Answer: Step 1
During step one no impulse has occurred yet. Thus, the muscle fiber is relaxed (at rest). The sarcomere is at its longest possible length due do the fact that myosin is not bound to the actin.
This step will end when the brain or spinal cord will send an impulse to the muscle. This will travel through the motor neuron and reach the neuromuscular junction. Here acetylcholine will be released, which in turn will trigger the impulse in the muscle.
