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Muscular Adaptations in
Drop Set vs. Traditional
Training: A Meta-Analysis
Max Coleman1, Khalil Harrison1, Roberto Arias1, Ericka Johnson1, Jozo Grgic2, John Orazem1 & Brad J.
Schoenfeld1
1Health Sciences Department, CUNY Lehman College, Bronx, NY, USA, 2Institute for Health and Sport, Victoria
University, Melbourne, VIC 8001, Australia.
Coleman, M., Harrison, K., Arias, R., Johnson, E., Grgic, J., Orazem, J., Schoenfeld, B. J. (2022).
Muscular Adaptations in Drop Set vs. Traditional Training: A Meta-Analysis.
International Journal of Strength and Conditioning
https://doi.org/10.47206/ijsc.v2i1.135
ABSTRACT
The purpose of this paper was to systematically
review and meta-analyze the effects of drop set
training (DS) vs. traditional training (TRAD) on
measures of muscle strength and hypertrophy. We
carried out a comprehensive search on PubMed/
MEDLINE, Scopus, Web of Science, and CINAHL
databases for studies that satised the following
criteria: (a) had a randomized experimental design
(either within- or between-group); (b) directly
compared DS versus TRAD; (c) assessed changes
in muscular strength and/or hypertrophy; (d) had a
training protocol that lasted a minimum of 6 weeks,
and; (e) involved apparently healthy participants. We
employed a robust variance meta-analysis model,
with adjustments for small samples. Study quality
was assessed by the Downs and Black checklist.
A total of 5 studies met inclusion criteria. Qualitative
assessment indicated the included studies were of
moderate to good quality. Results for the strength
outcomes indicated a trivial point estimate of the
effect size (ES) with a relatively narrow precision for
the condence interval (CI) estimate (0.07; 95% CI
= -0.14, 0.29). Similarly, results for the hypertrophy
outcomes indicated a trivial point estimate of the ES
with a relatively narrow precision for the CI estimate
(0.08; 95% CI = -0.08, 0.24). In conclusion, DS and
TRAD appear to have similar effects on muscular
strength and hypertrophy. Given that the 95%
CIs were fairly narrow and in the range of trivial to
small effects, it can be concluded that both DS and
TRAD are viable options for promoting muscular
adaptations; DS may provide a more time-efcient
(~30-70% reduction in time compared to TRAD)
alternative for achieving results.
INTRODUCTION
Resistance training (RT) is a well-established
interventional strategy for increasing human
strength and muscle mass (19) (26). Although there
is no universal agreement as to the underlying
mechanisms that govern hypertrophy, some
researchers have hypothesized that mechanical
tension, metabolic stress, and cell swelling may
contribute to the process (26). From an applied
standpoint, it has been speculated that manipulating
RT volume and relative effort (proximity to failure)
may positively impact these mechanisms and thus
augment exercise-induced muscle hypertrophy
(30).
Although the purported hypertrophic mechanisms
can be stimulated through traditional training
methods, various specialized techniques have been
developed to enhance results. Drop sets (DS) are
one of the most popular specialized techniques for
optimizing muscle hypertrophy (29). The method by
which DS are performed is not clearly dened in the
current literature nor is it universally agreed upon
within the lifting community. However, the strategy
is typically performed by taking an exercise to (or
close to) momentary failure followed by immediate
reductions in load (i.e., minimal to no rest between
the drops in weight) and then performing as many
additional repetitions as possible (29). Depending
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International Journal of Strength and Conditioning. 2022
on the protocol, a single, or multiple “drops” (i.e.,
reductions) in the load can be performed either on
some or all sets.
There are both mechanistic and pragmatic reasons
why DS may be superior to traditional training methods
from a hypertrophy standpoint. Mechanistically,
DS may increase time under tension, metabolite
accumulation, and cell swelling (29). Pragmatically,
DS allow for an increase in both volume as well as
a muscle’s exposure to high relative intensities.
Moreover, these effects are achieved via a greater
training density (work per unit of time) compared to
traditional training methods, thereby conceivably
making DS a time-efcient strategy for promoting
muscle development.
