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The principle of progressive overload must be adhered to for individuals to continually increase muscle size with resistance training. While the majority of trained individuals adhere to this principle by increasing the number of sets performed per exercise session, this does not appear to be an effective method for increasing muscle size once a given threshold is surpassed. Opposite the numerous studies examining differences in training loads and sets of exercise performed, a few studies have assessed the importance of training frequency with respect to muscle growth, none of which have tested very high frequencies of training (e.g., 7 days a week). The lack of studies examining such frequencies may be related to the American College of Sports Medicine recommendation that trained individuals use split routines allowing at least 48 h of rest between exercises that stress the same muscle groups. Given the attenuated muscle protein synthetic response to resistance exercise present in trained individuals, it can be hypothesized that increasing the training frequency would allow for more frequent elevations in muscle protein synthesis and more time spent in a positive net protein balance. We hypothesize that increasing the training frequency, as opposed to the training load or sets performed, may be a more appropriate strategy for trained individuals to progress a resistance exercise program aimed at increasing muscle size.
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CURRENT OPINION
Frequency: The Overlooked Resistance Training Variable
for Inducing Muscle Hypertrophy?
Scott J. Dankel
1
Kevin T. Mattocks
1
Matthew B. Jessee
1
Samuel L. Buckner
1
J. Grant Mouser
1
Brittany R. Counts
1
Gilberto C. Laurentino
1
Jeremy P. Loenneke
1
ÓSpringer International Publishing Switzerland 2016
Abstract The principle of progressive overload must be
adhered to for individuals to continually increase muscle
size with resistance training. While the majority of trained
individuals adhere to this principle by increasing the
number of sets performed per exercise session, this does
not appear to be an effective method for increasing muscle
size once a given threshold is surpassed. Opposite the
numerous studies examining differences in training loads
and sets of exercise performed, a few studies have assessed
the importance of training frequency with respect to muscle
growth, none of which have tested very high frequencies of
training (e.g., 7 days a week). The lack of studies exam-
ining such frequencies may be related to the American
College of Sports Medicine recommendation that trained
individuals use split routines allowing at least 48 h of rest
between exercises that stress the same muscle groups.
Given the attenuated muscle protein synthetic response to
resistance exercise present in trained individuals, it can be
hypothesized that increasing the training frequency would
allow for more frequent elevations in muscle protein syn-
thesis and more time spent in a positive net protein balance.
We hypothesize that increasing the training frequency, as
opposed to the training load or sets performed, may be a
more appropriate strategy for trained individuals to pro-
gress a resistance exercise program aimed at increasing
muscle size.
Key Points
Individuals are likely completing a volume of
resistance exercise above that which is beneficial for
muscle hypertrophy.
The muscle protein synthetic response to resistance
exercise would seemingly favor higher frequencies
of exercise.
Reducing the training volume and increasing the
frequency may be beneficial for muscle hypertrophy.
1 Introduction
The American College of Sports Medicine recommends
that individuals looking to increase muscle size perform
two to four sets of exercise targeting each muscle group
two to three times per week [1]. It is also recommended
that individuals perform between 8 and 12 repetitions per
set using a load corresponding to C70 % of the individual’s
one-repetition maximum (1RM) [1]. As individuals
become trained and start to adapt to resistance exercise, an
increased stress must be placed on the musculature to allow
the possibility for further muscle growth. This principle of
progressive overload can be adhered to by undertaking one
or more of the following three modifications: (1) increasing
the absolute training load performed for a set number of
repetitions, (2) increasing the number of sets, and/or (3)
increasing the frequency of exercise. It is well known that
increases in muscle size are attenuated with training [25],
with *70 % of muscle growth proposed to occur within
the first several weeks [6]. While part of the attenuated
&Jeremy P. Loenneke
jploenne@olemiss.edu
1
Department of Health, Exercise Science, and Recreation
Management, Kevser Ermin Applied Physiology Laboratory,
The University of Mississippi, P.O. Box 1848, University,
MS 38677, USA
123
Sports Med
DOI 10.1007/s40279-016-0640-8
muscle growth can be attributed to individuals approaching
their genetic potential (i.e., the finite amount of muscle
they can accrue), it may also be partially due to an
increased difficulty of providing a more effective stimulus.
Herein we discuss the current literature examining different
methods of progressive overload and explain why, in our
opinion, increasing the training frequency may be the most
effective way for trained individuals to progress a resis-
tance training program aimed at increasing muscle size.
2 Increasing the Absolute Load
One strategy by which an individual can progress a muscle
hypertrophy-focused training program is to increase the
absolute training load that is lifted for a set number of
repetitions (or maintain a constant absolute training load
and perform more repetitions per set). However, increasing
the absolute training load will become more difficult as
strength gains are attenuated with continued training [7].
Once an individual can no longer increase the absolute
training load while maintaining a similar repetition range,
they must adhere to the principle of progressive overload to
further increase muscle size. This can be done by either
increasing the number of sets performed for each muscle
group or increasing the frequency at which each muscle
group is trained.
3 Increasing the Sets
Individuals can progress a resistance training program by
increasing the number of sets performed for a given muscle
group. While this is commonly referred to as exercise
volume, the reporting of exercise volume has notable lim-
itations in that it is entirely dependent on the absolute and
relative load used. Briefly, muscle growth appears to be
highly dependent on fatiguing the muscle, whereby the
muscle is brought to a point at or near contractile failure to
increase motor unit recruitment/activation [8]. Low-load
protocols require substantially more repetitions to elicit
contractile failure, thus requiring more volume to produce
similar elevations in muscle protein synthesis [9,10] and
muscle hypertrophy [11]. Given that the level of effort to
reach volitional failure, as opposed to fatigue per se,
appears to be primarily driving muscle hypertrophy [8], we
refer to ‘sets of exercise’ rather than ‘exercise volume’ to
account for negligible differences in the reporting of
exercise volume (i.e., lower loads require greater absolute
volume to reach contractile failure [11]).
