i have a report on training to failure and the use of multiple sets versus one set, various rep ranges, and the use of machines or free weights. It gives specific studies that were done and the results. It is extremely interesting, it was written by my exercise physiology professor disputing ACSM's position stand on resistance training. If you want the link here it is the only bad part is its 64 pages or so, but u can skim through it. Basically it shows that there is hardly any difference between multiple sets to a single set when taken to failure and the use of rep ranges between 3 and 15 as long as failure is met in one set 2 to 3 times a week will elicit the same response to split work outs etc. There was a greater response however with working out 6 days a week basically in elite athletes. Heres the link very interesting stuff. It is the second link on the page.JEP online