http://www.timinvermont.com/fitness/failure.htm Here is a great article by Charles Staley. My opinion is that 'training to failure' should be periodized. If you are training four times per week, taking all sets to failure, then you are setting yourself up for a number of problems. One of which being CNS fatigue which can be a b%^&*h to recover from. Olympic lifters and those of whom partake in the famous Smolov squat routine, squat 3-4 times per week. How can they do this??? They do not take any set to failure, stopping 2-3 reps shy of failing. Want bigger quads??? Try a Smolov cycle. I gained 1 inch on my quads as an ectomorph on this routine in 7 weeks. Recreational lifters and bodybuilding competitors can also benefit from not training to failure. Infrequent training also has its benefits. Intensity of effort will be a big player in this type of training. I remember back to 2005 when I was training for the NYS Masters Bodybuilding Championship. I trained 3x per week. For about 4 weeks I was stuck at 4% bodyfat and held at the same body weight. NOTHING I did diet wise could help me get over the hump. I was training with low volume... maybe 4 sets per body part once per week, heavy. And I mean heavy. My reps were anywhere from 4-8. I was going to failure on the last set of any given exercise except for legs. Two week prior to the show, I decided to take my hack squats to failure. I started with one set of squats for 9 reps, stopping about 1 rep short of failure. This was very hard. Then I went to leg presses for 1 very hard set of 10 reps stopping 1-2 reps short of failure. My final exercise was machine hack squats. I did 6 reps to failure.... or so I thought. I decided to try for another rep, knowing that I would fail. I descended into the hole and it took me about 10 seconds to fight my way up. My entire body was shaking for about 6 hours afterwards. I slept for 12 hours and woke up exhausted. But then it it happened. When my BF guy took the reading next morning, I was 3.47%. I mean, I looked different in the mirror. I wound up beating a field of 12 for the 2005 NYS Masters Bodybuilding title. I believe to this day that that one rep transformed my body entirely. Point is... Periodize your training once you become more and more experienced. Newbie success is great. But once you sense plateaus, fatigue, sleeplessness, and zero progress.... it's time for a change. Train smart and listen to your body.