Final answer:
During muscle contraction, the myosin and actin filaments do not change in length. Instead, they slide by one another, causing the sarcomere to shorten while the filaments remain the same length.
Step-by-step explanation:
During muscle contraction, the myosin and actin filaments do not change in length. Instead, they slide by one another, causing the sarcomere to shorten while the filaments remain the same length.
The sliding filament theory of muscle contraction explains that myosin heads temporarily bind to actin filaments and pull them, resulting in the sliding motion.
This sliding movement is powered by ATP, which provides the energy for the contraction.