Ascending beta oscillation from finger muscle to sensorimotor cortex contributes to enhanced steady-state isometric contraction in humans

2014 ◽  
Vol 125 (10) ◽  
pp. 2036-2045 ◽  
Author(s):  
Manyoel Lim ◽  
June Sic Kim ◽  
Minaeh Kim ◽  
Chun Kee Chung
Keyword(s):  
Steady State ◽  
Isometric Contraction ◽  
Sensorimotor Cortex ◽  
Beta Oscillation

scholarly journals Sarcoplasmic reticulum and endothelium independently regulate venous smooth muscle [Ca2+]iand contraction

1999 ◽  
Vol 277 (2) ◽  
pp. H749-H755
Author(s):  
Régent Laporte ◽  
Ismail Laher
Keyword(s):  
Smooth Muscle ◽  
Steady State ◽  
Sarcoplasmic Reticulum ◽  
Salt Solution ◽  
Isometric Contraction ◽  
Cyclopiazonic Acid ◽  
Physiological Salt Solution ◽  
Sustained Contraction ◽  
Facial Vein ◽  
State Increase

In rings of rabbit facial vein (RFV), depletion of sarcoplasmic reticulum (SR) Ca2+ by caffeine abolished the subsequent isometric contraction to 25 mM K+ physiological salt solution (25K-PSS). However, the associated steady-state increase of smooth muscle intracellular free Ca2+concentration ([Ca2+]i), measured using fura PE3 and cuvette photometry, was not altered. Treatment with the specific SR Ca2+ pump inhibitor cyclopiazonic acid (30 μM) after caffeine-induced SR Ca2+ depletion restored and greatly augmented the 25K-PSS-induced contraction. This suggests that SR Ca2+ depletion leads to a dissociation of K+-induced [Ca2+]iincrease from contraction that was dependent on Ca2+ pump-mediated SR Ca2+ uptake. Endothelium removal augmented the 25K-PSS-induced [Ca2+]iincrease after caffeine-induced SR Ca2+ depletion. However, this was associated with only a small and transient contraction. Exposure of endothelium-denuded RFV to cyclopiazonic acid after caffeine-induced SR Ca2+ depletion further amplified the 25K-PSS-induced [Ca2+]iincrease, which was associated with a large and sustained contraction. However, the latter [Ca2+]iincrease was still higher than in endothelium-intact RFV. This suggests that the endothelium dampens the [Ca2+]irise associated with K+-induced Ca2+ influx, but independently of Ca2+ pump-mediated SR Ca2+ uptake.

scholarly journals Effect of Active Lengthening and Shortening on Small-Angle X-ray Reflections in Skinned Skeletal Muscle Fibres

2021 ◽  
Vol 22 (16) ◽  
pp. 8526
Author(s):  
Venus Joumaa ◽  
Ian C. Smith ◽  
Atsuki Fukutani ◽  
Timothy R. Leonard ◽  
Weikang Ma ◽  
...  
Keyword(s):  
Steady State ◽  
Small Angle ◽  
Isometric Contraction ◽  
Sarcomere Length ◽  
Force Enhancement ◽  
X Ray ◽  
Cross Bridge ◽  
Residual Force ◽  
Residual Force Enhancement ◽  
Cross Bridges

Our purpose was to use small-angle X-ray diffraction to investigate the structural changes within sarcomeres at steady-state isometric contraction following active lengthening and shortening, compared to purely isometric contractions performed at the same final lengths. We examined force, stiffness, and the 1,0 and 1,1 equatorial and M3 and M6 meridional reflections in skinned rabbit psoas bundles, at steady-state isometric contraction following active lengthening to a sarcomere length of 3.0 µm (15.4% initial bundle length at 7.7% bundle length/s), and active shortening to a sarcomere length of 2.6 µm (15.4% bundle length at 7.7% bundle length/s), and during purely isometric reference contractions at the corresponding sarcomere lengths. Compared to the reference contraction, the isometric contraction after active lengthening was associated with an increase in force (i.e., residual force enhancement) and M3 spacing, no change in stiffness and the intensity ratio I1,1/I1,0, and decreased lattice spacing and M3 intensity. Compared to the reference contraction, the isometric contraction after active shortening resulted in decreased force, stiffness, I1,1/I1,0, M3 and M6 spacings, and M3 intensity. This suggests that residual force enhancement is achieved without an increase in the proportion of attached cross-bridges, and that force depression is accompanied by a decrease in the proportion of attached cross-bridges. Furthermore, the steady-state isometric contraction following active lengthening and shortening is accompanied by an increase in cross-bridge dispersion and/or a change in the cross-bridge conformation compared to the reference contractions.