Conversely, it is conceivable that DS may be
suboptimal for increasing strength. Both training with
high loads as well as utilizing longer rest periods (>2
minutes) have been proposed as positive drivers
of strength (13) (28). However, DS involves the
use of very short rest periods in combination with
progressively lighter loads. Therefore, DS may not
be as benecial as traditional methods when trying
to optimize strength outcomes.
Despite the popularity of DS training as a muscle-
building strategy, its efcacy has not been well-
established in controlled research. Several studies
have been carried out on the topic, with somewhat
conicting results (9) (24) (32) (8) (2). Thus, there is
a need to synthesize the ndings of the literature to
draw evidence-based conclusions and identify gaps
in the literature for future investigation. The purpose
of this paper was to systematically review and meta-
analyze the effects of DS training vs. traditional
training (TRAD) on measures of muscle strength and
hypertrophy.
METHODS
This systematic review was conducted in accordance
with the guidelines of the “Preferred Reporting
Items for Systematic Reviews and Meta-Analyses”
(PRISMA) (25). The review was preregistered on the
Open Science Framework (https://osf.io/9suwd).
Search strategy
We carried out a comprehensive search on
PubMed/MEDLINE, Scopus, Web of Science, and
CINAHL databases using variations of the following
Boolean search syntax: (“drop set*” OR “drop-
set*” OR “descending set*” OR “breakdown set*”)
AND (hypertrophy OR “muscle mass” OR “cross-
sectional area” OR strength OR torque OR “muscle
thickness” OR “resistance exercise” OR “resistance
training”). We also screened the reference lists of
articles retrieved to discover additional studies that
might meet inclusion criteria (11).
Search/screening was carried out separately by four
researchers (MC, RA, KH and EJ) who read all titles
and abstracts. Initial screening was performed using
Rayyan software (https://www.rayyan.ai/). Full texts
were then perused for studies deemed potentially
relevant based on title and abstract. A nal decision
was then made as to whether a study merited
inclusion based on the stated criteria. Any disputes
on the inclusion of a given study were settled by a
fth researcher (BJS).
Inclusion criteria
We included studies that satised the following
criteria: (a) had a randomized experimental design
(either within- or between-group); (b) directly
compared DS versus TRAD; (c) assessed changes
in muscular strength and/or hypertrophy; (d) had a
training protocol that lasted a minimum of 6 weeks,
and; (e) involved apparently healthy participants. For
muscle strength outcomes, we considered studies
that used either isometric or dynamic tests, or both.
For muscle hypertrophy outcomes, we considered
studies that assessed whole muscle hypertrophy
with a direct, site-specic measurement (ultrasound,
computed tomography [CT], magnetic resonance
imaging [MRI]).
Data extraction
From each included study, two researchers (MC
and KH) independently extracted the following data:
author names, title and year of publication, sample
size, participant characteristics (i.e. sex, height,
weight, training status, age), description of the training
intervention (duration, volume, frequency, modality),
nutrition controlled (yes/no/NA), method for strength
assessment (i.e., one-repetition maximum [1RM],
dynamometry), method for hypertrophy assessment
(i.e. MRI, CT, ultrasound), adherence to the given
training program, mean pre- and post-study
muscle mass value with corresponding standard
deviation. In cases where measures of strength or
hypertrophy were not reported, we either extracted
the data from graphs (if available) via online
software (https://automeris.io/WebPlotDigitizer/) or
requested data from the corresponding authors. Any
Muscular Adaptations in Drop Set vs. Traditional Training: A Meta-
Analysis
2
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open access article distributed under the terms and conditions of the
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International Journal of Strength and Conditioning. 2022
Coleman, M., Harrison, K., Arias, R., Johnson, E., Grgic, J.,
Orazem, J., Schoenfeld, B. J
discrepancies in the extracted data were resolved
through discussion and mutual consensus of the
researchers. If consensus could not be reached, a
third researcher (BJS) resolved the dispute.
Methodological quality
We assessed the methodological quality of included
studies via the Downs and Black assessment tool
(6), which is a 27-item checklist that addresses the
following aspects of a study’s design: reporting
(items 1–10), external validity (items 11–13), internal
validity (items 14–26), and statistical power (item
27). Consistent with previous systematic reviews of
exercise interventions, we modied the checklist by
adding two items relating to participant adherence
(item 28) and training supervision (item 29) (12) (13)
(14). Each item in the checklist is scored with a “1”
if the criterion is satised or with “0” if the criterion is
not satised. Based on the summary scores, studies
were classied as follows: “good quality” (21–29
points); “moderate quality” (11–20 points); or “poor
quality” (less than 11 points) (13) (14). Two reviewers
(RA and EJ) independently rated each study; any
disagreements in study rating were resolved by a
third researcher (BJS).
