Final answer:
Muscle goes through a process called muscle contraction when lifting weights. Proper nutrition, rest, and consistent training are required for muscle repair and growth.
Step-by-step explanation:
When lifting weights, a muscle goes through a process called muscle contraction. This process is initiated by a neural signal from the brain to the muscle. The muscle fibers then contract, causing the muscle to shorten and generate force.
In order for the muscle to repair itself after lifting weights, several factors are required. First, proper nutrition is crucial to provide the necessary building blocks for muscle repair, such as protein. Second, rest is important to allow the muscle to recover and repair damaged tissues. Finally, consistent training is needed to stimulate the muscle to adapt and grow stronger.