I’m hoping somebody can clear up some confusion for me. In the bad old days before I discovered T-Mag I, like most people in the gym, didn’t used to pay much attention to time under tension and my 1RM squat was 462lbs. This set would probably have had a tempo of 101; total time under tension: 2 seconds. So then I started paying attention to TUT and adopting a 8- 10 reps at 501, for a total TUT of 40- 50 seconds. Trouble is I was only able to use about 88lbs! This is about 25% of my 1RM! Aren’t you supposed to be using 60- 80% of your 1RM for mass, generally speaking?!
As you now see, 1RM can actually be a rather vague term. The tremendous drop-off in your performance is a function of not being used to the higher TUT. Greg Wilson (I believe), an Australian researcher, showed that (in the bench at least) a 4-second combined eccentric and pause in the stretched position was necessary to dissipate momentum in the subsequent concentric; so, clearly, a large part of your previous 1 RM performance was due to momentum. This isn’t a bad thing if you’re a competitive weightlifter and your only goal is getting the weight up. If, however, you’re a bodybuilder and your primary training goal is muscle stimulation, you probably want to cut momentum out of your lifts. Keep your combined negatives/stretched-position pauses to 4 seconds, train hard, and don’t worry about %1RM (since 1RM can be misleading anyway) for now. Things’ll improve rapidly.