For as long as I can remember, coaches and fitness professionals have debated the merits of single versus multiple-set strength training. I have personally trained in both manners, and I have conducted numerous research studies on the effects of single and multiple-set exercise protocols. In all of my experiences and experiments, I have found no significant differences between these two training methods.
Consider our most frequently referenced study with 77 intermediate level strength participants who trained 3 days a week for 10 weeks with assisted bar-dips (pectoralis major, anterior deltoids, and triceps muscles) and assisted chin-ups (latissimus dorsi, and biceps muscles). Group One did 1 set of bar-dip and 1 set of chin-ups, Group Two performed 2 sets of bar-dips and 2 sets of chin-ups, and Group Three completed 3 sets of bar-dips and 3 sets of chin-ups. Groups Two and Three rested 2 minutes between successive sets of each exercise.
After 10 weeks of training, all three groups were assessed for their improvement in bar-dip and chin-up performance, tested with bodyweight. Group One experienced an average bar-dip/chin-up increase of 4.8 repetitions, Group Two increased their average bar-dip/chin-up score by 4.1 repetitions, and Group Three had an average improvement of 5.2 bar-dip/chin-up repetitions. Statistically, there were no significant differences among the single, double and triple-set training protocols.
A classic follow-up study conducted at the University of Florida revealed similar results. After 14 weeks of strength training the knee extension and knee flexor muscles with leg extensions and leg curls, the 38 subjects recorded almost identical average strength gains regardless of performing 1 set or 3 sets of each exercise (14.5% increase vs. 15.5% increase).
Although dozens of other studies have shown similar strength benefits from single and multiple set training, a recent meta-analyses of more than 100 studies indicated that 4 sets of exercise (targeting a specific muscle group) may be the most effective strength-building protocol. Ignoring the methodological problems associated with meta-analyses, performing 4 sets of each exercise presents two practical problems for many people, namely time availability and physical ability.
For example, time-pressured men and women may have difficulty spending approximately 10 minutes at each exercise station (4 sets of 1 minute each with 2 minutes recovery time between sets). At this rate, 12 exercises would require about 2 hours for completion, compared to about 25 minutes for a single-set training protocol.
For others, particularly previously sedentary, deconditioned, and elderly individuals, 4 sets of each exercise may be simply too physically demanding. Although they may be able to gradually progress to higher volume training programs, they would be well-advised to begin with 1 good set of each exercise.
Our research with more than 1100 beginning participants (previously inactive adults between 20 and 80 years of age) featured 1 set (8 to 12 repetitions) of 10 exercises, performed 2 or 3 days a week for a period of 8 weeks. This 20 minutes per session strength training program has produced significant increases in lean (muscle) weight and significant decreases in fat weight. As shown in Table 1, the men averaged almost 4 pounds more lean weight and 7 pounds less fat weight, and the women averaged almost 2 pounds more lean weight and 4 pounds less fat weight. These results compare favorable with all other published studies on beginning strength training, regardless of the number of sets or exercises performed.