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The Effects of a 7-Week Practical Blood Flow Restriction Program on Well-Trained Collegiate Athletes

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The purpose of this study was to examine the effects of a seven-week, practical blood flow restriction (BFR) protocol used in conjunction with a strength training program on measures of muscular strength and size in collegiate American football players. Sixty-two participants were divided into four groups. Three groups completed a traditional upper- and lower-body split strength program. Two of these groups also completed supplemental lifting sessions. Of these two, one completed the additional lifts with blood flow restriction. The final group completed a modified training program, followed by the supplemental lifts, with blood flow restriction. The supplemental lifting protocol consisted of bench press and squat, utilizing 20% 1RM for four sets with 30 repetitions performed in the first set and 20 repetitions performed in the following three. Each set was separated by 45 seconds of rest. The supplemental bench press was completed at the end of upper-body days, and the squat at the end of lower-body days. Dependent measures were taken prior to the start of the program and again upon conclusion: upper- and lower-body girths, 1RM bench and squat. Results of a 4 X 2 mixed model MANCOVA revealed a significant difference for the interaction on the dependent variables. Follow-up univariate ANOVAs indicated a significant difference for 1RM squat. This suggests that a practical BFR program used in addition to a traditional strength training program can be effective at increasing 1RM squat performance. The use of elastic knee wraps makes BFR a feasible training option for coaches and athletes.
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THE EFFECTS OF A 7-WEEK PRACTICAL BLOOD FLOW
RESTRICTION PROGRAM ON WELL-TRAINED
COLLEGIATE ATHLETES
PAUL E. LUEBBERS,
1
ANDREW C. FRY,
2
LUKE M. KRILEY,
1
AND MICHAEL S. BUTLER
1
1
Department of Health, Physical Education, and Recreation, Emporia State University, Emporia, Kansas; and
2
Department of
Health, Sport and Exercise Sciences, University of Kansas, Lawrence, Kansas
ABSTRACT
Luebbers, PE, Fry, AC, Kriley, LM, and Butler, MS. The effects of
a 7-week practical blood flow restriction program on well-trained
collegiate athletes. J Strength Cond Res 28(8): 2270–2280,
2014—The purpose of this study was to examine the effects of
a 7-week practical blood flow restriction (BFR) protocol used in
conjunction with a strength training program on measures of mus-
cular strength and size in collegiate American football players.
Sixty-two participants were divided into 4 groups. Three groups
completed a traditional upper- and lower-body split strength pro-
gram. Two of these groups also completed supplemental lifting
sessions. Of these 2, 1 completed the additional lifts with BFR.
The final group completed a modified training program, followed
by the supplemental lifts, with BFR. The supplemental lifting pro-
tocol consisted of bench press and squat, using 20% 1 repetition
maximum (1RM) for 4 sets with 30 repetitions performed in the
first set and 20 repetitions performed in the following 3 sets. Each
set was separated by 45 seconds of rest. The supplemental bench
press was completed at the end of upper-body days and the squat
at the end of lower-body days. Dependent measures were taken
before the start of the program and again on conclusion the fol-
lowing dependent variables were measured: upper- and lower-
body girths, 1RM bench, and squat. Results of a 4 32mixed-
model multivariate analysis of covariance revealed a significant
difference for the interaction on the dependent variables. Follow-
up univariate analysis of variances indicated a significant difference
for 1RM squat. This suggests that a practical BFR program used in
addition to a traditional strength training program can be effective at
increasing 1RM squat performance. The use of elastic knee wraps
makes BFR a feasible training option for coaches and athletes.
KEY WORDS KAATSU, occlusion, strength training,
hypertrophy
INTRODUCTION
Resistance training has many known athletic bene-
fits, including reducing the risk ofinjury, enhancing
muscular endurance, improving power, promoting
speed development, and increasing muscular
strength. Although many forms of resistance training exist,
weight training has long been a staple among coaches and
athletes for eliciting improvements in muscular fitness.
Traditional weight training program design calls for the
utilization of light weight and high repetitions for increasing
muscular endurance (e.g., ,60% 1 repetition maximum
[1RM] for multiple sets of 10 or more repetitions), whereas
increases in muscular size and strength are generally pursued
with the use of heavy weight and a low number of repeti-
tions (e.g., .70% 1RM for several sets of 6 repetitions or less)
(1,6,11). However, present-day research has demonstrated
that weight training with light weight and high repetitions
can result in significant increases in muscle size and strength
when it is used in conjunction with blood flow restriction
(BFR). These observations have been made in healthy,
untrained, and recreationally trained participants (2,31,32,39)
and in athletic populations (3,30,36).
Blood flow restriction training (also known as occlusion
training) is the act of reducing the amount of arterial blood
flow to the working muscles while occluding venous return
(8,25). This is achieved by placing a wrapping device around
the proximal end of the muscles in which the restriction is
desired. The resultant decreased delivery and cessation of
return is believed to be responsible for many of the proposed
mechanisms for the efficacy of BFR training in promoting
muscular strength and hypertrophy. The most prevalent the-
ories stem from the reduced oxygen availability and metab-
olite accumulation in the affected muscles. This low-oxygen
high-metabolite environment has been demonstrated to
increase the recruitment of high-threshold motor units
(31,37), which are typically only recruited under heaving
loading conditions (14,28). In addition, some research has
indicated that there can be an exaggerated growth hormone
release after BFR training (10,27,29), although the role
played by systemic growth hormone in hypertrophy has
been challenged in recent years (34).
Address correspondence to Paul E. Luebbers, pluebber@emporia.edu.
28(8)/2270–2280
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However, these mechanisms cannot account for some
circumstances in which BFR has been shown to be
beneficial, as much of the BFR research uses modalities
other than resistance training. In 2000, Takarada demon-
strated that static BFR was effective in attenuation of muscle
loss in bedridden patients recovering from anterior cruciate
ligament surgery. Being nonambulatory negates the recruit-
ment of any muscle fiber type, and metabolic build-up is
negligible. A similar study conducted by Kubota in 2008 also
demonstrated an offsetting of thigh muscle atrophy in
movement-restricted participants receiving a BFR treatment
(16). Abe et al. (4) observed increased muscular strength and
hypertrophy by using BFR in combination with slow tread-
mill walking. Although Abe did not measure metabolites,
Loenneke et al. (23) conducted comparable research in
which lactate was assessed. Analysis revealed that slow
treadmill walking using BFR did not result in metabolite
accumulation. So, although increased motor unit recruit-
ment and metabolite build-up may play a role in the positive
muscular adaptations seen with BFR training, it is apparent
that there are other mechanisms involved.
Loenneke et al. (18,20) have theorized that muscle cell
swelling may be an important factor. The decreased arterial
delivery and cessation of venous return during a BFR appli-
cation lead to a pooling of blood in the muscles distal to the
application site of occlusion. This pooling effect could cause
a shift in intra- and extracellular fluids leading to an increase
in muscle cell volume. Haussinger et al. (12) first theorized
that cell swelling may induce an anabolic response, and
follow-up work supports the concept (7,15). This mecha-
nism may explain why BFR seems to attenuate muscle atro-
phy during times of immobilization where there is an
absence of exercise and/or metabolite accumulation. It
would appear that this may be the 1 consistent factor across
all modalities of BFR training.
