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Equal-Volume Strength Training With Different Training Frequencies Induces Similar Muscle Hypertrophy and Strength Improvement in Trained Participants

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The main goal of the current study was to compare the effects of volume-equated training frequency on gains in muscle mass and strength. In addition, we aimed to investigate whether the effect of training frequency was affected by the complexity, concerning the degrees of freedom, of an exercise. Participants were randomized to a moderate training frequency group (two weekly sessions) or high training frequency group (four weekly sessions). Twenty-one participants (male: 11, female: 10, age: 25.9 ± 4.0) completed the 9-week whole-body progressive heavy resistance training intervention with moderate (n = 13) or high (n = 8) training frequency. Whole-body and regional changes in lean mass were measured using dual-energy x-ray absorptiometry, while the vastus lateralis thickness was measured by ultrasound. Changes in muscle strength were measured as one repetition maximum for squat, hack squat, bench press, and chest press. No differences between groups were observed for any of the measures of muscle growth or muscle strength. Muscle strength increased to a greater extent in hack squat and chest press than squat and bench press for both moderate (50 and 21% vs. 19 and 14%, respectively) and high-frequency groups (63 and 31% vs. 19 and 16%, respectively), with no differences between groups. These results suggest that training frequency is less decisive when weekly training volume is equated. Further, familiarity with an exercise seems to be of greater importance for strength adaptations than the complexity of the exercise.
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ORIGINAL RESEARCH
published: 05 January 2022
doi: 10.3389/fphys.2021.789403
Edited by:
Helmi Chaabene,
University of Potsdam, Germany
Reviewed by:
Brad Schoenfeld,
Lehman College, United States
Matt S. Stock,
University of Central Florida,
United States
*Correspondence:
Håvard Hamarsland
Havard.hamarsland@inn.no
Specialty section:
This article was submitted to
Exercise Physiology,
a section of the journal
Frontiers in Physiology
Received: 04 October 2021
Accepted: 03 December 2021
Published: 05 January 2022
Citation:
Hamarsland H, Moen H,
Skaar OJ, Jorang PW, Rødahl HS and
Rønnestad BR (2022) Equal-Volume
Strength Training With Different
Training Frequencies Induces Similar
Muscle Hypertrophy and Strength
Improvement in Trained Participants.
Front. Physiol. 12:789403.
doi: 10.3389/fphys.2021.789403
Equal-Volume Strength Training With
Different Training Frequencies
Induces Similar Muscle Hypertrophy
and Strength Improvement in Trained
Participants
Håvard Hamarsland*, Hermann Moen, Ole Johannes Skaar, Preben Wahlstrøm Jorang,
Håvard Saeterøy Rødahl and Bent R. Rønnestad
Section for Health and Exercise Physiology, Inland Norway University of Applied Sciences, Lillehammer, Norway
The main goal of the current study was to compare the effects of volume-equated
training frequency on gains in muscle mass and strength. In addition, we aimed to
investigate whether the effect of training frequency was affected by the complexity,
concerning the degrees of freedom, of an exercise. Participants were randomized to
a moderate training frequency group (two weekly sessions) or high training frequency
group (four weekly sessions). Twenty-one participants (male: 11, female: 10, age:
25.9 ±4.0) completed the 9-week whole-body progressive heavy resistance training
intervention with moderate (n= 13) or high (n= 8) training frequency. Whole-body and
regional changes in lean mass were measured using dual-energy x-ray absorptiometry,
while the vastus lateralis thickness was measured by ultrasound. Changes in muscle
strength were measured as one repetition maximum for squat, hack squat, bench press,
and chest press. No differences between groups were observed for any of the measures
of muscle growth or muscle strength. Muscle strength increased to a greater extent in
hack squat and chest press than squat and bench press for both moderate (50 and 21%
vs. 19 and 14%, respectively) and high-frequency groups (63 and 31% vs. 19 and 16%,
respectively), with no differences between groups. These results suggest that training
frequency is less decisive when weekly training volume is equated. Further, familiarity
with an exercise seems to be of greater importance for strength adaptations than the
complexity of the exercise.
Keywords: skeletal muscle, resistance training, training frequency, hypertrophy, strength, trained individuals
INTRODUCTION
Resistance training is an essential tool in the pursuit of athletic performance (McGuigan et al.,
2012) and for improving health (El-Kotob et al., 2020). To optimize the effects of resistance
training, the manipulation of several factors, primarily training volume, load, and frequency,
is central (American College of Sports Medicine, 2009). The current recommendations on
training frequency, defined as the number of sets or training sessions on a given muscle group
performed within a given timeframe, have been criticized for being based on limited evidence
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Hamarsland et al. Training Frequency in Trained Individuals
(Grgic et al., 2018;Ralston et al., 2018;Schoenfeld et al., 2019).
The latest meta-analyses suggest a limited role for training
frequency, given that the weekly training volume is kept identical
between groups (Grgic et al., 2018;Ralston et al., 2018;Schoenfeld
et al., 2019). However, in the current literature, studies isolating
frequency by keeping total weekly volume matched between
groups are limited; most include untrained participants and
compare training frequencies of one to three sessions per week.
As trained individuals are more likely to have greater training
frequencies than less trained individuals, and the frequencies
used are likely to be greater than those investigated in most
studies (Strömbäck et al., 2018), a need for more research on this
group has been expressed (Grgic et al., 2018;Ralston et al., 2018).
To our knowledge, there are ten published studies on volume
equated resistance training frequency in trained individuals
published to date (McLester et al., 2000;Schoenfeld et al., 2015;
Brigatto et al., 2018;Colquhoun et al., 2018;Gentil et al., 2018;
Gomes et al., 2019;Lasevicius et al., 2019;Saric et al., 2019;
Zaroni et al., 2019;Johnsen and van den Tillaar, 2021). Five of
these studies have focused on higher frequencies than 3 days per
week (Colquhoun et al., 2018;Gomes et al., 2019;Saric et al.,
2019;Zaroni et al., 2019;Johnsen and van den Tillaar, 2021).
Zaroni et al. (2019) reported greater muscle hypertrophy but no
differences in strength gain when comparing one (lower body)
and two (upper body) weekly sessions with five sessions per week
in young, trained men. Apart from this study, there seems to be
no difference in muscular adaptations when comparing one and
five (Gomes et al., 2019), two and four (Johnsen and van den
Tillaar, 2021), or three and six (Colquhoun et al., 2018;Saric et al.,
2019) weekly training sessions in young trained men.
Although the current evidence for a beneficial effect of higher
training frequencies in trained individuals is weak, it is based on
small studies with limited power to detect small but meaningful
differences between protocols. Thus, there is a need for more data
to be able to make precise and evidence-based recommendations.
In addition, there are several theoretical advantages to increased
training frequency. The protein synthetic response to a training
stimulus is considered to last for at least 24–48 h after a
bout of resistance exercise in untrained individuals (MacDougall
et al., 1995;Phillips et al., 1997;Burd et al., 2011). A higher
training frequency may therefore allow for more time with a
net positive protein balance and greater muscular adaptations to
resistance training. In contrast to untrained individuals, exercise-
induced elevations of protein synthesis appear to last only about
24 h after resistance exercise in resistance-trained individuals
(Damas et al., 2015). Thus, the advantages of higher training
frequencies may increase with training status. Further, it has
been suggested that distributing training volume across several
days may reduce fatigue during the sessions (Dankel et al., 2016)
and reduce recovery time between sessions (Pareja-Blanco et al.,
2020). This may allow for greater training loads, potentially
resulting in superior muscular adaptations to resistance training.
