I will talk from experience, I train a US RECORD HOLDER IN SWIMMING. Also I have trained many others. We not only believe in working to failure sometimes but actually overtraining til you can’t sleep and keep overtraining for weeks then have mood swings, immune system goes down etc. but then 2-3 days after all this the body will fly up faster than anything you have ever seen even while you are still “overtraining” according to the common definition of overtraining. Which I agree it is overtraining. You just have to go through the bad phase. All the studies out there quit when the bad side effects start happening and especially as the side effects are getting worse. This is not for good for 99.5% of the population will have no need for this. But to the select elite that need to break plateaus and excel to world record heights. Then it is useful. I will not give the details on how to do this because people pay a lot for this info and are very happy. And I don’t train anyone on steroids. Yes it will get worse and I did as well, I went backwards for about 4 days of an overtraining routine but afterwards flew a head so fast many thought I was on steroids. Yes, the personal doing this is risking a lot and has to get a massage everyday and eat very healthy.
I gave Shawn a thumb up for his answer in 217 except for the “Microcycles” part. What I am talking about that is beneficial for .05 percent of the population should be carried on for 6 weeks. DO NOT TRY THIS AT HOME!!!
If the body is healthy and movement is correct then failure is best!!! Although most aren’t ready for failure because of rounded shoulders from the computer, alterior pelvic tilt and a whole list of others.
Doing a 1 rep max then of course you go to failure or 10 reps etc. But there are many out there that shouldn’t be going to failure like the people on a very popular losing weight show on tv. Those guys are getting injured far more than they should and they don’t show you that on the tv show.
I think it is effective when posture isn’t a huge issue. While I don’t believe that there is a huge benefit of the last few reps that make you fail that some do. I believe (anecdotally) there is a physiological benefit and a very big psychological benefit. There are times on the field or court that you feel like you can’t keep going, but you’ve done it when training so you know that you can. If posture and stabilizer muscles are a big issue with the exercise then I believe you should end before failure so your muscles remember the good posture.