The American College of Sports Medicine recommends
that more advanced lifters use split routines training one to
three muscle groups per workout to allow for more sets per
muscle group to be completed within a given training
session [1]. In support of this recommendation, the
majority of bodybuilders perform around four sets per
exercise, while performing four different exercises target-
ing each muscle group, thus totaling 16 sets of exercise
targeting a specific muscle group within a single training
session [12]. While increasing the number of sets per-
formed in a given session would adhere to the principle of
progressive overload, there appears to be a point where no
additive benefit (with respect to muscle hypertrophy) is
seen from performing additional sets of exercise within a
given training session. The point at which the anabolic
response is maximized would also appear to be much lower
than what is typically performed by trained individuals
[12]. For example, one acute (short-term) study found no
difference in muscle protein synthesis after performing
three or six sets of resistance exercise [13], and this is
supported by a training study illustrating similar increases
in muscle size upon completing either four sets or eight sets
per training session [14]. Although both of these studies
were performed in untrained individuals [13,14], similar
increases in muscle size have been observed comparing
one, two, or four sets of exercise per training session over
10 weeks in trained individuals [15].
Although a meta-analysis supports the efficacy of
greater exercise volume [16], considerable heterogeneity
was present in the studies included for analysis [17], and
the only significant difference was observed when com-
paring one set with three sets. Even if a small difference
exists between one and three sets of exercise, there is likely
a threshold whereby increasing the sets of exercise per-
formed per muscle group within a given training session
does not necessarily provide greater muscle growth [18].
Specifically, this point of diminishing returns would likely
be much lower than what is typically performed by trained
individuals looking to increase muscle size (16 sets) [12].
This may be analogous to protein consumption where 10 g
of protein may be better than 5 g for muscle growth, but
consuming 80 g is not necessarily better for muscle growth
than consuming 40 g [19]. For this reason, increasing the
number of sets performed in a given training session may
simply prolong fatigue without providing a greater increase
in muscle size.
4 The Case for Frequency
Few studies have examined the efficacy of high-frequency
training, which may be in part related to the American
College of Sports Medicine’s recommendation that indi-
viduals rest at least 48 h between training similar muscle
groups [1]. This recommendation may also explain why
68 % of bodybuilders report only training a specific muscle
S. J. Dankel et al.
123
group once per week [12], and none of the 127 that were
sampled reported training a specific muscle group more
than twice per week [12]. It is also likely that the longer
recovery periods are necessary to allow sufficient recovery
from the previous bout of exercise, given that the average
bodybuilder performs 16 sets of exercise targeting a
specific muscle group within a given training session [12].
In response to resistance exercise, individuals undergo
an elevated muscle protein synthetic response that lasts at
least 24 [20], 36 [21], or 48 [22] h post-exercise. The
magnitude and duration of the elevated protein synthetic
response appears to be blunted in trained individuals [23].
Therefore, given that a relatively low number of sets (i.e.,
four sets to volitional failure) may be sufficient to elicit a
large increase in protein synthesis for up to 24 h post-
exercise [20], performing fewer sets may be more effective
at reducing prolonged fatigue and allowing the same
muscle group to be trained more frequently. The more
repetitive stimuli would hypothetically result in a greater
time spent in a net-positive protein balance, and it can
therefore be hypothesized that trained individuals may see
greater benefits in muscle growth by keeping the same
number of sets performed per week but simply dispersing
them over a greater number of training sessions (Fig. 1).
This would allow for the avoidance of ‘wasted sets’ in
terms of muscle hypertrophy, while also allowing for a
hypothetical refractory period to pass before additional
exercise is performed. While hypothetical, this refractory
period may work in a similar manner to that of nutrition-
induced muscle protein synthesis [24], whereby a certain
time period must elapse before the muscle protein synthetic
response from resistance exercise can be re-stimulated.
However, this refractory period may be relatively short and
may even be overcome within a 24-h window [25].
Increasing the training frequency may be somewhat less
effective for untrained individuals given the longer dura-
tion for which muscle protein synthesis is elevated post-
exercise (Fig. 2). Nonetheless, for trained individuals, it
would likely be beneficial to progressively increase the
training frequency from one to two times a week to two to
three times a week in which the same muscle groups are
stressed. As individuals become accustomed to training the
same muscle group at higher frequencies, it may be ben-
eficial to perform full-body routines daily, or every other
day, depending on how individuals recover from exercise.
5 Previous Studies Assessing Training Frequency
A review paper demonstrated that the increase in muscle
size per training session (*0.15 %) does not differ
depending on whether high or low frequencies are
employed [26]. Therefore, individuals who train more
frequently would likely observe larger increases in muscle
mass over the same time period given that more training
sessions can be performed. However, this review [26] was
not designed to examine the importance of training fre-
quency as all other training variables were not held con-
stant. Another recent meta-analysis concluded that volume-
equated resistance training dispersed over two sessions per
week was more effective than performing a larger volume
in one session [27]; however, the analysis included insuf-
ficient studies to enable evaluation of training frequencies
greater than twice per week. To our knowledge, only three
studies have set out to directly assess the importance of
training frequency while using a direct measure of muscle
size. One study assessed trained individuals targeting the
same muscle groups once versus three times per week [28]
and noted a general trend toward greater muscle growth
among those training three times a week. However, the
results from this study were somewhat inconclusive as the
only significant difference was noted in a muscle group that
was not directly trained (i.e., biceps brachii). Another study
assessing female athletes illustrated greater increases in
muscle size when the total resistance training volume was
split into two sessions per day as opposed to one [25]. It
was likely that the group training twice a day avoided
performing ‘wasted sets’ as described in Fig. 1and was
able to re-stimulate muscle protein synthesis after it
quickly returned to baseline, as is the case in trained
individuals. A similar study comparing the same training
volume over one or two sessions per week found no dif-
ferences in muscle size [29]; however, this study assessed
untrained males, and may differ for reasons mentioned in
Fig. 2. Despite two of these studies supporting our
hypothesis, the vast majority of studies assessing training
frequency have focused specifically on strength adapta-
tions, whereas those providing a measure of muscle size
have been limited to indirect measures of total lean mass
(e.g., skinfold measurements, whole body dual-energy
X-ray absorptiometry) [3034].
