Target the lower chest on a fixed, safe path.
Touch the lower chest, not the upper, to keep the tension on the lower pecs.
Setting a decline bench in the Smith machine angles your torso head-down, so the fixed bar path lines up with the lower chest fibres and the touch point lands low on the pecs. The triceps drive the lockout as with any press, while the track removes the balance issues that make free-weight decline work awkward to set up. It earns its place for direct lower chest loading with none of the spotter anxiety a decline position usually brings.
A modest decline, around 15 to 30 degrees, is enough to shift emphasis to the lower chest. Steeper angles mostly shorten the range and make getting in and out harder.
The decline line biases the lower pec fibres and typically lets you move more weight through a shorter range. If your lower chest lags, it is worth a run in your programme.
Low on the chest. Because the track is fixed, position the bench so the bar naturally meets your lower pecs, not your sternum or upper chest, before your first working set.