To obtain BFR, most research studies have used pneu-
matic wrapping devices, such as a KAATSU Master (Sato
Sports Plaza Ltd., Tokyo, Japan), or modified blood pressure
cuffs, which allow for precise control of the amount of
applied pressure. Although pneumatic devices allow for
control of the pressure during BFR training, generally, they
are not practical for use outside of a clinical or laboratory
situation because of being cost prohibitive and/or limited in
accessibility. In 2009, Loenneke and Pujol (22) proposed the
use of elastic knee wraps for BFR training (i.e., practical
BFR), which would make the method a feasible option for
general use. Quantification of the pressure exerted by a taut
elastic wrap in a real-world setting is not possible; therefore,
it was suggested that pulling the wraps tight to a moderate
perceptive pressure (e.g., a 7 on a scale of 0 to 10) would be
sufficient. This protocol has since been shown to be effective
in occluding venous return while sufficiently reducing arte-
rial delivery (35).
It is clear that the literature supports the efficacy of BFR
training for promoting positive muscular adaptations across
a variety of populations and modalities. However, few
studies have used elastic knee wraps (17,21,23,24,36), and
even fewer have used them outside of a laboratory setting
with an athletic population (36). Additional research in this
area will provide further insight into the use of practical BFR
in those who are already well trained.
The purpose of this study was to examine the effects of
a 7-week practical BFR protocol used in conjunction with
a traditional weight training program on measures of
muscular strength and size in collegiate American football
players. The protocol used in this investigation was modeled
after a practical BFR study conducted by Yamanaka et al.
(36), which also used an American football team. This study
was a field experiment conducted during the team’s off-
season, as a part of their strength and conditioning program.
It was hypothesized that those who completed the tradi-
tional training program, in combination with the supplemen-
tal lifting protocols, under conditions of practical occlusion
would experience greater gains in muscular strength and size
than those in the other treatment groups.
METHODS
Experimental Approach to the Problem
This investigation employed a pretest-posttest mixed model
design with a training intervention. Participants were re-
cruited from a National Collegiate Athletic Association
(NCAA) Division II American football team, from which
72 players volunteered to take part. All participants com-
pleted a 7-week off-season football strength and condition-
ing program. Before the start of the program, and again on
conclusion, the following dependent variables were mea-
sured: upper- and lower-body girths, and strength as
determined by 1RM bench press and squat.
There were 4 groups of participants in this study. The
football coaching staff was aware that the experimental
design called for one of the group’s training program to be
modified in such a way that its members would not com-
plete any high-intensity lifting. They expressed concern
about restricting players who held the traditional strength
and power positions (linemen and linebackers) from high-
intensity work. Their concern was addressed by removing
those positions from the initial selection pool and forming
the modified group (M/S/R) from the remaining subset of
players. Once the modified group was established, the line-
men and linebackers were returned to the selection pool
with the other remaining players and randomly assigned
among the other 3 groups (H/S/R, H/S, and H). For a com-
plete description of these groups, see Training Protocols and
Groups.
Subjects
The football program was a part of the Intercollegiate
Athletics Department at a midwestern regional university.
Permission to conduct the study was granted by the
university’s institutional review board. The coaching staff
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of the football team agreed to the recruitment of participants
from the team and allowing the necessary modifications to
be made to the strength and conditioning program. Details
of the study were verbally explained to the entire team by
the principal investigator at a team meeting. Seventy-two
team members volunteered to be participants. Each partici-
pant signed an informed consent document. All were
deemed healthy and able to train by the university’s medical
and athletic training staff.
The off-season training program took place during an
academic semester and lasted for 7 weeks, with 4 training
days each week—2 upper-body days and 2 lower-body days.
Players were assigned by their coaches to attend 1 of 3
training sessions each day, based on their class schedules.
Training sessions were held at 7:15 AM, 1:30 PM, and 3:30 PM.
The study began with 72 participants (18 in each group).
Because of non-BFR related injuries or lack of compliance
with the protocol, 10 players were removed from the study.
Complete data were collected on the 62 remaining partic-
ipants (20.3 61.1 year old, 99.1 619.7 kg, and 7.1 62.2
years of weight training experience).
Procedures
Pretests and Posttests. All participants attended pretest and
posttest sessions for assessment of dependent variables. Both
the pretests and posttests were split between 2 days. Pretest
Day 1 was comprised of upper- and lower-body girths and
1RM bench press. Body mass was measured for descriptive
and statistical purposes. This session was completed after 48
hours of rest. Pretest Day 2 followed the next day and
consisted of the 1RM squat test. The same measures were
again taken at the posttest sessions, which were completed at
the conclusion of the program. Posttest day 1 took place after
48 hours of rest, followed by posttest day 2, taking place the
very next day. All pretests and posttests took place during the
participants’ regular training session time. Figure 1 provides
a schematic of the testing and training sessions.
Body Mass and Girths. Body mass was measured with a Tanita
WB-3000plus Digital Physicians Scale (Arlington Heights,
IL, USA). The American College of Sports Medicine
protocols for measuring circumferences were used for
assessing arm and thigh girths (13). Chest girth was deter-
mined by placing the tape horizontally around the torso at
the level of the nipple, and measurement was taken at the
end of normal exhalation. All measurements, both pre and
post, were assessed using a Gulick tape measure and were
taken by the same investigator, whose test-retest reliability
was 0.55% coefficient of variation (CV) for the arm, 0.47%
CV for the thigh, and 0.48% CV for the chest.
1 Repetition Maximum Tests. Maximal strength for bench
press and squat were assessed following procedures set forth
by the football coaching staff. Players completed 1 warm-up
set of 10 repetitions using approximately 40% of their
estimated 1RM and a second warm-up set of 5 repetitions
using approximately 60% of their estimated max. After
adequate rest, players loaded the bar with approximately
80–85% of their estimated 1RM and completed 1 repetition.
Weight was added with each subsequent 1 repetition set
until the player could no longer complete a repetition cor-
rectly. The 1RM was determined as the last weight used in
which the participant successfully completed the lift with
proper form through the entire range of motion, as defined
by National Strength and Conditioning Association (NSCA)
(5). Conditions between the pre- and posttest 1RMs were made
as identical as possible (see discussion above and Figure 1).
Wearing a weightlifting belt was encouraged, but not required.
Figure 1. Testing and training schematic.
Practical Blood Flow Restriction
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Players who chose to wear a belt for a pretest 1RM also wore
abeltfortheposttest1RM.Thesamewastrueforthosewho
chose not to wear a belt. All 1RM tests, both pre and post, were
supervised by the same members of our research team, each of
whom is a NSCA Certified Strength and Conditioning Special-
ist (CSCS). Test-retest reliability as determined by our research
team for the 1RM bench press was 0.62% CVand 0.35% CV for
the 1RM squat.
Training Protocols and Groups
Each of the 4 groups completed a different training protocol
and/or training intervention, an overview of which can be
found in Table 1. Details of each can be found below and
examples can be found in Tables 2 and 3.