Lastly, more frequent neuromuscular stimuli may optimize
motor learning, increasing strength through neurological factors
(Shea:2000dt). This may be more pronounced in complex multi-
joint, free weight lifts, with greater degrees of freedom, compared
with simpler single joint or machine-based exercises. Although
neurological adaptations are primarily expected to occur at the
beginning of training, antagonist inhibition has been shown to
improve also after years of exercise (Balshaw et al., 2019). To the
best of our knowledge, no study has yet explored whether exercise
complexity influences the potential benefits of training frequency
in trained individuals.
Therefore, the current study aimed to compare the effects of
two and four weekly volume equated heavy resistance training
sessions on gains in muscle mass and -strength in resistance-
trained men and women. Further, we investigated whether the
effect of training frequency was influenced by the complexity of
the exercises. We hypothesized that a volume equated weekly
training frequency of four sessions per week would result
in greater muscular adaptations and strength gains than two
sessions per week. We further hypothesized that the benefits of
a higher training frequency would be greater in more complex
exercises (squat and bench press) compared to less complex
exercises (hack squat and chest press).
MATERIALS AND METHODS
Ethical Approval
The study was performed according to the ethical standards
established by the Declaration of Helsinki 2013 and was
approved by the Local Ethical Committee at the Inland Norway
University of Applied Sciences (20/03749) and pre-registered in
a Norwegian public database (Norwegian Center for Research,
project number 300667). All participants signed an informed
consent form before participation.
Participants
Thirty-four moderately resistance-trained men and women
volunteered to participate in the study. To be included in the
study, participants had to be between 18 and 35 years of age,
free of injury, performed one resistance-training workout per
week on average over the last 6 months, and be familiar with the
powerlifting exercises squat and bench press. Participants were
randomized into a high-frequency group (HF) (n= 17) and a
low-frequency group (LF) (n= 17) stratified by sex, age, years of
resistance training experience, and 1 repetition maximum (RM)
results from the first test. Participants who had more than 10 days
without a workout or were not able to complete 95% of the
planned sets were excluded (n= 3). Due to the ongoing sars-
CoV-2 pandemic, the number of participants who were allowed
to exercise simultaneously was controlled and training times were
strict. Participants who were unable to attend these times, due to
quarantine (n= 3) or sars-CoV-2 infection (n= 1), were excluded
(n= 3). Three participants were unable to complete the study due
to injuries and three participants dropped out of the study due
to personal reasons. Thus, 21 participants were included in the
analysis (HF: n= 8, LF:n= 13).
Experimental Design
The intervention consisted of a 9-week training period (see
Table 1). While the total amounts of weekly sets and training
load (RM) were identical, the HF and LF groups performed
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TABLE 1 | Training protocol.
Group Day 1 exercise: sets Day 2 exercise: sets Day 3 exercise: sets Day 4 exercise: sets Total weekly sets Repetitions and load
High
frequency
Squat: 2 Hack squat: 2 Squat: 2 Hack squat: 2 First workout: 70%
1RM Week 1–3: 12RM
Week 4–6: 10RM Week
7–9: 8RM
Hack squat: 1 Squat: 1 Hack squat: 1 Squat: 1
Bench press: 2 Chest press: 2 Bench press: 2 Chest press: 2
Chest press: 1 Bench press: 1 Chest press: 1 Bench press: 1
Lat pulldowns: 2 Seated row: 2 Lat pulldowns: 2 Seated row: 2
Total workout
sets
8 8 8 8 32
Low
frequency
Squat: 4 Hack squat: 4
Hack squat: 2 Squat: 2
Bench press: 4 Chest press: 4
Chest press: 2 Bench press: 2
Lat pulldowns: 4 Seated row: 4
Total workout
sets
16 16 32
4 and 2 sessions per week, respectively. Thus, HF performed
half the training volume of the LF per workout. The training
period was divided into three blocks based on RM number: week
1–3: 12RM, week. If failure was reached before the intended
repetition range, the resistance was quickly reduced to allow
for the remaining repetitions to be completed. If participants
were able to complete more than the intended repetitions the
set was performed to failure and the resistance was increased
at the next set. Each week, the exercise order was rotated to
balance the number of workouts, starting with a more complex
exercise (squat and bench press) and a less complex exercise
(hack squat and chest press in a machine). Four minutes of rest
was given between each set. To equate the warm-up sets across
each week, LF performed two sets (12 reps of 30% 1RM and 12
reps of 50% 1RM), whereas HF performed four sets (2×12 reps
of 30% 1RM and 2×12 reps of 50% 1RM). There was a strong
focus on completing all sets in every workout. All sessions were
supervised by trained personnel. To counteract a potential effect
of differences in protein intake participants were provided 20 g of
whey protein mixed in water after each workout. To balance the
protein supplementation, the protein was also ingested the day
after workouts in the low-frequency group. Before and after the
training period, participants performed a set of 1RM tests (squat,
hack squat, bench press, and chest press) and underwent a dual-
energy x-ray absorptiometry scan (DXA) and an ultrasound scan
of the vastus lateralis muscle from both legs.
Testing Procedures
The participants were instructed to avoid exercise and strenuous
physical activity for 48 h before all tests. Instructional videos
explaining the 1RM testing procedures were emailed to and
watched by all participants before testing. Before the 1RM test,
participants warmed up for 5 min on a rowing ergometer
(Concept 2 inc., Vermont, VT, United States) with an intensity
of 9–11 on the 6–20 Borg-scale (Borg, 1982), followed by two
sets of 20 walking lunges and two sets of 10 shoulder rotations
using a wooden dowel. On the first 1RM test, individual settings
were established for each participant, and identical settings were
used on subsequent testing. The 1RM tests were performed by
completing single repetitions with increasing load and 4 min
of rest between each repetition. The goal was to reach 1RM
on the tenth repetition. After attaining 1RM for squat and
bench press, participants had a 30-min break with a small meal
before completing the 1RM tests for hack squat and chest press.
The meal was identical at all 1RM tests within an individual
participant but differed between participants. The squat and
bench press were performed in a Tteka BN-02 combo (TTEKA
company, Montreal, QC, Canada). The execution of the squat
and bench press was performed according to the standardization
of the International Powerlifting Federation (2021) technical
rules, except the grip width in the bench press, which was set
to be 81 cm from the fifth finger to the fifth finger. The hack
squat was performed in a Cybex International Hack Squat (Cybex
International, Inc., Massachusetts, MA, United States). Joint
angles were measured using a goniometer. The correct depth was
set as a hip joint angle of 90and a knee joint angle smaller
than 90. Foot placement was adjusted to 22.5, 27.5 (middle of
the plate), or 32.5 cm to achieve the intended hip and knee
angles. The correct depth for each participant was noted on a
vertical measuring band attached to the hack squat. Chest press
was performed in a Cybex Converging Plate Loaded Chest Press
(Cybex International, Inc., Massachusetts, MA, United States).
The chest press started with arms in the extended position and
was finished with arms returned to the extended position. A band
was attached between the handles, and an accepted 1RM required
the band to touch the chest at proc. xiphoideus. During the lift,
the whole foot remained in contact with the floor, the buttocks
in contact with the seat and the back, shoulder blades, and
head in contact with the back support. A test leader controlled
all 1RM attempts.
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FIGURE 1 | Weekly training volume (A) and average load (B) with 2 (LF) and 4 (HF) weekly sessions during a 9-week resistance training intervention.
Body composition was determined using a dual-energy
x-ray absorptiometry (DXA) (Lunar Prodigy, GE Healthcare,
Madison, WI, United States) after an overnight fast and was
analyzed following the protocol of the manufacturer, using the
software of the manufacturer. The participants were placed in
the supine position with a neutral neck position. Hands were
semi-pronated and arms were placed close to the border of
the measurement area to simplify the post-scan measurements.
The foot position was standardized in a neutral position using
a foam rubber cast (10 cm between heels) with negligible
absorbance. Regions of interest were used to analyze different
body regions. Dividing lines between arms and thorax were
drawn through the glenohumeral joint. Dividing lines between
the thorax and legs were drawn midway through the femoral neck
at a 90-degree angle to the femoral neck. All DXA scans were
performed by a researcher blinded to subject randomization.