6 Decreasing the Training Frequency
Although increasing the training frequency may provide
greater muscle growth, it may be difficult to increase the
training frequency beyond a certain point. We propose that
once an individual has been training at a higher frequency
for a sufficient duration (e.g., 16 weeks), it may then be
beneficial to decrease the training frequency for a period of
time (e.g., 24 weeks). A previous study [35] demonstrated
that the muscle mass gained following 16 weeks of training
(nine sets per session three times per week) was maintained
after drastically reducing the exercise stimulus for an
additional 32 weeks (three sets per session once per week).
Frequency of Training for Muscle Hypertrophy
123
Therefore, once an individual increases the training fre-
quency and hypothetically increases muscle mass over a
period of time, he/she may then be able to reduce the
training frequency while still maintaining the added muscle
mass. While also hypothetical, this may allow for the
down-regulation of metabolic brakes [36] and the re-sen-
sitization of the muscle to the anabolic stimulus [37],
whereby an individual may then benefit from increasing the
training frequency again for reasons previously mentioned.
Some support for this hypothesis may exist in that the
rebounding of muscle hypertrophy following detraining is
such that no differences were observed when comparing
24 weeks of continuous training with another group per-
forming cycles of 6 weeks of training followed by 3 weeks
of detraining [38]. Even if this hypothesis is correct, there
would inevitably come a point where an individual can no
longer increase muscle mass as he/she has reached his/her
genetic ceiling.
7 Limitations of this Hypothesis
While increasing the training frequency would hypotheti-
cally allow for more frequent elevations in muscle protein
synthesis, the body would likely adapt, forcing a further
increase in training frequency to produce greater muscle
growth. Even so, many trained individuals are not training
the same muscle groups at high frequencies [12]; thus, this
Fig. 1 a Hypothetical protein
synthetic response to two
different exercise protocols with
the same number of sets
performed per week.
Performing fewer sets per
session at a higher frequency
will likely be sufficient for
increasing muscle size while
also limiting fatigue to allow for
higher frequencies and thus
more frequent stimulations of
muscle protein synthesis.
Performing more sets per
session while using a lower
training frequency may reduce
the time spent in a positive net
protein balance because the
large number of sets performed
within a given session may
exceed the ‘anabolic limit’,
resulting in wasted sets.
Additionally, performing more
sets within a given session
requires greater recovery time,
causing muscle protein
synthesis to return to basal
levels until re-stimulated again
during another training session.
bDemonstration of the greater
anabolic potential during each
protocol. No shading in the area
under the curve illustrates a
similar anabolic potential
between both frequencies. The
difference in the area under the
curve between protocols can be
attributed to the ‘wasted sets’
completed above the volume
threshold during the twice-
weekly protocol. AUC area
under the curve
S. J. Dankel et al.
123
would likely be the most beneficial way to further progress
a training program aimed at increasing muscle size.
Additionally, this hypothesis is based largely on the muscle
protein synthetic response to resistance exercise, which
does not always correlate well with long-term changes in
muscle size [39], nor does it take into account changes in
muscle protein breakdown. Even so, acute changes in
muscle protein synthesis would appear to be the primary
driver of muscle growth from resistance training in humans
[40,41], and the lack of a correlation between muscle
protein synthesis and muscle size may simply be due to the
‘snapshot’-specific nature of how muscle protein synthesis
is measured (i.e., muscle biopsies). Nonetheless, an
increase in muscle size would need to occur through the
accretion of new proteins, and would likely correlate well
with muscle growth if measured over time [42], making the
acute marker of muscle protein synthesis at least somewhat
indicative of the efficacy of a resistance exercise protocol.
8 Future Research Questions
The hypothesis that increasing training frequency, rather
than training load or sets performed, may be a more
effective strategy for trained individuals to increase muscle
size opens an avenue for future research to test whether
increased training frequency does indeed result in greater
muscle hypertrophy. Future studies may seek to compare
two groups of trained individuals performing at markedly
different training frequencies (e.g., 1 vs. 6 days per week)
while equating the total number of sets performed to
volitional failure. While this type of study design would
oppose the recommendation of resting at least 48 h
between exercises of the same muscle group [1], we have
unpublished data suggesting that even three sets of exercise
per day, for 21 straight days, elicited no signs of over-
training in previously trained individuals. By using a direct
measure of muscle size (e.g., ultrasound, magnetic
Fig. 2 Hypothetical depiction of muscle anabolism illustrating why
increasing the training frequency may be more beneficial in trained
individuals. aTrained and untrained individuals performing the same
frequency of exercise. (b) Depiction of where the area under the curve
favors trained or untrained individuals. No shading illustrates a
similar anabolic potential between trained and untrained individuals.
Notably, untrained individuals demonstrate longer durations in which
the muscle is primed for anabolism. cUntrained individuals training
the same muscle groups with different frequencies. dDepiction of
where the area under the curve favors higher frequency. No shading
under the curve illustrates similar anabolic potential between low and
high frequencies. Increasing the training frequency is of less
importance in untrained individuals because the muscle is still primed
for greater anabolism as a result of the previous bout. AUC area under
the curve
Frequency of Training for Muscle Hypertrophy
123
resonance imaging), the two groups can then be compared
and any differences in muscle size could be attributed to
differences in training frequencies. To test whether a
muscle could then be re-sensitized to the anabolic stimulus,
the high-frequency group could then be split into two
groups, one of which continues training at a high frequency
while the other reduces the frequency for a short period in
an attempt to sensitize the muscle to the reintroduction of
high-frequency training.
