Stand facing a cable machine with a high pulley and a straight bar, V-bar, or rope attachment. Grasp the handle with an overhand grip, keep your elbows close to your sides, and push the attachment downward until your arms are fully extended. Slowly return to the starting position while maintaining control and tension in the triceps throughout the movement.
The cable pushdown is one of the most reliable triceps isolation movements because the cable keeps constant tension on the muscle through the entire range, unlike free weight extensions where tension drops off near lockout. Program 3 to 4 sets of 10 to 15 reps after your main pressing work, whether that is bench press, overhead press, or dips.
Rotate attachments to shift emphasis: a straight bar allows the heaviest loading, a rope lets the hands separate at the bottom for a deeper peak contraction, and a V-bar sits in between. Training triceps directly twice a week on top of the indirect work from pressing movements is enough for most lifters; more than that often just adds fatigue without extra growth.
Neither is definitively superior. The rope allows a slightly greater stretch and peak squeeze since the hands can separate, while the straight bar typically allows more total weight. Alternating between them over time trains the triceps from slightly different angles.
This almost always happens when the elbows drift away from the sides and the torso leans in to help move the weight. Keep the upper arms pinned to your ribs and only let the elbows do the moving; if you need to lean and heave, the weight is too heavy.
Twice a week with isolation work like pushdowns is plenty for most lifters, especially when combined with the indirect triceps work that comes from regular bench and overhead pressing.
Log your cable pushdown sets in 1RM.fit and watch your estimated 1RM update automatically as you get stronger.