How do muscles contract?

The Sliding Filament Theory of Muscle Contraction is the most widely accepted theory that explains the mechanism of muscle contraction.   

According to this theory, the sliding of the thin actin filaments over the thick myosin filaments within a sarcomere generates tension, which results in muscle contraction.  

During muscle contraction, a cross-bridge is formed by the attachment between the actin filaments and the myosin heads. The myosin head then pulls the actin filaments towards the center of sarcomere, which causes the sarcomere to shorten in length, leading to muscle contraction. 

The myosin head detaches from the actin filament after muscle contraction, returning the sarcomere to its original resting length. This allows muscles to contract and relax in a repetitive pattern of binding and releasing.