Future studies may also be designed to compare differ-
ent exercise volumes to more closely detail the specific
point at which the anabolic potential of a given training
session has been reached. While a previous meta-analysis
was only able to assess one set versus three sets [16],
previous research in trained individuals found no differ-
ence between performing one, two, or four sets [15]of
exercise within a single training session. Thus, the specific
point at which performing more volume is not more
advantageous for muscle growth has not been determined
and may be exercise specific. For example, compound
movements may require additional sets to fully activate the
muscles of interest (e.g., bench press vs. triceps
extensions).
9 Conclusion
While the majority of studies within the resistance training
literature focus on increasing the sets of exercise to pro-
duce greater adaptations in muscle size, it is our opinion
that it is likely more beneficial to increase the training
frequency. Contrary to the American College of Sports
Medicine recommendations that trained individuals use
split routines to perform more sets of exercise within a
given training session [1], we feel that trained individuals
should train similar muscle groups more frequently while
reducing the number of sets performed in a given training
session. This hypothesis is made based on previous
research demonstrating that (1) increasing the number of
sets beyond a certain point has negligible effects on muscle
hypertrophy given the relatively low volume that appears
to maximally stimulate muscle protein synthesis; and (2)
the duration of the time period when muscle protein syn-
thesis is elevated in trained individuals appears to be
shortened.
Compliance with Ethical Standards
Funding No sources of funding were used to assist in the preparation
of this article.
Conflict of interest Scott Dankel, Kevin Mattocks, Matthew Jessee,
Samuel Buckner, J. Grant Mouser, Brittany Counts, Gilberto
Laurentino, and Jeremy Loenneke have no conflicts of interest rele-
vant to the content of this review.
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Frequency of Training for Muscle Hypertrophy
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... One possible explanation is that training increases protein synthesis, lasting 24-48 hours in untrained individuals (63) and 24 hours in trained individuals (17). Therefore, increasing the frequency of training sessions may allow for a longer net favorable protein balance period, which can enhance muscular adaptations (18). ...
... Moreover, increasing the frequency of neuromuscular stimuli in a weekly training regimen can enhance motor learning, particularly during sport-specific drills (71). Distributing the weekly workload over several days can help reduce fatigue during training sessions (18) and increase the duration of intersession recovery (62). ...
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This systematic review and meta-analysis aimed to assess the effects of the speed, agility, and quickness (SAQ) training method on linear sprinting, jumping, and change of direction speed (CODS) performance in soccer players. Three electronic databases (Web of Science, PubMed, and Scopus) were searched, and 17 studies were included in the three-level meta-analysis. The results indicated that SAQ training significantly improved linear sprinting (effect size [ES] = 0.79, 95% CI = 0.19 to 1.39, p = 0.01, I2 = 95.9%), jumping (ES = 0.83, 95% CI = 0.26 to 1.39, p = 0.01, I2 = 85.9%), and CODS performance (ES = 0.70, 95% CI = 0.29 to 1.11, p = 0.01, I2 = 82.8%) when compared to the control groups. Furthermore, a moderating effect of sprint distance (favoring 10-m versus 20-m or 30-m) was observed for the sprint performance. In addition, the moderating effect of jump type (favoring horizontal versus vertical) and training frequency (favoring >2 versus ≤2 sessions/week) was observed for jump performance. Lastly, a moderating effect of age (favoring >15 versus ≤15 years) was observed for CODS. In conclusion, coaches may prefer SAQ training to improve sprint, jump and CODS abilities of soccer players.
... This lack of knowledge might lead to a potential "threshold" in assessing the volume of resistance exercise. 61 Therefore, in resistance exercise, giving each skeletal muscle excessive repetitions and sets, thereby increasing the total volume of exercise, might not provide additional benefits to the body. 55 In this context, exercise snacks, characterized by high frequency and low volume, could be an effective alternative to traditional resistance exercises for stimulating physiological adaptations in the body. ...
... 62 Current physical activity guidelines recommend that adults engage in resistance exercises at least twice a week. 1 However, with a longer interval between these bi-weekly sessions, it is hypothesized that more frequent repetitions of resistance exercise could lead to more prolonged periods of net protein accretion in skeletal muscles. 61 Resistance exercise snacks, typically performed once or twice daily, may help maintain this increase in muscle protein. Although increasing the frequency of exercise may enhance skeletal muscle protein synthesis, due to the body's adaptability, it might be necessary to further increase the frequency to achieve greater muscle growth. ...
Article
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Physical inactivity remains a pressing global public health concern. Prolonged periods of sedentary behavior have been linked to heightened risks of non-communicable diseases such as cardiovascular diseases and type 2 diabetes, while engaging in any form of physical activity can elicit favorable effects on health. Nevertheless, epidemiological research indicates that people often struggle to meet recommended physical activity guidelines, citing time constraints, lack of exercise equipment, and environmental limitations as common barriers. Exercise snacks represents a time-efficient approach with the potential to improve physical activity levels in sedentary populations, cultivate exercise routines, and enhance the perception of the health benefits associated with physical activity. We review the existing literature on exercise snacks, and examine the effects of exercise snacks on physical function and exercise capacity, while also delving into the potential underlying mechanisms. The objective is to establish a solid theoretical foundation for the application of exercise snacks as a viable strategy for promoting physical activity and enhancing overall health, particularly in vulnerable populations who are unable to exercise routinely.
... Thomas and Burns conclude that higher training volume may be necessary to exceed lean tissue mass and strength gains presented in their study. This conclusion agrees with others that hypothesized that resistance training volume and associated frequency may be a significant determiner of outcomes especially hypertrophy (9,24,25). These results demonstrate the need for research assessing the impact of high volume and frequency RT on lean tissue mass and strength acquisition. ...
... iii) there is no plateau in hypertrophy with increasing per session volumes; iv) the average weekly 'fractional' set volume of 13.00 ± 8.87 in the included studies may have resulted in per session volumes that were either too high or too low, preventing beneficial effects of higher frequencies to be observed (116); v) an unidentified negative effect of higher frequency counteracts the theoretical positive effects. Please refer to our parallel project for additional insight on the effects of per session volume (117). ...
