Evidence for an Upper Threshold for Resistance Training Volume in Trained Women

Abstract

Introduction: The purpose of the present study was to compare the effects of different volumes of resistance training (RT) on muscle performance and hypertrophy in trained women. Methods: The study included 40 volunteers that performed RT for 24 weeks divided in to groups that performed five (G5), 10 (G10), 15 (G15) and 20 (G20) sets per muscle group per session. Ten repetition maximum (10RM) tests were performed for the bench press, lat pull down, 45º leg press, and stiff legged deadlift. Muscle thickness (MT) was measured using ultrasound at biceps brachii, triceps brachii, pectoralis major, quadriceps femoris, and gluteus maximus. Results: All groups significantly increased all MT measures and 10RM tests after 24 weeks of RT (p<0.05). Between group comparisons revealed no differences in any 10RM test between G5 and G10 (p>0.05). G5 and G10 showed significantly greater 10RM increases than G15 for lat pulldown, leg press and stiff legged deadlift. 10RM changes for G20 were lower than all other groups for all exercises (p<0.05). G5 and G10 showed significantly greater MT increases than G15 and G20 in all sites (p<0.05). MT increased more in G15 than G20 in all sites (p<0.05). G5 increases were
higher than G10 for pectoralis major MT, while G10 showed higher increases in quadriceps MT
than G5 (p<0.05). Conclusions: Five to 10 sets per week might be sufficient for attaining gains
in muscle size and strength in trained women during a 24-week RT program. There appears no
further benefit by performing higher exercise volumes. Since lack of time is a commonly cited
barrier to exercise adoption, our data supports RT programs that are less time consuming, which
might increase participation and adherence.

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Copyright © 2018 American College of Sports Medicine
Evidence for an Upper Threshold for Resistance Training Volume
in Trained Women
Matheus Barbalho1,2, Victor Silveira Coswig3 , James Steele4,5, James P. Fisher4,
Antonio Paoli6, and Paulo Gentil2
1Department of Biological Science and Health, University of Amazonia, Belém, Pará, Brazil;
2College of Physical Education and Dance, Federal University of Goiás, Goiânia, Goiás, Brazil;
3College of Physical Education, Federal University of Pará, Castanhal, Pará, Brazil; 4School of
Sport, Health and Social Sciences, Southampton Solent University, Southampton, United
Kingdom; 5ukactive Research Institute, London, United Kingdom; 6Department of Biomedical
Sciences, Physiological Laboratory, University of Padova, Padova, Italy
Accepted for Publication: 16 October 2018
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Evidence for an Upper Threshold for Resistance Training Volume
in Trained Women
Matheus Barbalho1,2, Victor Silveira Coswig3 , James Steele4,5, James P. Fisher4,
Antonio Paoli6, and Paulo Gentil2
1Department of Biological Science and Health, University of Amazonia, Belém, Pará, Brazil;
2College of Physical Education and Dance, Federal University of Goiás, Goiânia, Goiás, Brazil;
3College of Physical Education, Federal University of Pará, Castanhal, Pará, Brazil; 4School of
Sport, Health and Social Sciences, Southampton Solent University, Southampton, United
Kingdom; 5ukactive Research Institute, London, United Kingdom; 6Department of Biomedical
Sciences, Physiological Laboratory, University of Padova, Padova, Italy
Corresponding author:
Paulo Gentil
FEFD - Faculdade de Educação Física e Dança
Universidade Federal de Goiás - UFG
Campus Samambaia
Avenida Esperança s/n, Campus Samambaia- CEP: 74.690-900
Goiânia - Goiás - Brasil
Phone/Fax: +55 062 3521-1105
Email: paulogentil@gmail.com
Conflict of Interest. None to declare. This study was not funded. The results of the study are
presented clearly, honestly, and without fabrication, falsification, or inappropriate data
manipulation, and statement that results of the present study do not constitute endorsement by
ACSM.