The intraclass correlation (ICC) for lean body mass in our lab
is 0.99. The muscle thickness of m. vastus lateralis of both legs
were measured using B-mode ultrasonography (SmartUs EXT-1
M, Telemed, Vilnius, Lithuania) with a 39 mm 12 MHz, linear
array probe. Image depth was set to 8 cm, frequency to 12 Hz,
the dynamic range was set to 72 dB, and the gain was set to
43%. Longitudinal images were obtained 50% distally from the
trochanter major toward the femoral lateral epicondyle. Three
images were captured before and after the training intervention.
The probe’s position was marked on the skin and subsequently
marked on a soft transparent plastic sheet superimposed on the
thigh. Landmarks such as moles and scars were also marked on
the plastic sheet for relocation of the probe during post-training
measurements. Furthermore, pre-test images were used to locate
anatomical landmarks on the post-test images to ensure the
same measuring location. During analysis, pre and post-images
from the same participant were analyzed consecutively using the
Fiji software macro tool “Simple Muscle Architecture Analysis”
(Seynnes and Cronin, 2020). The average muscle thickness of the
three images from each leg was averaged, and the average of both
legs at the given time point was used for further analyses. All
ultrasound measures were performed by a researcher blinded to
subject randomization. ICC for ultrasound measures of vastus
lateralis in our lab is 0.96. After the training period, the DXA
and ultrasound were measured between 48 and 96 h after the last
training session.
Statistical Analysis
Statistical analyses were performed using jamovi (version 1.6.23.0
for mac; the jamovi project, retrieved from www.jamovi.org)
and GraphPad Prism (version 9.2.0 for mac; GraphPad Software,
La Jolla, CA, United States). The effect of HF vs. LF on
study variables was analyzed using ANCOVA, with post-
intervention outcomes as dependent variables and baseline
values and sex as covariates. Pearson’s correlation coefficients
(r) were calculated for changes in 1RM and lean mass.
The effect of HF vs. LF in simple and complex exercises
and training volume and load were analyzed by a two-
way ANOVA with repeated measures. Furthermore, the effect
size (ES) was calculated as Cohen’s dusing the mean pre-
post change in HF minus the mean pre-post change in LF,
divided by the pooled pre-test standard deviation (Morris,
2008). Outcomes are reported with standard deviation unless
otherwise specified. A two-tailed P-value less than 0.05 was
considered significant.
RESULTS
Muscle Strength
The weekly training volume and load are displayed in Figure 1.
Both groups improved 1RM in squat (HF: 16.3 ±5.2 kg,
LF: 14.8 ±4.2 kg), hack squat (HF: 33.4 ±13.9 kg, LF:
34.4 ±9.7), bench press (HF: 7.5 ±3.5, LF: 7.7 ±3.0 kg),
and chest press (HF: 15.9 ±13.8 kg, LF: 15.0 ±5.0 kg)
during the training intervention. The improvements in
1RM did not differ between groups (see Table 2 and
Figure 2).
Lean Mass and Muscle Thickness
Lean mass (HF: 1.14 ±2.0 kg, LF: 1.46 ±1.38 kg), lean
leg mass (HF:0.35 ±0.79 kg, LF:0.64 ±0.63 kg), lean trunk
mass (HF:0.41 ±1.17 kg, LF:0.66 ±0.93 kg), lean arm mass
(HF:0.38 ±0.40 kg, LF:0.18 ±0.24 kg), and vastus lateralis
thickness (HF:0.51 ±0.22 cm, LF:0.48 ±0.18) improved in
both groups. There were no differences between groups for
any of the measures of muscle growth (see Table 2 and
Figure 1).
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TABLE 2 | Comparisons between groups are based on estimated marginal
means.
ANCOVA HF vs. LF
Mean effect PES 95% CI
Lean mass total 0.1 kg 0.897 0.07 1.09 to 0.97
Lean mass legs 0.4 kg 0.296 0.54 1.61to 0.54
Lean mass trunk 0.0 kg 0.969 0.02 0.99 to 1.04
Lean mass arms 0.2 kg 0.210 0.61 0.41 to 1.63
VL thickness 0.00 cm 0.950 0.03 1.01 to 0.95
1RM total 5.5 kg 0.637 0.3 0.79 to 1.25
1RM squat 4.2 kg 0.192 0.69 0.41 to 1.79
1RM hack squat 1.27 kg 0.824 0.11 1.11 to 0.89
1RM bench press 0.7 kg 0.676 0.20 0.80 to 1.21
1RM chest press 2.7 kg 0.554 0.26 0.74 to 1.26
FIGURE 2 | Percent changes in one repetition maximum for squat, hack
squat, bench press, and chest press. Horizontal lines are averages with error
bars representing SD. #Difference between simple and complex exercises,
p<0.05.
Complex vs. Simpler Exercises
The hack squat 1RM (HF: 62.5 ±48.8%, LF: 50.2 ±23.6%)
increased more in relative terms than the squat 1RM (HF:
19.1 ±10.3%, LF: 18.7 ±8.6%) in both groups (P<0.01 for both).
Chest press 1RM increased more in relative terms than bench
press 1RM in HF (31.2 ±27.9% and 15.8 ±11.5%, respectively,
P= 0.011) but not in LF (13.8 ±7.4% and 21.3 ±7.8%,
respectively, P= 0.171). Combining both groups 1RM in the less
complex exercises increased more than more complex exercises
(Lower body: 18.9 ±10.7% vs. 54.9 ±36.3%, P<0.00; Upper
body: 14.6 ±9.9% vs. 25.0 ±20.2%, P= 0.001). The differences
between squat and hack squat, and bench press and chest press
did not differ between groups. There was a significant correlation
between changes in 1RM for all exercises (squat hack squat:
r= 0.64, squat bench press: r= 0.83, squat chest press: r= 0.69,
hack squat bench press: r= 0.74, hack squat chest press:
r= 0.73, bench press chest press: r= 0.78, p>0.001 for all).
There were no significant correlations between changes in muscle
strength and changes in muscle mass.
DISCUSSION
The current study found that in moderately resistance-trained
individuals distributing weekly resistance training volume into
two or four workouts did not result in different outcomes for
1RM, lean mass, or vastus lateralis thickness. Further, muscle
strength in complex exercises does not benefit more from a higher
training frequency than in simpler exercises.
In line with most previous studies, weekly training frequency
seems to be subordinate to training volume in terms of increasing
muscle mass, given training volume is kept identical within each
week (Colquhoun et al., 2018;Gomes et al., 2019). Our finding
goes against the theoretical benefit of multiple upregulations
of stimulating protein synthesis and thus increased anabolic
stimulus with an increased frequency. This could result from
a suboptimal training stimulus when the training volume was
distributed across 4 days. However, previous studies suggest that
relatively small training volumes can produce a robust muscle
protein synthetic response in resistance-trained and active
individuals (Burd et al., 2010, 2011). Several recent contributions
may help shed more light on this discrepancy. Evidence suggests
that volume-sensitive long-term adaptations of translational
capacity, rather than repeated acute changes in translational
efficiency, are associated with hypertrophy (Figueiredo, 2019;
Hammarström et al., 2020). This is further supported by the lack
of measurable differences in myofibrillar protein synthesis over
7 days with a matched training volume distributed across one or
five workouts (Shad et al., 2021). Alternatively, the manipulation
of resistance training variables may be secondary to other
intrinsic factors. At least when a sufficient stimulus is provided,
as suggested by Damas et al. (2019) who elegantly displayed
remarkable stability within individuals despite manipulating
resistance training variables, in contrast to a substantial between-
individual variability.
It has been suggested that an increased training frequency may
enhance neural adaptations to a greater extent in more complex
exercises compared with simple exercises (Shea et al., 2000).
