The American College of Sports Medicine ( ACSM) list several studies to support multi set programs to single set programs in both previously untrained subjects, untrained long subjects, and resistance-trained individuals. However, many of these studies have methodological concerns.
Berger, Effect of varied weight training programs on strength, conducted a study with no control for sets or reps, and subjects were not randomised. In fact the results demonstrated no significant difference between multi set v single set.
Sanborn, Short-Term Performance Effects of Weight Training With Multiple Sets Not to Failure vs. a Single Set to Failure in Women. Subjects were randomised. However, when testing vertical jumps, the multi set groups were given different technical instruction to the single set group.
Stone, A short term comparison of two different methods of resistance training on leg strength and power. The high set group reported to have greater improvements in squat and vertical jump. However, there was no significant difference for leg press strength, no significant increase as power (vertical jump and Lewis Formula), and no difference in lean muscle mass. No pre and post training data was provided.
Stowers, The Short Term effect of three different strength-power training methods. This study did not list intensity for the varied group v the 1 set or 3 set group.
Chief editor of the journal of strength and conditioning Dr Kramer. Published a number studies which were based on football players. The data was taken out of database over a decade later. One study didn’t have any controls, and subjects had there adherence tested by survey. Subjects used a particular protocol at home or in a gym.
Pharmaceutical companies for instance, can be very persuasive on the effectiveness of their product. A number of published studies have made various claims. For instance Vioox and came out in 1999 as new type of drug for treating Arthritis. They claimed not have side effects on gastrointestinal illness, however when later examined, one other Cox 2 inhibitor Celebrex showed no significant difference compared to Voltaren. More seriously, thousands of patients died of stroke and heart attack. Vioox was pulled from the market by Merck, conveniently after profiting three billion dollars in annual sales.
Historically there have been many other drugs (Laetrile, Interferon, etc ) which claimed to treat cancer. The studies were published, however studies were uncontrolled trials. Subsequent controlled studies showed Laetrile to be a toxic drug and not effective. Laetrile therapy gained enormous popularity in American, even though there was no proper evidence of patient benefit.