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Background: Weekly set volume and frequency are used to manipulate resistance training (RT) dosage. Previous research has identified higher weekly set volume as enhancing muscle hypertrophy and strength gains, but the nature of the dose-response relationship still needs to be investigated. Mixed evidence exists regarding the effects of higher weekly frequency. Objective: Before meta-analyzing the volume and frequency research, all contributing RT sets were classified as direct or indirect, depending on their specificity to the hypertrophy/strength measurement. Then, weekly set volume/frequency for indirect sets was quantified as 1 for 'total,' 0.5 for 'fractional,' and 0 for 'direct.' A series of multi-level meta-regressions were performed for muscle hypertrophy and strength, utilizing 67 total studies of 2,058 participants. All models were adjusted for the duration of the intervention and training status. Results: The relative evidence for the 'fractional' quantification method was strongest; therefore, this quantification method was used for the primary meta-regression models. The posterior probability of the marginal slope exceeding zero for the effect of volume on both hypertrophy and strength was 100%, indicating that gains in muscle size and strength increase as volume increases. However, both best fit models suggest diminishing returns, with the diminishing returns for strength being considerably more pronounced. The posterior probability of the marginal slope exceeding zero for frequency's effect on hypertrophy was less than 100%, indicating compatibility with negligible effects. In contrast, the posterior probability for strength was 100%, suggesting strength gains increase with increasing frequency, albeit with diminishing returns. Conclusions: Distinguishing between direct and indirect sets appears essential for predicting adaptations to a given RT protocol, such as using the 'fractional' quantification method. This method's dose-response models revealed that volume and frequency have unique dose-response relationships with each hypertrophy and strength gain. The dose-response relationship between volume and hypertrophy appears to differ from that with strength, with the latter exhibiting more pronounced diminishing returns. The dose-response relationship between frequency and hypertrophy appears to differ from that with strength, as only the latter exhibits consistently identifiable effects.
... Thus, there is strong evidence that resistance training frequency does not significantly affect muscle hypertrophy when volume is equated (29). However, previous findings suggest that higher-frequency resistance training programs, through more frequent stimulation of muscle protein synthesis pathways, may lead to a greater cumulative effect over time, resulting in enhanced hypertrophic responses compared with lower-frequency training programs (8). By contrast, evidence showed a significant effect of resistance training frequency on muscle strength gains, with higher training frequencies resulting in greater muscle strength gains (14). ...
Article
Ramos-Campo, DJ, Benito-Peinado, PJ, Caravaca, LA, Rojo-Tirado, MA, and Rubio-Arias, JÁ. Efficacy of split versus full-body resistance training on strength and muscle growth: a systematic review with meta-analysis. J Strength Cond Res XX(X): 000–000, 2024—No previous study has systematically compared the effect of 2 resistance training routines commonly used to increase muscle mass and strength (i.e., split [Sp] and full-body [FB] routines). Our objective was to conduct a systematic review and meta-analysis following PRISMA guidelines to compare the effects on strength gains and muscle growth in healthy adults. 14 studies (392 subjects) that compared Sp and FB routines in terms of strength adaptations and muscle growth were included. Regarding the effects of the Sp or FB routine on both bench press and lower limbs strength, the magnitude of the change produced by both routines was similar (bench press: mean difference [MD] = 1.19; [−1.28, 3.65]; p = 0.34; k = 14; lower limb: MD = 2.47; [−2.11, 7.05]; p = 0.29; k = 14). Concerning the effect of the Sp vs. FB routine on muscle growth, similar effects were observed after both routines in the cross-sectional area of the elbow extensors (MD = 0.30; [−2.65, 3.24]; p = 0.84; k = 4), elbow flexors (MD = 0.17; [−2.54, 2.88]; p = 0.91; k = 5), vastus lateralis (MD = −0.08; [−1.82, 1.66]; p = 0.93; k = 5), or lean body mass (MD = −0.07; [−1.59, 1.44]; p = 0.92; k = 6). In conclusion, the present systematic review and meta-analysis provides solid evidence that the use of Sp or FB routines within a resistance training program does not significantly impact either strength gains or muscle hypertrophy when volume is equated. Consequently, individuals are free to confidently select a resistance training routine based on their personal preferences.
... According to Burd et al. (41), even training with very light loads (30% of 1 RM) can stimulate muscle protein synthesis to a comparable extent as training with 90% of 1 RM, as long as the intensity of the effort is high. With the RES routine, participants could have benefited from the muscle protein synthesis response frequently throughout the intervention (42,43). All in all, this could have partially compensated for the disadvantages of the lower training loads. ...
Article
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Background Although resistance training (RT) is essential to preserve musculoskeletal fitness and maintain a healthy, independent life into old age, few women perform RT. We investigated whether resistance exercise snacking (RES) could be an efficient training approach for the workplace health promotion (WHP) to minimize barriers for participation and facilitate RT in women in order to improve musculoskeletal fitness. Methods This pilot-study followed a prospective, controlled intervention design. Female employees with sedentary occupations doing RT on less than 2 days/week before study participation were included. Participants self-selected for either intervention (IG) or control group (CG). While the IG [N = 15, mean age 42.1 (SD = 11.1) years] did 10 min of RES on working days for 12 weeks, the CG [N = 15, mean age 49.9 (SD = 9.7) years] was instructed to maintain their habitual physical activity. Primary endpoint was change in muscle mass. Secondary endpoint was change in maximum isometric strength. Balance, cardiovascular fitness, perceived health, and general life satisfaction was assessed for exploratory purpose. Measurements were taken before and after the intervention. Results 12 participants of IG and 14 of CG completed the study. Muscle mass improved significantly more in the IG [+0.42 (SD = 0.54) kg] compared to the CG [−0.16 (SD = 0.51) kg] (p = 0.01, ƞ²p = 0.24). Strength did not change significantly between groups. Nevertheless, there was a trend for greater improvements in the IG compared to the CG for trunk extension, trunk flexion, and upper body push but not upper body pull. Regarding exploratory endpoints, no significant between-group changes were found. Despite their poor fitness, both groups perceived their health as good and had high life satisfaction before and after the intervention. Conclusion RES could be an effective approach for the WHP to promote RT in inactive women with sedentary occupations and improve their muscle mass.