Given a more complex movement pattern, we expected strength
in squat and bench press to increase more compared with hack
squat and chest press in the HF group when compared with the
LF group. To the best of our knowledge, this is the first study
to investigate this effect from a resistance training perspective.
Contrary to our hypothesis, 1RM increased more in the less
complex exercises. The difference was surprisingly large given
the exercises had similar movement patterns and were trained
with the same weekly volume. This is possibly explained by the
participants having considerably more experience with squat and
bench press than hack squat and chest press (see Table 3). Thus,
our data suggest familiarity with an exercise to be of greater
importance than the complexity of the exercise when it comes to
improvements in muscle strength.
Although the relative changes in 1RM differed between
similar exercises, we observed moderate to strong correlations
between these changes in all measured exercises. This may
suggest that changes in e.g., both squat and hack squat 1RM
to a large extent, should represent changes in leg strength as a
phenomenon. However, as these correlations exist between all
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TABLE 3 | Descriptive data of participants before and after 9 weeks of heavy
resistance exercise.
Characteristic HF pre HF post LF pre LF post
N (/) 3/5 3/5 8/5 8/5
Age (years) 26.8 ±3.9 25.5 ±4.3
Body mass (kg) 80.7 ±15.7 74.6 ±12.8
Lean mass (kg) 53.7 ±12.4 54.8 ±12.4 53.7 ±9.4 55.2 ±12.1
Lean mass legs (kg) 18.5 ±4.7 18.9 ±4.4 18.2 ±3.1 18.8 ±4.4
Lean mass trunk (kg) 25.9 ±5.5 26.3 ±5.5 25.9 ±4.8 26.6 ±4.7
Lean mass arms (kg) 6.1 ±2.2 6.4 ±2.2 6.4 ±1.6 6.6 ±1.7
Body fat (%) 31.9 ±4.9 31.6 ±4.3 25.1 ±6.9 24.4 ±6.0
Vastus lateralis
thickness (cm)
2.4 ±0.5 2.9 ±0.4 2.6 ±0.4 3.1 ±0.4
Squat 1RM (kg) 106 ±56 122 ±56 96 ±37 110 ±34
Hack squat 1RM (kg) 88 ±61 122 ±57 89 ±52 123 ±53
Bench press 1RM (kg) 70 ±42 78 ±40 70 ±31 78 ±30
Chest press 1RM (kg) 93 ±67 108 ±60 97 ±52 112 ±49
Weekly sessions squat 1.5 ±0.9 1.3 ±0.8
Weekly sessions hack
squat
0.3 ±0.9 0 ±0
Weekly sessions bench
press
1.2 ±1.1 1.2 ±0.9
Weekly sessions chest
press
0.5 ±0.9 0.6 ±0.6
Resistance training age
(years)
3.6 ±2.2 3.5 ±1.3
Weekly sessions are an estimate of the weekly average number of sessions
including the exercise over the last 6 months. Values are average ±SD.
measured exercises, they may well be driven by the training state
of the participants. It is expected that the weaker participants will
improve more for all exercises during the training intervention.
Accordingly, the baseline 1RM performance did correlate
negatively with changes in 1RM during the intervention (from
0.83 to 0.94, p<0.001 for all measures). Strength is often
considered a relatively universal trait. However, the present and
previous data (Harris et al., 2007) suggest that a significant part
of improvements in strength are specific to the given exercise
and may differ significantly between similar exercises trained
identically over a training period.
The current study has several strengths, among these a full
supervision of all workouts, a 100% attendance, and a direct
measure of muscle growth. However, it shares the limitation of
a relatively short intervention period with the rest of the current
training frequency literature in trained individuals. Even with a
3-week cutback, due to corona restrictions, the current 9-week
study is longer than the previous 6- to 8-week interventions
(Colquhoun et al., 2018;Gomes et al., 2019;Zaroni et al.,
2019;Johnsen and van den Tillaar, 2021). Training protocols
with equated training volume, but different training frequencies
are not expected to result in large differences in adaptations.
Consequently, longer interventions may be needed to discern
differences between them. Measures of muscle thickness were
only obtained at one point along the vastus lateralis. Previous
studies have shown non-uniform hypertrophy in the quadriceps
in response to resistance exercise (Narici et al., 1996). Recently,
drop sets were reported to induce greater gains in hypertrophy
for the rectus femoris, but not vastus lateralis, compared with
traditional resistance exercise training (Varovi´
c et al., 2021).
Consequently, we cannot exclude the possibility of regional
differences in hypertrophy within or between muscles. Still,
any potential regional differences were not large enough to be
observed with the DXA measures. Given the large intraindividual
variability and limited resources, a unilateral approach to further
investigate the effects of training frequency seems sensible, at
least for muscle growth where cross-learning is unlikely to occur
(MacInnis et al., 2017). Furthermore, if two exercise regimens
are compared in a contralateral manner in resistance-trained
individuals, it is our belief that potential cross-learning effects on
strength too will be minimal.
CONCLUSION
In conclusion, the current study did not show an effect of
resistance training frequency on changes in muscle strength and
muscle growth when weekly resistance training volume was kept
identical in moderately resistance-trained individuals. Further,
higher resistance training frequency did not result in greater
improvements in strength for complex exercises compared to
simpler exercises.
DATA AVAILABILITY STATEMENT
The raw data supporting the conclusions of this article will be
made available by the authors, without undue reservation.
ETHICS STATEMENT
The studies involving human participants were reviewed
and approved by the Local Ethical Committee at Inland
Norway University of Applied Sciences (20/03749). The
patients/participants provided their written informed consent to
participate in this study.
AUTHOR CONTRIBUTIONS
HH, HM, OS, PJ, HR, and BR contributed to the conception and
design of the study. HM, OS, PJ, and HR conducted the training
intervention. HH, HM, OS, PJ, and HR performed the testing.
HH wrote the first draft of the manuscript. HM, OS, PJ, HR, and
BR wrote sections of the manuscript. All authors contributed to
manuscript revision, read, and approved the submitted version.
ACKNOWLEDGMENTS
The authors would like to thank Berit Hauge Aakvik for help
with the ultrasound and DXA scans during testing. Big thanks is
also extended to Spenst Arena Lillehammer for training facilities,
access to members, and being flexible and accommodating covid-
restrictions allowing the completion of the study.
Frontiers in Physiology | www.frontiersin.org 6January 2022 | Volume 12 | Article 789403
fphys-12-789403 December 28, 2021 Time: 17:1 # 7
Hamarsland et al. Training Frequency in Trained Individuals
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Conflict of Interest: The authors declare that the research was conducted in the
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... Most of the previous studies that have compared different training frequencies with an equal number of sets per week reported no statistical or magnitude differences in strength and hypertrophy between the intervention groups (Arazi et al., 2011;Benton et al., 2011;Brigatto et al., 2019;Candow et al., 2007;Hamarsland et al., 2022;Johnsen et al., 2021;Neves et al., 2022;Ochi et al., 2018;Saric et al., 2019;Yue et al., 2018). Consequently, meta-analyses and systematic reviews have concluded that weekly training frequency can be based on personal preference provided that weekly training volume is equated (Cuthbert et al., 2021;Grgic et al., 2019;Schoenfeld et al., 2019). ...
... Some interventions have compared relatively similar frequencies (e.g., 2 vs. 3 sessions per week), raising the possibility that the conditions were not sufficiently different to identify statistical differences between groups (Benton et al., 2011;Brigatto et al., 2019;Candow et al., 2007). Others have implemented a low weekly training volume for the specific muscle groups (Hamarsland et al., 2022;Johnsen et al., 2021;Neves et al., 2022;Ochi et al., 2018;Yue et al., 2018), which minimizes accumulated fatigue in the low frequency groups and thus potentially undermines the rationale for employing a high training frequency approach. Finally, it has been suggested that a training schedule consisting of more complex exercises (i.e., multi-joint) would benefit from a higher training frequency due to greater motor learning and a faster recovery, compared to single-joint exercises Soares et al., 2015). ...
