In 2000, the American College of Sports Medicine one of the most highly-respected exercise science organizations, published quidelines for healthy adults to "perform a minimum of 1 set of 8 to 12 repetitions of each exercise to the point of fatigue."    

In 2006, ACSM's guidelines for Exercise Testing and Prescription recommended that healthy adults "perform one set of each exercise to the point of fatigue." 

In 2010, in the eight edition of ACSM's Guidelines for Exercise Prescription, the recommendation for exercise sets is expanded as follows, "Each major muscle group (chest, shoulders, abdomen, back, hip, legs, arms) should be trained with two to four sets.  These sets may be of the same exercise or from different exercises affecting the same muscle group." 

From 1998 to 2010, several large-scale analyses have examined hundreds of studies that compared single-set and multiple-set strength training protocols.  Here is the results of the most recent research reviews:

• 2003, Rhea, 140 studies to determine the dose-response relationship for strength developmen.  Specifically, the effect size data indicted that two sets were more effective than one set, that three sets were more effective than two sets, and that four sets were more effective than three sets.  Their analysis led Rhea to state that "both trained and untrained individuals experience the greatest gains with a mean training volume of four sets per muscle group eliciting the greatest gains in strength.
• 2009, Krieger, 14 studies with 30 treatment groups and 92 effect sizes that compared the effects of single and multiple sets of resistance exercise on muscular strength.  Like Rhea, Krieger found that multiple-set training was associated with a larger effect size than single-set training.  Moireover, Krieger did not find any significant difference between two to three sets per exercise or four to six sets per exercise.  However, Krieger did report that two to three sets per exercise were associated with a significantly greater effect size than one set per exercise; 46% greater strength gains than one set, in both trained and untrained subjects.

From a practical perspective, it makes sense to select a training protocol that best fits the individual's objectives.  Single-set programs for an initial short training period (6 to 16 weeks) for an untrained individual results in siimilar strength gains as multiple-set programs.  However, as progression occurs and higher gains are desired, multiple-set programs are more effective.

In strength,

Dangerous Donna