Voluntary rate of torque development is impaired after a voluntary versus tetanic conditioning contraction

Smith, Cameron B.; Allen, Matti D.; Rice, Charles L.

doi:10.1002/mus.23888

Cited by 5 publications

(3 citation statements)

References 38 publications

(96 reference statements)

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“…On the basis of results from prior studies in our laboratory (27), it was hypothesized that corticospinal inhibition would be responsible for the absence of enhancement to voluntary contractile properties despite a concurrent large enhancement in evoked contractile properties. This study shows that, following a 10-s voluntary conditioning contraction, SP is elongated from control by ~10% and evoked twitch force and RFD are greatly increased (~90% and ~60%, respectively).…”

Section: Discussionmentioning

confidence: 99%

“…Postactivation potentiation has been studied extensively and is characterized by large increases in twitch force and RFD. However, studies attempting to demonstrate similar improvements to potentiated voluntary contraction have failed consistently to show substantial improvements and often show no change or even a decrement to voluntary contractile properties (10,27). However, changes that occur during contraction are not limited to the muscular components, and central changes are widely observed during brief and sustained contractions (8,15,20,22,31,33).…”

Section: Discussionmentioning

confidence: 99%

“…The positive effects of potentiation on involuntary contraction, typically evoked at the peripheral motor axon level, have been consistently and reliably observed (2,3,11,12); however, these externally evoked contractions do not reflect intrinsic functional voluntary task performance. Investigations to determine the effect of potentiation on voluntary contractions have failed to demonstrate the remarkable enhancements shown during evoked electrically stimulated contraction and have largely shown equivocal results compared with unpotentiated contractile properties (4,5,10,15,27,28). By definition, the primary difference between the voluntary and involuntary (electrically evoked) contraction is the source of activation: the central nervous system producing voluntary activation compared with a stimulating electrode that excites the peripheral axons.…”

Section: Introductionmentioning

confidence: 99%

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Coexistence of peripheral potentiation and corticospinal inhibition following a conditioning contraction in human first dorsal interosseous muscle

Smith

Allen

Rice

2020

Journal of Applied Physiology

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In skeletal muscle, post-activation potentiation (PAP) is observed following a conditioning contraction (CC) as a large (2- to 3-fold) increase in evoked twitch force and rate of force development (RFD). However, this enhancement has not been observed to occur during potentiated voluntary contractions. The purpose of this study was to determine if the lack of voluntary potentiation may be related to the development of central (corticospinal) inhibition. Participants (N=10, all males) completed voluntary and evoked index finger abduction contractions and transcranial magnetic stimulated (TMS) motor evoked potentials (MEP) of the motor cortex were recorded from the ﬁrst dorsal interosseous (FDI). Central inhibition was assessed by measuring the silent period following the MEP. The FDI was potentiated via 10s conditioning contractions at 60% of maximal index finger abduction strength, using both voluntary and evoked tetanic contractions. Immediately following CC and transcutaneous electrical twitches. Following both voluntary and tetanic CC, force and RFD of the twitch were similarly increased (~200% and ~160% respectively). The silent period was elongated by ~10% following both forms of CC. These results indicate that corticospinal inhibition does occur following CC, but that it is unrelated to the voluntary activation during the CC. These results also show that following CC, the positive contractile effects at the muscle are concurrently accompanied by inhibitory effects at the corticospinal level.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Coexistence of peripheral potentiation and corticospinal inhibition following a conditioning contraction in human first dorsal interosseous muscle

Smith

Allen

Rice

2020

Journal of Applied Physiology

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Modulation of Skeletal Muscle Contraction by Myosin Phosphorylation

Vandenboom

2016

Comprehensive Physiology

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The striated muscle sarcomere is a highly organized and complex enzymatic and structural organelle. Evolutionary pressures have played a vital role in determining the structure-function relationship of each protein within the sarcomere. A key part of this multimeric assembly is the light chain-binding domain (LCBD) of the myosin II motor molecule. This elongated "beam" functions as a biological lever, amplifying small interdomain movements within the myosin head into piconewton forces and nanometer displacements against the thin filament during the cross-bridge cycle. The LCBD contains two subunits known as the essential and regulatory myosin light chains (ELC and RLC, respectively). Isoformic differences in these respective species provide molecular diversity and, in addition, sites for phosphorylation of serine residues, a highly conserved feature of striated muscle systems. Work on permeabilized skeletal fibers and thick filament systems shows that the skeletal myosin light chain kinase catalyzed phosphorylation of the RLC alters the "interacting head motif" of myosin motor heads on the thick filament surface, with myriad consequences for muscle biology. At rest, structure-function changes may upregulate actomyosin ATPase activity of phosphorylated cross-bridges. During activation, these same changes may increase the Ca2+ sensitivity of force development to enhance force, work, and power output, outcomes known as "potentiation." Thus, although other mechanisms may contribute, RLC phosphorylation may represent a form of thick filament activation that provides a "molecular memory" of contraction. The clinical significance of these RLC phosphorylation mediated alterations to contractile performance of various striated muscle systems are just beginning to be understood. © 2017 American Physiological Society. Compr Physiol 7:171-212, 2017.

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Does postactivation potentiation (PAP) increase voluntary performance?

Zimmermann

MacIntosh

Pupo

2020

Appl. Physiol. Nutr. Metab.

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The transient increase in torque of an electrically evoked twitch following a voluntary contraction is called postactivation potentiation (PAP). Phosphorylation of myosin regulatory light chains is the most accepted mechanism explaining the enhanced electrically evoked twitch torque. While many authors attribute voluntary postactivation performance enhancement (PAPE) to the positive effects of PAP, few actually confirmed that contraction was indeed potentiated using electrical stimulation (twitch response) at the time that PAPE was measured. Thus, this review aims to investigate if increases in voluntary performance after a conditioning contraction (CC) are related to the PAP phenomenon. For this, studies that confirmed the presence of PAP through an evoked response after a voluntary CC and concurrently evaluated PAPE were reviewed. Some studies reported increases in PAPE when PAP reaches extremely high values. However, PAPE has also been reported when PAP was not present, and unchanged/diminished performance has been identified when PAP was present. This range of observations demonstrates that mechanisms of PAPE are different from mechanisms of PAP. These mechanisms of PAPE still need to be understood and those studying PAPE should not assume that regulatory light chain phosphorylation is the mechanism for such enhanced voluntary performance. Novelty The occurrence of PAP does not necessarily mean that the voluntary performance will be improved. Improvement in voluntary performance is sometimes observed when the PAP level reaches extremely high values. Other mechanisms may be more relevant than that for PAP in the manifestation of acute increases in performance following a conditioning contraction.

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Voluntary rate of torque development is impaired after a voluntary versus tetanic conditioning contraction

Abstract: Twitch potentiation was similar between conditioning contraction types, but ballistic RTD was lower after post-tetanus than post-voluntary. The results indicate central inhibition or fatigue concurrent with peripheral potentiation.

Cited by 5 publications

References 38 publications

Coexistence of peripheral potentiation and corticospinal inhibition following a conditioning contraction in human first dorsal interosseous muscle

Coexistence of peripheral potentiation and corticospinal inhibition following a conditioning contraction in human first dorsal interosseous muscle

Modulation of Skeletal Muscle Contraction by Myosin Phosphorylation

Does postactivation potentiation (PAP) increase voluntary performance?

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