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250
Journal of Strength and Conditioning Research, 2002, 16(2), 250–255
q2002 National Strength & Conditioning Association
A Comparison of Linear and Daily Undulating
Periodized Programs with Equated Volume and
Intensity for Strength
MATTHEW R. RHEA, STEPHEN D. BALL, WAYNE T. PHILLIPS,
AND
LEE N. BURKETT
Exercise and Wellness Research Laboratory, Department of Exercise Science and Physical Education, Arizona
State University, Tempe, Arizona 85287.
ABSTRACT
The purpose of this study was to compare linear periodization
(LP) and daily undulating periodization (DUP) for strength
gains. Twenty men (age 521 62.3 years) were randomly
assigned to LP (n510) or DUP (n510) groups. One repe-
tition maximum (1RM) was recorded for bench press and leg
press as a pre-, mid-, and posttest. Training involved 3 sets
(bench press and leg press), 3 days per week. The LP group
performed sets of 8 RM during weeks 1–4, 6 RM during
weeks 4–8, and 4 RM during weeks 9–12. The DUP group
altered training on a daily basis (Monday, 8 RM; Wednesday,
6 RM; Friday, 4 RM). Analysis of variance with repeated mea-
sures revealed statistically significant differences favoring the
DUP group between T1 to T2 and T1 to T3. Making program
alterations on a daily basis was more effective in eliciting
strength gains than doing so every 4 weeks.
Key Words: weight training, variation, plateau, resis-
tance training, periodization
Reference Data: Rhea, M.R., S.D. Ball, W.T. Phillips,
and L.N. Burkett. A comparison of linear and daily
undulating periodized programs with equated volume
and intensity for strength. J. Strength Cond. Res. 16(2):
250–255. 2002.
Introduction
D
etermining the most effective and efficient meth-
od of strength development has been a primary
focus of strength coaches and strength researchers for
decades. Whether it is an elite athlete looking for an
edge on the playing field, a police officer preparing for
possible confrontations, or an elderly individual hop-
ing to maintain an independent lifestyle, increasing
strength can be an important goal. It is vital that pro-
fessionals be able to prescribe the most appropriate
and effective program for these individuals, ideally a
program that has been tested in an objective research
setting and has demonstrated its effectiveness.
Although the strength training community has yet
to agree on the optimal program design for strength
development, one concept that strength-training ex-
perts generally agree upon is that some form of peri-
odization must be a major part of any program to op-
timize strength gains. Periodization is a planned var-
iation of acute program variables that has been shown
to be more effective in eliciting strength and body
mass improvements than nonperiodized programs (2,
7, 10, 13–15, 17). The concept of periodization can be
traced to Selye’s general adaptation syndrome (12),
which theorizes that systems will adapt to any chang-
es they might experiences in an attempt to meet the
demands of stressors. The goal of a periodized pro-
gram is to optimize the principle of ‘‘overload’’, the
process by which the neuromuscular system adapts to
unaccustomed loads or stressors. For the neuromus-
cular system to adapt maximally to the training load
or stress, it is important to alter training volume and
intensity as demonstrated by the body of research
comparing periodized programs to nonperiodized
programs (cited previously). Faced with increased de-
mands, the neuromuscular system adapts with in-
creases in muscular strength. Once the system has
adapted to that demand or load, strength increases are
no longer needed and increases will eventually stop.
Periodization is designed to avoid this problem by con-
tinually changing the load placed on the neuromus-
cular system. In addition to increasing overload, pe-
riodization may be beneficial by adding variation to
workouts, thus avoiding staleness and plateaus in
strength gains.
Periodization can be accomplished by manipulat-
ing the number of sets, repetitions, or exercises per-
formed, the amount or type of resistance used, the
amount of rest between sets or exercises, the type of
contractions performed, or the training frequency. The
classic form of linear periodization (LP) divides a typ-
Linear vs. Daily Undulating Periodization for Strength
251
Table 1. Subject descriptives.*
Group† Age (y) Height (cm) Weight (kg) % Body fat
Training
experience (y)
LP (n510)
DUP (n510)
21.2 (3.1)
20.2 (2.4)
178.2 (6.8)
181.8 (8.4)
90.4 (16.5)
86.3 (21.4)
16.3 (4.2)
17.6 (8.7)
5.4 (2.1)
5.0 (2.6)
* Values expressed represent group means (standard deviation).