Statistical analyses
Meta-analysis was performed as previously
described (15) using the Robumeta package within
R version 3.6.1. In brief, the contrast across the
DS versus TRAD groups for each hypertrophy and
strength outcome was calculated as the difference
in effect sizes (ES), where the ES was determined
as the posttest-pretest mean change in each group,
divided by the pooled pretest SD, and multiplied by
an adjustment for small sample bias (22). ESs was
interpreted as: “trivial” (≤0.20); “moderate” (0.21–
0.50); “large” (0.51–0.80); and “very large” (>0.80)
(5). ESs were presented with their respective 95%
condence intervals (CI). The variance of the
difference in ES depends on the within-subject
posttest-pretest correlation, which often is not
available from the published data. We thus estimated
this correlation where applicable (back-solving from
paired t-test p-values or SDs of posttest-pretest
change scores, when presented) and, based on
results, employed a moderately conservative value
to calculate the variance for all studies.
When studies report multiple ESs, one approach
is to use the study average effect size, which may
result in a loss of information (10). Therefore, a robust
variance meta-analysis model, with adjustments for
small samples, was used to account for correlated
ESs within studies (31). This meta-analysis model is
specically designed and used when dealing with
dependent ESs (e.g., muscle hypertrophy assessed
at multiple sites within a single study) (10). First,
an overall meta-analysis was conducted for the
hypertrophy and strength outcomes that included
all available studies. We had intended to carry out
subanalyses to explore the effects of training status
(trained vs. untrained), training volume (volume
equated vs. not equated), and body region (upper
vs. lower region) to determine if these variables
had confounding effects on muscular adaptations.
However, the total number of included studies were
insufcient to carry out these analyses.
Publication bias was checked by examining
funnel plot asymmetry and calculating trim-and-
ll estimates. Heterogeneity was explored using
the I2 statistic, with values of ≤50%, 50–75%, and
>75% indicating low, moderate, and high levels of
heterogeneity, respectively. To assess the potential
undue inuence of any single study, we performed
leave-one-out analysis where each study was
removed one at a time, and we then re-estimated the
intervention effect and its CIs without the removed
study. This was repeated for each study in the
sample.
Traditional null hypothesis signicance testing has
been extensively critiqued (1) (21) and thus was
not employed to determine statistical signicance.
Instead, we considered the implications of all results
compatible with these data, from the lower limit to the
upper limit of the interval estimates, with the greatest
interpretive emphasis placed on the point estimate.
RESULTS
The initial search revealed 116 studies of potential
relevance to this review. After removal of duplicates,
we screened 52 records, of which 10 were considered
for eligibility. After scrutinizing the full texts of these
studies, we determined that 5 met inclusion criteria
for at least one outcome measure (32) (8) (24) (2)
(9). Figure 1 presents the PRISMA ow chart of the
search process.
3
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4
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open access article distributed under the terms and conditions of the
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International Journal of Strength and Conditioning. 2022
Muscular Adaptations in Drop Set vs. Traditional Training: A Meta-
Analysis
Figure 1. PRISMA ow chart of the search process
Study Characteristics
All eligible studies employed young, male partici-
pants (19 to 27 years of age). The number of repe-
titions performed in each set ranged from 3 to 104.
Participants trained in close proximity to muscular
failure across all studies. Three of the 5 studies em-
ployed untrained individuals (24) (32) (9); the other
2 studies employed trained individuals (≥2 years
RT experience) (2) (8). Two studies assessed the
upper body muscles (biceps and triceps) (24) (9)
while 3 studies assessed the lower body (quadri-
ceps) (2) (32) (8). Three studies equated volume
load (2) (9) (8) and 2 studies did not (32) (24). A
complete descriptive analysis of the study charac-
teristics can be found in Table 1.
International Journal of Strength and Conditioning. 2022
5
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open access article distributed under the terms and conditions of the
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Table 1. Study Characteristics
STUDY Subjects Design Duration Strength As-
sessment
Hypertrophy
Assessment
Volume
Equated
ANGLERI
ET AL.
