To summarize the article for people who don't feel like reading or w/e:
1. Different training parameters work better for trained (greater than 1 year experience) and untrained (less than 1 year experience) individuals.
2. Similar results for men vs women.
3. Best results for untrained individuals come at 4 sets per muscle group, three times/week, at average intensity of 60% of 1RM.
4. Best results for trained individuals come at 4 sets per muscle group, two times/week, at average intensity of 80% of 1RM.
@vancouver
They are almost certainly just talking about 1 exercise. So for chest, probably 4 sets of bench. If you're working purely for increasing your 1RM strength (real or theoretical), its unlikely that you'd be splitting 4 sets into 2 each of barbell and dumbbell. Ultimately, they were using 1 exercise as a measurement to determine the strength increases.
That said, the specific exercise used may have varied between individuals studied (ie perhaps some of the studies used incline bench as opposed to bench). We don't know because the authors of the paper looked at studies that other people had done, they didn't tailor the specific parameters themselves, nor did they include a list of the data, at least in the visible portion of the article.