The transition from rest to full activity in muscle: the velocity of shortening

摘要: The active state of muscle is characterized by two mechanical properties, the capacity to exert or resist a force and ability shorten. former known reach its full extent very quickly after stimulus; development latter has been examined experimentally. Isotonic twitches frog9s sartorius were recorded at 0oC with equipment high sensitivity small inertia. Following latent period, about 8 msec, was required for velocity shortening be reached, which it maintained some time. delay not due inertia, but substantial part probably attributed statistical distribution speed response in individual fibres. In ultimate contractile elements, therefore, transition from rest activity extremely rapid.