Traditional High-Intensity Training Program (H). In brief, this
was a weightlifting program focused largely on increasing
strength. It used sets, repetitions, and loading schemes
of traditional high-intensity programs (i.e., multiple low-
repetition sets with high %1RM). While the intricacies of the
program changed over the course of the 7 weeks, at its
foundation were lifts traditionally used in American football
programs: bench press, overhead press, power cleans, squats,
and variations of each. Auxiliary lifts, such as bicep curls,
triceps extensions, calf raises, and abdominal work were also
included. Training was split into alternating upper- and
lower-body days, each being trained twice per week,
although not always in the same sequence. There were 4
training days per week, occurring on Mondays, Tuesdays,
Thursdays, and Fridays. Tables 2 and 3 provide representa-
tive workouts for lower- and upper-body days. The program
followed this lifting format for the duration of the 7-week
program.
Modified Training Program (M). This protocol was identical to
the traditional training program, with the exception that
high-intensity bench press, squat, and their variations were
excluded (Tables 2 and 3).
TABLE 1. Groups, training programs, and protocols.*
Group
Modified program
(M)
Traditional high-intensity
program (H)
Supplemental 20% 1RM
protocol (S)
Blood flow restriction
(R)
H/S/R ✓✓
H/S ✓✓
H
M/S/R ✓✓
*1RM = 1 repetition maximum.
TABLE 2. Representative lower-body day for each group: Total volume-load.*
Exercise Set Rep Load (kg)
H/S/R H/S H M/S/R
Vol-load Vol-load Vol-load Vol-load
Squat 1 8 130 (65%) 1,040 1,040 1,040
1 6 140 (70%) 840 840 840
1 4 160 (80%) 640 640 640
1 2 170 (85%) 340 340 340
1 2 180 (90%) 360 360 360
Lateral squats 3 5 130 (65%) 1,950 1,950 1,950
Good mornings 3 6 45.5 819 819 819 819
DB lunges3 8 22.7 544.8 544.8 544.8 544.8
Glute-Ham raises 3 6 11.4 205.2 205.2 205.2 205.2
Supplemental squats 1 30 40 (20%) 1,200 1,200 1,200
3 20 40 (20%) 2,400 2,400 2,400
Total vol-load (kg) 10,339 10,339 6,739 5,169
*Participants with a 200 kg 1RM squat.
DB = dumbbell.
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Supplemental 20% 1 Repetition Maximum Lifting Protocol (S).
Participants completed these sessions together, at the same
time, at the conclusion of their training workouts. All
sessions were supervised by the same 2 primary researchers
to ensure compliance. The supplemental squats were
performed at the end of lower-body training days, and the
supplemental bench press was performed at the end of upper-
body days. Barbell load was set at 20% of pretest 1RM. A list
of each participant’s barbell load was posted at each lifting
station to ensure correct loads were used. Players completed
1 set of 30 repetitions followed by 3 sets of 20 repetitions, with
45 seconds of rest between each set (Tables 2 and 3). The
pace of the concentric and eccentric phases of each repetition
was set at 1.5:1.5 seconds. This cadence was guided by a series
of ascending and descending tones that were played through
the weight room’s stereo system from a prerecorded .mp3 file.
All 4 sets, including the rest periods, were incorporated into
the .mp3 file and verbal instructions for the sessions. This
provided consistency between all sessions throughout the
duration of the program and allowed for the investigators to
closely monitor the participants for compliance.
Practical Blood Flow Restriction (R). Restriction of blood flow
in the participants receiving the occlusion treatment was
accomplished with the use of powerlifting elastic knee wraps
with hook-and-loop closure (Grizzly Fitness, Kitchener, ON,
Canada). The wrap dimensions were 7.6 3167.6 cm (3.0 3
66.0 in) and were graduated every 1.3 cm (0.5 in) perpen-
dicular to the edge with a silver permanent marker. For the
BFR bench press, the wraps were applied to the proximal end
of the upper extremities (above the bicep, below the deltoid).
For the BFR squat, the wraps were applied at proximal end of
the lower extremities (at the top of thigh, near the inguinal
crease). The wraps were initially applied without tension, but
secure enough to remain in place. Just before the start of the
lifting session, the wraps were pulled to a 7.6 cm (3.0 in)
overlap as measured by the silver markings and secured. This
tension was maintained for the entire 4-set lifting session,
including the rest periods. The wraps were removed immedi-
ately at the conclusion of the lifting sessions.
H/S/R Group. This group completed the traditional high-
intensity training program (H) and the supplemental 1RM
lifting protocols (S). They did so with the wraps in place,
under conditions of practical BFR (R).
H/S Group. This group completed the traditional high-
intensity training program (H) and the supplemental 1RM
lifting protocols (S). However, they did not use the wraps;
therefore, they did not receive the BFR treatment.
H Group. This group completed only the traditional high-
intensity training program (H). They did not participate in
the supplemental lifting sessions and at no time did they use
the wraps.
M/S/R Group. This group completed the Modified Training
Program (M). At the end of these sessions, they also
completed the supplemental 1RM lifting sessions (S) and
did so under conditions of practical BFR (R).
Training Sessions. To accommodate players’ class schedules,
the athletes were assigned by their coaches to attend 1 of the
3 training sessions each day. Training sessions were held at
7:15 AM, 1:30 PM, and 3:30 PM. Members of each training
group were present during all training sessions.
TABLE 3. Representative upper-body day for each group: Total volume-load.*
Exercise Set Rep Load (kg)
H/S/R H/S H M/S/R
Vol-load Vol-load Vol-load Vol-load
Bench press 1 8 81 (65%) 650 650 650
1 6 87.5 (70%) 525 525 525
1 4 100 (80%) 400 400 400
1 2 106.25 (85%) 215 215 215
1 2 112.5 (90%) 225 225 225
Lockout press 4 2 81 (65%) 650 650 650
Upright rows 3 6 45 810 810 810 810
Single-arm DBrows 3 8 45.5 1,092 1,092 1,092 1,092
Tricep DB extensions 3 10 25 750 750 750 750
DB hammer curls 3 10 22.7 681 681 681 681
Supplemental bench 1 30 25 (20%) 750 750 750
3 20 25 (20%) 1,500 1,500 1,500
Total vol-load (kg) 8,248 8,248 5,998 5,583
*Participants with a 125 kg 1RM bench press.
DB = dumbbell.
Practical Blood Flow Restriction
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Participants did not wear knee or elbow wraps during the
workout sessions. In addition, they were instructed to refrain
from any resistance training outside of football practice for
the duration of the study.
Statistical Analyses
A432 mixed-model multivariate analysis of covariance
(MANCOVA), with training groups serving as the
between-factor, pre- and posttests as the within-factor, and
body mass as the covariate was performed using PASW
Statistics 18. The level of significance was set at 0.05. Sepa-
rate univariate 1 34 analysis of variance (ANOVA) tests
were conducted on each dependent variable as a follow-up
test for any significant main effects from the MANCOVA.
The univariate follow-up ANOVA tests were also mixed
model with training groups serving as the between-factor
and pre- and posttests as the within-factor. Post hoc tests
were conducted to examine any significant effects from the
univariate ANOVAs.
