Percent voluntary inactivation and peak force predictions with the interpolated twitch technique in individuals with high ability of voluntary activation

2011 ◽  
Vol 32 (10) ◽  
pp. 1591-1603 ◽  
Author(s):  
Trent J Herda ◽  
Ashley A Walter ◽  
Pablo B Costa ◽  
Eric D Ryan ◽  
Katherine M Hoge ◽  
...  
Keyword(s):  
Peak Force ◽  
Voluntary Activation ◽  
High Ability ◽  
Interpolated Twitch Technique

scholarly journals Unlike voluntary contractions, stimulated contractions of a hand muscle do not reduce voluntary activation or motoneuronal excitability

2020 ◽  
Vol 128 (5) ◽  
pp. 1412-1422
Author(s):  
J. M. D’Amico ◽  
D. M. Rouffet ◽  
S. C. Gandevia ◽  
J. L. Taylor
Keyword(s):  
Central Fatigue ◽  
Voluntary Activation ◽  
Motoneuron Excitability ◽  
Interpolated Twitch Technique ◽  
Hand Muscle ◽  
Voluntary Contractions

We demonstrate that reductions in voluntary activation and motoneuron excitability following 2-min isometric maximal contractions in humans occur only when fatigue is produced through voluntary contractions and not through electrically stimulated contractions. This is contrary to studies that suggest that changes in the superimposed twitch and therefore voluntary activation are explained by changes in peripheral factors alone. Thus, the interpolated twitch technique remains a viable tool to assess voluntary activation and central fatigue.

scholarly journals Reliability of Tibialis Anterior Muscle Voluntary Activation Using the Interpolated Twitch Technique and the Central Activation Ratio in People with Stroke

2021 ◽  
Vol 11 (2) ◽  
pp. 176
Author(s):  
Sharon Olsen ◽  
Nada Signal ◽  
Imran Khan Niazi ◽  
Gemma Alder ◽  
Usman Rashid ◽  
...  
Keyword(s):  
Electrical Stimulation ◽  
Lower Bound ◽  
Tibialis Anterior ◽  
Tibialis Anterior Muscle ◽  
Central Fatigue ◽  
Chronic Stroke ◽  
Voluntary Activation ◽  
Central Activation Ratio ◽  
Interpolated Twitch Technique ◽  
Activation Ratio

Voluntary activation (VA) is measured by applying supramaximal electrical stimulation to a muscle during a maximal voluntary contraction (MVC). The amplitude of the evoked muscle twitch is used to determine any VA deficit, and indicates incomplete central neural drive to the motor units. People with stroke experience VA deficits and greater levels of central fatigue, which is the decrease in VA that occurs following exercise. This study investigated the between-session reliability of VA and central fatigue of the tibialis anterior muscle (TA) in people with chronic stroke (n = 12), using the interpolated twitch technique (ITT), adjusted-ITT, and central activation ratio (CAR) methods. On two separate sessions, supramaximal electrical stimulation was applied to the TA when it was at rest and maximally activated, at the start and end of a 30-s isometric dorsiflexor MVC. The most reliable measures of VA were obtained using the CAR calculation on transformed data, which produced an ICC of 0.92, and a lower bound confidence interval in the good range (95% CI 0.77 to 0.98). Reliability was lower for the CAR calculation on non-transformed data (ICC 0.82, 95% CI 0.63 to 0.91) and the ITT and adjusted-ITT calculations on transformed data (ICCs 0.82, 95% CIs 0.51 to 0.94), which had lower bound confidence intervals in the moderate range. The two ITT calculations on non-transformed data demonstrated the poorest reliability (ICCs 0.62, 95% CI 0.25 to 0.74). Central fatigue measures demonstrated very poor reliability. Thus, the reliability for VA in people with chronic stroke ranged from good to poor, depending on the calculation method and statistical analysis method, whereas the reliability for central fatigue was very poor.

Are Voluntary Activation Determined By The Interpolated Twitch Technique And Mechanomyographic Amplitude Synonymous?