Medicine & Science in Sports & Exercise, Publish Ahead of Print
DOI: 10.1249/MSS.0000000000001818
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Abstract
Introduction: The purpose of the present study was to compare the effects of different volumes
of resistance training (RT) on muscle performance and hypertrophy in trained women. Methods:
The study included 40 volunteers that performed RT for 24 weeks divided in to groups that
performed five (G5), 10 (G10), 15 (G15) and 20 (G20) sets per muscle group per session. Ten
repetition maximum (10RM) tests were performed for the bench press, lat pull down, 45º leg
press, and stiff legged deadlift. Muscle thickness (MT) was measured using ultrasound at biceps
brachii, triceps brachii, pectoralis major, quadriceps femoris, and gluteus maximus. Results: All
groups significantly increased all MT measures and 10RM tests after 24 weeks of RT (p<0.05).
Between group comparisons revealed no differences in any 10RM test between G5 and G10
(p>0.05). G5 and G10 showed significantly greater 10RM increases than G15 for lat pulldown,
leg press and stiff legged deadlift. 10RM changes for G20 were lower than all other groups for
all exercises (p<0.05). G5 and G10 showed significantly greater MT increases than G15 and G20
in all sites (p<0.05). MT increased more in G15 than G20 in all sites (p<0.05). G5 increases were
higher than G10 for pectoralis major MT, while G10 showed higher increases in quadriceps MT
than G5 (p<0.05). Conclusions: Five to 10 sets per week might be sufficient for attaining gains
in muscle size and strength in trained women during a 24-week RT program. There appears no
further benefit by performing higher exercise volumes. Since lack of time is a commonly cited
barrier to exercise adoption, our data supports RT programs that are less time consuming, which
might increase participation and adherence.
Key words: muscle hypertrophy, muscle strength, bodybuilding, overtraining, dose-response.
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Introduction
Resistance training (RT) has become one of the most popular methods of exercise for
improving physical fitness (1). For women, RT has been shown to bring many benefits, such as
increased muscle strength (2) and bone mineral density (3), improvements in maternal health and
perinatal outcomes during pregnancy (4), changes in body composition (5), and improvements in
health-related outcomes in old age (6) and in breast cancer survivors (7). It is argued that the
optimization of the results produced from a RT program depends on the manipulation of a
number of variables, including: order of exercise, rest interval, number of exercises performed,
exercise selection, and training volume (8, 9). Training volume has been the focus of several
studies and discussions that aim to stablish an optimal dose between the amount of training
performed and the results obtained by a RT intervention (10–13).
Several studies have evaluated the use of lower- compared to higher- training volumes,
supporting the efficacy of lower training volume in body composition, muscle thickness, and
strength (6, 14–16), while some studies show a superiority for higher volumes of training (17–
20). Meta-analyses by Schoenfeld et al. (10) and Ralston et al. (21) noted a linear dose-response
relationship suggesting the superiority of higher volume training and recommended that, for
maximizing muscle hypertrophy and strength respectively, one should perform at least 10 sets
per week for each muscle group. However, the use of meta-analyses within RT has been
questioned recently due to the considerable heterogeneity of experimental designs in studies
within the field (8, 11). More recently, a review by Teixeira et al. (12) concluded that it is not
possible at present to suggest that high volume of sets offers better results than low volume of
sets for upper body muscle hypertrophy.
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The extent to which volume should be increased, has been questioned by some evidence
that suggested a plateau in anabolic response after a given volume is reached or even the
existence of an inverted “U” shaped curve in the dose-response relationship between training
volume and hypertrophy. A recent study by Ogaswara et al. (22) reported that muscle protein
synthesis reached a plateau after three or five sets of resistance exercise, and no further increase
was observed when going up to 20 sets, suggesting a threshold effect for exercise volume within
a session. Previously, Wernbom et al. (13) suggested the occurrence of a plateau in muscle
hypertrophy after a threshold volume is reached and, according to the authors, there might be a
decline in training response when the volume is extended beyond the point of the plateau.
It is important to note that the majority of previous studies have been carried out in males,
with the few conducted with females using elderly women and or/untrained participants. The few
studies performed with young trained participants involved men (23–26) or a mixed sample of
men and women (27). Whilst many studies reported that men and women show similar results
after an RT program (2), their acute responses have been shown to differ, especially regarding
fatigability (28, 29) and muscle recovery (30), which might suggest that manipulating training
volume might have a different impact on women when compared to men. Therefore, it is
important to consider sex differences in response to different manipulations of training variables.
