Doing a set with a large number of reps is neither easy nor useless. It's not easy because you're supposed to do it until failure. And if you're aiming at imp

Doing a set with a large number of reps is neither easy nor useless. It's not easy because you're supposed to do it until failure. And if you're aiming at improving your muscular endurance, then lots of reps with a light weight are more useful than low reps with a heavier weight. There are several studies that show this. Example: http://www.springerlink.com/content/t96qmxyaa7x7le0c/ http://www.springerlink.com/content/t96qmxyaa7x7le0c/ Subjects were divided into four groups: a low repetition group (Low Rep, n=9) performing 3–5 repetitions maximum (RM) for four sets of each exercise with 3 min rest between sets and exercises, an intermediate repetition group (Int Rep, n=11) performing 9–11 RM for three sets with 2 min rest, a high repetition group (High Rep, n=7) performing 20–28 RM for two sets with 1 min rest, and a non-exercising control group (Con, n=5). (...) Maximal strength improved significantly more for the Low Rep group compared to the other training groups, and the maximal number of repetitions at 60% 1RM improved the most for the High Rep group.