†LP5linear periodization; DUP 5daily undulating periodization.
ical strength-training program into different periods
or cycles: macrocycles (9–12 months), mesocycles (3–4
months), and microcycles (1–4 weeks), gradually in-
creasing the training intensity while decreasing the
training volume within and between cycles. A less-
used form of periodization called undulating periodi-
zation, first advocated by Poliquin (11), is character-
ized by more frequent alterations in the intensity and
volume. Rather than making changes over a period of
months, the undulating model makes these same
changes on a weekly or even daily basis. For example,
a subject may progress from high volume–low inten-
sity to low volume–high intensity within the same
week by performing sets of 12–15 repetition maxima
(RM) on Monday, sets of 8–10 RM on Wednesday, and
sets of 3–5 RM on Friday. The phases are much shorter
in undulating periodization, providing more frequent
changes in stimuli, which are speculated to be highly
conducive to strength gains (11). The above program
may place considerable stress on the neuromuscular
system because of the rapid and continuous change in
program variables. It is this stress that theoretically
makes the program effective in eliciting increased
amounts of strength gain or in aiding athletes to over-
come staleness (a plateau) in their training.
Most previous research has only focused on dif-
ferences between periodized and nonperiodized
programs. Few studies have investigated undulating
periodization, and only one study (2) has ever at-
tempted to compare linear periodization with un-
dulating periodization. Baker et al. (2) reported no
significant difference in strength gains when alter-
ing the volume and intensity every 2 weeks in an
undulating group and every 3–4 weeks in a linear
group. No significant differences in strength gains
were found between groups. It is likely that the dif-
ferences between the linear and undulating training
programs were not severe enough to elicit statisti-
cally significant differences.
Ivonov et al. (6) compared undulating periodiza-
tion with a nonperiodized program in track athletes
competing in throwing events. Undulating periodiza-
tion was found to be superior in eliciting strength
gains as compared with the nonperiodized program
in both bench press and squat exercises.
Kraemer et al. (8) compared a multiset version of
daily undulating periodization (DUP) to a nonperiod-
ized, single-set program in female collegiate tennis
players. This study, which spanned 9 months, dem-
onstrated superiority of the DUP program in eliciting
strength increases.
Researchers have recently declared the need for
further research regarding the effectiveness of the un-
dulating model as compared with the linear model (3,
4, 16). Fleck and Kraemer also suggest investigating
the specific combination of variables that will elicit
maximum gains in strength (4).
Methods
Research Approach
The purpose of this study was to examine a more in-
tensive approach to undulating periodization than that
used by Baker et al. (2) by altering volume and inten-
sity on a daily basis. To our knowledge, this study is
the first to compare LP and DUP. It is also important
to note that many previous periodization studies have
failed to equate training volume and training intensity
between groups. Failure to do so makes it impossible
for researchers to attribute differences in strength
gains to the program design or to differences in vol-
ume or intensity between groups. In the present study,
volume and intensity were equated for both groups
throughout the training program to attribute any out-
comes to the differences in periodization. Maximal
strength in the bench press and the leg press was des-
ignated as the dependent variable and method of pe-
riodization (LP and DUP) was set as the independent
variable.
Subjects
Twenty men (age 21 62.3 years) were recruited from
college weight-training classes. Subjects gave their in-
formed consent to participate in the study, which was
approved by an Institutional Review Board before be-
ginning the research. Subjects filled out questionnaires
evaluating their prior strength-training experience. All
subjects reported participating in a strength-training
program (at least 2 days per week) for a minimum of
2 years before beginning the study. Each subject re-
ported that he had been following a program equiva-
lent to LP during the previous 2 years. Subject char-
acteristics are listed in Table 1.