No prior studies have considered trained women, and many have not considered set
volumes much higher than 10 per muscle group per week. Considering the controversy around
the topic and the importance of defining an adequate dose-response for muscle hypertrophy and
performance in women, the aim of the present study was to compare the effects of different
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volumes of RT in these outcomes in trained women. Our hypothesis was that different training
volumes will result in similar increases in muscle size and strength.
Materials and methods
Study overview
In order to examine the effects of performing different weekly RT volumes on muscle
performance and upper and lower body muscle thickness (MT), 40 young women with at least 3
years of previous RT experience were randomly divided into four groups of 10 participants. Each
performed a RT program consisting of weekly volumes of 5 sets per muscle group (G5), 10 sets
per muscle group (G10), 15 sets per muscle group (G15), or 20 sets per muscle group (G20). The
training program followed a non-linear periodization model for 24 weeks. Before and after the
training period, participants were tested for 10 repetition maximum (10RM) for the bench press,
lat pull down, 45º leg press, and stiff legged deadlift. MT was measured using ultrasound at
biceps brachii, triceps brachii, pectoralis major, quadriceps femoris, and gluteus maximus before
and after evaluation.
Participants
A priori sample analysis revealed that to achieve a 0.6 effect size (ES) with a power of
0.8, a total of 35 participants would be necessary. Recruitment was performed from January
through to June 2017, until achieving 40 participants. To participate in the study, the volunteers
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had to be at least 18 years old and have no clinical conditions that limited their participation or
that could be aggravated by the study protocol, as attested by a physician. Participants also had to
have been performing RT uninterruptedly for the previous 3 years with a frequency of at least 3
sessions per week. All participants were habituated to training each muscle group once or twice
per week with the performance of 18 sets for upper body and 24 sets for the lower body. The
minimum attendance for the training intervention was established as 80% (31). Although there
was no control over participants' diets, they were instructed to maintain their usual diets and
were regularly questioned to see if any notable changes had occurred (e.g. the use of ergogenic
aids, significant changes to protein or carbohydrate intake, becoming vegetarian, etc.). There
were no dropouts or exclusions in the study and mean attendance was 93%, with no difference
between groups. After being informed about the experimental procedures and the risks and
benefits, the participants signed an informed consent form. The study was approved by the
CESUPA Ethics Committee under the number CAAE 69724617.7\.0000.5169.
Ten repetitions maximum (10RM) test
Before and after 24 weeks of the intervention, participants performed 10RM tests on the
bench press, lat pull down, 45º leg press and stiff-legged deadlift (Life Fitness, Hammer
Strength, São Paulo, Brazil). The tests were divided into 3 consecutive days. On the first day,
participants were tested in the bench press; the second involved the lat pull down; and the third,
the leg press and stiff-legged deadlift. The 10RM was chosen over the 1RM because when
participants are training at high repetition ranges, it seems more appropriate to evaluate
performance through multiple repetition tests (33).
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Before the tests, the participants warmed up with 10 reps at a comfortable self-selected
load and then rested for 5 minutes. Then, the initial load was defined based on the participants'
training history. If the volunteer could not perform 10 repetitions or performed more than 10
repetitions, the load was adjusted by 1-10kg and another attempt was performed after 5 minutes
of rest. No more than three attempts were necessary in any occasion. The ICC of this procedure
was determined in our laboratory prior to the study by performing two identical test sessions
separated in one week, values ranged from 0.93 to 0.99. In this analysis, the standard error of
measurement (SEM) was generally less than 3%.
Muscle Thickness
Participants were tested before and 24 weeks training period for MT of the biceps brachii,
triceps brachii, pectoralis major, quadriceps femoris and gluteus maximus muscles in the right
side of the body. For the biceps and triceps brachii, measurements were taken 60% distal
between the lateral epicondyle of the humerus and the acromion process of the scapula.
Pectoralis major MT was measured four centimeters below the coracoid process at 60% of the
distance between the acromion process of the scapula and the middle of the sternum (50% of the
distance between the xyphoid process and the jugular notch). Quadriceps femoris MT was
measured at 50% between the lateral condyle of the femur and greater trochanter. Gluteus
maximums measurement was performed at 50% of the distance between the sacral vertebra and
the greater trochanter.
All tests were performed between 7 and 8AM. The participants were instructed to have a
normal breakfast at least 1 hour prior to the exam and to hydrate normally 24h before the test.