2016 ◽  
Vol 48 ◽  
pp. 897
Author(s):  
Nathaniel DM Jenkins ◽  
Amelia Miramonti ◽  
Cory Smith ◽  
Ethan C. Hill ◽  
Kristen C. Cochrane ◽  
...  
Keyword(s):  
Voluntary Activation ◽  
Interpolated Twitch Technique

Comparison Between Isometric and Concentric Motor Fatigability in Persons With Multiple Sclerosis and Healthy Controls – exploring central and peripheral contributions of motor fatigability

2021 ◽  
pp. 154596832110175
Author(s):  
Tobias Gaemelke ◽  
Morten Riemenschneider ◽  
Ulrik Dalgas ◽  
Tue Kjølhede ◽  
Cuno Rasmussen ◽  
...  
Keyword(s):  
Multiple Sclerosis ◽  
Regression Analysis ◽  
Knee Extensor ◽  
Voluntary Contraction ◽  
Voluntary Activation ◽  
Knee Extensors ◽  
Healthy Controls ◽  
Isokinetic Dynamometer ◽  
Interpolated Twitch Technique ◽  
Group Regression

Background Motor fatigability (i.e. contraction-induced reduction in muscle strength) from a concentric task associate stronger to walking and perception of fatigue in persons with multiple sclerosis (pwMS), compared with an isometric task. However, the central and peripheral contributions of motor fatigability between these tasks have not been investigated. Objective Compare the central and peripheral contributions of motor fatigability in the knee extensors in a sustained isometric fatigability protocol versus a concentric fatigability protocol and in pwMS versus healthy controls (HCs). Methods Participants (n=31 pwMS; n=15 HCs) underwent neuromuscular testing before and immediately after two knee extensor fatigability tasks (sustained isometric and concentric) in an isokinetic dynamometer. Neuromuscular testing of fatigability consisted of maximal voluntary contraction, voluntary activation (central/neural contributor), and resting twitch (peripheral/muscular contributor) determined by the interpolated twitch technique. Results Sustained isometric and concentric fatigability protocols resulted in motor fatigability for both pwMS and HCs, with no between-protocols differences for either group. Regression analysis showed that motor fatigability variance in pwMS was mainly attributed to central fatigability in the sustained isometric protocol and to both central and peripheral fatigability in the concentric protocol. In HCs, the variance in sustained isometric and concentric fatigability were attributed to both peripheral and central fatigability. Conclusion Central and peripheral contributions of motor fatigability differed between sustained isometric and concentric protocols as well as between pwMS and HCs. These between-protocol differences in pwMS provide a neuromuscular dimension to the reported difference in the strength of associations of concentric and isometric tasks to walking and perception of fatigue in pwMS.

scholarly journals Delayed recovery of velocity-dependent power loss following eccentric actions of the ankle dorsiflexors

2010 ◽  
Vol 109 (3) ◽  
pp. 669-676 ◽  
Author(s):  
Geoffrey A. Power ◽  
Brian H. Dalton ◽  
Charles L. Rice ◽  
Anthony A. Vandervoort
Keyword(s):  
Power Loss ◽  
Muscle Power ◽  
Low Frequency ◽  
Eccentric Contraction ◽  
Voluntary Contraction ◽  
Voluntary Activation ◽  
Shortening Velocity ◽  
Interpolated Twitch Technique ◽  
In Series ◽  
Ankle Dorsiflexors

Unaccustomed eccentric exercise has been shown to impair muscle function, although little is known regarding this impairment on muscle power. The purpose of this study was to investigate changes in neuromuscular properties of the ankle dorsiflexors during and after an eccentric contraction task and throughout recovery in 21 (10 men, 11 women) recreationally active young adults (25.8 ± 2.3 yr). All subjects performed 5 sets of 30 eccentric contractions at 80% of maximum isometric voluntary contraction (MVC) torque. Data were recorded at baseline, during the fatigue task, and for 30 min of recovery. There were no significant sex differences for all fatigue measures; thus data were pooled. After the fatigue task, MVC torque declined by 28% ( P < 0.05) and did not recover fully, and voluntary activation of the dorsiflexors, as assessed by the interpolated twitch technique, was near maximal (>99%) during and after the fatigue task ( P > 0.05). Peak twitch torque was reduced by 21% at 2 min of recovery and progressively decreased to 35% by 30 min ( P < 0.05). Low-frequency torque depression (10-to-50 Hz ratio) was present at 30 s of recovery, increased to 51% by 10 min, and did not recover fully ( P < 0.05). Velocity-dependent concentric power was reduced by 8% immediately after task termination and did not recover fully within 30 min ( P < 0.05). The main findings of an incomplete recovery of MVC torque, low-frequency torque depression, and shortening velocity indicate the presence of muscle damage, which may have altered excitation-contraction coupling and cross-bridge kinetics and reduced the number of functional sarcomeres in series, ultimately leading to velocity-dependent power loss.