... training frequencies with training volume (i.e., number of sets) equated between the groups (Benton et al., 2011;Hamarsland et al., 2022;Johnsen et al., 2021;Saric et al., 2019;Yoshida et al., 2022;Yue et al., 2018;Zaroni et al., 2019). However, this study is somewhat unique due to the large difference between the frequencies, a progressive training program consisting of multi-joint exercises, a relatively high weekly training volume, and a population consisting of resistance-trained adults. ...
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This study compared the effects of a weekly lower body resistance‐training program divided into low frequency (LOW, one long session) versus high frequency (HIGH, four shorter sessions) in resistance‐trained individuals. Twenty‐two adults with more than 6 months resistance training experience were randomized to either the LOW or HIGH intervention group. Both groups completed an 8‐week training program consisting of four multi‐joint exercises targeting the hip and knee extensors. The program progressed from 12‐repetition maximum (RM) to 6‐RM, with 4–5 sets per exercise performed throughout the intervention. The four exercises were conducted either in one session or four sessions (one exercise per session) per week. 1‐RM in the squat, muscle thickness of the vastus lateralis, muscle mass of the lower body (measured using bioelectrical impedance), and jump height were assessed pre‐ and post‐intervention. The HIGH group demonstrated a statistically significant increase in 1‐RM compared to the LOW group (7 kg, p = 0.01), while no statistically significant differences were found between the groups for the other outcomes (p = 0.26–0.63). Both interventions resulted in statistically significant increases in 1‐RM squat (8 and 15 kg), muscle thickness (2.3 and 2.8 mm), and jump height (1.5 and 1.9 cm) from pre‐to post‐test. There were no statistical changes in lower‐body muscle mass for either group (p = 0.16–0.86). In conclusion, a weekly training protocol of four multi‐joint lower‐limb exercises distributed over four sessions resulted in greater increases in maximal strength compared to one session in resistance‐trained adults. Both frequencies were similarly effective in improving muscle hypertrophy and jump height.
... Also comparing weekly RT frequencies of one or three times/week in trained individuals, Schoenfeld et al. [22] did not found significant differences in 1RM increases in the bench press (6.8% and 10.2%) and squat (10.6% and 11.3%) exercises, for the RT performed one and three times a week, respectively. Indeed, the literature has not shown differences in muscle strength gains when different RT frequencies were compared in trained individuals, regardless of whether the TTV was equalized [22,[37][38][39][40][41] or not [42][43][44][45]. However, these studies also have not considered between-subjects' data variability in their design. ...
... Differently from the McLester Jr. et al. [35], that estimated muscle mass increase and body composition alterations through skinfold measurements, most recent studies performed these same measurements through dual-energy x-ray absorptiometry [38,39,42,45], air displacement plethysmography [46], and ultrasound images [22, 37, 39-41, 43, 44, 46]. In many of these studies [22, 39-41, 44, 46] authors did not find differences in lower limbs muscle CSA when different RT frequencies were compared. ...
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Several studies comparing resistance training (RT) frequencies may have been affected by the large between-subject variability. This study aimed to compare the changes in lower limbs maximal dynamic strength (1RM) and quadriceps femoris cross-sectional area (CSA) after a RT with different weekly frequencies in strength-trained individuals using a within-subject design. Twenty-four men participated in a 9-week RT program, being randomly divided into two conditions: resistance training with equalized total training volume (RTEV) and with unequalized total training volume (RTUV). The RT protocol used the unilateral leg press 45° exercise and each subject’s lower limb executed one of the proposed frequencies (one and three times/week). All conditions effectively increased 1RM and CSA (p<0.001); however, no significant differences were observed in the values of 1RM (p = 0.454) and CSA (p = 0.310) between the RT frequencies in the RTEV and RTUV conditions. Therefore, RT performed three times a week showed similar increases in 1RM and CSA to the program performed once a week, regardless of training volume equalization. Nevertheless, when the higher RT frequency allowed the application of a greater TTV (i.e., RTUV), higher effect size (ES) values (0.51 and 0.63, 1RM and CSA, respectively) were observed for the adaptations.
... According to recent studies, when training volume is equal, the frequency of resistance training may not have a significant effect on muscle hypertrophy [51,52,53,54]. When volume was matched, several studies have found no discernible differences in muscle growth between training frequencies of one to three times per week and two to three times per week. ...
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Resistance training (RT) is a key factor in promoting muscle hypertrophy and overall muscle health. Recent research highlights the role of RT frequency in optimizing hypertrophic outcomes. The purpose of this literature review is to explore the influence of training frequency on muscle hypertrophy and evaluates its effectiveness in tailoring programs to individual needs. A total of 63 research papers published between the years 2019 to 2024 were accessed and used for this review that met the criteria. The review indicates that while training volume is the primary driver of hypertrophy, frequency adjustments may enhance outcomes in specific contexts, such as recovery capacity and advanced adaptations. This review underscores the potential of frequency as a variable to optimize RT programs for improved muscle health.
... However, studies comparing different frequencies at the same intensity and volume are lacking (34)(35)(36). In this sense, previous literature suggests that when exercise or physical activity volume and intensity are kept constant, frequency does not significantly impact muscle mass or cardiovascular risk (37,38). ...
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Background Excessive sedentary time has been negatively associated with several health outcomes, and physical activity alone does not seem to fully counteract these consequences. This panorama emphasizes the essential of sedentary time interruption programs. “The Up Project” seeks to assess the effectiveness of two interventions, one incorporating active breaks led by a professional and the other utilizing a computer application (self-led), of both equivalent duration and intensity. These interventions will be compared with a control group to evaluate their impact on physical activity levels, sedentary time, stress perception, occupational pain, and cardiometabolic risk factors among office workers. Methods This quasi-experimental study includes 60 desk-based workers from universities and educational institutes in Valparaiso, Chile, assigned to three groups: (a) booster breaks led by professionals, (b) computer prompts that are unled, and (c) a control group. The intervention protocol for both experimental groups will last 12 weeks (only weekdays). The following measurements will be performed at baseline and post-intervention: cardiometabolic risk based on body composition (fat mass, fat-free mass, and bone mass evaluated by DXA), waist circumference, blood pressure, resting heart rate, and handgrip strength. Physical activity and sedentary time will be self-reported and device-based assessed using accelerometry. Questionnaires will be used to determine the perception of stress and occupational pain. Discussion Governments worldwide are addressing health issues associated with sedentary behavior, particularly concerning individuals highly exposed to it, such as desk-based workers. Despite implementing certain strategies, there remains a noticeable gap in comprehensive research comparing diverse protocols. For instance, studies that contrast the outcomes of interventions led by professionals with those prompted by computers are scarce. This ongoing project is expected to contribute to evidence-based interventions targeting reduced perceived stress levels and enhancing desk-based employees’ mental and physical well-being. The implications of these findings could have the capacity to lay the groundwork for future public health initiatives and government-funded programs.
... In contrast, another study [90] applied two weekly PJT sessions over a period of 8 weeks, with a RSI improvement of ~ 20% after a total of 660 jumps. Contrary to our findings, previous results suggest that training frequency is a less decisive moderator when the training load is equated [163][164][165]. Indeed, a recent review [154] reported no effects of PJT frequency on soccer athletes' athletic performance (e.g., jump height) when the weekly training load was equated. ...
