 healthy young men at maximum voluntary contraction (MVC), and the transverse relaxation time (T2) value was taken from mfMR images at rest and immediately after KEE with 4 sets of 10 repetitions at a load equal to 60% of their 10-rep maximum, with and without skin cooling. The cooling was carried out by ice pack on the surface of the skin of the VL for 3 min before resting mfMRI and MVC tests, and before KEE, during KEE, and during the KEE rest intervals. The percent change in T2 of the m. vastus intermedius was significantly increased by skin cooling in comparison to the change without skin cooling, p < 0.05. This result suggests that skin cooling alters the activation pattern of the different heads of the quadriceps. Key words: cold, mfMRI, synergy, recruitment, neuromuscular plasticity

Sense of Effort Determines Lower Limb Force Production During Dynamic Movement in Individuals With Poststroke Hemiparesis

2009 ◽  
Vol 23 (8) ◽  
pp. 811-818 ◽  
Author(s):  
Ann M. Simon ◽  
Brian M. Kelly ◽  
Daniel P. Ferris
Keyword(s):  
Lower Limb ◽  
Maximum Voluntary Contraction ◽  
Force Production ◽  
Voluntary Contraction ◽  
Sense Of Effort ◽  
Paretic Limb ◽  
Significant Difference ◽  
Force Scaling ◽  
Limb Rehabilitation ◽  
Isometric Forces

Objective. This study’s purpose was to determine if individuals who have had a stroke primarily use sense of effort to gauge force production during static and dynamic lower limb contractions. If relying on sense of effort while attempting to generate equal limb forces, participants should produce equal percentages of their maximum voluntary strength rather than equal absolute forces in their limbs. Methods. Ten stroke participants performed isometric and isotonic lower limb extensions on an exercise machine. Results. When participants attempted to produce equal bilateral isometric forces, there was a significant difference in absolute force between limbs (ANOVA, P < .0001) but no significant difference when force was normalized to each limb’s maximum voluntary contraction (MVC) force ( P = .5129). During bilateral isotonic contractions, participants produced less absolute force in their paretic limb ( P = .0005) and less relative force in their paretic limb (normalized to MVC force) when participants were given no instructions on how to perform the extension ( P = .0002). When participants were instructed to produce equal forces, there was no significant difference between relative forces in the 2 limbs ( P = .2111). Conclusions. For both isometric and isotonic conditions hemiparetic participants relied primarily on sense of effort, rather than proprioceptive feedback, for gauging lower limb force production. This outcome indicates that sense of effort is the major factor determining force production during movements. Lower limb rehabilitation therapies should not only train strength in the paretic limb but should also train patients to recalibrate force-scaling abilities to improve function.

scholarly journals Cerebellar Transcranial Magnetic Stimulation Reduces the Silent Period on Hand Muscle Electromyography During Force Control

2020 ◽  
Vol 10 (2) ◽  
pp. 63 ◽  
Author(s):  
Akiyoshi Matsugi ◽  
Shinya Douchi ◽  
Kodai Suzuki ◽  
Kosuke Oku ◽  
Nobuhiko Mori ◽  
...  
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Magnetic Stimulation ◽  
Primary Motor Cortex ◽  
Maximum Voluntary Contraction ◽  
Motor Evoked Potential ◽  
Silent Period ◽  
Voluntary Contraction ◽  
Resting Motor Threshold ◽  
First Dorsal Interosseous Muscle ◽  
The Right

This study aimed to investigate whether cerebellar transcranial magnetic stimulation (C-TMS) affected the cortical silent period (cSP) induced by TMS over the primary motor cortex (M1) and the effect of interstimulus interval (ISI) on cerebellar conditioning and TMS to the left M1 (M1-TMS). Fourteen healthy adult participants were instructed to control the abduction force of the right index finger to 20% of the maximum voluntary contraction. M1-TMS was delivered during this to induce cSP on electromyograph of the right first dorsal interosseous muscle. TMS over the right cerebellum (C-TMS) was conducted prior to M1-TMS. In the first experiment, M1-TMS intensity was set to 1 or 1.3 × resting motor threshold (rMT) with 20-ms ISI. In the second experiment, the intensity was set to 1 × rMT with ISI of 0, 10, 20, 30, 40, 50, 60, 70, or 80 ms, and no-C-TMS trials were inserted. In results, cSP was significantly shorter in 1 × rMT condition than in 1.3 × rMT by C-TMS, and cSP was significantly shorter for ISI of 20–40 ms than for the no-C-TMS condition. Further, motor evoked potential for ISI40-60 ms were significantly reduced than that for ISI0. Thus, C-TMS may reduce cSP induced by M1-TMS with ISI of 20–40 ms.