... Resistance training (RT) is considered as the most effective method to develop muscle strength and hypertrophy, and to change muscle architecture (MA) parameters (e.g., increases in pennation angle and fascicle length) (1,21,53).The magnitude of such muscular adaptations is related to the adequate configuration of training variables. Training frequency is, therefore, considered a determinant variable in the hypertrophic response to a given RT program (13,22). ...
Article
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International Journal of Exercise Science 15(4): 1661-1679, 2022. The purpose of the present study was to investigate muscle thickness and strength outcomes of the quadriceps femoris induced by different resistance training (RT) frequencies and detraining. In addition, muscle architecture (MA) parameters were also assessed. Twenty-seven healthy resistance-trained subjects (men, n = 17; women, n = 10; 20.8 ± 1.9 years; RT experience = 3.3 ± 1.6 years) volunteered to participate in this study. One leg of each subject was randomly allocated into the 2 sessions per week condition (2x) and the contralateral leg was then placed in the 4 sessions per week condition (4x). There were 16 RT sessions in 2x and 4x. After 4 weeks, 4x were divided into 2 other conditions: more 4 weeks with 2x(4x (+2x)) and detraining (4x (+Det)). Muscle thickness (MT), fascicle length (FL), pennation angle (PA) of the quadriceps muscles and one-repetition maximum for unilateral knee extension (1RMKE) were evaluated. A significant increase of 1RMKE in 2x, 4x, and 4x (+2x) and a decrease in 4x (+Det) was observed (all p < 0.05). The MA showed similar results in most dependent variables for MT, FL and PA. Specifically 4x (+Det) condition demonstrated antagonistic results when compared to the 4x (+2x) in MT of rectus femoris (p = 0.001) and increased FL in vastus intermedius (p = 0.001).
... There may also be a muscle-specific effect with a lower number of sets (i.e., single set) providing superior training adaptations with upper body training versus more pronounced training gains with three sets versus one set for the lower body [72]. For optimal muscle hypertrophy, Dankel et al. [77] suggested in their review that with trained individuals, similar muscle groups should be trained more frequently while reducing the number of sets per training session. They indicated that increasing set number past a certain threshold or ceiling has negligible effects on muscle hypertrophy. ...
Article
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Background Findings from original research, systematic reviews, and meta-analyses have demonstrated the effectiveness of resistance training (RT) on markers of performance and health. However, the literature is inconsistent with regards to the dosage effects (frequency, intensity, time, type) of RT to maximize training-induced improvements. This is most likely due to moderating factors such as age, sex, and training status. Moreover, individuals with limited time to exercise or who lack motivation to perform RT are interested in the least amount of RT to improve physical fitness. Objectives The objective of this review was to investigate and identify lower than typically recommended RT dosages (i.e., shorter durations, lower volumes, and intensity activities) that can improve fitness components such as muscle strength and endurance for sedentary individuals or beginners not meeting the minimal recommendation of exercise. Methods Due to the broad research question involving different RT types, cohorts, and outcome measures (i.e., high het-erogeneity), a narrative review was selected instead of a systematic meta-analysis approach. Results It seems that one weekly RT session is sufficient to induce strength gains in RT beginners with < 3 sets and loads below 50% of one-repetition maximum (1RM). With regards to the number of repetitions, the literature is controversial and some authors report that repetition to failure is key to achieve optimal adaptations, while other authors report similar adaptations with fewer repetitions. Additionally, higher intensity or heavier loads tend to provide superior results. With regards to the RT type, multi-joint exercises induce similar or even larger effects than single-joint exercises. Conclusion The least amount of RT that can be performed to improve physical fitness for beginners for at least the first 12 weeks is one weekly session at intensities below 50% 1RM, with < 3 sets per multi-joint exercise.
Article
Handball is a body-contact Olympic ball sport that is characterized by fast-paced defensive and offensive actions. Players must coordinate explosive movements (e.g., changing of direction) and handball-specific skills (e.g., passing). Maximising performance requires a systematic approach to training, and this includes physical, psychological, technical, and tactical preparation. Purpose: The aim of this study was to determine the effects of movement-based (MOV; unspecific sport stimulus) or game-based (GAM; sport-specific stimulus) flywheel resistance training intervention in highly trained youth handball players. Methods: Twenty-five highly trained youth male handball players completed 2 sessions per week of flywheel resistance training (MOV, n = 12; GAM, n = 13) over the 7-week intervention period. Change of direction tests (180º Change of Direction Speed test in both legs, and V-cut test), and Handball Throwing test were conducted before and after the intervention. Results: Both groups significantly improved V-cut, and 180º Change of Direction Speed test performance (P<0.05; d = 0.79-2.05). Notwithstanding, the GAM group demonstrated greater improvements in V-cut and COD180ASY when compared to the MOV group (P<0.05), with small effect. Handball throwing speed performance remained unchanged independently of training condition (P>0.05). Conclusions: These findings provide further support for the training principle of ‘specificity’ and highlight the importance of including a game-based training stimulus during resistance training. This is a key consideration for coaches wanting to enhance physical performance in youth handball players.