252 Rhea, Ball, Phillips, and Burkett
Table 2. Training program (3 workouts·week
21
).*
LP group†
Weeks 1–4
3 sets 8RM
Weeks 5–8
3 sets 6RM
Weeks 9–12
3 sets 4RM
DUP group
Day 1
3 sets 8RM
Day 2
3 sets 6RM
Day 3
3 sets 4RM
* Training volume and intensity throughout the training
program identical for each group.
†LP5linear periodization; DUP 5daily undulating pe-
riodization; RM 5repetition maxima.
Testing
Subjects participated in 6 instruction/training ses-
sions before the pretest to ensure proper technique
and comprehension of the testing process. The 1RM
was used as a measure of pretraining strength of the
upper and lower body using the bench press and leg
press. Bench press testing and training were per-
formed on a standard free-weight bench press station.
The Cybex incline leg press machine was used for
lower body testing and training. To obtain reliable
baseline strength values, the pretraining 1RM values
were performed on 3 separate occasions separated by
several days. A high interclass correlation was found
between the second and third 1RM trials (R50.99).
The greatest 1RM from the last 2 trials was used in
the statistical analysis as the baseline measure. All
1RM testing was conducted on the same equipment
with identical subject–equipment positioning over-
seen by the same trained investigator according to
guidelines set forth by the American College of
Sports Medicine (1). Subjects were required to warm
up and perform light stretching before performing
approximately 10 repetitions with a relatively light
resistance for each exercise. The resistance was then
increased to an amount estimated to be less than the
subject’s 1RM. The resistance was progressively in-
creased in incremental loads after each successful at-
tempt until failure. All 1RM values were determined
in 3 to 5 attempts. Strength testing was repeated after
weeks 6 and 12 of resistance training.
Statistical analysis of both bench press and leg
press baseline data demonstrated that no significant
differences between groups (p.0.05) existed in
strength at baseline. This ensured that both groups be-
gan the study at comparable levels.
Training Protocol
After testing, subjects were randomly divided into 2
groups (LP or DUP) and began a 12-week training
program on the leg press and bench press. Subjects
trained 3 days per week, with each session lasting ap-
proximately 40 minutes. Each subject performed a 10-
minute aerobic warm-up and stretching exercises be-
fore beginning each workout. A warm-up set was also
performed on each lift with light resistance and in-
volved approximately 10 repetitions. Both leg press
and bench press lifts were performed during the same
training session with random assignment of order for
each session. Subjects also performed abdominal
crunches (3–4 sets of 15–25 repetitions), biceps curls (3
38–12 RM), and lat pull-downs (3 38–12 RM). Sub-
jects were prohibited from performing any other
strength-building exercises during the 12-week pro-
gram.
The training volume and intensity were altered dif-
ferently for each group (see Table 2). However, both
volume (total reps performed) and intensity (RM)
were equated among the groups. This was done to
control for differences in training volume or intensity.
Therefore, the only difference between the training
programs was the order in which subjects performed
the workouts.
The LP group performed 3 sets of 4–8 RM (8 RM
each session for the first 4 weeks, 6 RM for weeks 5–
8, and 4 RM during weeks 9–12) as suggested by Stone
(13). The DUP group also performed 3 sets of 4–8 RM
each session. The first session of each week consisted
of 8 RM sets, the second session consisted of 6 RM
sets, and the third session consisted of 4 RM sets. Each
session was separated by a minimum of 48 hours. This
cycle was repeated for 12 weeks with 1 week of active
rest (participation in physical activity with the excep-
tion of weight training) between weeks 5 and 6.
Body Composition
Body volume was determined by whole-body plethys-
mography (Bod Pod, Life-Measurement Instruments,
Concord, CA) and converted into percent fat values
using the Siri equation (5). The initial measured tho-
racic gas volume was entered for the posttest to ensure
reliability. Subjects were required to wear a Lycra
swim cap and tight fitting Lycra-Spandex bike shorts,
or swimming briefs, for each trial. Bod Pod testing was
performed by the same trained technician for all sub-
jects.
