Peak triceps surae muscle activity is not specific to knee flexion angles during MVIC

AbstractFollowing active muscle stretch, a muscle’s force capacity is increased, which is known as residual force enhancement (rFE). As earlier studies found modulations of cortical excitability in the presence of rFE, this study aimed to test whether corticospinal drive contributes to rFE. Fourteen participants performed submaximal plantar flexion stretch-hold and fixed-end contractions at 30% of their maximal voluntary soleus muscle activity in a dynamometer. During the steady state of the contractions, participants either received subthreshold or suprathreshold transcranial magnetic stimulation (TMS) of their motor cortex while triceps surae muscle responses to stimulation were obtained by electromyography (EMG) and net plantar flexion torque was recorded. B-mode ultrasound imaging was used to confirm muscle stretch during stretch-hold contractions in a subset of participants. Following stretch of the plantar flexors, an average rFE of 7% and 11% was observed for contractions with subthreshold and suprathreshold TMS, respectively. 41-46 milliseconds following subthreshold TMS, triceps surae muscle activity was suppressed by 19-25%, but no difference in suppression was found between contraction conditions. Similarly, the reduction in plantar flexion torque following subthreshold TMS was not different between contraction conditions. Motor evoked potentials, silent periods and superimposed twitches following suprathreshold stimulations were also not different between contraction conditions. As stimulations of the motor cortex by TMS did not result in any differences between stretch-hold and fixed-end contractions, we conclude that corticospinal drive does not contribute to the increased torque production in the presence of rFE following active muscle stretch.New & NoteworthyThis study tested whether corticospinal drive contributes to the increased torque capacity in the presence of rFE. Through subthreshold and suprathreshold TMS of the motor cortex, triceps surae muscle activity was respectively supressed or increased in the presence of rFE and during a reference contraction without rFE. As similar responses were observed between contraction contractions, we conclude that corticospinal drive likely does not contribute to the increased torque capacity in the presence of rFE.

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Muscle Activity of the Triceps Surae With Novel Propulsion Heel-Lift Orthotics in Recreational Runners

Orthopaedic Journal of Sports Medicine ◽

10.1177/2325967120956914 ◽

2020 ◽

Vol 8 (10) ◽

pp. 232596712095691

Author(s):

Rubén Sánchez-Gómez ◽

Ricardo Becerro-de-Bengoa-Vallejo ◽

Carlos Romero Morales ◽

Marta Elena Losa-Iglesias ◽

Aitor Castrillo de la Fuente ◽

...

Keyword(s):

Muscle Activity ◽

Intraclass Correlation ◽

Triceps Surae ◽

Emg Activity ◽

Gastrocnemius Medialis ◽

Triceps Surae Muscle ◽

Lateralis Muscle ◽

Recreational Runners ◽

Gastrocnemius Lateralis ◽

Heel Lift

Background: The triceps surae muscle has been identified with propulsion during running gait, and typical heel-lift orthotics (THOs) have been used to treat some sports injuries of this structural-biomechanical unit. The effects of a novel propulsion heel-lift orthotic (PHO) on surface electromyography (EMG) activity of the gastrocnemius during a full cycle of running have yet to be tested. Purpose/Hypothesis: We aimed to assess EMG changes in gastrocnemius medialis and lateralis muscle activity when wearing THOs, PHOs, or neutral sports shoes only (SO) during running. We hypothesized that EMG activity of the triceps surae muscle would be lower for PHOs than THOs or SO during running. Study Design: Controlled laboratory study. Methods: A total of 26 healthy, regular recreational runners of both sexes (mean age, 33.58 ± 6.02 years) with a neutral Foot Posture Index and rearfoot strike pattern were recruited to run on a treadmill at 9 km/h using aleatory THOs of 6 and 9 mm, PHOs, and SO while EMG activity of the gastrocnemius medialis and lateralis muscles was recorded over a 30-second period. Intraclass correlation coefficients were calculated to assess reliability. Results: The intraclass correlation coefficient values indicated near perfect reliability, ranging from 0.801 for 6-mm THOs to 0.959 for SO in the gastrocnemius lateralis muscle. EMG activity of the gastrocnemius lateralis muscle was greater for PHOs (25.516 ± 4.780 mV) than for SO (23.140 ± 4.150 mV) ( P < .05), but EMG activity of the gastrocnemius medialis muscle did not show any statistically significant difference between conditions (23.130 ± 2.980 mV vs 26.315 ± 2.930 mV, respectively) ( P = .3). Conclusion: A novel PHO may increase muscle activity of the gastrocnemius lateralis during a full cycle of running gait; consequently, its prescription to treat triceps surae muscle injuries is cautioned. Clinical Relevance: The prescription of novel PHOs could increase EMG activity, which has not been previously described.