RESULTS
The means and SDs are listed in Table 4. MANCOVA results
revealed a significant difference for the interaction on the
dependent variables, Wilks’ L= 0.606, F(15, 146.711) =
1.943, p= 0.023, multivariate ή
2
= 0.154. To follow-up the
significant MANCOVA on the interaction, separate univari-
ate ANOVAs were conducted on each of the 5 dependent
variables. Only one of the follow-up ANOVAs showed a sig-
nificant effect. A significant interaction was found for 1RM
squat, F(3, 57) = 6.460, p= 0.001, ή
2
= 0.254 (Figure 2). To
help interpret the interaction, a 1-way ANOVA was com-
puted on the change scores for the 1RM squat. This
ANOVA showed a significant difference between groups,
F(3, 58) = 6.00, p= 0.001. Results of Fisher LSD post hoc
tests revealed that the H/S/R group experienced greater
gains in 1RM squat performance than did the M/S/R group
(p,0.000), the H/S group (p= 0.025), and the H group
(p= 0.009).
MANCOVA results revealed no significant difference
for the group factor on the dependent variables, Wilks’
L= 0.75, F
(15, 146.711)
= 1.10, p= 0.360, multivariate ή
2
=
0.093. MANCOVA results also revealed no significant differ-
ence for the time factor on the dependent variables, Wilks’
L= 0.830, F
(5, 53)
= 2.172, p= 0.071, multivariate ή
2
= 0.170.
Because the MANCOVA showed a nonsignificant main
effect for group, follow-up analyses were not required.
However, to better understand
how current results compare to
those of Yamanaka et al. (36),
additional analyses were con-
ducted on 1RM bench press
performance and circumfer-
ence measures.
For 1RM bench press, depen-
dent t-tests were run to examine
changes from pre- to posttest
for the dependent variables,
and a 1 34 ANOVA was con-
ducted on change scores, which
is a comparable analysis to the
independent t-tests performed
by Yamanaka et al. on percent
change. Although the t-test on
1RM bench revealed that there
was a significant increase across
groups (t
(1,61)
= 6.713, p,
0.000), the ANOVA did not
detect differences between the
groups (F
(3,58)
=1.687,p.
0.180).
Dependent t-tests on arm and
thigh circumferences indicated
a significant increase across
groups (arm = t
(1,61)
=2.04,
p= 0.046; thigh = t
(1,61)
=7.22,
p,0.000), but no change for
chest girth (t
(1,61)
=0.34,p=
0.739). The ANOVA did not
TABLE 4. Girth and strength measures.
Group N
Pretest Posttest
Mean changeMean SD Mean SD
Arm (cm)
H/S/R 17 34.7 3.0 35.3 3.0 0.52
H/S 14 36.3 3.8 36.7 3.7 0.49
H 15 35.6 3.0 36.4 3.1 0.78
M/S/R 16 31.7 1.8 31.6 3.2 20.16
Chest (cm)
H/S/R 17 102.2 10.3 101.7 9.7 20.57
H/S 14 107.1 13.9 106.5 11.4 20.58
H 15 106.5 11.8 107.3 10.6 0.76
M/S/R 16 95.0 3.4 94.9 3.1 20.01
Thigh (cm)
H/S/R 17 59.5 4.7 61.5 3.9 1.98
H/S 14 61.1 5.1 63.1 5.9 2.04
H 15 60.6 6.2 62.9 6.6 2.36
M/S/R 16 55.6 3.3 57.3 2.6 1.71
Bench press (kg)
H/S/R 17 123.3 20.7 132.0 24.4 8.69
H/S 14 135.1 19.7 142.4 19.0 7.3
H 15 137.0 24.4 144.1 25.0 7.12
M/S/R 16 115.2 13.4 117.9 13.5 2.7
Squat (kg)
H/S/R 17 193.2 25.0 218.1 24.6 24.87
H/S 14 196.6 27.6 210.9 26.8 14.13
H 15 197.0 35.1 210.6 38.9 13.64
M/S/R 16 174.4 22.2 180.4 24.9 5.97
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detect differences between groups for any girth measurement
(arm = F
(3,58)
= 0.946, p= 0.424; thigh = F
(3,58)
= 0.102, p=
0.958; chest = F
(3,58)
= 1.043, p= 0.381).
DISCUSSION
The purpose of this study was to investigate the effects of
a 7-week practical BFR protocol used in conjunction with
traditional weight training on measures of muscular strength
and size in collegiate American football players. We hypoth-
esized that those who supplemented the traditional high-
intensity strength training program with the low-intensity
lifting protocol under conditions of practical occlusion
would experience greater gains in muscular strength and
size than those in the other treatment groups. The results
partially support the hypothesis.
The primary results of this study were as follows: (a)
H/S/R experienced significantly larger increases in 1RM
squat than the other training groups; (b) although there was
a significant increase in 1RM bench press across groups, the
addition of the supplemental lifting protocol, with or without
occlusion, made no difference in the extent of those gains;
(c) although thigh and arm size increased significantly across
groups, the addition of the supplemental lifting protocol,
with or without occlusion, made no difference in the extent
of those increases.
The supplementary low-intensity training protocol used in
this study to examine the BFR treatment was a modification
of that used by Yamanaka et al. (36), who also used a colle-
giate American football team as the testing population. Both
the Yamanaka et al. study and this investigation used a train-
ing load of 20% 1RM with a set and repetition scheme of
1 set of 30 repetitions, followed by 3 sets of 20 repetitions,
with 45 seconds of rest between each set.
The differences were that Yamanaka et al. (36) used a 5.0-
cm wide elastic wrap (manufacturer not reported) and tight-
ened to a 5.1 cm (2.0 in) overlap, whereas we used a 7.6-cm
wide wrap and used a 7.6 cm (3.0 in) overlap to achieve the
BFR. They used a cadence of 2.0:1.0 seconds for pacing the
eccentric and concentric components of each lift, whereas
we used a cadence of 1.5:1.5 seconds, based on work by
Yasuda et al. (38).
Also, they performed both the BFR squat and bench press
on the same day, as their 4-week program completed 3 total-
body workouts per week (36). Our 7-week program used an
upper- and lower-body split routine, with each being per-
formed twice per week, for a total of 4 lifting days per week.
Therefore, the BFR squat and bench press lifts were on
separate days, each following the respective lower-body or
upper-body workouts.
Finally, their study used 2 training groups, both of which
completed the supplementary 20% 1RM lifting sessions,
although only 1 received the practical BFR wrap treatment
(36). We replicated this scenario with our H/S and H/S/R
groups. However, we incorporated 2 additional groups in an
effort to further clarify the potential effects of practical BFR
training in a well-trained population. Yamanaka et al. re-
ported significant differences between groups in 1RM bench
press and squat performance gains, with those in the BFR
treatment group experiencing larger increases. In addition,
they also observed differences in chest size, with the BFR
group again seeing greater increases. The results of this study
only partially replicated the findings of Yamanaka et al.