(2017)
32 young,
resistance
trained men
Subjects had their legs randomly assigned to 1 of 3 groups: TRAD
(3-5 sets of 6-12 repetitions at 75% 1RM), crescent pyramid (3-5 sets
of 6-15 repetitions at 65-85% 1RM) or DS (3-5 sets of 50-70% 1RM
to failure). All subjects performed unilateral 45-degree leg press and
unilateral leg extension. Each group rested 2 minutes between sets.
DS group performed up to 2 drop sets (reduction of 20%) after failure
was reached in each set.
12 weeks Unilateral leg
extension &
unilateral leg
press
Ultrasound Yes
ENES ET
AL. (2021)
28 young,
resistance
trained men
Subjects were randomly assigned to 1 of 3 groups: DS (3 sets of 10
reps plus one drop set of 6 reps), rest pause (3 sets of 10 reps plus
6 extra reps after 20 second rest), or TRAD (4 sets of 12 reps). Each
group trained 2 times per week. All groups performed back squat, leg
press, leg curl, leg extension, and stiff legged deadlift. TRAD used
70% 1 RM while DS used 75% 1RM to 55% 1RM. All groups rested
120 seconds between sets.
8 weeks Back squat Ultrasound Yes
FINK ET AL.
(2017)
16 young,
recreation-
ally active
men
Subjects were randomly assigned to either DS or TRAD. DS per-
formed a single set of triceps extensions at 12 RM immediately de-
creasing load by 20% each time failure was reached three times
consecutively. TRAD performed 3 sets of 12 RM with 90 seconds rest
between sets. DS group did not rest between drops.
6 weeks N/A MRI Yes
OZAKI ET
AL. (2017)
9 young,
untrained
men
Subjects had each arm randomly assigned to one of three groups
performing the biceps curl: 3 sets of TRAD with a high load (80%
1RM), 3 sets of TRAD with a low load (30%), or 1 set of DS with a high
load (80% 1RM) with 4 descending sets to 30% 1RM. High load TRAD
rested 3 minutes between sets, low load TRAD rested 90 seconds
between each set, and DS did not rest between each drop set.
8 weeks Dumbbell
curl & peak
isometric
elbow exion
at 60° elbow
exion
MRI No
VAROVIC
ET AL.
(2021)
16 young,
recreation-
ally active
men
Subjects had their legs randomly assigned to DS or TRAD performing
the unilateral leg extension. The DS leg preformed a 5RM to failure,
reduced load by 20% and performed reps to failure, and then again
reduced load by 10-15% and trained to failure again. The TRAD leg
used a 15 RM load to failure. The leg that trained rst was alternated
between each training session. The number of sets progressed grad-
ually for both groups throughout the study starting at 3 and ending
with 15.
8 weeks Leg exten-
sion & peak/
avg. isoki-
netic knee
extension at
60°/s
Ultrasound No
Abbreviations: DS: drop set training; TRAD: traditional training; RM: repetition maximum; MRI: magnetic resonance imaging
Coleman, M., Harrison, K., Arias, R., Johnson, E., Grgic, J.,
Orazem, J., Schoenfeld, B. J
International Journal of Strength and Conditioning. 2022
Muscular Adaptations in Drop Set vs. Traditional Training: A Meta-
Analysis
6
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open access article distributed under the terms and conditions of the
Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).
Methodological Quality
Qualitative assessment of the studies evaluated
using the Downs and Black checklist showed a mean
score of 18.4 (range: 16 to 21 points). Based on our
a priori established categorization criteria, 2 studies
were considered of good quality and 3 studies were
deemed to be moderate quality; no study was rated
as being of poor quality.
Meta-Analytic Results
In regard to strength outcomes, the main model
consisted of 11 comparisons nested within 4 studies.
Results indicated a trivial point estimate of the ES
with a relatively narrow precision for the CI estimate
(0.07; 95% CI = -0.14, 0.29). Figure 2 shows the
forest plot for studies that compared the effects of
DS vs. TRAD on measures of muscle strength.
With respect to hypertrophy outcomes, analysis
consisted of 13 comparisons nested within 5 studies.
