I was talking to some people who are all about time under tension (TUT) instead of sets x reps. This makes sense. If you do a set of 8 reps of bench, but you do it really fast, it's a completely different load on your body than if you do 8 reps of bench slowly. Some of these hardcore TUT guys have little metronomes with them at the gym so they can make sure each rep is the correct number of seconds. That's hardcore. But I think it's kind of true... say your goal is to bench 315 for 5 reps. So you're working up to it, and finally that day comes. You load up 315, unrack it, and knock off 5 quick reps in like 10 seconds (1 sec down, no pause, 1 sec up, no pause). But say your normal workouts have a temp of 3 seconds down and 2 seconds up. Well, you go tyour 315x5, but you kinda did it fast because you were concerned about number of reps rather than the quality of the set. So does anyone base their programs on TUT? Like, a set has to last at least 40 seconds regardless of how many reps you get? So on bench, 10 reps that take 4 seconds each is the same as 8 reps that take 5 seconds each (they both have a TUT of 40 seconds). If you increase from 8 to 10 reps, but your total TUT stays the same, you haven't gotten any stronger nor have you done any more work. You're fooling yourself into thinking you've improved because you've done more reps. There are other factors, like the faster you go the more you have to take acceleration into the equation, and if you go too slowly, your muscles start to recooperate a bit, but we're not talking super fast or super slow sets here. One rep that takes 40 seconds is not the same as the two examples above, which are the same.