scholarly journals The influence of residual force enhancement on spinal and supraspinal excitability

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e5421 ◽  
Author(s):  
Caleb T. Sypkes ◽  
Benjamin J. Kozlowski ◽  
Jordan Grant ◽  
Leah R. Bent ◽  
Chris J. McNeil ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Steady State ◽  
Evoked Potentials ◽  
Isometric Contraction ◽  
Motor Evoked Potentials ◽  
Isometric Force ◽  
Force Enhancement ◽  
Active Muscle ◽  
Residual Force ◽  
Residual Force Enhancement

Background Following active muscle lengthening, there is an increase in steady-state isometric force as compared with a purely isometric contraction at the same muscle length and level of activation. This fundamental property of skeletal muscle is known as residual force enhancement (RFE). While the basic mechanisms contributing to this increase in steady-state isometric force have been well documented, changes in central nervous system (CNS) excitability for submaximal contractions during RFE are unclear. The purpose of this study was to investigate spinal and supraspinal excitability in the RFE isometric steady-state following active lengthening of the ankle dorsiflexor muscles. Methods A total of 11 male participants (20–28 years) performed dorsiflexions at a constant level of electromyographic activity (40% of maximum). Half of the contractions were purely isometric (8 s at an ankle angle of 130°), and the other half were during the RFE isometric steady-state following active lengthening (2 s isometric at 90°, a 1 s lengthening phase at 40°/s, and 5 s at 130°). Motor evoked potentials (MEPs), cervicomedullary motor evoked potentials (CMEPs), and compound muscle action potentials (M-waves) were recorded from the tibialis anterior during the purely isometric contraction and RFE isometric steady-state. Results Compared to the purely isometric condition, following active lengthening, there was 10% RFE (p < 0.05), with a 17% decrease in normalized CMEP amplitude (CMEP/Mmax) (p < 0.05) and no change in normalized MEP amplitude (MEP/CMEP) (p > 0.05). Discussion These results indicate that spinal excitability is reduced during submaximal voluntary contractions in the RFE state with no change in supraspinal excitability. These findings may have further implications to everyday life offering insight into how the CNS optimizes control of skeletal muscle following submaximal active muscle lengthening.

Agonist-induced myosin phosphorylation during isometric contraction and unloaded shortening in airway smooth muscle

1992 ◽  
Vol 262 (1) ◽  
pp. L53-L62 ◽  
Author(s):  
C. M. Hai ◽  
B. Szeto
Keyword(s):  
Signal Transduction ◽  
Smooth Muscle ◽  
Steady State ◽  
Airway Smooth Muscle ◽  
Isometric Contraction ◽  
Airway Smooth Muscle Cell ◽  
Myosin Phosphorylation ◽  
Kinase C ◽  
Transduction Mechanisms ◽  
Muscle Cell Membrane

We measured myosin phosphorylation during isometric contraction at optimal length (Lo) and unloaded shortening induced by K(+)-depolarization, electrical stimulation, carbachol, histamine, and phorbol dibutyrate (PDB) in bovine trachealis. Peak myosin phosphorylation during unloaded shortening was lower than that during isometric contraction in response to all stimuli. The lower peak myosin phosphorylation during unloaded shortening appeared to be a stretch-sensitive response because myosin phosphorylation was either equally low or further reduced during the second unloaded shortening of preshortened tissues. Similar to peak myosin phosphorylation, steady-state myosin phosphorylation was also lower during unloaded shortening in carbachol-induced contractions. However, steady-state phosphorylation during unloaded shortening and isometric contraction were not significantly different in histamine- and PDB-induced contractions. Since the coupling between Ca2+ and myosin phosphorylation was not stretch sensitive, these results suggest the coexistence of stretch-sensitive and stretch-insensitive signal transduction mechanisms in the airway smooth muscle cell membrane, and the stretch-insensitive signal transduction mechanism might involve protein phosphorylation by protein kinase C.

