On the Rhythm of Muscular Response to Volitional Impulses in Man

Schäfer, E. A.

doi:10.1113/jphysiol.1886.sp000210

Cited by 67 publications

(17 citation statements)

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“…The gain is already reduced by more than an order of magnitude at a frequency of 10 Hz. These results indicate that the contractile properties of human motor units will be a strong factor in limiting the component of physiological tremor near this frequency (Schafer, 1886;Hammond, Merton & Sutton, 1956;Lippold, 1970).…”

Section: Resultsmentioning

confidence: 91%

The contractile properties of human motor units during voluntary isometric contractions

Milner-Brown¹,

Stein²,

Yemm³

1973

The Journal of Physiology

426

191

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SUMMARY1. The electrical activity of single motor units has been recorded from the first dorsal interosseus muscle of normal human subjects during voluntary, isometric contractions, together with the force generated by the muscle.2. By averaging the force correlated with the impulses from a single motor unit, the contraction time and twitch tension generated by that motor unit could be measured. When the rate of discharge was limited, either voluntarily or by automatic selection of intervals for analysis, the time for the tension to decline to half its maximum value (half-relaxation time) could also be measured for some motor units.3. Under our experimental conditions the trains of impulses from different motor units in most subjects were generated quite independently as tested by (a) measuring the correlation between activity 'in single units and that in the whole muscle as recorded by the surface electromyogram (e.m.g.), (b) measuring the cross-correlations between pairs of single units and (c) comparing the tension generated by stimulating single motor units with the average tension correlated in time with voluntary activity of single units in the same location.4. In one normal subject evidence of synchronization between separate motor units was obtained. Cross-correlation studies suggested that the cause of the synchronization was the presence of substantial common excitation received by the various motor units in the muscle.5. The frequency response for the contractions of single motor units was well fitted by that for a linear, second-order system with nearly critical damping. However, when stimulation of a few motor units was superimposed on a voluntary contraction, underdamped (oscillatory) responses were seen which were probably of reflex origin.

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Section: Resultsmentioning

confidence: 91%

The contractile properties of human motor units during voluntary isometric contractions

Milner-Brown¹,

Stein²,

Yemm³

1973

The Journal of Physiology

426

191

View full text Add to dashboard Cite

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“…Since the findings of Scha¨fer (1886), physiological tremor (hereafter referred to as tremor) has received much attention from a physiological and a clinical point of view. Tremor is defined as an involuntary and continuous oscillation in every limb segment of a healthy human.…”

Section: Introductionmentioning

confidence: 99%

The origins of physiological tremor as deduced from immersions of the finger in various liquids

Takanokura

Kokuzawa

Sakamoto

2002

European Journal of Applied Physiology

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To investigate the influence of gravity on physiological tremor during a holding stretch of the finger, tremor during immersion of the finger in liquids was measured. Liquids with various densities and various coefficients of viscosity were used. Tremor was detected using an acceleration sensor, and power spectrum analysis was performed on the acceleration signal of the tremor. The total power of the tremor spectrum decreased with an increase of the density and an increase of the coefficient of viscosity, the high frequency domain of the tremor spectrum showing a larger decrease than the low frequency domain. Linear regression analysis showed that the viscosity of the liquid had a larger effect on tremor than the buoyancy due to the liquid. A model was proposed for tremor during immersion of the finger in liquid. The effect of the buoyancy and the viscosity on tremor was examined using the proposed model. The origin of two frequency bands in the tremor spectrum was verified by both the immersion experiment and the proposed model. The stretch-reflex system via the spinal cord produced a high frequency band around 25 Hz, while the supraspinal system caused a low frequency band around 10 Hz. The neuromuscular function of the human body was evaluated using the amplitude and the frequency of tremor.

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“…Tremor is present in all individuals, occurring at rest (resting tremor) (Brumlik 1962;Marsden et al 1969a) and during postural maintenance of the limb (postural tremor) (Halliday and Redfearn 1956;Marshall and Walsh 1956;Schafer 1886). Tremor is also a frequent symptom of movement disorders, such as essential tremor (ET) and Parkinson's disease (PD) (Deuschl et al 1998;Elble and Koller 1990).…”

Section: Introductionmentioning

confidence: 99%

Effects of Aging on the Regularity of Physiological Tremor

Sturman¹,

Vaillancourt²,

Corcos³

2005

Journal of Neurophysiology

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. The purpose of this investigation was to determine the effects of healthy aging on the regularity of physiological tremor under rest and postural conditions. Additionally, we examined the contribution of mechanical reflex factors to age-related changes in postural physiological tremor. Tremor regularity, tremorelectromyographic (EMG) coherence, tremor amplitude, and tremor modal frequency were calculated for 4 age groups (young: 20 -30 yr, young-old: 60 -69 yr, old: 70 -79 yr, and old-old: 80 -94 yr) under resting and loaded postural conditions. There were 6 important findings from this study: 1) there were no differences between the young and elderly subjects for any of the dependent variables measured under the rest condition; 2) postural physiological tremor regularity was increased in the elderly; 3) postural physiological tremor-EMG coherence was also increased in the elderly, and there was a strong linear relation between peak tremor-EMG coherence in the 1-to 8-Hz frequency band and regularity of tremor. This relation was primarily driven by the increased magnitude of tremor-EMG coherence at 5.85 and 6.83 Hz; 4) enhanced mechanical reflex properties were not responsible for the increased magnitude of tremor-EMG coherence in the elderly subjects; 5) tremor amplitude was not different between the 4 age groups, but there was a slight decline in tremor modal frequency in the oldest age group in the unloaded condition; and 6) despite the increases in postural physiological tremor regularity and the magnitude of low frequency tremor-EMG coherence with age, there was a clear demarcation between healthy aging and previously published findings related to tremor pathology.

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On the Rhythm of Muscular Response to Volitional Impulses in Man

Cited by 67 publications

References 0 publications

The contractile properties of human motor units during voluntary isometric contractions

The contractile properties of human motor units during voluntary isometric contractions

The origins of physiological tremor as deduced from immersions of the finger in various liquids

Effects of Aging on the Regularity of Physiological Tremor

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