Repeated circumference measures were taken us-
ing a Gulick tape measure. Circumference measures
were taken at the chest and at mid-thigh (9).
Statistical Analyses
These data were analyzed using an analysis of vari-
ance with repeated measures and, where appropriate,
Tukey’s post hoc tests were used to determine differ-
ences among groups and across time. The level of sig-
nificance in this study was set at p#0.05.
Results
Absolute and percentage strength increases were
compared between groups. Both LP and DUP groups
increased strength significantly (p,0.05) in both leg
and bench presses over the course of the training pro-
gram (T1 to T3). Mean percent increases in strength
Linear vs. Daily Undulating Periodization for Strength
253
Table 3. Strength measures across time and absolute
strength increases across time.†
Group
Bench press [kg (SD)]
T1 T2 T3
LP
DUP
83.41 (12.86)
66.59 (19.23)
88.41 (11.75)
73.41 (21.1)
94.55 (10.72)
83.41 (20.27)
Leg press [kg (SD)]
T1 T2 T3
LP
DUP
266.82 (55.38)*
230.23 (65.05)*
296.36 (55.13)*
298.18 (73.77)*
331.36 (68.18)*
350.23 (80.82)*
% Strength increases across time
T1 2T2 T2 2T3 T1 2T3
Bench press (% change† [SD])
LP
DUP
5.9 (4.9)*
10.7 (7.9)*
7.3 (5.4)
16.2 (14.9)
14.4 (10.4)*
28.8 (19.9)*
Leg press (% change† [SD])
LP
DUP
12.0 (9.9)*
31.0 (13.5)*
11.7 (9.2)
18.0 (9.1)
25.7 (19.0)*
55.8 (22.8)*
† % Change 5T2 2T1/T1; T3 2T2/T2; T3 2T1/T1.
Values expressed represent group means (standard devia-
tion). LP 5linear periodization; DUP 5daily undulating
periodization.
* Significant differences between groups (p,0.05).
for LP group were 14.37% and 25.61% for bench press
and leg press respectively, compared with 28.78%
and 55.78% for the DUP group. The DUP group ex-
perienced significantly greater percent gains in
strength from T1 to T2 and from T1 to T3 (p,0.05)
compared with the LP group. Analysis of absolute
strength increases demonstrated significant differenc-
es (p,0.05) for leg press between T1 and T2 and T1
and T3. However, absolute increases for bench press
did not reach statistical significance at any time (p5
0.08) (Table 3).
No significant differences were found for body
composition or circumference measures.
Discussion
This study is the first study to investigate differences
in strength gains between DUP and LP programs. The
data from our study suggest that a daily form of un-
dulating periodization elicits greater percentage
strength gains than a linear periodized program. In
terms of absolute gains, this difference only occurred
in the leg press. One previous study (8) has examined
DUP training; however, subjects in that study were un-
trained (with regard to weight training) women, and
thus, may be incomparable with the current study,
which used recreationally trained men. To date, there
are no comparable studies for the strength increases
observed in our DUP group. Future research should
be done to compare the increases in strength mea-
sured in the DUP group of current study (33% and
56% in the bench press and leg press, respectively).
The degree of improvement for the LP group is similar
to results of other studies using similar subjects and
training (2, 17).
In 1988, Poliquin (11) theorized that more frequent
changes in stimulus would enhance strength gains. In
his original undulated program, alterations were to be
made every 2 weeks. Such a program was found to
elicit similar strength gains as a LP program. The pre-
sent study altered training variables on a daily basis
and, as hypothesized, the DUP group demonstrated
significantly more strength gains than LP.
The neuromuscular system may become accus-
tomed to a periodized program when followed for an
extended length of time, even though periodized pro-
grams are designed to avoid this plateau effect. In our
study all subjects reported following a program equiv-
alent to LP for 2 years before recruitment. Those who
continued with a similar program (LP group) contin-
ued making improvements but not to the same degree
as those in the DUP group. By making alterations to
the periodization concept, it appears that the neuro-
muscular system will further adapt, eliciting even
greater strength gains. It is possible that the greater
strength gains demonstrated by the DUP group was a
result of changing the type of periodized program
rather than the greater effectiveness of DUP training
itself. Further research is needed to make a determi-
nation in this regard (i.e., recruiting subjects who had
been following a DUP program and then assigning 1
group to follow an LP program).