Phosphagen and metabolite content during contraction in porcine carotid artery

1983 ◽  
Vol 244 (5) ◽  
pp. C385-C390 ◽  
Author(s):  
J. M. Krisanda ◽  
R. J. Paul
Keyword(s):  
Steady State ◽  
Carotid Artery ◽  
Isometric Contraction ◽  
Time Course ◽  
Isometric Force ◽  
Apparent Lack ◽  
Tissue Extracts ◽  
Metabolic Signal ◽  
Metabolite Content ◽  
Porcine Carotid Artery

Previous studies (Paul, R. J. Chemical energetics of vascular smooth muscle. In: Handbook of Physiology: The Cardiovascular System. Bethesda, MD: Am. Physiol. Soc., 1980, p. 201-235) have shown that vascular oxygen consumption reaches a steady state at approximately twice the basal rate during maintenance of isometric contraction. The time course of the attainment of a metabolic steady state, the metabolic signal for the observed increase in respiration, and the contribution of endogenous phosphagens to the energetics of isometric contraction are not known with certainty. To this end, the time course of the tissue content of ATP, ADP, AMP, phosphocreatine (PCr), inorganic phosphate (Pi), and lactate were measured during a KCl-induced isometric contraction in porcine carotid artery and compared with values in the basal state. Oxygenated unpoisoned strips were frozen at 0, 0.5, 1, and 15 min of contraction, and tissue extracts were analyzed using analytical isotachophoresis. No statistically significant changes from the basal levels of ATP and PCr were measured. A small but significant increase in ADP was seen at all times. An increase in Pi of 1.25 mumol/g was observed at 0.5 min, which decreased in time. Tissue lactate content increased by 1.79 mumol/g after 1 min of contraction. The calculated range of cellular free ADP (ADPfree), 44-123 microM, may be sufficient to saturate oxidative phosphorylation. This and the apparent lack of change of ADPfree from basal during contraction suggest that it does not play a role in the coordination of metabolism and contractility. From as early as 0.5 min, when less than 40% of peak isometric force is attained, intermediary metabolism provides the total ATP required for contraction.

scholarly journals Perception of effort during an isometric contraction is influenced by prior muscle lengthening or shortening

2021 ◽  
Author(s):  
Benjamin Kozlowski ◽  
Benjamin Pageaux ◽  
Emma H Hubbard ◽  
Benjamin St. Peters ◽  
Philip J Millar ◽  
...  
Keyword(s):  
Steady State ◽  
Muscle Contraction ◽  
Isometric Contraction ◽  
Muscle Activation ◽  
Muscle Length ◽  
Motor Command ◽  
History Dependence ◽  
Neuromuscular Activation ◽  
Perception Of Effort

Purpose: Following a shortening or lengthening muscle contraction, the torque produced in the isometric steady state is distinctly lower (residual torque depression; rTD) or higher (residual torque enhancement; rTE), respectively, compared to a purely isometric contraction at the same final muscle length and level of activation. This is referred to as the history dependence of force. When matching a given torque level, there is greater muscle activation (electromyography; EMG) following shortening and less activation following lengthening. Owing to these differences in neuromuscular activation, it is unclear whether perception of effort is altered by the history dependence of force. Methods: Experiment 1 tested whether perception of effort differed between the rTD and rTE state when torque was matched. Experiment 2 tested whether perception of effort differed between the rTD and rTE state when EMG was matched. Finally, experiment 3 tested whether EMG differed between the rTD and rTE state when perception of effort was matched. Results: When torque was matched, both EMG and perception of effort were higher in the rTD compared to rTE state. When EMG was matched, torque was lower in the rTD compared to rTE state while perception of effort did not differ between the two states. When perception of effort was matched, torque was lower in the rTD compared to rTE state and EMG did not differ between the two states. Conclusion: The combined results from these experiments indicate that the history dependence of force alters ones perception of effort, dependent on the level of motor command.