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Purpose: The development of hypertrophy is related to genetics as much as strength training. Recent studies have focused on the effects of microRNAs (miRNAs). This study aims to examine the relationship between the Tri-set training protocol, which provides hypertrophy development, and plasma Mir-1, Mir-128a, Mir-133, and Mir-206. Materials and Methods: 26 volunteers studying at Manisa Celal Bayar University Faculty of Sport Sciences participated in this research. The Tegner Activity Scale was used to measure the physical activity level of the participants and their weight training histories were noted. On the first day, 12 maximum repetition tests of Full Squat (SQ), Dead Lift (DL) and 45° Leg Press (LP) were adhered to. On the second day, the participants' height, weight, and other anthropometric measurements were made and blood was taken from the participants before applying the training protocol. On the third day, the training protocol was applied. On the fourth day, post-training blood samples were taken. Statistical analysis of the data collected from the participants was analyzed using the Paired Sample T-Test and Pearson correlation analysis method. Results: While there was an increase in the expression levels of mir-1, mir 128a and mir-206 before and after the training, this difference was not found to be statistically significant (p<0.05). According to the correlation analysis of expression levels before and after training, a correlation was found at the level of r= 0.760 for mir-1 and at the level of r= 0.737 for mir-128a. Conclusion: Tri-set training method increases mir-1, mir-128a miRNA levels. This indicates that these two miRNAs have a significant effect on the development of hypertrophy. Keywords: miRNA, Tri set training, Hypertrophy, Resistance training
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Background A number of resistance training (RT) program variables can be manipulated to maximize muscular hypertrophy. One variable of primary interest in this regard is RT frequency. Frequency can refer to the number of resistance training sessions performed in a given period of time, as well as to the number of times a specific muscle group is trained over a given period of time. Objective We conducted a systematic review and meta-analysis to determine the effects of resistance training frequency on hypertrophic outcomes. Methods Studies were deemed eligible for inclusion if they met the following criteria: (1) were an experimental trial published in an English-language refereed journal; (2) directly compared different weekly resistance training frequencies in traditional dynamic exercise using coupled concentric and eccentric actions; (3) measured morphologic changes via biopsy, imaging, circumference, and/or densitometry; (4) had a minimum duration of 4 weeks; and (5) used human participants without chronic disease or injury. A total of ten studies were identified that investigated RT frequency in accordance with the criteria outlined. Results Analysis using binary frequency as a predictor variable revealed a significant impact of training frequency on hypertrophy effect size (P = 0.002), with higher frequency being associated with a greater effect size than lower frequency (0.49 ± 0.08 vs. 0.30 ± 0.07, respectively). Statistical analyses of studies investigating training session frequency when groups are matched for frequency of training per muscle group could not be carried out and reliable estimates could not be generated due to inadequate sample size. Conclusions When comparing studies that investigated training muscle groups between 1 to 3 days per week on a volume-equated basis, the current body of evidence indicates that frequencies of training twice a week promote superior hypertrophic outcomes to once a week. It can therefore be inferred that the major muscle groups should be trained at least twice a week to maximize muscle growth; whether training a muscle group three times per week is superior to a twice-per-week protocol remains to be determined.
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Skeletal muscle mass is regulated by a balance between muscle protein synthesis (MPS) and muscle protein breakdown (MPB). In healthy humans, MPS is more sensitive (varying 4–5 times more than MPB) to changes in protein feeding and loading rendering it the primary locus determining gains in muscle mass. Performing resistance exercise (RE) followed by the consumption of protein results in an augmentation of MPS and, over time, can lead to muscle hypertrophy. The magnitude of the RE-induced increase in MPS is dictated by a variety of factors including: the dose of protein, source of protein, and possibly the distribution and timing of post-exercise protein ingestion. In addition, RE variables such as frequency of sessions, time under tension, volume, and training status play roles in regulating MPS. This review provides a brief overview of our current understanding of how RE and protein ingestion can influence gains in skeletal muscle mass in young, healthy individuals. It is the goal of this review to provide nutritional recommendations for optimal skeletal muscle adaptation. Specifically, we will focus on how the manipulation of protein intake during the recovery period following RE augments the adaptive response.
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Resistance exercise training (RET) is widely used to increase muscle mass in athletes and also aged/cachectic populations. However, the time course and metabolic and molecular control of hypertrophy remain poorly defined. Using newly developed deuterium oxide (D2O)-tracer techniques, we investigated the relationship between long-term muscle protein synthesis (MPS) and hypertrophic responses to RET. A total of 10 men (2361 yr) undertook 6 wk of unilateral (1-legged) RET [6 x 8 repetitions, 75% 1 repetition maximum (1-RM) 3/wk], rendering 1 leg untrained (UT) and the contralateral, trained (T). After baseline bilateral vastus lateralis (VL) muscle biopsies, subjects consumed 150 ml D2O (70 atom percentage; thereafter 50 ml/wk) with regular body water monitoring in saliva via high-temperature conversion elemental analyzer:isotope ratio mass spectrometer. Further bilateral VL muscle biopsies were taken at 3 and 6 wk to temporally quantify MPS via gas chromatography: pyrolysis: isotope ratio mass spectrometer. Expectedly, only the T leg exhibited marked increases in function [i.e., 1-RM/maximal voluntary contraction (60 degrees)] and VL thickness (peaking at 3 wk). Critically, whereas MPS remained unchanged in the UT leg (e.g., similar to 1.35 +/- 0.08%/d), the T leg exhibited increased MPS at 0-3wk(1.6 +/- 0.01%/d), but not at3-6wk(1.29 +/- 0.11%/d); this was reflected by dampened acute mechanistic target of rapamycin complex 1 signaling responses to RET, beyond 3 wk. Therefore, hypertrophic remodeling is most active during the early stages of RET, reflecting longer-term MPS. Moreover, D2O heralds promise for coupling MPS and muscle mass and providing insight into the control of hypertrophy and efficacy of anabolic interventions.
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The purpose of this study was to investigate the effects of training muscle groups 1 day per week using a split-body routine versus 3 days per week using a total-body routine on muscular adaptations in well-trained men. Subjects were 20 male volunteers (height = 1.76 ± 0.05 m; body mass = 78.0 ± 10.7 kg; age = 23.5 ± 2.9 years) recruited from a university population. Participants were pair-matched according to baseline strength and then randomly assigned to 1 of 2 experimental groups: a split-body routine (SPLIT) where multiple exercises were performed for a specific muscle group in a session with 2-3 muscle groups trained per session (n = 10), or; a total-body routine (TOTAL), where 1 exercise was performed per muscle group in a session with all muscle groups trained in each session (n = 10). Subjects were tested pre- and post-study for 1 repetition maximum strength in the bench press and squat, and muscle thickness of forearm flexors, forearm extensors, and vastus lateralis. Results showed significantly greater increases in forearm flexor muscle thickness for TOTAL compared to SPLIT. No significant differences were noted in maximal strength measures. The findings suggest a potentially superior hypertrophic benefit to higher weekly resistance training frequencies.
