Ankle variability is amplified in older adults due to lower EMG power from 30–60Hz

Kwon, Min-hyuk; Baweja, Harsimran S.; Christou, Evangelos A.

doi:10.1016/j.humov.2012.05.002

Cited by 12 publications

(3 citation statements)

References 39 publications

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“…Even though the task was not cognitively challenging, it did require a certain level of attention. Therefore, age-associated decreases in the high-frequency components of the neural drive to muscle may have reflected an impairment in the cortical control that contributed to the augmented fluctuations of common input at lower frequencies (Kwon et al 2012;Lodha and Christou 2017;Park et al 2017). Because of the weak association between gamma coherence and age and the relatively small sample size in our study, however, this interpretation should be further tested in future studies.…”

Section: Discussionmentioning

confidence: 77%

Decrease in force steadiness with aging is associated with increased power of the common but not independent input to motor neurons

Castronovo

Mrachacz-Kersting

Stevenson

et al. 2018

Journal of Neurophysiology

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Declines in motor function with advancing age have been attributed to changes occurring at all levels of the neuromuscular system. However, the impact of aging on the control of muscle force by spinal motor neurons is not yet understood. In this study on 20 individuals aged between 24 and 75 yr (13 men, 7 women), we investigated the common synaptic input to motor neurons of the tibialis anterior muscle and its impact on force control. Motor unit discharge times were identified from high-density surface EMG recordings during isometric contractions at forces of 20% of maximal voluntary effort. Coherence analysis between motor unit spike trains was used to characterize the input to motor neurons. The decrease in force steadiness with age ( R = 0.6, P < 0.01) was associated with an increase in the amplitude of low-frequency oscillations of functional common synaptic input to motor neurons ( R = 0.59; P < 0.01). The relative proportion of common input to independent noise at low frequencies increased with variability (power) in common synaptic input. Moreover, variability in interspike interval did not change and strength of the common input in the gamma band decreased with age ( R = 0.22; P < 0.01). The findings indicate that age-related reduction in the accuracy of force control is associated with increased common fluctuations to motor neurons at low frequencies and not with an increase in independent synaptic input. NEW & NOTEWORTHY The influence of aging on the role of spinal motor neurons in accurate force control is not yet understood. We demonstrate that aging is associated with increased oscillations in common input to motor neurons at low frequencies and with a decrease in the relative strength of gamma oscillations. These results demonstrate that the synaptic inputs to motor neurons change across the life span and contribute to a decline in force control.

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Section: Discussionmentioning

confidence: 77%

Decrease in force steadiness with aging is associated with increased power of the common but not independent input to motor neurons

Castronovo

Mrachacz-Kersting

Stevenson

et al. 2018

Journal of Neurophysiology

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“…1) Age-related differences in force control are primarily observed during constant force contractions (Christou 2011;Galganski et al 1993;Kouzaki and Shinohara 2010;Kwon et al 2012;Tracy et al 2002). Very few studies exist that compare young and older adults during force increase and release.…”

Section: Age and Force Variabilitymentioning

confidence: 99%

Motor control differs for increasing and releasing force

Park

Kwon

Solis

et al. 2016

Journal of Neurophysiology

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“…The frequency of action potentials also declines, which can be caused by reduced excitability of axonal membranes or decreased level of stimulation of nerve activation. Moreover, the synchronisation of frequency of individual motor units discharges due to the reduced number of common nerve inputs to the motor unit pool as a result of atrophy, reinnervation of motor units, creating new synapses is also decreased [26,28]. Dendrites of a motor neuron create new connections with other neurons.…”

Section: Factors Affecting Reliability Of the Measurementmentioning

confidence: 99%