Comparison of the EMG in Normal Test Subjects, Hemiparetic Patients and Parkinson Patients; with Special Reference to Changes in Response to Fatigue

Visser, Sako; Rijke, W. de

doi:10.1159/000114310

Cited by 5 publications

(2 citation statements)

References 10 publications

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“…The test design was described in detail in a previous publication [Visser and De Ruke, 1974], and only a brief summary need be given here ( fig. 1).…”

Section: Methodsmentioning

confidence: 99%

Influence of Sex and Age on EMG Contraction Pattern

Visser¹,

Rijke²

1974

Eur Neurol

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A study was made of the influence of sex and age on the EMG contraction pattern. Constant isometric contractions were executed with the adductor pollicis muscle for 60 sec under standardized conditions. The EMG was derived from this muscle with surface electrodes and with intramuscular needle electrodes, then converted analoge to digital and analysed with the aid of a PDP 8/I computer. Values measured were the integrated amplitude, peak-to-peak amplitude, and peak number. In order to produce a given tension, women as a rule required a higher amplitude and a larger peak number in the EMG than men. These differences are virtually absent when a contraction of half the maximum strength is requested. The comparability of results is therefore enhanced by examining subjects at contractions expressed in percentages of maximum strength. These differences between men and women suggest that women activate more motor units to produce the same contraction. An explanation of this phenomenon is yet to be found. The slight decrease in amplitude and peak number which occurs with increasing age, is usually not significant but nevertheless not to be neglected. On one hand, it can be explained by an increase in duration of action potentials and, on the other hand, by muscle fiber atrophy.

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“…The test design was described in detail in a previous publication [Visser and De Ruke, 1974], and only a brief summary need be given here ( fig. 1).…”

Section: Methodsmentioning

confidence: 99%

Influence of Sex and Age on EMG Contraction Pattern

Visser¹,

Rijke²

1974

Eur Neurol

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“…Such changes include increases in threshold voltages and threshold currents for action potential activation by short‐duration current pulses 17, 110. Regardless of the respective contributions of supraspinal or spinal mechanisms, loss of normally functioning motor units and firing rate reductions may reduce the efficiency of muscle contraction, leading to increased effort, to fatigue, and ultimately to a perceived sense of weakness for voluntary force generation 88, 115, 249…”

Section: Immediate Effects Of Central Lesionmentioning

confidence: 99%

Pathophysiology of spastic paresis. I: Paresis and soft tissue changes

2005

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Spastic paresis follows chronic disruption of the central execution of volitional command. Motor function in patients with spastic paresis is subjected over time to three fundamental insults, of which the last two are avoidable: (1) the neural insult itself, which causes paresis, i.e., reduced voluntary motor unit recruitment; (2) the relative immobilization of the paretic body part, commonly imposed by the current care environment, which causes adaptive shortening of the muscles left in a shortened position and joint contracture; and (3) the chronic disuse of the paretic body part, which is typically self-imposed in most patients. Chronic disuse causes plastic rearrangements in the higher centers that further reduce the ability to voluntarily recruit motor units, i.e., that aggravate baseline paresis. Part I of this review focuses on the pathophysiology of the first two factors causing motor impairment in spastic paresis: the vicious cycle of paresis-disuse-paresis and the contracture in soft tissues.

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Muscle fibre conduction velocity, mean power frequency, mean EMG voltage and force during submaximal fatiguing contractions of human quadriceps

Arendt-Nielsen

Mills

1988

Europ. J. Appl. Physiol.

105

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In 5 healthy male subjects the changes in muscle fibre conduction velocity, mean power frequency, mean EMG voltage, and force in the quadriceps were measured during submaximal fatiguing contractions, ranging from 60 to 100% of maximum force. Surface EMG was recorded from vastus lateralis. The analysis was divided into 2 parts - before and after force had begun to decline (endurance point). The conduction velocity and mean power frequency declined less before the endurance point than after this point. For all forces, the mean EMG voltage increased up to the endurance point. After the endurance point, the effect of fatigue had a decreasing influence on mean EMG voltage.

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Comparison of the EMG in Normal Test Subjects, Hemiparetic Patients and Parkinson Patients; with Special Reference to Changes in Response to Fatigue

Cited by 5 publications

References 10 publications

Influence of Sex and Age on EMG Contraction Pattern

Influence of Sex and Age on EMG Contraction Pattern

Pathophysiology of spastic paresis. I: Paresis and soft tissue changes

Muscle fibre conduction velocity, mean power frequency, mean EMG voltage and force during submaximal fatiguing contractions of human quadriceps

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