Influence of posture on isometric fatigue

1978 ◽  
Vol 45 (2) ◽  
pp. 270-274 ◽  
Author(s):  
A. R. Lind ◽  
R. Burse ◽  
R. H. Rochelle ◽  
J. S. Rinehart ◽  
J. S. Petrofsky
Keyword(s):  
Blood Flow ◽  
Maximum Voluntary Contraction ◽  
Voluntary Contraction ◽  
Right Atrial ◽  
Isometric Contractions ◽  
Sitting Position ◽  
Trained Subjects ◽  
Recumbent Posture ◽  
Flow Through ◽  
The Right

The isometric strength of four trained subjects was unaltered by changes in posture. But the endurance of an isometric contraction held to fatigue at 25 and 40% of the maximum voluntary contraction (MVC) was 20% greater in the sitting than in the recumbent posture. This difference was abolished when the exercise was performed with the arm's circulation arrested. At rest, the blood flow through the forearm was greater when the subjects were in the recumbent than in the sitting position but the reverse was true during isometric contractions. In these two postures, there was no difference in the right atrial pressure during the contraction, suggesting that the low-pressure baroreceptors are not responsible for the differences in blood flow during exercise. To date no mechanism is available to explain these observations.

scholarly journals Exercise-Induced Fatigue in One Leg Does Not Impair the Neuromuscular Performance in the Contralateral Leg but Improves the Excitability of the Ipsilateral Corticospinal Pathway

2019 ◽  
Vol 9 (10) ◽  
pp. 250
Author(s):  
Saied Jalal Aboodarda ◽  
Cindy Xin Yu Zhang ◽  
Ruva Sharara ◽  
Madeleine Cline ◽  
Guillaume Y Millet
Keyword(s):  
Maximum Voluntary Contraction ◽  
Knee Extension ◽  
Voluntary Contraction ◽  
Voluntary Activation ◽  
Knee Extensors ◽  
Force Output ◽  
Neuromuscular Performance ◽  
Corticospinal Pathway ◽  
Neuromuscular Assessment ◽  
The Right

To investigate the influence of pre-induced fatigue in one leg on neuromuscular performance and corticospinal responses of the contralateral homologous muscles, three experiments were conducted with different exercise protocols; A (n = 12): a 60 s rest vs. time-matched sustained left leg knee extension maximum voluntary contraction (MVC), B (n = 12): a 60 s rest vs. time-matched left leg MVC immediately followed by 60 s right leg MVC, and C (n = 9): a similar protocol to experiment B, but with blood flow occluded in the left leg while the right leg was performing the 60 s MVC. The neuromuscular assessment included 5 s knee extensions at 100%, 75%, and 50% of MVC. At each force level, transcranial magnetic and peripheral nerve stimuli were elicited to investigate the influence of different protocols on the right (tested) knee extensors’ maximal force output, voluntary activation, corticospinal excitability, and inhibition. The pre-induced fatigue in the left leg did not alter the performance nor the neuromuscular responses recorded from the right leg in the three experiments (all p > 0.3). However, enhanced corticospinal pathway excitability was evident in the tested knee extensors (p = 0.002). These results suggest that the pre-induced fatigue and muscle ischemia in one leg did not compromise the central and peripheral components of the neuromuscular function in the tested contralateral leg.

Optimal Pennation Angle of the Primary Ankle Plantar and Dorsiflexors: Variations with Sex, Contraction Intensity, and Limb

2006 ◽  
Vol 22 (4) ◽  
pp. 255-263 ◽  
Author(s):  
Kurt Manal ◽  
Dustyn P. Roberts ◽  
Thomas S. Buchanan
Keyword(s):  
Maximum Voluntary Contraction ◽  
Voluntary Contraction ◽  
Pennation Angle ◽  
Medial Gastrocnemius ◽  
Optimal Length ◽  
Lateral Gastrocnemius ◽  
Consistent Finding ◽  
The Right ◽  
Male Subjects ◽  
Female Subjects

Ultrasonography was used to measure the pennation angle of the human tibialis anterior (TA), lateral gastrocnemius (LG), medial gastrocnemius (MG), and soleus (Sol). The right and left legs of 8 male and 8 female subjects were tested at rest and during maximum voluntary contraction (MVC). Joint angles were chosen to control muscle tendon lengths so that the muscles were near their optimal length within the length– tension relationship. No differences in pennation angle were detected between the right and left legs. Another consistent finding was that the pennation angle at MVC was significantly greater than at rest for all muscles tested. Optimal pennation angles for the TA, MG, and Sol were significantly greater for the men than for the women. Optimal pennation angles for the TA, LG, MG, and Sol for the male subjects were 14.3°, 23.7°, 34.6°, and 40.1° respectively, whereas values of 12.1°, 16.3°, 27.3°, and 26.3° were recorded for the female subjects. The results of this study suggest the following: (1) similar values for pennation angle can be used for the right and left TA, LG, MG, and Sol; (2) pennation angle is significantly greater at MVC than at rest for all muscles tested; and (3) sex-specific values for optimal pennation angle should be used when modeling the force-generating potential of the primary muscles responsible for ankle plantar and dorsiflexion.

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