Activities of Single Motor Units in Man During Slight Voluntary Efforts

Gilson, A. S.; Mills, W. B.

doi:10.1152/ajplegacy.1941.133.3.658

Cited by 53 publications

(17 citation statements)

References 1 publication

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“…On the other hand, the results of the recording experiments confirm previous work that changes in frequency of discharge do play a part in the contraction of voluntary muscle, particularly at low tensions (Adrian & Bronk, 1929;Lindsley, 1935;Hoefer & Putnam, 1939). The lack of activity at rest confirms the work of Smith (1934) and Gilson & Mills (1941).…”

Section: Discussionsupporting

confidence: 88%

“…therefore became of interest to discover how the frequency of a unit varied with changes in tension in the muscle during a voluntary contraction. This has been investigated to a limited extent previously, but only at contraction strengths which were a small percentage of maximum levels (Gilson & Mills, 1941). This was because at high levels of activity analysis of the frequency of single units became impossible through interference from adjacent units.…”

mentioning

confidence: 99%

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Motor unit activity in the voluntary contraction of human muscle

Bigland¹,

Lippold²

1954

The Journal of Physiology

303

126

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In a muscle contracting voluntarily, the tension is proportional to the electrical activity, both under isometric (Lippold, 1952) and under isotonic conditions (Bigland & Lippold, 1954). The measure of this electrical activity was obtained by determining the area under the action potential curve recorded from surface electrodes over the belly of the muscle, and was considered to represent the 'excitation' in the muscle, i.e. to be a function of the number and the frequency of discharge of motor units. Such a composite measure, however, could not distinguish between the two means by which a voluntary contraction is graded (variation in the number of active units or their frequency), and it. therefore became of interest to discover how the frequency of a unit varied with changes in tension in the muscle during a voluntary contraction. This has been investigated to a limited extent previously, but only at contraction strengths which were a small percentage of maximum levels (Gilson & Mills, 1941). This was because at high levels of activity analysis of the frequency of single units became impossible through interference from adjacent units.The efficiency of muscle reaches its maximum level when the frequency of stimulation of its fibres is just sufficient to produce maximum tetanic tension; at frequencies above and below this, the muscle fibre is less efficient (Bronk, 1930). These facts might indicate that the fibres in a muscle would tend to operate near their tetanic frequency, and that changes in tension would, as. a result, be brought about mainly by means of recruiting motor units whose frequency of discharge would rapidly rise to and remain at tetanic level.We have studied the problem in two ways. First, by stimulating a human muscle artificially and determining the relation between frequency and tension produced as has been done already in anaesthetized animals (Adrian & Bronk, 1929;Brown & Burns, 1949). The expected results would be a proportionality between mean tension and frequency until a certain frequency is reached, above which no further increase in tension would occur, indicating that this represented full tetanic frequency in the muscle fibres.

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Section: Discussionsupporting

confidence: 88%

mentioning

confidence: 99%

Motor unit activity in the voluntary contraction of human muscle

Bigland¹,

Lippold²

1954

The Journal of Physiology

303

126

View full text Add to dashboard Cite

show abstract

“…Incidentally our results throw fresh light on the origin of double spikes from motoneurones, a subject on which there is a large literature (Eccles & Hoff, 1932;Gilson & Mills, 1941;Hoff & Grant, 1944;Denslow, 1948;Toennies & Jung, 1948;Gordon & Holbourn, 1949). They do so by demonstrating the connexion of this phenomenon with level of excitability and with some recent intracellular observations.…”

Section: Discussionsupporting

confidence: 75%

The behaviour of tonic α and β motoneurones during stimulation of recurrent collaterals

Granit¹,

Pascoe²,

Steg³

1957

The Journal of Physiology

152

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“…One of the muscle nerves of the limb was cut across centrally and a single fibre of about 20,u diameter was dissected out at a point 2-6 cm from the muscle. The distal one-third of the muscle was freed from the surrounding tissue and the maxrimum tension 166 Y. KOBAYASHI, K. OSHIMA AND I. TASAKI developed by tetanic stimulation of the nerve fibre was measured by the method described previously (Tasaki & Mizutani, 1944 Gilson & Mills, 1941) in one of the large fibres. The results of our measurements were as follows:…”

Section: Motor Effrects Of the Impulses In Effierent Fibresmentioning

confidence: 99%