Yamanaka at al. (36) reported that the BFR treatment
group experienced significantly greater gains in 1RM squat
than those of the non-BFR control group. This investigation
replicated that finding. Univariate follow-up tests to the sig-
nificant interaction showed a significant difference for 1RM
squat, with the H/S/R group experiencing greater gains
than the other training groups (Figure 2).
This disproportionate increase was likely a result of the
use of practical BFR in conjunction with the low-intensity
supplemental lifting protocol at the conclusion of the
traditional high-intensity workout. A brief review of the
training groups aids in understanding this interpretation.
First, M/S/R also performed the supplemental lifts with the
practical occlusion application (i.e., the wraps), but com-
pleted only the modified training program, which excluded
any traditional high-intensity squat variations. This seems to
indicate that performing low-intensity BFR after high-
intensity training results in greater increases than can be
expected when performing BFR in the absence of high-
intensity training. Second, H/S completed the high-intensity
training and the low-intensity supplemental lifts, but not
under conditions of practical occlusion. Therefore, the
occlusion application appears to provide an additional
stimulus for strength gains beyond the low-intensity supple-
mental lifting protocol even when used in conjunction with
high-intensity training. Finally, the gains experienced by
Figure 2. Group 3time interaction for 1 repetition maximum squat. * =
significantly different from the other 3 training groups (p#0.05).
Practical Blood Flow Restriction
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M/S/R and H/S were the same as those seen by H, who
completed only the traditional high-intensity workout. The
lack of difference among these 3 groups further supports the
concept that the additional gains seen by H/S/R are likely
the result of the combination of high-intensity training
followed by the low-intensity supplemental sessions under
conditions of practical BFR.
As with the 1RM squat, Yamanaka et al. (36) reported
significant increases in 1RM bench press performance, with
the BFR treatment group experiencing greater gains than
the non-BFR control group. This investigation did not sup-
port this finding. Because the MANCOVA showed a nonsig-
nificant main effect for group, follow-up analyses were not
required. But as previously noted, additional analyses were
conducted to better understand how current results compare
to those of the Yamanaka et al. study (see Results). Although
the dependent t-test on 1RM bench revealed that there was
a significant increase across groups, the ANOVA did not
detect differences between groups. This indicates that in
reference to upper-body strength, neither the supplemental
lifting protocol nor practical BFR application provided any
additional benefit beyond what was experienced with the
traditional high-intensity training regimen.
One possible explanation for this is that the upper-body
high-intensity workout had already provided a maximum
stimulus for increasing strength and that the potential gains
often seen with BFR training were attenuated accordingly.
Wernbom et al. (33) noted in their review of resistance train-
ing that there appears to be a sigmoidal dose-response in
reference to training volume, whereas gains in muscle mass
seem to increase with greater volumes or durations of work,
but that there is a point of diminishing returns. They go on
to indicate that moderate volumes of work appear to result
in the largest responses. Although Wernbom et al. are refer-
encing muscle mass and not strength per se, it seems reason-
able that a similar dose-response would exist with strength
gains as strength is a property of the neuromuscular system.
Therefore, it is possible that the volume of the upper-body
high-intensity training protocol was near the peak of the
dose-response curve and that the additional dose provided
by the supplemental training volume and/or the BFR occlu-
sion stimulus could not elicit further response.
Although the high-intensity workout may have provided
sufficient stimulus for strength gains in H, H/S, and H/S/R,
it does not explain the gains experienced by M/S/R, who
only completed the modified training protocol before the
BFR training. It is possible that the BFR application could
account for the strength gains, which has been demonstrated
previously in trained populations (3,30,36). However, in the
absence of a non-BFR, modified training group with which
to compare, it can only be speculated.
Another possibility is that although M/S/R did not
perform any of the traditional “high-intensity” lifts, they still
completed a substantial amount of total work. The overall
volume of BFR training sessions can be quite high even
though BFR training is often described as low-intensity
work. Defining workout intensity by the percentage of the
1RM (%1RM) of a given lift for an individual is common and
is often referred to as relative intensity (9). But, although
BFR training typically uses a low relative intensity of 20–
30% 1RM, the work volume for a session of BFR exercise
can be substantial and possibly comparable to the work vol-
ume of a traditional “high-intensity” session. For example,
a bench press 1RM of 100.0 kg would dictate a barbell load
for a BFR session using 20% 1RM to be 20.0 kg. If the BFR
protocol was identical to that used in this study, a total of 90
repetitions with that load would be performed, resulting in
an exercise volume-load (repetitions 3weight) of 1,800 kg.
If a more traditional high-intensity workload of 80% of that
same 1RM (80.0 kg) were used to complete a typical high-
intensity workout of 4 sets of 6 repetitions, the total exercise
volume-load would be 1,920.0 kg—only 120.0 kg more than
the BFR session. Therefore, it is plausible that the volume-
load completed by M/S/R was high enough on the dose-
response curve that strength gains resulted, despite the
absence of using a high relative intensity.
Although research generally indicates that traditional
high-intensity programs are superior for strength gains,
there is some work that suggests that using a low relative
intensity along with higher repetitions may also be effective
at promoting strength, provided enough volume is used,
even in the absence of BFR (26). However, because total
workloads for each participant were not calculated for this
study, this remains speculative.
The possibility that the upper-body high-intensity training
program alone may have provided a maximal strength gain
stimulus is also supported by observations made during this
study that seem to oppose those made by Yamanaka et al. (36)
in their investigation. They stated that all participants in their
study were able to complete every repetition in the supple-
mental protocols and that personal conversation with the
participants after the sessions indicated that the players felt
that the number of repetitions “was not sufficient for them to
reach exhaustion.” Interestingly, our observations during this
study were quite different. Although no data were collected
on repetitions completed, we observed that some participants
had to pause or skip a repetition during the supplemental
lifting sessions. Personal discussions indicated that these par-
ticipants were simply getting fatigued and needed a brief
respite to continue. Although this was only occasionally seen
during the squat exercise, it was more common during the
bench press sessions. This was true for participants who were
in both H/S and H/S/R (non-wrapped and wrapped), which
indicates that the fatigue could not have been because of the
use of the practical BFR wraps alone.
This is also supported by our observations that those in
M/S/R did not skip repetitions during the sets, even though
they were also using the elastic wraps in the same manner as
H/S/R. Because M/S/R completed only the modified
training program before BFR training (i.e., no high-intensity
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squats, bench press, or their variations), it suggests that the
fatigue experienced by H/S and H/S/R was more likely
a result of the high-intensity training program that they
completed just before the supplemental training, rather than
the extra lifting sessions and/or the BFR wraps. Although
Yamanaka et al. (36) did not report the details of the strength
and conditioning program used in their study, it seems rea-
sonable to surmise that it was of a lower overall volume than
the high-intensity training program used by H, H/S, and H/
S/R in this investigation. The volume of the workout and
BFR training protocol used by Yamanaka et al. may have been
sufficiently low enough on the dose-response curve that the
extra stimulus provided by the BFR wraps was able to pro-
duce an increased response.
