Answer
The weak noncovalent bonds between the subunits of actin and myosin filaments are important for allowing the filaments to flex and move during this process.
Work Step by Step
The contractile force produced by muscle fibers during movement and lifting heavy items is actually caused by the interaction between actin and myosin filaments, even though both actin and myosin filaments are made up of subunits bound together by weak noncovalent connections.
Myosin filaments use ATP energy to create cross-bridges with actin filaments during muscle contraction. Actin filaments are pulled towards the center of the sarcomere, the fundamental functional unit of muscle fibers, by the myosin heads once they have attached to them, shortening the muscle fiber as a result .This repeated attachment, pulling, and detachment of myosin and actin filaments creates the force necessary for muscle contraction and movement.