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Measurements were performed 3-5 days after the last training session, in order to avoid the
influence of swelling. During this period, participants were instructed not to participate in any
exercise or intense activity. MT was measured using B mode ultrasound (Toshiba Tossbe model,
7.5 MHz linear transduction). A water-soluble transmission gel was applied to the measurement
site and a 7.5 MHz ultrasound probe was placed perpendicular to the tissue interface but care
was taken not to compress to the skin. Once the technician was satisfied with the quality of the
image produced, the image was frozen. A cursor was then used to measure MT, which was taken
as the distance from the subcutaneous interface of adipose muscle tissue to a muscle-bone
interface. All MT measures were performed in a specialized clinical center by the same
experienced technician, that was not involved in the study and who was blind to group
allocation. The ICC was 0.93-0.98 and the SEM was 3-5%.
Training
Training was performed 3 times a week, divided into 3 different programs, as shown in
table 1. Each muscle group was trained once a week and all sessions were supervised with a ratio
of at least one supervisor to five trainees (34), by exercise specialists that were not involved in
the study design. All groups performed the same exercises in the same order, these exercises and
number of sets per exercise are presented in Table 1. Whilst we recognize that there are many
forms of manipulating volume, including changing movement velocity, number of repetitions,
load, training frequency, etc. we decided to manipulate sets to follow previous studies (10, 12)
and also because this is a common strategy in real world settings. Repetition intervals and rest
intervals were also the same and all groups trained to momentary failure as previously defined
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(35). Therefore, the groups differed only in the number of sets performed. The protocol followed
a model of non-linear periodization, as shown in Table 2. The volunteers were instructed to
perform the concentric and eccentric phases in two seconds each, without pausing between
muscle actions.
Statistical Analysis
Between group effects were examined using ANCOVA, comparing the delta change
(post- minus pre-intervention values) values while using pre-intervention values as covariates.
Post hoc comparisons where made with multiple comparison corrections using the Bonferroni
procedure. Estimated marginal means were calculated for the change in outcome measures and
within groups changes were determined by examination of the 95% confidence intervals (CI) for
these. Significant change within the group was considered to have occurred if the 95% CIs for
changes did not cross zero. Statistical analysis was performed using JASP (version 0.8.5.1,
University of Amsterdam, Netherlands), with alpha for significance accepted at <0.05. Multi
paired estimation plots were produced for data visualization using Estimation Statistics (Ho and
Claridge-Chang, 2017).
Results
The characteristics of the participants are presented in Table 3. Both pre- and post-intervention
results, in addition to estimated marginal means for changes in each outcome and their 95%CIs,
are reported in Table 4.
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10RM tests
Statistically significant between group effects were found for change in bench press
(F(1,35) = 9.737, p < 0.001), lat pull down (F(1,35) = 13.251, p < 0.001), leg press (F(1,35) = 58.631,
p < 0.001), and stiff legged deadlift (F(1,35) = 51.662, p < 0.001).
For bench press change, post hoc between group comparisons revealed the following
results: G5 did not differ from G10 (p > 0.999) or G15 (p > 0.999) but was significantly greater
than G20 (p < 0.001), G10 did not differ from G15 (p = 0.342) but was significantly greater than
G20 (p < 0.001), and G15 was significantly greater than G20 (p = 0.030).
For lat pulldown change, post hoc between group comparisons revealed the following
results: G5 did not differ from G10 (p > 0.999) or G15 (p =0.151) but was significantly greater
than G20 (p < 0.001), G10 was significantly greater than G15 (p = 0.013) and G20 (p < 0.001),
and G15 did not differ from G20 (p = 0.112).
For leg press change, post hoc between group comparisons revealed the following results:
G5 did not differ from G10 (p > 0.999) but was significantly greater than G15 (p <0.001) and
G20 (p < 0.001), G10 was significantly greater than G15 (p <0.001) and G20 (p < 0.001), and
G15 did not differ from G20 (p = 0.057).
For stiff leg deadlift change, post hoc between group comparisons revealed the following
results: G5 did not differ from G10 (p > 0.999) but was significantly greater than G15 (p <0.001)
and G20 (p < 0.001), G10 was significantly greater than G15 (p <0.001) and G20 (p < 0.001),
and G15 did not differ from G20 (p = 0.051).
