The point where your working muscle is fully fatigued to the extent that it can no longer complete another repetition.  The muscles are so fatigued that you are pushing or pulling as hard as you can but unable to move the weight. 


Research for strength training shows that there is an ideal length of time with resistance for each exercise.  The weight needs to be “light” enough to hit 60 seconds and also “heavy” enough that you reach full muscle failure before 2 minutes. As you progress in your workouts, you will get stronger and will be able to last past two minutes.  This is PROGRESS and now it’s time for a weight increase!
Hitting full muscle failure yields OPTIMAL RESULTS and is the most important part of your workout.


“Your RESULTS from exercise are directly proportional to your INTENSITY OF EFFORT and have more to do with this than any other training factor…”

-Drew Baye, highly-experienced personal trainer, former fitness model, author, long-standing proponent of high intensity training.