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Afferent Contribution to Locomotor Muscle Activity During Unconstrained Overground Human Walking: An Analysis of Triceps Surae Muscle Fascicles

Journal of Neurophysiology ◽

10.1152/jn.00852.2009 ◽

2010 ◽

Vol 103 (3) ◽

pp. 1262-1274 ◽

Cited By ~ 14

Author(s):

R. af Klint ◽

N. J. Cronin ◽

M. Ishikawa ◽

T. Sinkjaer ◽

M. J. Grey

Keyword(s):

Soleus Muscle ◽

Muscle Activity ◽

Force Feedback ◽

Triceps Surae ◽

Human Walking ◽

Plantar Flexor ◽

Triceps Surae Muscle ◽

Muscle Fascicle ◽

Flexor Muscles ◽

Plantar Flexor Muscles

Plantar flexor series elasticity can be used to dissociate muscle–fascicle and muscle–tendon behavior and thus afferent feedback during human walking. We used electromyography (EMG) and high-speed ultrasonography concomitantly to monitor muscle activity and muscle fascicle behavior in 19 healthy volunteers as they walked across a platform. On random trials, the platform was dropped (8 cm, 0.9 g acceleration) or held at a small inclination (up to ±3° in the parasagittal plane) with respect to level ground. Dropping the platform in the mid and late phases of stance produced a depression in the soleus muscle activity with an onset latency of about 50 ms. The reduction in ground reaction force also unloaded the plantar flexor muscles. The soleus muscle fascicles shortened with a minimum delay of 14 ms. Small variations in platform inclination produced significant changes in triceps surae muscle activity; EMG increased when stepping on an inclined surface and decreased when stepping on a declined surface. This sensory modulation of the locomotor output was concomitant with changes in triceps surae muscle fascicle and gastrocnemius tendon length. Assuming that afferent activity correlates to these mechanical changes, our results indicate that within-step sensory feedback from the plantar flexor muscles automatically adjusts muscle activity to compensate for small ground irregularities. The delayed onset of muscle fascicle movement after dropping the platform indicates that at least the initial part of the soleus depression is more likely mediated by a decrease in force feedback than length-sensitive feedback, indicating that force feedback contributes to the locomotor activity in human walking.

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Corticospinal excitability remains unchanged in the presence of residual force enhancement and does not contribute to increased torque production

PeerJ ◽

10.7717/peerj.12729 ◽

2022 ◽

Vol 10 ◽

pp. e12729

Author(s):

Jasmin Frischholz ◽

Brent J. Raiteri ◽

Andrew G. Cresswell ◽

Daniel Hahn

Keyword(s):

Motor Cortex ◽

Muscle Activity ◽

Plantar Flexion ◽

Corticospinal Excitability ◽

Triceps Surae ◽

Force Enhancement ◽

Triceps Surae Muscle ◽

Residual Force ◽

Residual Force Enhancement ◽

Fixed End

Background Following stretch of an active muscle, muscle force is enhanced, which is known as residual force enhancement (rFE). As earlier studies found apparent corticospinal excitability modulations in the presence of rFE, this study aimed to test whether corticospinal excitability modulations contribute to rFE. Methods Fourteen participants performed submaximal plantar flexion stretch-hold and fixed-end contractions at 30% of their maximal voluntary soleus muscle activity in a dynamometer. During the steady state of the contractions, participants either received subthreshold or suprathreshold transcranial magnetic stimulation (TMS) of their motor cortex, while triceps surae muscle responses to stimulation were obtained via electromyography (EMG), and net ankle joint torque was recorded. B-mode ultrasound imaging was used to confirm muscle fascicle stretch during stretch-hold contractions in a subset of participants. Results Following stretch of the plantar flexors, an average rFE of 7% and 11% was observed for contractions with subthreshold and suprathreshold TMS, respectively. 41–46 ms following subthreshold TMS, triceps surae muscle activity was suppressed by 19–25%, but suppression was not significantly different between stretch-hold and fixed-end contractions. Similarly, the reduction in plantar flexion torque following subthreshold TMS was not significantly different between contraction conditions. Motor evoked potentials, silent periods and superimposed twitches following suprathreshold TMS were also not significantly different between contraction conditions. Discussion As TMS of the motor cortex did not result in any differences between stretch-hold and fixed-end contractions, we conclude that rFE is not linked to changes in corticospinal excitability.

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