T.W., et al. 2007. A comparison of periodization models during nine weeks with
equated volume and intensity for strength. Journal of Strength and
Conditioning Research, 21 (4), 1245–50.
Personal trainers and group fitness
instructors are habitually seeking effective and optimal programs to maximize
training adaptations in clients and students. Although muscular-strength
researchers have not determined which type of strength training program is most
advantageous, the present thought is that some form of periodization is central
to the design (Bufford et al. 2007). Periodization refers to
an organized plan of exercise where acute training variables—such as number of
repetitions, number of sets, intensity, recovery between sets, type of exercise
(fixed form and/or freeform), repetition tempo, type of contraction
(concentric, eccentric, isometric) and training frequency—are systematically
The roots of periodization program design date back to the 1950s
and early 1960s, when European sports scientists and coaches were training some
of the best athletes of that period. The human body has a tremendous capacity
for muscular-fitness adaptation, and a primary goal of periodization is to
progressively and systematically overload the body so that it attains its
muscular-fitness potential. While there are many schemes of periodization, the
three very popular models in the present investigation are linear
periodization, daily undulating periodization and weekly undulating
Ten women and 18 men (average age = 22
years), all untrained in resistance exercise, volunteered for this 9-week
study. Subjects completed a 4-week familiarization program (three sessions per
week) to learn proper resistance training technique and execution before being
randomly assigned to one of the three periodization models. Subjects were
required to attend at least 90% of the training sessions in order to remain
qualified as participants.
Subjects were tested at the beginning,
middle and end of the 9-week periodization study. Tests included skinfold body
composition assessment (consisting of triceps, midaxillary, abdominal,
suprailiac, subscapular, thigh and pectoral skinfold sites), chest and thigh
circumference measurements, and one-repetition maximum of the bench press and
leg press. All testing sessions took place at the same time of day and were
conducted by the same researcher.
Periodization Training Models
As noted, the three training models were
linear periodization (five men, four women), daily undulating periodization
(seven men, three women) and weekly undulating periodization (six men, three
women) (see Figures 1, 2 and 3 for the program design of these models). Groups
trained 3 days per week with 48 hours between sessions. All groups performed
the exact same exercises on each day of the week (see Table 1).
All subject training was supervised by the same individuals, and
the subjects self-assessed their training intensity for every exercise set with
a Borg 10-point rating of perceived exertion (RPE) scale (see Table 2).
Subjects were encouraged to achieve an RPE of 8 or 9 on the final repetition of
Table 1. Daily Exercises Performed by Groups
Each group performed exactly the same number of abdominal and
low-back exercises throughout the 9-week study. Groups completed 3 sets each
day, with no additional resistance other than body weight. Repetitions ranged
from 15 to 12 to 10 and varied according to each group’s program design.
Table 2. Borg 10-Point Rating of Perceived Exertion Scale
Although improvements were seen in all
variables, no periodization model was shown to be statistically superior to the
other models. Table 3 summarizes the percent changes observed in this 9-week
The comparison of these three
periodization models distinguishes this study as a particularly novel
investigation. The incorporation of untrained men and women is also entirely
original—and useful for personal trainers who regularly initiate exercise programs
with untrained clients.
In particular, the 32% increase (bench press) and 108% increase
(leg press) in strength for women (with all groups combined) should be
highlighted (see Table 3). Although muscle fiber characteristics (slow twitch
and fast twitch) have been observed to be quite similar in men and women, these
findings are impressive (and without scientific explanation from the authors).
One hypothesis for why periodization training is so effective is that it
provides a systematic and satisfactory overload to specific muscle fiber types
while other muscle fibers are getting needed recovery time. It is quite
interesting to observe that the leg press strength increases for both the men
and women were dramatically greater than the bench press improvements. This
indicates that with untrained men and women, in a 9-week training program,
lower-body adaptations are more prominent.
There was no difference in the RPE ratings of subjects in the
different groups. This suggests that (1) all subjects trained at relatively
similar intensities and (2) no model of periodization training elicited any
overtraining symptoms, such as muscular fatigue, impaired strength performance,
aching joints, pain or decreased efficiency of movement.
Results of this study show very positive and similar improvements
with linear, daily undulating and weekly undulating periodization. The results
suggest that rotating all of these models into a training program may be
advantageous. Since personal trainers and other fitness professionals approach
training sessions and group classes as a lifetime approach to health and
fitness for their clients, this rotating approach is very feasible—and may also
help prevent stagnation and boredom. That said, with regular assessment of
physiological parameters (body composition, muscular strength, muscular
endurance, balance, etc.), a personal trainer may determine that a client
adapts more readily to one of the models, and the trainer might eventually
select that model as a primary tool to use with the client in question.
Table 3. Percent Changes in Physiological Variables Tested
Len Kravitz, PhD, is the program coordinator of exercise
science and a researcher at the University of New Mexico (UNM), where he
recently won the Outstanding Teacher of the Year award. In 2006 he was honored
as the Can-Fit-Pro Specialty Presenter of the Year and as the ACE Fitness
Educator of the Year.
Lawrence Herrera is a third-year university studies student at
UNM. His program has an emphasis in exercise science and nutrition. He is a
certified personal trainer with the National Academy of Sports Medicine.