As seen in Table 4, all groups produced statistically significant within group changes in
all 10RM outcomes based upon their 95%CIs. Figure 1 shows multi-paired estimation plots
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including individual pre- and post-intervention data and paired delta with bootstrapped 95%CIs
for each group and for each 10RM outcome measure.
Muscle thickness
Statistically significant between group effects were found for change in biceps brachii
MT (F(1,35) = 23.219, p < 0.001), triceps brachii MT (F(1,35) = 31.503, p < 0.001), pectoralis major
MT (F(1,35) = 36.59, p < 0.001), quadriceps MT (F(1,35) = 44.232, p < 0.001), and gluteus
maximus MT (F(1,35) = 37.647, p < 0.001).
For biceps brachii MT change, post hoc between group comparisons revealed the
following results: G5 did not differ from G10 (p > 0.999) but was significantly greater than G15
(p <0.001) and G20 (p < 0.001), G10 was significantly greater than G15 (p < 0.001) and G20 (p
< 0.001), and G15 did not differ from G20 (p = 0.108).
For triceps brachii MT change, post hoc between group comparisons revealed the
following results: G5 did not differ from G10 (p = 0.797) but was significantly greater than G15
(p <0.001) and G20 (p < 0.001), G10 was significantly greater than G15 (p = 0.002) and G20 (p
< 0.001), and G15 was significantly greater than G20 (p = 0.012).
For pectoralis major MT change, post hoc between group comparisons revealed the
following results: G5 did not differ from G10 (p = 0.867) but was significantly greater than G15
(p <0.001) and G20 (p < 0.001), G10 was significantly greater than G15 (p < 0.001) and G20 (p
< 0.001), and G15 was significantly greater than G20 (p = 0.040).
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For quadriceps MT change, post hoc between group comparisons revealed the following
results: G5 did not differ from G10 (p = 0.228) but was significantly greater than G15 (p <0.001)
and G20 (p < 0.001), G10 was significantly greater than G15 (p < 0.001) and G20 (p < 0.001),
and G15 did not differ from G20 (p = 0.085).
For gluteus maximus MT change, post hoc between group comparisons revealed the
following results: G5 did not differ from G10 (p = 0.835) but was significantly greater than G15
(p <0.001) and G20 (p < 0.001), G10 was significantly greater than G15 (p < 0.001) and G20 (p
< 0.001), and G15 was significantly greater than G20 (p = 0.007).
As seen in Table 4, all groups produced statistically significant within group changes in
all MT outcomes based upon their 95%CIs. Figure 2 shows multi-paired estimation plots
including individual pre- and post-intervention data and paired delta with bootstrapped 95%CIs
for each group and for each MT outcome measure.
Discussion
The present study compared muscle performance and hypertrophy adaptations in trained
women performing different volumes of RT. The results showed that all groups had significant
improvements in all variables, however the magnitude of these improvements appeared to differ.
Comparison between groups revealed that G5 did not show any statistically significant
differences in relation to G10 in any of the 10RM or MT outcomes measured. However, in all
instances G20 showed statistically significantly smaller changes compared with G5 and G10
across all outcome measures, and in some cases G15 also.
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To the best of our knowledge, this is the first study to compare different RT volumes in
trained women for a relatively long period (24 weeks) and our results suggest that five sets per
week might be adequate to promote optimal adaptations in terms of muscle size and performance
in most outcomes. Moreover, our results suggest that increasing training volume beyond 10 sets
per week might be detrimental to muscle performance and hypertrophy.
Haas et al (27) studied 42 trained men and women who were habituated to perform one
set per exercise. Half of the participants remained training with one set and the other half
increased from one to three sets per exercise. Training was performed three times per week;
therefore, the groups performed three or nine sets per week, respectively. According to the
results, there were no differences in the changes in body composition and 1RM increases in the
leg press and chest press between groups. Interestingly, the dropout rate of the group that
increased volume was 25%, due to low attendance or injury, while there were no dropouts in the
lower volume group. Later, Rhea et al. (25) compared 16 recreationally trained men that trained
for 12 weeks with 3 weekly training sessions and found different results for lower body strength.