In reference to the work volume-load of the lower-body
sessions, H/S/R did experience a greater increase in 1RM
squat compared with H and H/S. This suggests that the high-
intensity lower-body training program did not provide
a maximal stimulus for strength gains. Therefore, the volume
was likely lower on the dose-response curve relative to the
upper-body training, allowing for the addition of the practical
BRF application to elicit a greater strength response.
Similar to Yamanaka et al. (36), this investigation em-
ployed the use of girth measurements in an effort to assess
changes in muscular size, namely at the thigh, chest, and
upper arm. The aforementioned study observed increases
in chest girth but not thigh or arm girth. Thefindings of this
investigation were contrary. As with the 1RM bench press,
the MANCOVA revealed no interaction for group on cir-
cumferences, so additional analyses were conducted to bet-
ter compare current results to those of Yamanaka et al. (see
Results). The dependent t-tests on arm and thigh circum-
ferences indicated a significant increase across groups, but no
change for chest girth. The ANOVA did not detect differ-
ences between groups for any girth measurement. So, while
there was no change in chest size, there were small but
significant increases at the thigh and the arm across groups,
but no differences among the treatments. However, the prac-
tical significance of these results for changes in girths be-
comes questionable when consideration is given to the
magnitude of the changes, as can be seen in Table 4.
This study was not without limitations. Because of using
elastic knee wraps in a practical manner to achieve BFR,
knowing the precise pressure actually applied to each
participant was not possible. Benefits from BFR occur when
there is adequate pressure to occlude venous return, but yet
only restrict arterial delivery (25). Wilson et al. (35) have
shown that elastic wraps (7.6 cm wide) applied with a per-
ceptive pressure of 7 on a scale of 0–10 are effective at
allowing a restricted arterial flow while occluding venous
return in the thigh muscle.
Perceptive pressure is a subjective measure and will likely
differ among individuals and may even vary for each person
on a day-by-day basis. Yamanaka et al. (36) used a 5.1 cm
(2.0 in) overlap to achieve BFR in their study but did not
report on the procedure used to determine that degree of
tension. Before the start of our training program, we re-
cruited 4 athletes in an effort to standardize the elastic wrap
pressure to be used in the study. We explained to them the
concept of the 0–10 scale of perceptive pressure and how to
use it in reference to wrap pressure (35). We then applied
a wrap to the upper leg with just enough tightness to remain
in place (perceptive pressure = zero), and a note was made
of the location of the end of the wrap. Then, the wrap was
slowly pulled tight until the participant indicated that the
tightness had reached a perceptive pressure of 7. The wrap
was then secured in place. The difference between where the
end of the wrap was before the tightening to where it was
secured after the tightening (i.e., the overlap) was measured,
on which the wrap was removed.
This procedure was repeated with every participant and
each required a slightly different overlap to reach a percep-
tive pressure of 7. The overlaps were then averaged, with
a result of approximately 7.0 cm (2.75 in). Following the
same procedure on the arms, we found an average overlap of
approximately 6.6 cm (2.60 in). We concluded that an
overlap of 7.6 cm (3.0 in) for both the upper body and
lower body during the study would likely be sufficient to
obtain a perceptive pressure of 7 for most of the participants
in the study. The use of a single overlap measure for both
applications also simplified the procedures and reduced
potential errors in applying and tightening the wraps.
Another potential limitation is that the participants in this
study were well-trained, male, collegiate American football
players. The results might not be generalizable to other
athletic populations, non-athletes, or those who are weight-
training novices.
Future research should examine high-intensity programs
of various work volumes and their relationship with the
effects of concurrent practical BFR programs. This could
provide additional insight into determining whether a dose-
response does exist when the 2 are used in conjunction and if
so, where the point of diminishing returns can be expected. If
it is found that practical BFR, when used together with
lower volumes of high-intensity work, can elicit strength
gains that are similar to, or exceed those typically observed
with traditional higher volumes of high-intensity work, then
this could have implications for future program design.
A lower overall training volume and/or lower external load
may allow athletes to recover faster, reduce their risk of
injury, and lessen their chance of overtraining. Taken
together with an increase in strength, this could translate
to improved athletic performance.
Investigating the dose-response in the context of in-season
strength and conditioning programs would be especially
relevant as these programs normally reduce volume as focus
shifts from strength training to actual competition. This shift
generally results in athletes experiencing declines in strength
as the season progresses. An effective combination of low
volume, high-intensity work and practical BFR may result in
Practical Blood Flow Restriction
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the maintenance or increase of strength during the compet-
itive season, which is typically not experienced.
Also, limb size and possibly body composition appear to
play a role in how much pressure is needed to achieve
adequate BFR (19). Therefore, additional research should
examine how to best individualize perceptive pressure when
using practical BFR, for both the lower- and upper-body
applications.
In conclusion, this study demonstrated that the use of
a practical BFR program in conjunction with a traditional
high-intensity off-season training program was effective in
increasing 1RM squat performance in well-trained collegiate
athletes.
PRACTICAL APPLICATIONS
The results of this study indicate that practical BFR training
can be effective in increasing 1RM squat performance when
added to an off-season, high-intensity collegiate American
football strength and conditioning program. Elastic power-
lifting knee wraps are relatively affordable and easy to use
compared with traditional BFR methods. This reduction in
the cost and complexity typically associated with BFR
training provides athletic programs, teams, coaches, and
athletes an increased opportunity to incorporate BFR into
their strength and conditioning programs.
ACKNOWLEDGMENTS
The authors would like to thank the Emporia State
University football team and coaching staff for their partic-
ipation and dedication to this study. Also, we would like to
thank the ESU Research and Grants Center and the ESU
Teachers College for their help in funding this project.
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... It is generally accepted that high-intensity resistance training (≥70% of 1RM) can stimulate gains in muscle strength (22). However, previous studies have shown that low-load BFR resistance and endurance exercises performed with BFR can increase maximal strength (28,31,(37)(38)(39)(40). The results of the present study are consistent with previous research in that the leg with BFR exercise showed increased muscle strength. ...
... Walking and cycling with BFR can also positively influence maximal strength (28,31,40,44) According to recent metaanalysis, training with BFR can more effectively improve strength and hypertrophy than low-load training performed with unrestricted blood flow (45). Furthermore, previous findings suggest that significant muscle development is possible in athletes after low-load training with BFR (37)(38)(39). Although evidence suggests that high-intensity exercise without BFR provides a more neurological stimulus than low-intensity resistance exercise with BFR (46,47), well-trained athletes show limited potential for further neural adaptations (48). ...
