In general, the number of sets done is inversely proportional to the number of reps
performed (5). If 20 rep sets are done, only 1-2 sets may be needed while 4 rep sets may require 4
or more sets.
Most research on the topic of sets has been done on beginners who are not representative
of advanced lifters. In beginners, one set gives the same results as three in terms of strength and
muscle size gains, at least over the first fourteen weeks of training (15). Most authorities agree
that 1-2 sets per exercise are sufficient for beginning trainees during the first six to eight weeks of
training (5,8,16). Whether advanced lifters need more sets is a matter of great debate. After this
initial conditioning period where only 1-2 sets are done per exercise, more sets (3-6 per exercise)
may be necessary to elicit further strength gains (5).
Reps, sets, loads and the repetition continuum
Although not all authorities agree, there is thought to be a continuum of adaptations which
may occur with different repetition sets (17). That is, optimal strength gains appear to occur
between 2 and 20RM loads (17) with strength gains becoming progressively lower as more than
20 reps per set are done. In a classic review paper, Atha determined that 4-6 sets of 4-6RM gave
optimal improvements in maximal strength but that higher and lower loads were not as beneficial
(18).
There is a dynamic interaction between the variables of reps, sets and loads. The load
used (% of 1RM) ultimately determines how many reps per set are done. Reps per set (or set
time) ultimately determines how many total sets must be done. The interaction between the
three will affect what adaptation is seen.
The interplay between load and volume (sets and reps) can be looked at as an interplay
between tension and fatigue. Tension is roughly equivalent to the weight being lifting (as a
percentage of maximum). Fatigue refers to the total amount of metabolic work done. In general,
the following appears to hold true.
High tension/low fatigue: 1-5 RM : develops 1RM strength primarily (18)
Low tension/high fatigue: 25+RM : develops muscular endurance
Moderate tension/moderate fatigue: 6-20RM : develops muscle size (19)
The above chart does not take set time into account. It is more accurate to say that low
set times will develop primarily strength, medium set times hypertrophy, and long set times
muscular endurance. However, this is highly variable and many individuals can develop
hypertrophy with very low or very high reps.
Frequency of training
Beginners typically train every other day, three times per week. However, research has
found that beginners may get similar strength gains (about 75-85%) lifting twice a week (20). As
lifters advance, they will need to train a given bodypart less frequently as they will be training it