In this study, one group performed one set of bench press and leg press and the other performed
three sets. No difference between groups were found for body composition, anthropometric
measures and bench press 1RM; however, the increases in leg press 1RM were higher for the
three sets group.
Our results are comparable with previous results in trained men. Ostrowski et al. (24)
compared three groups, performing three, six or 12 sets per exercise per week. The participants
were habituated to train with 12 sets per week, therefore, there was a decrease in training volume
for two groups, while the other maintained the same routine. The results showed that, after 10
weeks, all groups significantly increased 1RM in the bench press and squat, vertical jump, bench
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throw, rectus femoris MT and triceps brachii MT, with no difference between them.
Interestingly, despite the fact that there was no difference in testosterone:cortisol ratio among
groups, the groups that performed three and six sets per week (and therefore decreased training
volume) had a trend to increase testosterone:cortisol ratio, while the trend was for a decrease in
the group that performed 12 sets per weeks. This could be interpreted as evidence that the group
completing 12 sets per week presented signs of overtraining, which could might also explain the
impaired results in G15 and G20. These, and the above results, are similar to ours when
generally showing no difference in a range between 3 and 12 sets per muscle group per week and
agrees with the suggestion of Ogaswara et al. (22). It is important to note that the study by
Ogasawara et al. was performed in rats, and there might be important differences in anabolic
signaling and protein turnover between rat and humans; however, it presents an interesting
evidence of a ceiling effect for anabolic response to RT. When analyzing trained men, Burd et al.
(36) reported that a higher number of sets was more anabolic than a lower; however, the study
only compared 1 and 3 sets, and the ceiling effect might occur at a higher number of sets, as
suggested by our results.
In a recent study, Amirthalingam et al. (23) compared the effects of a higher (~14 sets
per muscle group per week) versus lower volume (~9 sets per muscle group per week) RT
intervention upon body composition, muscle size, and strength. Training involved a split routine,
with each exercise performed once per week for 6 weeks. No significant increases were found
for leg lean body mass or measures of MT across groups. There were significant increases in
lean body mass measures, with greater increases in trunk and arm lean body mass for the lower
volume group. Significant increases were found for muscle strength for both groups, with greater
increases in the lower volume group for bench press and lat pull-down 1RM. According to the
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authors, it seems that gains plateau beyond a certain volume and, exceeding that point, may lead
to negative results due to overtraining. As noted, despite the heterogeneity in the literature,
similar findings were reported in a meta-analysis by Wernbom et al. (13), who suggested that
existence of a plateau in muscle hypertrophy evidence for a decline in training response when
the volume is extended beyond the point of the plateau. The present study supports these
observations and suggests that a threshold seems to be reached near 10 sets per week.
Our findings do seemingly conflict with previous meta-analyses (10, 21) suggesting that
a linear dose-response relationship exists, supporting at least 10 sets to induce optimal for gains
in muscle size and strength, and possibly greater gains with higher volumes. However, the use of
meta-analysis for determining RT dose has been questioned due to the large number of variables
involved in RT and the methodological inconsistencies in the current literature (8, 11). Our
results are also partially contrary to a recent study conducted by Schoenfeld et al. that compared
the effects of different training volumes in trained men and utilized even greater volumes than
those supported in recent meta-analyses (26). In this study, there was no difference in upper body
muscle strength or triceps MT among the groups that performed 6, 18 or 30 sets per week.
Regarding biceps MT, the increases were higher for 30 sets in comparison to six, with no other
significant difference reported. For lower body, the volumes were 9, 27 or 45 sets per week and
the differences for muscle strength were not significantly different among groups.
Notwithstanding, the group that performed 45 sets showed larger increases in rectus femoris and
vastus lateralis MT when compared to the groups that performed 9 sets, with no other significant
differences.
