Coactivation of the antagonist muscle does not covary with steadiness in old adults

Burnett, Robert; Laidlaw, Douglass H.; Enoka, Roger M.

doi:10.1152/jappl.2000.89.1.61

Cited by 149 publications

(178 citation statements)

References 35 publications

Supporting

Mentioning

150

Contrasting

Unclassified

Order By: Relevance

“…The power spectral density for displacement and acceleration when the LVDT was attached were similar to those reported previously (Burnett et al, 2000;Shinohara et al, 2005a). The LVDT had a relatively minor influence on displacement at low frequencies (<4 Hz) (Fig.…”

Section: Frequency Content and Correlation Between Measures Of Fluctusupporting

confidence: 85%

Fluctuations in motor output of a hand muscle can be altered by the mechanical properties of the position sensor

Shinohara

Keenan

Enoka

2008

Journal of Neuroscience Methods

Self Cite

View full text Add to dashboard Cite

Fluctuations in motor output are typically quantified by the standard deviation (SD) of displacement or acceleration. The aim of the study was to determine the influence of a linear variable-displacement transducer (LVDT) on the SDs and spectral content of displacement and acceleration during steady isometric and anisometric contractions performed with the first dorsal interosseus muscle. Thirteen young adults supported six loads when performing position-holding and position-tracking tasks when the LVDT either was or was not attached to the index finger. The LVDT reduced the magnitude of the SDs in displacement and acceleration and disrupted the load-dependent modulation of the spectral properties of these signals. When the LVDT was not connected to the finger, the displacement SD was greatest during concentric contractions, the acceleration SD was greatest during eccentric contractions, and there were load-dependent changes in the power density spectra. Although the LVDT may be used for assessing relative changes in displacement, its ability to provide absolute measures of fluctuations in motor output is limited. The results provide baseline measures of the fluctuations in motor output during steady contractions with a hand muscle and how the method used to detect displacement alters these measures.

show abstract

Section: Frequency Content and Correlation Between Measures Of Fluctusupporting

confidence: 85%

Fluctuations in motor output of a hand muscle can be altered by the mechanical properties of the position sensor

Shinohara

Keenan

Enoka

2008

Journal of Neuroscience Methods

Self Cite

View full text Add to dashboard Cite

show abstract

“…In addition, lengthening contractions are also associated with reduced motor performance [12][13][14]. Interestingly, the magnitude of this deficit is thought to be increased by advancing age, with greater impairments in performance observed in old adults during lengthening movements [13,[15][16][17][18], which may contribute to the increased incidence of falls in the elderly [19].…”

Section: Introductionmentioning

confidence: 99%

Intracortical Inhibition Assessed with Paired-Pulse Transcranial Magnetic Stimulation is Modulated during Shortening and Lengthening Contractions in Young and Old Adults

Opie

Semmler

2016

Brain Stimulation

View full text Add to dashboard Cite

In all cases accepted manuscripts should: link to the formal publication via its DOI  bear a CC-BY-NC-ND license -this is easy to do, click here to find out how  if aggregated with other manuscripts, for example in a repository or other site, be shared in alignment with our hosting policy  not be added to or enhanced in any way to appear more like, or to substitute for, the published journal article Embargo 1935-861X Brain Stimulation 129 May 2017 Age-and movement-related changes in intracortical inhibitionPage 2 AbstractBackground: The modulation of intracortical inhibition is thought to be impaired in older

show abstract

“…One prediction of this theory is that the accuracy of goaldirected movements should decline as the amplitude of the force fluctuations increases. Therefore, the accuracy of goal-directed movements should vary with changes in movement velocity (41), the type of muscle contraction performed (2, 3, 5), and the age of the individual (1,12,15,23,38).The purpose of the study was to assess the effect of movement velocity on the fluctuations in acceleration and the ability to achieve a target velocity when young and old adults performed anisometric contractions with the first dorsal interosseus muscle. The results were consistent with the prediction of the minimum variance theory that movement accuracy declines with an increase in the fluctuations of acceleration; nonetheless, the relations differed for young and old adults.…”

mentioning

confidence: 99%

mentioning

confidence: 99%

Fluctuations in acceleration during voluntary contractions lead to greater impairment of movement accuracy in old adults

Christou

Shinohara

Enoka

2003

Journal of Applied Physiology

Self Cite

View full text Add to dashboard Cite

Christou, Evangelos A., Minoru Shinohara, and Roger M. Enoka. Fluctuations in acceleration during voluntary contractions lead to greater impairment of movement accuracy in old adults. J Appl Physiol 95: 373-384, 2003. First published March 21, 2003 10.1152/japplphysiol.00060. 2003.-The purpose of the study was to assess the effect of movement velocity on the relation between fluctuations in acceleration and the ability to achieve a target velocity during voluntary contractions performed by young (29.5 Ϯ 4.3 yr) and old (74.9 Ϯ 6.2 yr) adults. Subjects performed concentric and eccentric contractions with the first dorsal interosseus muscle while lifting a submaximal load (15% of maximum) at six movement velocities (0.03-1.16 rad/s). Fluctuations in acceleration, the accuracy of matching the target velocity, and electromyographic (EMG) activity were determined from three trials for each contraction type and movement velocity. The fluctuations in acceleration increased with movement velocity for both concentric and eccentric contractions, but they were greatest during fast eccentric contractions (ϳ135%) when there was stronger modulation of acceleration in the 5-to 10-Hz bandwidth. Nonetheless, EMG amplitude for first dorsal interosseus increased with movement velocity only for concentric and not eccentric contractions. Consistent with the minimum variance theory, movement accuracy was related to the fluctuations in acceleration for both types of contractions in all subjects. For a given level of fluctuations in acceleration, however, old subjects were three times less accurate than young subjects. Although the EMG amplitude at each speed was similar for young and old adults, only the young adults modulated the power in the EMG spectrum with speed. Thus the fluctuations in acceleration during voluntary contractions had a more pronounced effect on movement accuracy for old adults compared with young adults, probably due to factors that influenced the frequency-domain characteristics of the EMG. concentric contraction; eccentric contraction; electromyogram; first dorsal interosseus; frequency spectrum THE FORCE EXERTED BY A MUSCLE during a voluntary contraction is not constant, but rather it fluctuates about an average value (2,15,25,33,36). The neural mechanisms most responsible for the fluctuations in the force exerted by hand muscles appear to be the regularity with which motoneurons discharge action potentials and the common modulation of motor unit discharge in the agonist and antagonist muscles (7,10,13,16,41). Fluctuations in muscle force impose a significant constraint on the ability of the nervous system to control movement by influencing the capacity to exert a desired force and to achieve an intended trajectory (17,18,43).The minimum variance theory postulates that the central nervous system attenuates this constraint during the performance of goal-directed movements by selecting activation strategies that minimize the variance in the trajectory of the movement (18,43). One prediction of this theory is t...

show abstract

Coactivation of the antagonist muscle does not covary with steadiness in old adults

Cited by 149 publications

References 35 publications

Fluctuations in motor output of a hand muscle can be altered by the mechanical properties of the position sensor

Fluctuations in motor output of a hand muscle can be altered by the mechanical properties of the position sensor

Intracortical Inhibition Assessed with Paired-Pulse Transcranial Magnetic Stimulation is Modulated during Shortening and Lengthening Contractions in Young and Old Adults

Fluctuations in acceleration during voluntary contractions lead to greater impairment of movement accuracy in old adults

Contact Info

Product

Resources

About