Quadriceps neuromuscular function and self-reported functional ability in knee osteoarthritis

2012 ◽  
Vol 113 (2) ◽  
pp. 255-262 ◽  
Author(s):  
M. J. Berger ◽  
C. A. McKenzie ◽  
D. G. Chess ◽  
A. Goela ◽  
T. J. Doherty
Keyword(s):  
Knee Osteoarthritis ◽  
Functional Ability ◽  
Muscle Power ◽  
Voluntary Contraction ◽  
Voluntary Activation ◽  
Knee Oa ◽  
Interpolated Twitch Technique ◽  
Multiple Regression Models ◽  
General Power ◽  
Isometric Torque

The purposes of this study were to determine 1) the relationships of self-reported function scores in patients with knee osteoarthritis (OA) to both maximal isometric torque and to isotonic power at a variety of loads, and 2) the degree to which muscle volume (MV) or voluntary activation (VA) are associated with torque and power measures in this population. Isometric maximal voluntary contraction (MVC) torque and isotonic power [performed at loads corresponding to 10, 20, 30, 40, and 50% MVC, and a minimal load (“Zero Load”)] were measured in 40 participants with knee OA. Functional ability was measured with the Western Ontario and McMaster Osteoarthritis Index (WOMAC) function subscale. MV was determined with magnetic resonance imaging, and VA was measured with the interpolated twitch technique. In general, power measured at lower loads (Zero Load and 10–30% MVC, r2= 0.21–0.28, P < 0.05) predicted a greater proportion of the variance in function than MVC torque ( r2= 0.18, P < 0.05), with power measured at Zero Load showing the strongest association ( r2= 0. 28, P < 0.05). MV was the strongest predictor of MVC torque and power measures in multiple regression models ( r2= 0.42–0.72). VA explained only 6% of the variance in MVC torque and was not significantly associated with power at any load ( P > 0.05). Quadriceps MVC torque and power are associated with self-reported function in knee OA, but muscle power at lower loads is more predictive of function than MVC torque. The variance in MVC torque and power between participants is due predominantly to differences in MV and has little to do with deficits in VA.

Can the Academic Self-Concept be Positive and Realistic?

2005 ◽  
Vol 19 (3) ◽  
pp. 129-132 ◽  
Author(s):  
Reimer Kornmann
Keyword(s):  
Academic Performance ◽  
Opposite Effect ◽  
Self Esteem ◽  
Point Of View ◽  
The Other ◽  
Self Concept ◽  
High Ability ◽  
Self Image ◽  
Other Hand

Summary: My comment is basically restricted to the situation in which less-able students find themselves and refers only to literature in German. From this point of view I am basically able to confirm Marsh's results. It must, however, be said that with less-able pupils the opposite effect can be found: Levels of self-esteem in these pupils are raised, at least temporarily, by separate instruction, academic performance however drops; combined instruction, on the other hand, leads to improved academic performance, while levels of self-esteem drop. Apparently, the positive self-image of less-able pupils who receive separate instruction does not bring about the potential enhancement of academic performance one might expect from high-ability pupils receiving separate instruction. To resolve the dilemma, it is proposed that individual progress in learning be accentuated, and that comparisons with others be dispensed with. This fosters a self-image that can in equal measure be realistic and optimistic.

Effects of Differences in Numeric Ability on the Perception of Adversity Risk to Others and Self

2013 ◽  
Vol 25 (2) ◽  
pp. 95-104 ◽  
Author(s):  
Coy Callison ◽  
Rhonda Gibson ◽  
Dolf Zillmann
Keyword(s):  
Risk Assessments ◽  
High Ability ◽  
News Report ◽  
Bodily Injury ◽  
Adolescent Groups ◽  
Study Participants

This study used an experimental news report about confrontational robberies by adolescent groups in Mexican resorts that presented statistics with or without personalized cases of victimization. Study participants estimated the risk of harm to victims and the extent of their suffering. They also indicated their own risk and concern for their own safety. The readers’ numeric ability was ascertained thereafter. A trisection of this ability showed that persons of high ability comparatively overestimated others’ risk but underestimated their own; this despite indicating greater concerns for their own safety. These results were not altered by consideration of the readers’ empathic, experiential, and rational traits. The incorporation of personalized cases of victimization in the news report did not appreciably influence risk assessments. The involvement of cases resulting in major bodily injury, however, increased estimates of the incidence of such robberies.

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