This randomized controlled study aims to compare the acute effects of bench press (BP) and machine chest press (MCP) exercises on the mechanical properties of the pectoralis major muscle in resistance-trained bodybuilders. Sixteen male athletes are randomly assigned to BP or MCP groups. Both groups perform four sets of ten repetitions at 80% of one-repetition maximum with equalized volume load. Muscle mechanical properties, including oscillation frequency, stiffness, decrement, relaxation time, and creep, are measured using MyotonPRO before and immediately after exercise. The study hypothesizes that BP will induce greater stiffness due to higher stabilization demands, whereas MCP will produce greater increases in oscillation frequency due to more isolated loading.