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Background: The reactive strength index (RSI) is meaningfully associated with independent markers of athletic (e.g., linear sprint speed) and neuromuscular performance (e.g., stretch-shortening-cycle [SSC]). Plyometric jump training (PJT) is particularly suitable to improve the RSI due to exercises performed in the SSC. However, no literature review has attempted to meta-analyse the large number of studies regarding the potential effects of PJT on the RSI in healthy individuals across the lifespan. Aim: The aim of this systematic review with meta-analysis was to examine the effects of PJT on the RSI of healthy individuals across the lifespan compared with active/specific-active controls. Methods: Three electronic databases (PubMed, Scopus, WoS) were searched up to May 2022. According to the PICOS approach, the eligibility criteria were: i) healthy participants, ii) PJT interventions of ≥3 weeks, iii) active (e.g., athletes involved in standard training) and specific-active (e.g., individuals using heavy resistance training) control group(s), iv) a measure of jump-based RSI pre-post training, and v) controlled studies with multi-groups in randomized and non-randomized designs. The Physiotherapy Evidence Database (PEDro) scale was used to assess the risk of bias. The random-effects model was used to compute the meta-analyses, reporting Hedges’ g effect sizes (ES) with 95% confidence intervals (95% CIs). Statistical significance was set at p ≤0.05. Subgroup analyses were performed (chronological age; PJT duration, frequency, number of sessions, total number of jumps; randomization). A meta-regression was conducted to verify if PJT frequency, duration, and total number of sessions predicted the effects of PJT on the RSI. Certainty or confidence in the body of evidence was assessed using Grading of Recommendations Assessment, Development, and Evaluation (GRADE). Potential adverse health effects derived from PJT were researched and reported. Results: Sixty-one articles were meta-analysed, with a median PEDro score of 6.0, a low risk of bias and good methodological quality, comprising 2,576 participants with an age range of 8.1 to 73.1 years (males, ~78%; aged under 18 years, ~60%), 42 studies included participants with a sport background (e.g., soccer, runners). The PJT duration ranged from 4 to 96 weeks, with 1-3 weekly exercise sessions. The RSI testing protocols involved the use of contact mats (n=42) and force platforms (n=19). Most studies reported RSI as mm/ms (n=25 studies) from drop jump analysis (n=47 studies). In general, PJT groups improved RSI compared to controls: ES= 0.54, CI= 0.46-0.62, p< 0.001. Training-induced RSI changes were greater (p= 0.023) for adults (i.e., age ≥18 years [group mean]) compared with youth. PJT was more effective with a duration of >7 weeks vs. ≤7 weeks, >14 total PJT sessions vs. ≤14 sessions, 3 weekly sessions vs. <3 sessions (p= 0.027 – 0.060). Similar RSI improvements were noted after ≤1,080 vs. >1,080 total jumps, and for non-randomized vs. randomized studies. Heterogeneity (I2) was low (0.0-22.2%) in nine analyses and moderate in three analyses (29.1-58.1%). According to the meta-regression, none of the analysed training variables explained the effects of PJT on RSI (p=0.714-0.984, R2 = 0.0). The certainty of the evidence was moderate for the main analysis, and low-to-moderate across the moderator analyses. Most studies did not report soreness, pain, injury, or related adverse effects related to PJT. Conclusions: The effects of PJT on the RSI were greater compared with active/specific-active controls, including traditional sport-specific training as well as alternative training interventions (e.g., high-load slow-speed resistance training). This conclusion is derived from 61 articles with low risk of bias (good methodological quality), low heterogeneity, and moderate certainty of evidence, comprising 2,576 participants. PJT-related improvements on RSI were greater for adults vs. youths, after >7 training weeks vs. ≤7 weeks, with >14 total PJT vs. ≤14 sessions, and with 3 vs. <3 weekly sessions.
... Furthermore, no differences in improvements were observed between both CCT training frequencies for the30 m linear sprint, MBT, and isokinetic leg strength. Results for the isokinetic leg strength test indicated that there were no differences in the magnitude of improvement between the CCT-2 and CCT-3 groups, which is in line with previous literature that has suggested that training frequency is a less decisive moderator for lower limb strength when training load is equated [26,43,44]. ...
Article
Full-text available
Complex contrast training (CCT) is an exercise modality that utilizes both high-load resistance activity and low-load plyometric activity in a set-by-set fashion within a single exercise session. Such a combination of exercises targets multiple aspects of the force–velocity curve and may thus lead to improvement of various components of physical fitness. However, no previous study has attempted to compare the effects of load-equated two vs. three CCT sessions per week on measures of physical fitness. Forty-five male participants aged 21.4 ± 2.0 years were randomly assigned to either two weekly CCT sessions (CCT-2; n = 15), three weekly CCT sessions (CCT-3; n = 15), or an active control group (CG; n = 15). Selected measures of physical fitness were assessed pre- and post-six weeks of training. The tests included the assessment of 15 and 30 m linear sprint speeds, upper (medicine ball throw) and lower limb muscle power (standing long jump and countermovement jump with arm thrust), muscle strength (isokinetic peak knee extensor/flexor torque), and change-of-direction speed (modified agility T-test (MAT)). Significant group–time interactions were observed for all dependent variables (all p < 0.001, ɳp2 = 0.51–0.78) using ANOVA. Post hoc tests indicated significant performance improvements for the CCT-2 and CCT3 groups for all dependent variables (Hedge’s g = 0.28–3.26, %Δ = 2.4–16.7), including the 15 and 30 m linear sprint speeds (p < 0.001), medicine ball throw (p < 0.001), standing long jump (p < 0.001), countermovement jump with arm thrust (p
... While all participants performed all 36 training sessions with non-significant differences in training volume, it took the experimental group approximately 14 fewer minutes, or 31.8% less workout time per session. Some research indicates that muscle strength is not influenced by time as long as the volume is equal [40]. Similarly, in a review of duration, frequency, and length, the greatest improvements were seen when exercise participants reached levels within 90-100% of their VO2max [41]. ...
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Exergaming, combining elements of video game into the realm of exercise, has recently incorporated immersive virtual reality (IVR) with resistance training. Thirty-two participants (14 females, mean age = 24.3) were randomized to IVR or self-directed control group (SELF) and worked out thrice weekly for 12 weeks (for 36 sessions). The IVR group spent 14 fewer minutes per session (p < 0.001) while reporting the sessions “enjoyable’. Compared to SELF, the IVR group had significantly greater improvement in changes from baseline to post-training in upper-and-lower muscular strength (1-RM) and muscular endurance (85% 1-RM) (14.3 kg vs. 10.0 kg for 1-RM upper, 28.6 kg vs. 22.5 kg for 1-RM lower, 2.6 reps vs. 1.9 reps for 85% 1-RM of upper, 2.7 vs. 2.0 reps for 85% 1-RM of lower, all p < 0.001), peak leg power (1424 vs. 865 W, p < 0.001), body fat% (−3.7% vs. −1.9%, p < 0.001), heart rate variability (4.3 vs. 1.8 ms, p < 0.001), rVO2max (3.28 vs. 0.89 mL/min/kg, p < 0.001) with decreased systolic BP (−0.4 vs. −2.3 mmHg, p < 0.001), and level of perceived exertion during workouts (RPE 14 vs. 16, p < 0.001). With its high-paced and action-filled gaming coupled with superior fitness and cardiometabolic outcomes, this IVR exergaming platform should be considered as another exercise modality for performance and health-related training.
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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.