The conflict between these results with our results and the previous literature might be in
the protocol used. Schoenfeld et al. (26) had participants train each muscle group 3 times per
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week using a full body routine whereas in the present study our participants trained each muscle
group once per week using a split routine. Thus, the spreading of such extreme volumes over
multiple sessions may yield benefits whereas the completion of such volumes within single
sessions may not. However, previous studies showed that it may take at least 4 days for the
muscle to recover from 7-8 sets (30, 37, 38), therefore, further studies are needed to analyze the
long-term effects (i.e. 24 weeks) of high-volume and high-frequency RT, since the muscles
might be trained without adequate recovery. Different definitions of set endpoints might also
have influenced the results between studies, particularly as momentary failure might be
interpreted in different ways if careful instruction and definitions are not used (35). Even when
instructed to reach momentary failure, many participants might not end the set when they are not
able to perform another repetition, but rather due to the confounding effects of perceived
discomfort, which might be especially true for lower body (34, 39). In such cases, an increase in
training volume might bring additional benefit (40). Indeed, Schoenfeld et al. (26) noted that the
participants in their study did not regularly train to momentary failure, whereas the participants
in the present study had previous experience of such training. Indeed, participants in the study of
Hass et al. (27) had been engaged in a minimum of 1 years training performing a circuit of 9
exercises for a single set of each to momentary failure prior to being randomized to either
continue using single sets or to increase to 3 sets per exercise. As noted, they found no difference
for any outcomes between groups.
Considering that most people who advocate lower-volume training suggest that exercises
should be performed with higher efforts, controlling for intensity of effort might be a key factor
when analyzing the effects of different training volumes (11, 45, 46). In agreement with this, a
recent study in older adults showed that supervised training with lower volume and higher effort
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improved functionality and body composition in older participants, yet when participants
changed to performing unsupervised training with higher volumes and lower efforts they
experienced detraining to a degree similar to those who completely ceased training (47).
Therefore, one important aspect of the present study is that the participants were closely
supervised in order to reach the defined set endpoint, since previous studies showed that lack of
supervision might be associated with a lower likelihood of reaching momentary failure (34).
A limitation of the present study was the absence of dietary control. However, the
participants were constantly questioned to see if there were any relevant changes in their dietary
habits and no significant changes were reported. Notwithstanding, in addition to the long-term
influence of dietary habits in the adaptations to a RT program, there is data showing that water
and food consumption may alter anthropometric assessments (48, 49); therefore, the lack of a
rigid dietary control might have also acutely influenced MT measures.
In conclusion, the present results suggest that as little as five sets per week might be
sufficient for attaining optimal gains in muscle strength and size in trained women during a 24-
week RT program, at least when all sets are closely supervised and performed to muscle failure.
Since lack of time is a commonly cited barrier to exercise adoption (50, 51), our data supports
training programs that are uncomplicated and time efficient. This is important for exercise
prescription from personal trainers, strength coaches and medical practitioners; that the health
and fitness benefits associated with RT are attainable with a time efficient volume of training
that might suit lay persons and athletes with time commitments that prevent the performance of
larger training volumes.
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Conflict of Interest
None to declare. This study was not funded.
Acknowledgment
The results of the study are presented clearly, honestly, and without fabrication,
falsification, or inappropriate data manipulation, and statement that results of the present study
do not constitute endorsement by ACSM.
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Figure legends
1 – Multi-paired estimation plots for 10 repetition maximum (10RM) changes.
G5 – 5 sets per week per muscle group, G10 – 10 sets per week per muscle group, G15 – 15 sets
per week per muscle group, G20 – 20 sets per week per muscle group.
Figure 2 – Multi-paired estimation plots for muscle thickness (MT) changes.
G5 – 5 sets per week per muscle group, G10 – 10 sets per week per muscle group, G15 – 15 sets
per week per muscle group, G20 – 20 sets per week per muscle group.
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Figure 1
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Figure 2
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Table 1. Training programs
Number of sets
Mondays
Thursdays
Fridays
G5
G10
G15
G20
Barbell bench press
Lat pull down
45º leg press
2
4
5
7
Inclined barbell bench press
Cable row
Barbell squat
2
4
5
7
Military press
Upright barbell row
Stiff-legged deadlift
1
2
5
6
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Table 2. Training Periodization
Week
Repetition range
Rest Interval
1, 5, 9, 13, 17, 21
12-15RM
30-60 seconds
2, 6, 10, 14, 18, 22
4-6RM
3-4 minutes
3, 7, 11, 15, 19, 23
10-12RM
1-2 minutes
4, 8, 12, 16, 20, 24
6-8RM
2-3 minutes
RM: Repetition maximum
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Table 3 – Groups characteristics
Group
Age
Height
Body Mass
Experience
G5
24.9±1.97
165.3±4.06
63.4±4.14
3.3±0.95
G10
24.6±1.17
168.2±3.68
64.7±4.90
3.2±1.03
G15
25.1±1.20
167±4.40
62.6±4.67
3.6±0.70
G20
24.1±1.20
166.4±4.20
62.9±3.84
3.5±0.97
G5 – 5 sets per week per muscle group, G10 – 10 sets per week per muscle group, G15 – 15 sets
per week per muscle group, G20 – 20 sets per week per muscle group
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Table 4 – Pre and post intervention measures of ten repetition maximum tests and muscle
thickness for each group.