The driving mechanisms behind the increased ef-
fectiveness of DUP are not completely understood. Re-
sistance training has been shown to result in adapta-
tions such as muscle fiber hypertrophy-hyperplasia,
muscle fiber transformation, nervous system adapta-
tions, body compositional changes, bioenergetic ad-
aptations, and endocrine system adaptations (3). Mea-
suring and monitoring all such mechanisms was be-
yond the scope of our study. However, the body com-
position and circumference measures in our study
found no significant changes from baseline to post-
training. Therefore, the greater strength increases ob-
served in the DUP group were not due to body com-
position or hypertrophic changes. Because DUP makes
more frequent changes in training stimuli, it could be
speculated that this type of program places greater
stress on the neurological components of the neuro-
muscular system. This increased stress would presum-
ably require further adaptations from this system. It is
possible that this added stress elicits greater adapta-
tions of the neuromuscular system and therefore great-
er gains in strength as compared with LP. Further re-
search including measures of nerve activity and mus-
254 Rhea, Ball, Phillips, and Burkett
cle samples must be conducted to investigate such
speculation.
Although the current subjects were experienced
strength trainers, making the results applicable to
others experienced in weight training, additional re-
search is needed to observe the effects of such a pro-
gram on other populations such as inexperienced
strength trainers, elite athletes, elderly populations,
and women. Also, this study was relatively short in
duration (12 weeks) and with relatively few subjects.
Long-term studies with larger sample sizes would be
valuable in examining the differences in methods of
periodization.
Another possible limitation of this study involves
the issue of overtraining. In weeks 10–12, subjects in
the DUP began to report extended muscle soreness
and fatigue, whereas the LP group did not. Although
these were anecdotal reports, it may be noteworthy.
Interestingly, the strength gains in the second half
of the program were not significantly different be-
tween groups. It is apparent that the undulating
concept was successful in eliciting greater gains in
the first 6 weeks of training, but no statistical dif-
ference (p.0.05) was measured in weeks 6–12 (Ta-
ble 3). Without more frequent 1RM measures, it is
unclear exactly when strength gains in both groups
began to become more similar. Further research is
needed to identify the optimal duration of a daily
undulating program.
The results from this study support the use of
DUP for maximizing strength compared with the tra-
ditional LP. Because of the multitude of differing
combinations between program variables, there are
innumerable periodized programs. More research
needs to be done to determine what specific combi-
nation of variables will elicit maximum gains in
strength. Future comparisons of different types of UP,
especially DUP, should be conducted to attempt to
identify the optimal combinations and alterations of
training variables.
Practical Applications
The data from this current study suggest that DUP
provides the added stress and variation necessary to
elicit maximal strength gains by altering the volume
and intensity of training on a daily rather than
monthly basis. Anyone interested in making strength
gains might benefit from this type of training, espe-
cially those that have been training regularly for an
extended period of time. The DUP form of periodi-
zation may prove particularly beneficial for elite ath-
letes by helping them avoid the plateau effect in
strength gains that is often experienced by long-term
weight lifters; however, further research using elite
athletes would be required to determine such a ben-
efit. Large increases in strength without large gains
in muscle mass, as experienced by the DUP group,
may also benefit athletes in sports such as wrestling,
competitive weight lifting, and boxing who attempt
to curtail weight gain to participate in specific weight
classes.
Program directors, coaches, trainers, athletes, and
anyone participating in DUP training should be aware
of and attempt to avoid overtraining, which may ac-
company such a program. The optimal duration one
should participate in a DUP program is not presently
known, nor the optimal combination of variables that
will maximize strength. However, the present study
did demonstrate that over a 12-week period a DUP
program elicits greater percentage strength gains than
the more conventional LP program.
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Address correspondence to Matthew Rhea, Depart-
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