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Objective Consumption of pomegranate extract along with resistance training can improve the blood flow, resting metabolism and cause weight loss. However, their effect on body composition and weight control has not been studied. This study aims to investigate the effect of 8 weeks of resistance training combined with pomegranate extract supplementation on resting metabolic rate, hypertrophy and muscle strength of inactive male college students. Methods In this quasi-experimental study, 42 inactive male college students voluntary participated after signing a written informed consent form. They were randomly divided into four groups: resistance training (n=11), resistance training + supplementation (n=11), supplementation (n=10), and control (n=10). The resistance training was performed for 8 weeks, 3 sessions per week and included two movements for the upper body (barbell chest press and barbell shoulder press) and two movements for the lower body (leg extension and leg press with machine). The pomegranate extract was consumed at a dose of 100 mL 3 times a week (half an hour before training). Data analysis was performed using one-way analysis of variance with least significant difference post hoc test and paired t-test considering a significance level of P≤0.05. Results The rate of muscle hypertrophy (hip circumference) increased significantly after intervention in two groups of resistance training and resistance training + supplementation, which was higher in the combined intervention group (P=0.001). The maximum strength in lower body muscles also increased significantly after intervention in these two groups (P=0.001). Body fat percentage decreased significantly in the resistance training + supplementation group (P=0.03). No significant change was observed in the resting metabolic rate of the study groups (P>0.05). Conclusion It seems that the combination of resistance training with pomegranate extract supplementation increases the muscle strength and hypertrophy in young men.
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The study aimed to compare the effects of drop set resistance training (RT) versus traditional RT on markers of maximal muscle strength and regional hypertrophy of the quadriceps femoris. Sixteen recreationally active young men had one leg randomly assigned to the drop-set method (DS) and the other to training in a traditional manner (TRAD). Participants performed unilateral seated leg extensions using a periodized approach for eight weeks. Rectus femoris (RF) and vastus lateralis (VL) muscle thickness (MT), estimated one repetition maximum (RM) in the unilateral knee extension, and peak and average isokinetic knee extension torque at 60◦/s angular velocity were measured pre- and post-study. Both conditions increased muscle thickness of the RF and VL from preto post-intervention. DS showed statistically greater increases in the RF at 30% and 50% of muscle length, whereas no MT differences were detected at 70% muscle length nor at any aspect of the VL. Both DS and TRAD increased estimated one RM from pre- to post-study (+34.6% versus +32.0%, respectively) with no between-condition differences noted. Both conditions showed similar increases in peak torque (DS: +21.7%; TRAD: +22.5%) and average torque (DS: +23.6%; TRAD: +22.5%) from pre- to post-study. Our findings indicate a potential benefit of the drop-set method for inducing non-uniform hypertrophic gains in the RF muscle pursuant to leg extension training. The strategy did not promote an advantage in improving hypertrophy of the VL, nor in strength-related measures, compared to traditional training
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Background In resistance training, the role of training frequency to increase maximal strength is often debated. However, the limited data available does not allow for clear training frequency “optimization” recommendations. The purpose of this study was to investigate the effects of training frequency on maximal muscular strength and rate of perceived exertion (RPE). The total weekly training volume was equally distributed between two and four sessions per muscle group. Methods Twenty-one experienced resistance-trained male subjects (height: 1.85 ± 0.06 m, body mass: 85.3 ± 12.3 kg, age: 27.6 ± 7.6 years) were tested prior to and after an 8-week training period in one-repetition maximum (1RM) barbell back squat and bench press. Subjects were randomly assigned to a SPLIT group ( n = 10), in which there were two training sessions of squats and lower-body exercises and two training sessions of bench press and upper-body exercises, or a FULLBODY group ( n = 11), in which four sessions with squats, bench press and supplementary exercises were conducted every session. In each session, the subjects rated their RPE after barbell back squat, bench press, and the full session. Results Both groups significantly increased 1RM strength in barbell back squat (SPLIT group: +13.25 kg; FULLBODY group: +14.31 kg) and bench press (SPLIT group: +7.75 kg; FULLBODY group: +8.86 kg) but training frequency did not affect this increase for squat ( p = 0.640) or bench press ( p = 0.431). Both groups showed a significant effect for time on RPE on all three measurements. The analyses showed only an interaction effect between groups on time for the RPE after the squat exercise ( p = 0.002). Conclusion We conclude that there are no additional benefits of increasing the training frequency from two to four sessions under volume-equated conditions, but it could be favorable to spread the total training volume into several training bouts through the week to avoid potential increases in RPE, especially after the squat exercise.
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The objective of this overview of systematic reviews was to determine the benefits and harms of resistance training (RT) on health outcomes in adults aged 18 years or older, compared with not participating in RT. Four electronic databases were searched in February 2019 for systematic reviews published in the past 10 years. Eligibility criteria were determined a priori for population (community dwelling adults), intervention (exclusively RT), comparator (no RT or different doses of RT), and health outcomes (critical: mortality, physical functioning, health-related quality of life, and adverse events; important: cardiovascular disease, type 2 diabetes mellitus, mental health, brain health, cognitive function, cancer, fall-related injuries or falls, and bone health). We selected 1 review per outcome and we used the GRADE process to assess the strength of evidence. We screened 2089 records and 375 full-text articles independently, in duplicate. Eleven systematic reviews were included, representing 364 primary studies and 382 627 unique participants. RT was associated with a reduction in all-cause mortality and cardiovascular disease incidence, and an improvement in physical functioning. Effects on health-related quality of life or cognitive function were less certain. Adverse events were not consistently monitored or reported in RT studies, but serious adverse events were not common. Systematic reviews for the remaining important health outcomes could not be identified. Overall, RT training improved health outcomes in adults and the benefits outweighed the harms. (PROSPERO registration no.: CRD42019121641.) NoveltyThis overview was required to inform whether there was new evidence to support changes to the recommended guidelines for resistance training.
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In vivo measurements of muscle architecture (i.e. the spatial arrangement of muscle fascicles) are routinely included in research and clinical settings to monitor muscle structure, function and plasticity. However, in most cases such measurements are performed manually, and more reliable and time-efficient automated methods are either lacking completely, or are inaccessible to those without expertise in image analysis. In this work, we propose an ImageJ script to automate the entire analysis process of muscle architecture in ultrasound images: Simple Muscle Architecture Analysis (SMA). Images are filtered in the spatial and frequency domains with built-in commands and external plugins to highlight aponeuroses and fascicles. Fascicle dominant orientation is then computed in regions of interest using the OrientationJ plugin. Bland-Altman plots of analyses performed manually or with SMA indicate that the automated analysis does not induce any systematic bias and that both methods agree equally through the range of measurements. Our test results illustrate the suitability of SMA to analyse images from superficial muscles acquired with a broad range of ultrasound settings.
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Key points For individuals showing suboptimal adaptations to resistance training, manipulation of training volume is a potential measure to facilitate responses. This remains unexplored. Here, 34 untrained individuals performed contralateral resistance training with moderate and low volume for 12 weeks. Moderate volume led to larger increases in muscle cross‐sectional area, strength and type II fibre‐type transitions. These changes coincided with greater activation of signalling pathways controlling muscle growth and greater induction of ribosome synthesis. Out of 34 participants, thirteen displayed clear benefit of MOD on muscle hypertrophy and sixteen showed clear benefit of MOD on muscle strength gains. This coincided with greater total RNA accumulation in the early phase of the training period, suggesting that ribosomal biogenesis regulates the dose–response relationship between training volume and muscle hypertrophy. These results demonstrate that there is a dose‐dependent relationship between training volume and outcomes. On the individual level, benefits of higher training volume were associated with increased ribosomal biogenesis. Abstract Resistance‐exercise volume is a determinant of training outcomes. However not all individuals respond in a dose‐dependent fashion. In this study, 34 healthy individuals (males n = 16, 23.6 (4.1) years; females n = 18, 22.0 (1.3) years) performed moderate‐ (3 sets per exercise, MOD) and low‐volume (1 set, LOW) resistance training in a contralateral fashion for 12 weeks (2–3 sessions per week). Muscle cross‐sectional area (CSA) and strength were assessed at Weeks 0 and 12, along with biopsy sampling (m. vastus lateralis). Muscle biopsies were also sampled before and 1 h after the fifth session (Week 2). MOD resulted in larger increases in muscle CSA (5.2 (3.8)% versus 3.7 (3.7)%, P < 0.001) and strength (3.4–7.7% difference, all P < 0.05. This coincided with greater reductions in type IIX fibres from Week 0 to Week 12 (MOD, −4.6 percentage points; LOW −3.2 percentage points), greater phosphorylation of S6‐kinase 1 (p85 S6K1Thr412, 19%; p70 S6K1Thr389, 58%) and ribosomal protein S6Ser235/236 (37%), greater rested‐state total RNA (8.8%) and greater exercise‐induced c‐Myc mRNA expression (25%; Week 2, all P < 0.05). Thirteen and sixteen participants, respectively, displayed clear benefits in response to MOD on muscle hypertrophy and strength. Benefits were associated with greater accumulation of total RNA at Week 2 in the MOD leg, with every 1% difference increasing the odds of MOD benefit by 7.0% (P = 0.005) and 9.8% (P = 0.002). In conclusion, MOD led to greater functional and biological adaptations than LOW. Associations between dose‐dependent total RNA accumulation and increases in muscle mass and strength point to ribosome biogenesis as a determinant of dose‐dependent training responses.