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Purpose: The effects of short-term blood flow restriction (BFR) exercise on muscle blood flow perfusion and performance during high-intensity exercise were determined in elite para-alpine standing skiers to assess whether this would be an effective training regimen for elite athletes with disabilities. Methods: Nine national-level para-alpine standing skiers (mean age, 20.67 ± 1.34 y; four women) were recruited. Non-dominant lower limbs were trained with BFR (eight in final analyses); dominant lower limbs without BFR (seven in final analyses). The 2-week protocol included high-load resistance, local muscle endurance (circuit resistance training), and aerobic endurance (stationary cycling) training performed 4 times/wk, with BFR during local muscle endurance and aerobic endurance sessions. Muscle strength was measured by maximal voluntary isometric contraction (MVIC) in the knee extensors; microcirculatory blood perfusion (MBP), by laser doppler blood flow; and muscle strength and endurance, by the total amount of work (TW) performed during high-intensity centrifugal and concentric contractions. Results: BFR significantly increased absolute and relative MVIC (P < 0.001, P = 0.001), MBP (P = 0.011, P = 0.008), and TW (P = 0.006, P = 0.007) from pretraining values, whereas only absolute MVIC increased without BFR (P = 0.047). However, the MVIC increase with BFR exercise (35.88 ± 14.83 N·m) was significantly greater (P = 0.040) than without BFR exercise (16.71 ± 17.79 N·m). Conclusions: Short-term BFR exercise significantly increased strength endurance, muscle strength, and microcirculatory blood perfusion in national-level para-alpine standing skiers. Our study provides new evidence that BFR exercise can improve local muscle blood perfusion during high-intensity exercise and informs BFR exercise strategies for athletes with disabilities.
... The elastic wrap (5 cm wide) was pulled to overlap 5.08 cm in relation to the initial length of the elastic applied without tension; thus, an arbitrary fixed prescription was used for all individuals. This same technique was later used in several studies [16][17][18]. It is important to highlight that the aforementioned procedures of the studies [8][9][10][11][12][13][14][15] regarding the prescription of pBFR pressure were performed without knowing what effect was being caused on the arterial and venous blood flow. ...
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Most studies with blood flow restriction (BFR) training have been conducted using devices capable of regulating the restriction pressure, such as pneumatic cuffs. However, this may not be a viable option for the general population who exercise in gyms, squares and sports centers. Thinking about this logic, practical blood flow restriction (pBFR) training was created in 2009, suggesting the use of elastic knee wraps as an alternative to the traditional BFR, as it is low cost, affordable and practical. However, unlike traditional BFR training which seems to present a consensus regarding the prescription of BFR pressure based on arterial occlusion pressure (AOP), studies on pBFR training have used different techniques to apply the pressure/tension exerted by the elastic wrap. Therefore, this Current Opinion article aims to critically and chronologically examine the techniques used to prescribe the pressure exerted by the elastic wrap during pBFR training. In summary, several techniques were found to apply the elastic wrap during pBFR training, using the following as criteria: application by a single researcher; stretching of the elastic (absolute and relative overlap of the elastic); the perceived tightness scale; and relative overlap of the elastic based on the circumference of the limbs. Several studies have shown that limb circumference seems to be the greatest predictor of AOP. Therefore, we reinforce that applying the pressure exerted by the elastic for pBFR training based on the circumference of the limbs is an excellent, valid and safe technique.
... 1 When setting the loads for resistance training, the maximal weight a subject can lift with one repetition (one repetition maximum; 1RM) is initially calculated to deduce the relative rates of this value (%1RM). [2][3][4][5][6] In knee extension exercises, the 1RM tends to be estimated based on the relationship between the load and number of repetitions. Furthermore, as knee extension is an angular movement involving a single joint, it is recommended that the 1RM measurement should also involve measurements of the joint torque and angular velocity. ...
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Objective: When performing knee extension using a leg extension machine, the lower limb is pushed back in the direction in which knee flexion occurs in response to the freefall of the weight after maximal knee extension. Therefore, eccentric contractions of the knee extensors are needed, which may lead to cumulative fatigue of the extensors, consequently reducing the reliability of the knee extensor torque values. This study aimed to determine the relationship between joint torque and angular velocity in one repetition maximum (1RM) measurement for knee extension using a leg extension machine with and without a modification to prevent counter-rotation. Methods: Twenty-one healthy adult men (mean age: 27.7±5.4 years) participated in the study. A leg extension machine was modified to prevent counter-rotation due to the freefall of weights. The subjects performed knee extension using the modified leg extension machine, and the joint torque and angular velocity were calculated using two-dimensional analysis. A regression equation between these two factors was created to estimate the maximal isometric torque. Results: Both the joint torque and angular velocity tended to increase after modification of the leg extension machine, although these differences were not significant. Similarly, there were no significant post-modification changes in the estimated maximal isometric torque. Conclusions: Our results showed that the joint torque, angular velocity, and estimated maximal isometric torque remained unchanged after machine modification; thus, the modified leg extension machine may make it possible to produce the knee extensor torque more safely in 1RM measurement.
... However, current recommendations for a training frequency of 2-4 times per week, mirror those of traditional resistance training for strength and hypertrophy increases (Kraemer and Ratamess, 2004;Fleck;, Schoenfeld et al., 2017. Despite variances in the duration of BFRT interventions, three weeks or longer is typically advocated as a prerequisite for adequate strength and hypertrophy adaptations to occur (Martin-Hernandez et al., 2013;Luebbers et al., 2014;Kang et al., 2015). Considerations of cuff application in BFRT are also important, with key variables of cuff pressure, width and material requiring attention (Abe et al., 2019;. ...
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Tendinopathy is chronic tendon disease which can cause significant pain and functional limitations for individuals and collectively place a tremendous burden on society. Resistance training has long been considered the treatment of choice in the rehabilitation of chronic tendinopathies, with both eccentric and heavy slow resistance training demonstrating positive clinical effects. The application of progressive tendon loads during rehabilitation is essential to not compromise tendon healing, with the precise dosing parameters of resistance training and external loading a critical consideration. Blood-flow restriction training (BFRT) has become an increasingly popular method of resistance training in recent years and has been shown to be an effective method for enhancing muscle strength and hypertrophy in healthy populations and in musculoskeletal rehabilitation. Traditional resistance training for tendinopathy requires the application of heavy training loads, whereas BFRT utilises significantly lower loads and training intensities, which may be more appropriate for certain clinical populations. Despite evidence confirming the positive muscular adaptations derived from BFRT and the clinical benefits found for other musculoskeletal conditions, BFRT has received a dearth of attention in tendon rehabilitation. Therefore, the purpose of this narrative review was threefold: firstly, to give an overview and analysis of the mechanisms and outcomes of BFRT in both healthy populations and in musculoskeletal rehabilitation. Secondly, to give an overview of the evidence to date on the effects of BFRT on healthy tendon properties and clinical outcomes when applied to tendon pathology. Finally, a discussion on the clinical utility of BFRT and its potential applications within tendinopathy rehabilitation, including as a compliment to traditional heavy-load training, will be presented.
... BFR impact on maximal strength currently remains insufficiently examined. Although some research indicated that BFR may improve 1RM performance, the authors examined chronic adaptations following 6-and 7-week resistance training programs [25,26]. Only one study by Wilk et al. [48] examined the acute impact of BFR on the result of the 1RM test. ...
