scholarly journals You are as fast as your motor neurons: speed of recruitment and maximal discharge of motor neurons determine the maximal rate of force development in humans

2019 ◽  
Vol 597 (9) ◽  
pp. 2445-2456 ◽  
Author(s):  
Alessandro Del Vecchio ◽  
Francesco Negro ◽  
Ales Holobar ◽  
Andrea Casolo ◽  
Jonathan P. Folland ◽  
...  
Keyword(s):  
Motor Neurons ◽  
Rate Of Force Development ◽  
Maximal Rate ◽  
Force Development ◽  
Maximal Discharge

scholarly journals The influence of temperature on ryanodine sensitivity and the force-frequency relationship in the myocardium of rainbow trout

1992 ◽  
Vol 167 (1) ◽  
pp. 47-60 ◽  
Author(s):  
L. Hove-Madsen
Keyword(s):  
Rainbow Trout ◽  
Mammalian Species ◽  
Rest Period ◽  
Rate Of Force Development ◽  
Force Frequency ◽  
Maximal Rate ◽  
Force Development ◽  
Time To Peak ◽  
Influence Of Temperature On ◽  
Frequency Relationship

The relationship between stimulation frequency and contraction was established for ventricular strips from rainbow trout heart at 5, 15 and 25 degrees C. Compared to mammalian species, changes in temperature had little impact on force development in trout ventricle at physiologically relevant stimulation frequencies. However, the force-frequency relationship was changed from a biphasic response with a minimum around 0.2 Hz at 5 and 15 degrees C to a monophasic decline in force with increasing frequency at 25 degrees C. Ryanodine reversed the negative force-frequency relationship at 25 degrees C. Potentiation of twitch force after a 5 min rest period was increased from 121 +/− 4% at 15 degrees C to 209 +/− 12% at 25 degrees C. A similar augmentation was seen for the maximal rate of force development. Rest potentiation of both force and maximal rate of force development (dF/dT) was abolished by ryanodine at both 15 and 25 degrees C. The ryanodine concentration causing a half-maximal reduction in rest potentiation of force was 51 nmol l-1 at 25 degrees C and 483 nmol l-1 at 15 degrees C. Rest potentiation was maximally reduced by 10 mumol l-1 ryanodine to 50 and 79% of the value in the absence of ryanodine at 25 and 15 degrees C, respectively. At 5 degrees C, rest potentiation was similar to that at 15 degrees C. At 5 degrees C, there was no rest potentiation of dF/dT and ryanodine did not reduce rest potentiation of force. Instead, rest potentiation was correlated with a potentiation of time to peak tension (TPT) at 5 degrees C. Thus, in trout ventricle, force correlates with TPT at 5 degrees C and seems to be regulated by a ryanodine-insensitive mechanism, while at 25 degrees C force is correlated with the maximal rate of force development and the sarcoplasmic reticulum appears to contribute significantly to excitation-contraction coupling.

scholarly journals The relative strength of common synaptic input to motor neurons is not a determinant of the maximal rate of force development in humans

2019 ◽  
Vol 127 (1) ◽  
pp. 205-214 ◽  
Author(s):  
Alessandro Del Vecchio ◽  
Deborah Falla ◽  
Francesco Felici ◽  
Dario Farina
Keyword(s):  
Motor Unit ◽  
Motor Neurons ◽  
Synaptic Input ◽  
Discharge Rate ◽  
Rate Of Force Development ◽  
Force Generation ◽  
Unit Discharge ◽  
Force Development ◽  
Motor Unit Synchronization ◽  
Motor Unit Discharge

Correlation between motor unit discharge times, often referred to as motor unit synchronization, is determined by common synaptic input to motor neurons. Although it has been largely speculated that synchronization should influence the rate of force development, the association between the degree of motor unit synchronization and rapid force generation has not been determined. In this study, we examined this association with both simulations and experimental motor unit recordings. The analysis of experimental motor unit discharges from the tibialis anterior muscle of 20 healthy individuals during rapid isometric contractions revealed that the average motor unit discharge rate was associated with the rate of force development. Moreover, the extent of motor unit synchronization was entirely determined by the average motor unit discharge rate ( R > 0.7, P < 0.0001). The simulation model demonstrated that the relative proportion of common synaptic input received by motor neurons, which determines motor unit synchronization, does not influence the rate of force development ( R = 0.03, P > 0.05). Nonetheless, the estimates of correlation between motor unit spike trains were significantly correlated with the rate of force generation ( R > 0.8, P < 0.0001). These results indicate that the average motor unit discharge rate, but not the degree of motor unit synchronization, contributes to most of the variance of human contractile speed among individuals. In addition, estimates of correlation between motor unit discharge times depend strongly on the number of identified motor units and therefore are not indicative of the strength of common input. NEW & NOTEWORTHY It is commonly assumed that motor unit synchronization has an impact on the rate of force development of a muscle. Here we present computer simulations and experimental data of human tibialis anterior motor units during rapid contractions that show that motor unit synchronization is not a determinant of the rate of force production. This conclusion clarifies the neural determinants of rapid force generation.

Intra- and inter-rater reliability of the rate of force development of hip abductor muscles measured by hand-held dynamometer

2017 ◽  
Vol 22 (1) ◽  
pp. 19-24 ◽  
Author(s):  
Kazuya Takeda ◽  
Shigeo Tanabe ◽  
Soichiro Koyama ◽  
Tomoko Nagai ◽  
Hiroaki Sakurai ◽  
...  
Keyword(s):  
Rate Of Force Development ◽  
Rater Reliability ◽  
Force Development ◽  
Hip Abductor

scholarly journals Influence Of Acidic pH On The Rate Of Force Development In Cardiac Muscle

2009 ◽  
Vol 96 (3) ◽  
pp. 621a
Author(s):  
Frederick S. Korte ◽  
Michael Regnier ◽  
Todd E. Gillis
Keyword(s):  
Cardiac Muscle ◽  
Rate Of Force Development ◽  
Acidic Ph ◽  
Force Development

Neuromuscular rate of force development deficit in Parkinson disease

2017 ◽  
Vol 45 ◽  
pp. 14-18 ◽  
Author(s):  
Kelley G. Hammond ◽  
Ronald F. Pfeiffer ◽  
Mark S. LeDoux ◽  
Brian K. Schilling
Keyword(s):  
Parkinson Disease ◽  
Rate Of Force Development ◽  
Force Development

Torque–velocity characteristics and contractile rate of force development in elite badminton players

2007 ◽  
Vol 7 (3) ◽  
pp. 127-134 ◽  
Author(s):  
Lars L. Andersen ◽  
Benny Larsson ◽  
Hanne Overgaard ◽  
Per Aagaard
Keyword(s):  
Rate Of Force Development ◽  
Force Development
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