The desire to increase muscle size and strength have inspired their fair
share of fads and pseudoscience, promising impressive gains if you do this
or buy that. There is something to be said for trends inspiring innovation,
but for clients who are serious about achieving maximal strength or
hypertrophy (muscle growth), training is not a guessing game. Following a
science-based system will always be the best place to begin.
Decades' worth of studies have led to the creation, testing and retesting
of highly effective evidence-based models (see "Charting a Course for
Clients") that can help exercisers achieve these goals. Here, we'll discuss
training for hypertrophy versus maximal strength-a difference that some
experienced exercisers may not realize exists-and how to design a program
that best meets each client's goals.
Size, Strength and How They're Related
Hypertrophy is the increase in the size of existing skeletal muscle fibers (Goldberg et al. 1975).
The National Academy of Sports Medicine
(2018) defines it as "the enlargement of skeletal muscle fibers in response
to being recruited to develop increased levels of tension, as seen in
resistance training. [It] is characterized by an increase in the
cross-sectional area of individual muscle fibers resulting from an increase
in myofibril proteins (myofilaments)."
Factors such as muscle tension, muscle cell disruption and resultant metabolic
waste in and around muscle fibers cause this cellular adaption.
The effects can often be felt 24-48 hours after
training in the form of delayed-onset muscle soreness. However, it usually
takes up to several months for visible changes to occur, as they happen
only after thousands of individual muscle fibers have grown larger (Staron
et al. 1994). Increasing hypertrophy has historically appealed to people
such as bodybuilders who seek maximal (and observable) muscle growth.
Strength is the ability of the nervous system to recruit as many muscle fibers as
possible when needed. NASM (2018) defines strength as "the ability of the
neuromuscular system to produce internal tension (in the muscles and
connective tissues that pull on the bones) to overcome an external force
[or external load].
Strength is considered a neuromuscular adaptation, which means it
is largely dependent on the nervous system's ability to communicate with
the muscular system as demonstrated by Weier, Pearce & Kidgell (2012),
who found that the brain displayed structural changes in the beginning
weeks of a strength training program. Strength is important not only for
sports performance, but also for day-to-day life, as it supports lifting
and moving about the environment. Maximal strength, specifically,
is "the maximum force an individual's muscle can produce in a single
voluntary effort, regardless of the rate of force production" (NASM 2018).
So, how are the two related? An individual with more muscle mass has larger
muscle fibers, and this could generate more tension leading to increased
strength. An individual who displays strength may be able to train longer,
which can encourage muscle fibers to grow larger leading to hypertrophy.
Therefore, training for one will impact the other. However, to
significantly develop either hypertrophy or maximal strength, specific (and
differing) training programs must be
Training Variables That Affect Size and Max Strength
Several important variables ultimately determine whether a program will
lead to muscle growth or increased strength. Five key variables discussed
here are: 1) intensity, 2) repetitions, 3) rest period, 4) sets and 5)
exercise selection. While these variables are discussed separately, they
are all intricately interwoven.
For hypertrophy to occur, all muscle fibers involved need to be stressed,
damaged and fatigued. Different types of muscle fibers fatigue at different
rates and under different conditions. The intensity must be high enough to
generate stress, but low enough to allow sufficient repetitions for
fatigue. Hedrick (1995) suggested that a moderate intensity (75-85% of
1-repetition maximum) is sufficient.
In order to improve strength, the body must be significantly overloaded.
Recall that strength is a neuromuscular adaptation, so the connection
between the nervous system and the muscular system must speed up.
Neuromuscular changes can happen quickly for the untrained individual, but
gains quickly fade off if the load is not increased. Therefore, for more
than just foundational levels of strength, an individual is encouraged to
work out with intensities of 85-100% of 1-RM (NASM 2018).
The tricky thing about intensity is that it is not generalizable to all
exercises. For example, someone's bench press will be much different on a
flat bench than on an incline. To establish a true estimate of how much an
individual can lift, they must be tested on different exercises.
The acute variables of intensity and reps work closely together. As
intensity goes up, reps must go down.
Hypertrophy, which occurs at a moderate intensity and tempo, should be
performed with a moderate number of reps. Hedrick (1995) and Schoenfeld
(2010) suggest that the repetition range should be 6-12. If an individual
is performing a lift at 85% of 1-RM, he should aspire to complete 6
repetitions. Conversely, performing a lift at 75% of 1-RM warrants about 12
repetitions. (Note: A person beginning hypertrophy training should perform
more reps at a lower intensity, slowly increasing intensity and decreasing
reps over time.) The repetition tempo is 2/0/2, which is 2 seconds eccentric action,
0 seconds isometric hold and 2 seconds concentric contraction (NASM 2018).
Training for maximal strength occurs at higher levels of intensity. Thus,
the repetitions must be drastically lower. Campos et al. (2002) identified
that the neuromuscular changes of strength training occur at 1-5
repetitions. The repetition tempo for maximal strength is as fast as can
safely be controlled, shown as X/X/X (see sidebar).
The moderate repetitions and intensity of hypertrophy training necessitates
a moderate rest period of 60-90 seconds (Hedrick 1995). A longer rest
period may reduce the hypertrophic effect of training; whereas a shorter
recovery may not allow completion of the sets required to induce
Training for maximal strength is much different: When training at
near-maximum intensities, near-maximum recovery is required. Studies
suggest that 3-5 minutes are needed for a muscle group to recover
completely (Willardson & Burkett 2006). If the rest period is too
short, the lifter will not be able to complete multiple sets at the high
intensity, typically resulting in minimal to no increases in strength.
Muscles do not naturally want to grow; they must be forced to grow through
consistent periods of stress. Therefore, higher volumes of training have
been found to yield better results for hypertrophy (Hedrick 1995).
Typically, 3-5 sets are recommended for optimal hypertrophy.
Conversely, the development of strength may occur with a moderate volume.
For this reason, Peterson et al. (2004) suggested that 2-6 sets were ideal
for improving strength, with the NASM guideline being 4-6 sets (2018).
For both strength and hypertrophy, multijoint exercises are highly
recommended. These are foundational movements such as squats, bench
presses, deadlifts, shoulder presses and rows.
Schoenfeld (2010) suggested that multijoint exercises are ideal for
hypertrophy because they promote uniform growth of muscle tissue, which is
essential for maximizing overall muscle girth. It's worth noting that
hypertrophy training also requires variety. Muscles have many different
attachment sites with fibers running in many different directions.
Therefore, performing similar exercises at various angles and in different
positions will enhance the muscle growth effect.
Strength similarly benefits from foundational lifts, which integrate more
muscles (prime mover, stabilizer, synergist, etc.) than single-joint
exercises do. Therefore, multijoint moves lead to more improvements in
strength overall. In a segment produced by T-Nation, notable strength
coaches Bret Contreras, Brad Schoenfeld & Charles Staley add that
specificity matters (to get strong in the squat, you need to squat) and
that secondary lifts can be used to address weak points (Contreras 2013).
Training for Strength and Size Simultaneously?
Many people think (and train) as though hypertrophy and strength occur at
the same time. In fact, many training variables do overlap. For example,
higher-intensity hypertrophy training meets the lower-intensity needs of
strength, which leads to some strength increases. However, it is a very
small window of overlap. To more effectively achieve the two, training
hypertrophy and strength as separate entities will yield the best results.