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The goal of the current work was to profile positive (mTORC1 activation, autocrine/paracrine growth factors) and negative [AMPK, unfolded protein response (UPR)] pathways that might regulate overload-induced mTORC1 activation with the hypothesis that a number of negative regulators of mTORC1 will be engaged during a supra-physiological model of hypertrophy. To achieve this, mTORC1-IRS1/2 signaling, BiP/CHOP/IRE1α, and AMPK activation were determined in rat plantaris muscle following synergist ablation (SA). SA resulted in significant increases in muscle mass of ~4% per day throughout the 21 days of the experiment. The expression of the insulin-like growth factors were high throughout the 21d of overload. However, IGF signaling was limited since IRS1 and 2 were undetectable in the overloaded muscle from day 3 to day 9. The decreases in IRS1/2 protein were paralleled by increases in GRB10(Ser501/503) and S6K1(Thr389) phosphorylation, two mTORC1 targets that can destabilize IRS proteins. PKB(Ser473) phosphorylation was higher from 3-6 days and this was associated with increased TSC2(Thr939) phosphorylation. The phosphorylation of TSC2(Thr1345) (an AMPK site) was also elevated whereas phosphorylation at the other PKB site, Thr(1462), was unchanged at 6d. In agreement with the phosphorylation of Thr(1345), synergist ablation led to activation of α1-AMPK during the initial growth phase, lasting the first 9 days before returning to baseline by day 12. The UPR markers CHOP and BiP were elevated over the first 12 days following ablation, whereas IRE1α levels decreased. These data suggest that during supra-physiological muscle loading, at least three potential molecular brakes engage to down-regulate mTORC1.
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Aim: The purpose of the present study was to compare the effects of equal-volume resistance training (RT) performed once or twice a week on muscle mass and strength of the elbow flexors in untrained young men. Methods: Thirty men (23 ± 3 years) without previous resistance training experience were divided into two groups: Group 1 (G1) trained each muscle group only once a week and group 2 (G2) trained each muscle twice a week during 10 weeks. Baseline and 10 weeks post-test elbow flexors muscle thickness (MT) were measured using a B-Mode ultrasound. Peak torque (PT) was assessed by an isokinetic dynamometer before and after the training program. Results: Elbow flexors MT increased significantly (P<0.05) from 31.70 ± 3.31 to 33.43 ± 3.46 mm in G1, and from 32.78 ± 4.03 to 35.09 ± 3.55 mm in G2. Elbow flexors PT also increased (P<0.05) from 50.77 ± 9.26 to 54.15 ± 10.79 N.m in G1, and from 48.99 ± 11.52 to 55.29 ± 10.24 N.m in G2. The results of ANOVA did not reveal group by time interactions for any variable, indicating no difference between groups for the changes in MT or PT. Conclusion: The results from the present study suggest that untrained men experience similar gains in muscle mass and strength with equal volume RT performed one or two days per week.
Article
The purpose of this study was to determine the effect strength training frequency has on improvements in lean mass and strength. Participants were 7 women and 12 men, age (χ̄= 34.64 years ± 6.91 years), with strength training experience, training age (χ̄= 51.16 months ± 39.02 months). Participants were assigned to one of two groups to equal baseline group demographics. High frequency training group (HFT) trained each muscle group as the agonist, 3 times per week, exercising with 3 sets per muscle group per session (3 total body workouts). Low frequency training group (LFT) trained each muscle group as the agonist one time per week, completing all 9 sets during that one workout. LFT consisted of a routine split over three days: 1) pectoralis, deltoids, and triceps; 2) upper back and biceps; 3) quadriceps, hamstrings, calves, and abdominals. Following eight weeks of training, HFT increased lean mass by 1.06 kg ± 1.78 kg, (1.9%), and LFT increased lean mass by .99 kg ± 1.31 kg, (2.0%). HFT strength improvements on the chest press was 9.07 kg ± 6.33 kg, (11%), and hack squat 20.16 kg ± 11.59 kg, (21%). LFT strength improvements on chest press was 5.80kg ± 4.26 kg, (7.0%), and hack squat 21.83 kg ± 11.17 kg, (24 %). No mean differences between groups were significant. These results suggest that HFT and LFT of equal set totals result in similar improvements in lean mass and strength, following 8 weeks of strength training.
Article
Muscle protein synthesis (MPS) is stimulated by resistance exercise (RE) and is further stimulated by protein ingestion. The summation of periods of RE-induced increases in MPS can induce hypertrophy chronically. As such, studying the response of MPS with resistance training (RT) is informative, as adaptations in this process can modulate muscle mass gain. Previous studies have shown that the amplitude and duration of increases in MPS after an acute bout of RE are modulated by an individual's training status. Nevertheless, it has been shown that the initial responses of MPS to RE and nutrition are not correlated with subsequent hypertrophy. Thus, early acute responses of MPS in the hours after RE, in an untrained state, do not capture how MPS can affect RE-induced muscle hypertrophy. The purpose of this review is provide an in-depth understanding of the dynamic process of muscle hypertrophy throughout RT by examining all of the available data on MPS after RE and in different phases of an RT programme. Analysis of the time course and the overall response of MPS is critical to determine the potential protein accretion after an RE bout. Exercise-induced increases in MPS are shorter lived and peak earlier in the trained state than in the untrained state, resulting in a smaller overall muscle protein synthetic response in the trained state. Thus, RT induces a dampening of the MPS response, potentially limiting protein accretion, but when this occurs remains unknown.