Results indicated a trivial point estimate of the ES
with a relatively narrow precision for the CI estimate
(0.08; 95% CI = -0.08, 0.24). We did not detect
appreciable evidence of heterogeneity between
studies for hypertrophic outcomes (I2 = 0%). Figure
3 shows the forest plot for studies that compared the
effects of DS versus TRAD on measures of muscle
hypertrophy.
Figure 2. Forest plot of studies meeting inclusion criteria for strength
7
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International Journal of Strength and Conditioning. 2022
Figure 3. Forest plot of studies meeting inclusion criteria for hypertrophy
The funnel plots for strength were relatively sym-
metrical, indicating a lack of small study bias and
thus potentially publication bias; this conclusion is
supported by the results of Egger’s test (p = 0.74;
Figure 4A). Moreover, we did not detect apprecia-
ble evidence of heterogeneity between studies for
the strength outcomes (I2 = 0%). Analysis of outliers
showed that the dumbbell curl comparison in the
study by Ozaki et al. (24) was potentially inuential;
however, leave-one-out analysis showed its exclu-
sion did not result in an appreciable difference in
results.
The funnel plots for hypertrophy were relatively sym-
metrical, indicating a lack of small study bias and
thus conceivably publication bias; this conclusion is
supported by the results of Egger’s test (p = 0.48;
Figure 4B). Moreover, we did not detect appreciable
evidence of heterogeneity between studies for the
hypertrophy outcomes (I2 = 0%). Analysis of outli-
ers identied the muscle thickness comparison of
the rectus femoris at 30% muscle length in the study
by Varovic et al. (32) as being potentially inuential;
however, leave-one-out analysis showed its exclu-
sion did not result in an appreciable difference in
results.
Coleman, M., Harrison, K., Arias, R., Johnson, E., Grgic, J.,
Orazem, J., Schoenfeld, B. J
International Journal of Strength and Conditioning. 2022
Muscular Adaptations in Drop Set vs. Traditional Training: A Meta-
Analysis
8
Copyright: © 2021 by the authors. Licensee IUSCA, London, UK. This article is an
open access article distributed under the terms and conditions of the
Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).
DISCUSSION
This is the rst meta-analysis to compare the effects
of DS vs. TRAD on muscular adaptations. Overall,
our results suggest that DS are likely to produce sim-
ilar effects on muscular strength and hypertrophy as
TRAD. As discussed in the following sections, the
effect size differences were largely trivial, indicating
minimal differences between conditions.
Strength Results
While a mechanistic rationale can be made for the
use of DS to enhance hypertrophy, the same can-
not be said for increasing muscle strength. While
strength gains conceivably are optimized with the
Figure 4. Funnel plots and trim-and-ll plots for: (A) Strength; (B) Hypertrophy
use of relatively heavy loads and long rest intervals
(28) (13), DS involves a progressive reduction of
loads with minimal rest between drops across a set.
Hence, the strategy would seem to be detrimental
to strength-related adaptations. However, despite
the higher absolute intensities of load employed in
TRAD, our results showed similar changes between
conditions. As with the hypertrophy results, the trivial
point estimate of the ES (0.07) and relatively narrow
precision for the CI estimate (-0.14, 0.29) indicates
that there is likely a lack of difference between DS
and TRAD.
Although on the surface the results would seem to
indicate that DS can serve as a viable alternative to
TRAD for increasing maximal strength, it should be
International Journal of Strength and Conditioning. 2022
noted that the TRAD protocol in all studies meeting
inclusion criteria involved moderate to lower loads
(≤80% 1RM). Research indicates a dose-response
relationship between strength gains and magni-
tude of load, with heavier loads consistently show-
ing greater improvements in dynamic strength (4).
Thus, further research is required to determine how
strength gains may be affected with the use of heavy
loads (≥90% 1RM) in both DS and TRAD.
Hypertrophy
DS are commonly employed to enhance muscle
development via increasing the intensity of effort of
training and extending the time-under-tension of the
set. Conceivably, these factors heighten both me-
chanical tension and metabolic stress, which have
been proposed exercise-induced mechanisms of
hypertrophy (26). Despite this logical rationale, our
ndings demonstrated that similar increases in mus-
cle size can be obtained through TRAD or DS. The
trivial point estimate of the ES (0.08) and relative-
ly narrow precision for the CI estimate (-0.08, 0.24)
suggest that utilizing DS does not produce an addi-
tive stimulus for hypertrophy.
