Free weights vs machines: which really works your chest more?

This study looked at how two common chest exercises—bench press and machine chest press—change the stiffness and tone of the chest muscle right after exercise. Sixteen male bodybuilders did either bench press or machine chest press at the same intensity. The goal was to see which exercise causes more muscle stiffness or tone changes. Results help understand how different exercises affect muscles, but no treatment or health outcome was tested.