Old-school back thickness that never quits.
Keep your chest pinned to the pad and pull with your back, not your lower spine.
The T Bar Row is a mid-back mass builder with the chest pad doing the boring job of holding your torso angle so your lats, rhomboids, and traps can do the exciting one. The fixed pivot path lets you row heavy without your lower back becoming the weak link, and the deep stretch at the bottom of each rep is where the growth stimulus lives. Your biceps assist on every pull, which is why heavy rowing quietly builds arms too.
Mostly the mid-back, lats, rhomboids, and lower traps, with the biceps helping on every rep. The chest-supported setup means your spinal erectors are not the limiting factor, so the target muscles actually get loaded.
The T bar with a chest pad removes the lower back demand, so you can push closer to failure safely. If your lower back is already fried from squats and deadlifts, the T bar is the smarter rowing slot.
You are probably yanking with your hands instead of driving your elbows back. Slow the lowering phase, let your arms reach fully into the stretch, then think about pulling your elbows toward your hips.