G5
G10
G15
G20
Pre
Post
Change
s(95%C
I)
Pre
Post
Change
s(95%C
I)
Pre
Pos
t
Change
s(95%C
I)
Pre
Pos
t
Change
s(95%C
I)
10RM
tests(kg)
Bench
press
24.
2±4
.6
36.7
±5.6
12.5(10.
32-
14.7)
24.
8±3
.7
38.4
±6.1
13.6(11.
4-15.8)
25.
4±3
.4
36±
4.9
10.6(8.4
-12.8)
24.
2±3
30.
1±3
5.9(3.7-
8.7)
Lat pull
down
21.
4±4
.2
32.7
±5.6
11.3(9.4
-13.2)
23±
3.6
35.9
±6.6
12.9(10.
9-14.8)
23.
8±3
32.
6±4
.6
8.8(6.9-
10.7)
23.
4±2
.1
28.
9±2
.2
5.5(3.6-
7.4)
45º Leg
Press
71.
6±3
.0
112.
8±8.
1
41.2(36.
9-45.4)
75±
4.0
119.
3±9.
9
44.3(40.
1-48.5)
73.
2±4
.6
92.
8±7
.3
19.6(15.
4-23.8)
74.
4±3
.4
85.
7±3
.4
11.3(7.1
-15.5)
Stiff
legged
deadlift
34.
2±6
.2
56.2
±6.4
22(19.7
-24.3)
34.
6±2
.3
56.8
±4.0
22.2(19.
9-24.5)
34.
1±4
.4
44.
3±5
.3
10.2(7.9
-12.5)
34±
2.1
39.
7±2
.9
5.7(3.4-
8.0)
Muscle
thickness(
mm)
Biceps
brachii
26.
8±3
.4
30.5
±3.8
3.7(3.1-
4.3)
26.
8±3
.4
30.7
±3.8
3.9(3.3-
4.5)
26.
7±5
.8
28.
8±6
.3
2.1(1.5-
2.7)
26.
2±4
.0
27.
3±4
.7
1.1(0.5-
1.7)
Triceps
brachii
35.
4±3
.4
40.5
±4.0
5.1(4.4-
5.7)
35.
8±2
.7
40.3
±3.4
4.5(3.8-
5.1)
35.
3±5
.6
38.
1±5
.9
2.8(2.1-
3.4)
35.
2±3
.8
36.
6±4
.6
1.4(0.7-
2.1)
Pectoralis
35.
41.4
6(5.2-
35.
40.9
5.3(4.5-
35.
38.
2.9(2.1-
35±
36.
1.4(0.6-
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G5 – 5 sets per week per muscle group, G10 – 10 sets per week per muscle group, G15 – 15 sets
per week per muscle group, G20 – 20 sets per week per muscle group, 10RM – 10 maximum
repetitions, CI – confidence interval
major
4±2
.8
±3.6
6.8)
6±2
.8
±3.4
6.1)
5±5
.1
4±5
.5
3.7)
3.7
4±5
2.2)
Quadricep
s femoris
57.
6±4
.2
64.2
±4.8
6.6(5.7-
7.5)
59.
2±3
.4
67.2
±4.3
8(7.1-
8.9)
59.
1±4
.3
62.
6±4
.7
3.5(2.6-
4.4)
57±
5.2
58.
8±5
.4
1.8(0.9-
2.7)
Gluteus
maximus
33.
6±3
.7
38.1
±4.6
4.5(3.9-
5.1)
34.
4±3
.9
39.6
±4.6
5.2(4.6-
5.8)
34.
3±4
.7
37±
4.8
2.7(2.1-
3.3)
33±
4.6
34.
1±4
.7
1.1(0.5-
1.7)
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