Abstract
1. We observed in a previous study on the human foot dorsiflexor muscles that the fatigue-induced decline in motor output during sustained maximal voluntary contractions (MVCs) was temporarily counteracted during the initial phase of superimposed high-frequency (150 Hz) muscle vibration, whereas prolonged muscle vibration seemed to accentuate the fatigue-induced decline in gross EMG activity and motor unit firing rates. A more extensive investigation of this late effect of muscle vibration on MVCs was performed in the present study. 2. Prolonged periods of superimposed muscle vibration caused a reduction of EMG activity, motor unit firing rates and contraction force in both intermittent and sustained MVCs. This vibration-induced effect had the following main characteristics: (i) it developed slowly during the course of about 1 min of sustained vibration and subsided within 10-20 s after the end of vibration; (ii) it was much more pronounced in some subjects than in others (not age-dependent) and it was accentuated by preceding muscle exercise; (iii) it affected primarily the subject's ability to generate and/or maintain high firing rates in high-threshold motor units. 3. Since the effect developed while vibration at the same time exerted a tonic excitatory influence on the alpha-motoneurone pool (as evidenced by the presence of a tonic vibration reflex) it is argued that the vibration-induced suppression of motor output in MVCs probably does not depend on alpha-motoneurone inhibition, but on a reduced accessibility of these neurones to the voluntary commands. It is suggested that contributing mechanisms might be vibration-induced presynaptic inhibition and/or 'transmitter depletion' in the group Ia excitatory pathways which constitute the afferent link of the gamma-loop.
Full text
PDFSelected References
These references are in PubMed. This may not be the complete list of references from this article.
- Bongiovanni L. G., Hagbarth K. E. Tonic vibration reflexes elicited during fatigue from maximal voluntary contractions in man. J Physiol. 1990 Apr;423:1–14. doi: 10.1113/jphysiol.1990.sp018007. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Burke R. E. Motor unit types of cat triceps surae muscle. J Physiol. 1967 Nov;193(1):141–160. doi: 10.1113/jphysiol.1967.sp008348. [DOI] [PMC free article] [PubMed] [Google Scholar]
- CURTIS D. R., ECCLES J. C. Synaptic action during and after repetitive stimulation. J Physiol. 1960 Feb;150:374–398. doi: 10.1113/jphysiol.1960.sp006393. [DOI] [PMC free article] [PubMed] [Google Scholar]
- De Gail P., Lance J. W., Neilson P. D. Differential effects on tonic and phasic reflex mechanisms produced by vibration of muscles in man. J Neurol Neurosurg Psychiatry. 1966 Feb;29(1):1–11. doi: 10.1136/jnnp.29.1.1. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Desmedt J. E., Godaux E. Mechanism of the vibration paradox: excitatory and inhibitory effects of tendon vibration on single soleus muscle motor units in man. J Physiol. 1978 Dec;285:197–207. doi: 10.1113/jphysiol.1978.sp012567. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Färkkilä M., Pyykkö I., Korhonen O., Starck J. Vibration-induced decrease in the muscle force in lumberjacks. Eur J Appl Physiol Occup Physiol. 1980 Feb;43(1):1–9. doi: 10.1007/BF00421349. [DOI] [PubMed] [Google Scholar]
- Gillies J. D., Lance J. W., Neilson P. D., Tassinari C. A. Presynaptic inhibition of the monosynaptic reflex by vibration. J Physiol. 1969 Nov;205(2):329–339. doi: 10.1113/jphysiol.1969.sp008968. [DOI] [PMC free article] [PubMed] [Google Scholar]
- HENNEMAN E., SOMJEN G., CARPENTER D. O. FUNCTIONAL SIGNIFICANCE OF CELL SIZE IN SPINAL MOTONEURONS. J Neurophysiol. 1965 May;28:560–580. doi: 10.1152/jn.1965.28.3.560. [DOI] [PubMed] [Google Scholar]
- Hagbarth K. E., Kunesch E. J., Nordin M., Schmidt R., Wallin E. U. Gamma loop contributing to maximal voluntary contractions in man. J Physiol. 1986 Nov;380:575–591. doi: 10.1113/jphysiol.1986.sp016303. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Hultborn H., Meunier S., Morin C., Pierrot-Deseilligny E. Assessing changes in presynaptic inhibition of I a fibres: a study in man and the cat. J Physiol. 1987 Aug;389:729–756. doi: 10.1113/jphysiol.1987.sp016680. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Hultborn H., Meunier S., Pierrot-Deseilligny E., Shindo M. Changes in presynaptic inhibition of Ia fibres at the onset of voluntary contraction in man. J Physiol. 1987 Aug;389:757–772. doi: 10.1113/jphysiol.1987.sp016681. [DOI] [PMC free article] [PubMed] [Google Scholar]
- MCPHEDRAN A. M., WUERKER R. B., HENNEMAN E. PROPERTIES OF MOTOR UNITS IN A HOMOGENEOUS RED MUSCLE (SOLEUS) OF THE CAT. J Neurophysiol. 1965 Jan;28:71–84. doi: 10.1152/jn.1965.28.1.71. [DOI] [PubMed] [Google Scholar]
- Milner-Brown H. S., Stein R. B., Yemm R. The orderly recruitment of human motor units during voluntary isometric contractions. J Physiol. 1973 Apr;230(2):359–370. doi: 10.1113/jphysiol.1973.sp010192. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Samuelson B., Jorfeldt L., Ahlborg B. Influence of vibration on endurance of maximal isometric contraction. Clin Physiol. 1989 Feb;9(1):21–25. doi: 10.1111/j.1475-097x.1989.tb00952.x. [DOI] [PubMed] [Google Scholar]
- Vallbo A. B., Hagbarth K. E., Torebjörk H. E., Wallin B. G. Somatosensory, proprioceptive, and sympathetic activity in human peripheral nerves. Physiol Rev. 1979 Oct;59(4):919–957. doi: 10.1152/physrev.1979.59.4.919. [DOI] [PubMed] [Google Scholar]