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The purpose of the present study was to compare changes in muscle strength and hypertrophy between volume-equated resistance training (RT) performed 2 versus 3 times per week in trained men. Thirty-six resistance-trained men were randomly assigned to one of the two experimental groups: a split-body training routine (SPLIT) with muscle groups trained twice per week (n = 18) over four weekly sessions, or a total-body routine (TOTAL), with muscle groups being trained three times per week (n = 18) over three weekly sessions. The training intervention lasted 10 weeks. Testing was carried out pre- and post-study to assess maximal muscular strength in the back squat and bench press, and hypertrophic adaptations were assessed by measuring muscle thickness of the elbow flexors, elbow extensors, and quadriceps femoris. Twenty-eight subjects completed the study. Significant pre-to-post intervention increases in upper and lower-body muscular strength occurred in both groups with no significant between-group differences. Furthermore, significant pre-to-post intervention increases in muscle size of the elbow extensors and quadriceps femoris occurred in both groups with no significant between-group differences. No significant pre-to-post changes were observed for the muscle size of elbow flexors both in the SPLIT or TOTAL group. In conclusion, a training frequency of 2 versus 3 days per week produces similar increases in muscular adaptations in trained men over a 10-week training period. However, effect size differences favored SPLIT for all hypertrophy measures, indicating a potential benefit for training two versus three days a week when the goal is to maximize gains in muscle mass.
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Training frequency is considered an important variable in the hypertrophic response to regimented resistance exercise. The purpose of this paper was to conduct a systematic review and meta-analysis of experimental studies designed to investigate the effects of weekly training frequency on hypertrophic adaptations. Following a systematic search of PubMed/MEDLINE, Scoups, and SPORTDiscus databases, a total of 25 studies were deemed to meet inclusion criteria. Results showed no significant difference between higher and lower frequency on a volume-equated basis. Moreover, no significant differences were seen between frequencies of training across all categories when taking into account direct measures of growth, in those considered resistance-trained, and when segmenting into training for the upper body and lower body. Meta-regression analysis of non-volume-equated studies showed a significant effect favoring higher frequencies, although the overall difference in magnitude of effect between frequencies of 1 and 3+ days per week was modest. In conclusion, there is strong evidence that resistance training frequency does not significantly or meaningfully impact muscle hypertrophy when volume is equated. Thus, for a given training volume, individuals can choose a weekly frequency per muscle groups based on personal preference.
Article
The impact of resistance exercise frequency on muscle protein synthesis rates remains unknown. The aim of this study was to compare daily myofibrillar protein synthesis rates over a 7-day period of low-frequency (LF) versus high-frequency (HF) resistance exercise training. Nine young men (21 ± 2 years) completed a 7-day period of habitual physical activity (BASAL). This was followed by a 7-day exercise period of volume-matched, LF (10 × 10 repetitions at 70% one-repetition maximum, once per week) or HF (2 × 10 repetitions at ∼70% one-repetition maximum, five times per week) resistance exercise training. The participants had one leg randomly allocated to LF and the other to HF. Skeletal muscle biopsies and daily saliva samples were collected to determine myofibrillar protein synthesis rates using ² H 2 O, with intracellular signaling determined using Western blotting. The myofibrillar protein synthesis rates did not differ between the LF (1.46 ± 0.26%/day) and HF (1.48 ± 0.33%/day) conditions over the 7-day exercise training period ( p > .05). There were no significant differences between the LF and HF conditions over the first 2 days (1.45 ± 0.41%/day vs. 1.25 ± 0.46%/day) or last 5 days (1.47 ± 0.30%/day vs. 1.50 ± 0.41%/day) of the exercise training period ( p > .05). Daily myofibrillar protein synthesis rates were not different from BASAL at any time point during LF or HF ( p > .05). The phosphorylation status and total protein content of selected proteins implicated in skeletal muscle ribosomal biogenesis were not different between conditions ( p > .05). Under the conditions of the present study, resistance exercise training frequency did not modulate daily myofibrillar protein synthesis rates in young men.
Article
Protein synthesis is deemed the underpinning mechanism enhancing protein balance required for skeletal muscle hypertrophy in response to resistance exercise. The current model of skeletal muscle hypertrophy induced by resistance training states that the acute increase in the rates of protein synthesis after each bout of resistance exercise is the basis for muscle growth. Within this paradigm, each resistance exercise session would add a specific amount of muscle mass; therefore, muscle hypertrophy could be defined as the result of intermittent and short-lived increases in muscle protein synthesis rates following each resistance exercise session. Although a substantial amount of data has accumulated in the last decades regarding the acute changes in protein synthesis (or translational efficiency) following resistance exercise, considerable gaps on the mechanism of muscle growth still exist. Ribosome biogenesis and translational capacity have emerged as important mediators of skeletal muscle hypertrophy. Recent advances in the field have demonstrated that skeletal muscle hypertrophy is associated with markers of translational capacity and long-term changes in protein synthesis under resting conditions. This review will discuss the caveats of the current model of skeletal muscle hypertrophy induced by resistance training while proposing a working model that takes into consideration the novel data generated by independent laboratories utilizing different methodologies. It is argued, herein, that the role of protein synthesis in the current model of muscle hypertrophy warrants revisiting.
Article
The manipulation of resistance training (RT) variables is used among athletes, recreational exercisers and compromised populations (e.g., elderly) attempting to potentiate muscle hypertrophy. However, it is unknown whether an individual's inherent predisposition dictates the RT-induced muscle hypertrophic response. Twenty resistance-trained young (26(3)y) men performed 8wk unilateral RT (2∙wk ⁻¹ ) with one leg randomly assigned to a standard progressive RT (CON), and the contralateral leg to a variable RT (VAR, modulating exercise load, volume, contraction type and interset rest interval). The VAR leg completed all 4 RT variations every 2wk. Bilateral vastus lateralis cross-sectional area (CSA) was measured pre- and post-RT, and acute integrated myofibrillar protein synthesis (MyoPS) rates were assessed at rest and over 48h following the final RT session. Muscle CSA increase was similar between CON and VAR (P>0.05), despite higher total training volume (TTV) in VAR (P<0.05). The 0-48h integrated MyoPS increase post-exercise was slightly greater for VAR than CON (P<0.05). All participants were considered 'responders' to RT, although none benefited to a greater extent from a specific protocol. Between-subjects variability (MyoPS, 3.30%; CSA, 37.8%) was 40-fold greater than the intra-subject (between legs) variability (MyoPS, 0.08%; CSA, 0.9%). The higher TTV and greater MyoPS response in VAR did not translate to a greater muscle hypertrophic response. Manipulating common RT variables elicited similar muscle hypertrophy than a standard progressive-RT program in trained young men. Intrinsic individual factors are key determinants of the MyoPS and change in muscle CSA compared with extrinsic manipulation of common RT variables.