When attempting to reconcile discrepancies be-
tween mechanistic theory and practical ndings,
it should be noted that training to failure does not
appear to be obligatory for optimal muscular gains.
Meta-analytic data show relatively similar hyper-
trophic changes when sets are taken to failure vs.
when stopping one or two repetitions short of fail-
ure (15). This implies that as long as training is
performed with a high intensity of effort, training to
failure might not produce additional increases in
muscle growth. Moreover, evidence indicates that
time-under-tension during a given training session
may be more important to hypertrophy than the
time-under-tension of a given set performed during
the session (27). Taken as a whole, these ndings
lend support to our ndings of similar hypertrophic
effects between DS and TRAD.
Interestingly, Varovic et al. (32) observed greater
muscle thickness increases in the proximal- and
mid-portions of the rectus femoris favoring DS vs
TRAD. This was the only study to investigate hyper-
trophic changes at different sites along the length of
the rectus femoris. A compelling body of research
indicates that muscles can hypertrophy in a non-uni-
form fashion (3) (23) (18) (7) (34). The mechanisms
for such regional hypertrophic adaptations remain
undetermined but may involve selective muscle ac-
tivation during exercise performance (33). A ration-
ale for how this phenomenon may occur in DS is not
readily apparent. Of note, both Varovic et al. (32)
and Enes et al. (8) observed similar regional chang-
es across the length of the vastus lateralis between
conditions. Whether differential ndings may be
explained by differences in structural attachments
between the rectus femoris and vastus lateralis
(biarticular vs monoarticular, respectively) warrants
further investigation.
Limitations
The largest limitation of this meta-analysis is that only
5 studies met inclusion criteria. Moreover, while the
quality of the included studies was generally good,
the individual studies had relatively small sample
sizes. This highlights the relative paucity of research
on DS, and thus underscoring the need for caution
when drawing evidence-based inferences from the
current literature. It is also important to note that all
studies to date were carried out with young, male
participants. Hence, future research should investi-
gate the effects of DS on females and older individu-
als to determine if sex/age inuences results. There
also were insufcient data to subanalyze the effects
of training status and volume load on results; addi-
tional investigation is warranted to develop a better
understanding of how these factors may inuence
DS results. In addition, studies assessed hypertro-
phy in only three muscle groups (biceps, triceps and
quadriceps), and only 2 studies assessed growth at
various sites along the length of the muscle. Thus,
future research should endeavor to evaluate hyper-
trophic changes across a broad range of muscle
groups as well as examine region specic hyper-
trophy to better understand potential differences
between TRAD and DS. Finally and importantly, DS
is a general concept that can be employed in myri-
ad ways. Future research therefore should analyze
if and how different iterations of DS (e.g., multiple
drops per set, drops only on the last set of an exer-
cise, etc.) might alter muscular adaptations.
CONCLUSION
Based on the current data, it seems that DS has a
similar effect on muscular strength and hypertrophy
as TRAD. This would seem to indicate that both DS
and TRAD are viable options for promoting muscu-
lar adaptations. It should be noted, however, that
DS can be structured in a manner that improves the
time-efciency of a workout. Two of the 5 includ-
ed studies showed DS to have signicantly short-
er training durations with either similar or superior
9
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open access article distributed under the terms and conditions of the
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Coleman, M., Harrison, K., Arias, R., Johnson, E., Grgic, J.,
Orazem, J., Schoenfeld, B. J
International Journal of Strength and Conditioning. 2022
hypertrophic results when compared to TRAD (~30-
70% reduction in time compared to TRAD) (24) (9).
This has important practical implications given that
a lack of time is a known barrier to participation in
structured exercise programs (17) (16). In addition,
advanced training methods such as DS may help to
overcome plateaus and to prevent training monot-
ony (20), which in turn may further help to improve
exercise motivation and adherence. Given that all
included studies involved young males as study
participants, future research is needed to determine
the effect of DS on muscular adaptations across dif-
ferent populations.
DISCLOSURES
BJS serves on the scientic advisory board for
Tonal Corporation, a manufacturer of tness
equipment. The other authors report no conicts
of interest.
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