SPontaneous Oscillatory Contraction (SPOC): auto-oscillations observed in striated muscle at partial activation.

Striated muscle is well known to exist in either of two states-contraction or relaxation-under the regulation of Ca concentration. Described here is a less well-known third, intermediate state induced under conditions of partial activation, known as SPOC (SPontaneous Oscillatory Contraction). This state is characterised by auto-oscillation between rapid-lengthening and slow-shortening phases.