Oxygen consumption and contractile force during vibrations of cat soleus muscle.

The influence of longitudinal vibrations (50 Hz, 0.4 mm) on isometric twitch force development (4 Hz), blood flow and oxygen consumption was studied in the acutely denervated soleus muscle of the anesthetized cat. It was found that the sinusoidal vibrations reduced the twitch amplitude by 60 per cent whereas oxygen consumption and blood flow were lowered by 15 per cent only. Similar reduction in twitch force was also obtained by lowering the nerve stimulation intensity (4 Hz). This was associated with a diminution in oxygen consumption, the degree of which was linearly related to the attenuation of active force, i.e. the number of activated motor units. The results are in agreement with previous observations as to the mechanical effect of vibrations on active force in smooth and striated muscle. They demonstrate that vibrations prevent the contractile response with maintained high oxygen consumption which adds further support to the hypothesis forwarded by Joyce et al. (1969) that vibrations cause increased rate of detachment of actin-myosin cross-links. In addition it appears possible that vibrations to some extent prevent formation of such cross-links.