The primary muscle targeted during traditional push-ups is the pectoralis major, located in the chest. Push-ups are a compound exercise that also engages the triceps, shoulders, and core muscles, contributing to overall upper body strength. The effectiveness of push-ups lies in their ability to promote muscle endurance and functional strength as they require stability and control. Variations in hand positioning or body angles can further focus on different muscle groups within the arms and chest, allowing for a customized workout that suits various fitness levels and goals.