Muscle fatigue-induced enhancement of corticomuscular coherence following sustained submaximal isometric contraction of the tibialis anterior muscle

2011 ◽  
Vol 110 (5) ◽  
pp. 1233-1240 ◽  
Author(s):  
Junichi Ushiyama ◽  
Masanori Katsu ◽  
Yoshihisa Masakado ◽  
Akio Kimura ◽  
Meigen Liu ◽  
...  
Keyword(s):  
Muscle Fatigue ◽  
Isometric Contraction ◽  
Sensorimotor Cortex ◽  
Tibialis Anterior ◽  
Tibialis Anterior Muscle ◽  
Muscular Activity ◽  
Spectral Density Function ◽  
Voluntary Contraction ◽  
Oscillatory Activity ◽  
Acute Changes

Oscillatory activity of the sensorimotor cortex shows coherence with muscle activity within the 15- to 35-Hz frequency band (β-band) during weak to moderate sustained isometric contraction. We aimed to examine the acute changes in this corticomuscular coupling due to muscle fatigue and its effect on the steadiness of the exerted force. We quantified the coherence between the electroencephalogram (EEG) recorded over the sensorimotor cortex and the rectified surface electromyogram (EMG) of the tibialis anterior muscle as well as the coefficient of variance of the dorsiflexion force (ForceCV) and sum of the auto-power spectral density function of the force within the β-band (Forceβ-PSD) during 30% of maximal voluntary contraction (MVC) for 60 s before (prefatiguing task) and after (postfatiguing task) muscle fatigue induced by sustained isometric contraction at 50% of MVC until exhaustion in seven healthy male subjects. The magnitude of the EEG-EMG coherence increased in the postfatiguing task in six of seven subjects. The maximal peak of EEG-EMG coherence stayed within the β-band in both pre- and postfatiguing tasks. Interestingly, two subjects, who had no significant EEG-EMG coherence in the prefatiguing task, showed significant coherence in the postfatiguing task. Additionally, ForceCV and Forceβ-PSD significantly increased after muscle fatigue. These data suggest that when muscle fatigue develops, the central nervous system enhances oscillatory muscular activity in the β-band stronger coupled with the sensorimotor cortex activity accomplishing the sustained isometric contraction at lower performance levels.

scholarly journals The presence of corticomuscular coherence during unipedal stance

2021 ◽  
Author(s):  
Sylmina Dalily Alkaff ◽  
Junichi Ushiyama
Keyword(s):  
Postural Control ◽  
Isometric Contraction ◽  
Sensorimotor Cortex ◽  
Center Of Pressure ◽  
Medial Gastrocnemius ◽  
Bipedal Stance ◽  
Corticomuscular Coherence ◽  
Cortical Involvement ◽  
Base Of Support ◽  
Surface Electromyograms

Objective: To elucidate cortical involvement in postural control during unipedal stance by observing corticomuscular coherence (CMC) between the sensorimotor cortex and ankle joint muscles. Methods: Twenty-one participants performed three tasks: bipedal stance, unipedal stance, and isometric contraction. We measured the maximal peak of CMC (CMCmax) between electroencephalograms overlying the foot representation area and surface electromyograms from the tibialis anterior (TA), medial gastrocnemius (MG), lateral gastrocnemius (LG), and soleus (SOL), respectively, for each task. We measured the center of pressure (COP) during both stance tasks. Results: Although there was no significant CMC during bipedal stance, significant CMC was observed for all muscles during unipedal stance, with larger COP fluctuation. The results revealed significant differences in CMCmax between unipedal and bipedal stance tasks (TA, p = 0.002; MG, p = 0.016; LG, p = 0.003; SOL, p = 0.009). Additionally, CMCmax was obtained in higher frequency bands during the unipedal stance task than during the isometric contraction task. Conclusions: Significant CMC indicates direct involvement of the sensorimotor cortex in postural control during unipedal stance. Significance: Greater postural demands due to narrow base-of-support during unipedal stance requires voluntary control of muscle activity by the sensorimotor cortex.

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