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Kalp-damar sistemi, doku veya organların işlevlerini kontrol edilebilmek için gerekli olan kan ihtiyacını karşılaması gerekmektedir. Bu ihtiyacın karşılanması sırasında yaşanacak olan denge ve kesinti sorunları ilgili doku ya da organdaki işlev bozukluğuna yol açarak iskemi durumunu ortaya çıkarmaktadır. Bu durumda yaşanan oklüzyon-reperfüzyon durumu (kan akımı kısıtlama ve tekrar serbestleme / yetersizlik-kanlanma) bazı doku-organ hasarlarına sebebiyet verebilmektedir. Aynı zamanda, yaşanan bu evrede bazı metabolit oluşumları nedeniyle farklı dokularda da negatif yönde etkilenmeler ortaya çıkabilmektedir. (1) İskemik ön koşullandırma (kalp kası üzerinde) ilk olarak 1986 yılında uygulanmıştır. (2) Kalp kasında (miyokard), kalbi besleyen damarların (koroner) oklüzyonu (40 dakikalık) öncesi, reperfüzyon aralıkları (5’ er dakikalık) düzenlenerek ilgili damarların tıkanması sonucunda hücrelerdeki ölüm (nekroz) oranı (yaklaşık %75) oldukça azalmıştır. (3,4) İskemik ön koşullandırmada deneyi; hayvanlarda (köpek) yapılan, ölümcül olmayan, kardiyak iskemi-reperfüzyon aralıklarının daha sonra uzun süreli kardiyak iskemiye karşı koruma sağladığını gösteren bir deneydir. Kısa aralıklı oklüzyon-reperfüzyon döngülerine ve ardından hiperemiye maruz kalmadan oluşan iskemik ön koşullandırmanın (iskemik preconditioning / IPC) dokuları iskemiye karşı koruduğu kanıtlanmıştır. (2)
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Blood flow restriction (BFR) therapy is being used more frequently for rehabilitation from orthopedic injuries. Several physiologic mechanisms of action, at local and systemic levels, have been proposed. Numerous studies have investigated the effects of BFR training in healthy athletes; however, limited clinical data exist supporting the use of BFR after surgery. Given that BFR training may facilitate muscle development using low-load resistance exercises, it offers a unique advantage for the post-surgical patient who cannot tolerate traditional high resistance training. [Orthopedics. 2021;44(6):xx-xx.].
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Blood flow restriction (BFR) with low-load resistance exercise (RE) is often used as a surrogate to traditional high-load RE to stimulate muscular adaptations, such as hypertrophy and strength. However, it is not clear whether such adaptations are achieved through similar cellular and molecular processes. We compared changes in muscle function, morphology and signaling pathways between these differing training protocols. Twenty-one males and females (mean ± SD: 24.3 ± 3.1 years) experienced with resistance training (4.9 ± 2.6 years) performed nine weeks of resistance training (three times per week) with either high-loads (75-80% 1RM; HL-RT), or low-loads with BFR (30-40% 1RM; LL-BFR). Before and after the training intervention, resting muscle biopsies were collected, and quadricep cross-sectional area (CSA), muscular strength and power were measured. Approximately 5 days following the intervention, the same individuals performed an additional 'acute' exercise session under the same conditions, and serial muscle biopsies were collected to assess hypertrophic- and ribosomal-based signaling stimuli. Quadricep CSA increased with both LL-BFR (7.4±4.3%) and HL-RT (4.6±2.9%), with no significant differences between training groups (p=0.37). Muscular strength also increased in both training groups, but with superior gains in squat 1RM occurring with HL-RT (p<0.01). Acute phosphorylation of several key proteins involved in hypertrophy signaling pathways, and expression of ribosomal RNA transcription factors occurred to a similar degree with LL-BFR and HL-RT (all p>0.05 for between-group comparisons). Together, these findings validate low-load resistance training with continuous BFR as an effective alternative to traditional high-load resistance training for increasing muscle hypertrophy in trained individuals.
Thesis
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SUMMARY Purpose: The overarching aim of this thesis was to investigate the effect of short-term blocks with high-frequency low-load blood flow restricted resistance exercise (BFRRE) on muscular adaptations in untrained individuals, recreationally trained individuals and elite strength athletes. Three independent studies with four original papers have been completed towards this objective. High-frequency BFRRE has been shown to induce rapid muscle growth accompanied by increased numbers of satellite cells and myonuclei. However, the satellite cell and myonuclear responses appears to plateau after an initial block of training and it may be speculated that a rest period can reset the responsiveness of the system after the initial training response. Thus, the aims of Study I and II were to investigate the effect and time-course of changes in fiber and whole muscle areas, myonuclear and satellite cell numbers and muscle strength during two five-day blocks of high-frequency low-load BFRRE, separated by 10 days of rest. In addition, the importance of performing BFRRE sets to failure on cellular adaptations has not been investigated. Therefore, Study II compared the effect of a failure- vs. a non-failure high-frequency BFRRE protocol. Despite the impressive rates of muscle growth reported in some studies on high-frequency BFRRE, several recent studies have shown that BFRRE increases markers of muscle damage and cellular stress. To shed light on possible mechanisms for myocellular stress and damage after strenuous high-frequency BFRRE, heat shock protein (HSP) responses, glycogen content and inflammatory markers were investigated in Study I (paper II). Finally, the impact of low-load BFRRE has not yet been investigated in highly specialized strength athletes, such as powerlifters. Thus, the aim of Study III was to investigate the effect of implementing two five-day blocks of high-frequency low-load BFRRE during six weeks of periodized strength training in elite powerlifters, on the changes in number of satellite cells, myonuclei and muscle size and strength. METHODS: A total of 47 healthy men and women participated in the studies. Thirteen recreationally trained sports students in Study I (24±2 yrs [mean±SD], 9 men) and 17 untrained men in Study II (25±6 yrs), completed two 5-day-blocks of seven BFRRE sessions, separated by a 10-day rest period. A failure BFRRE protocol consisting of four sets with knee extensions to voluntary failure at 20% of one-repetition maximum (1RM) was performed with both legs in Study I, and randomized to one of the legs in Study II. The other leg in Study II performed a non-failure BFRRE protocol (30, 15, 15, 15 repetitions). In Study I, muscle samples from m. vastus lateralis (VL) obtained before and 1h after the first session in the first and second block (“Acute1” and “Acute2”), after three sessions (“Day4”), during the “Rest Week”, and at three (“Post3”) and ten days post-intervention (“Post10”), were analyzed for muscle fiber area (MFA), myonuclei, satellite cells, mRNA, miRNA, HSP70, αB-crystallin, glycogen (PAS staining), CD68+ (macrophages) and CD66b+ (neutrophils) cell numbers. Muscle strength (1RM knee-extension) and whole muscle size (ultrasonography and magnetic resonance imaging) was measured up until 20 days after the last exercise session (Post20). In Study II, muscle samples obtained before, at midtraining, and 10 days post-intervention (Post10) were analyzed for muscle fiber area (MFA), myonuclei, and satellite cells. Muscle thickness, cross-sectional area and echo intensity were measured by ultrasonography, and knee-extension strength with 1RM and maximal isometric contraction (isomMVC) up until Post24. In Study III, seventeen national level powerlifters (25±6 yrs, 15 men) were randomly assigned to either a BFRRE group (n=9) performing two blocks (week 1 and 3) of five BFRRE front squat sessions within a 6.5-week training period, or a conventional training group (Con; n=8) performing front squats at ~70% of 1RM. The BFRRE consisted of four sets (first and last set to voluntary failure) at ~30% of 1RM. Muscle biopsies were obtained from VL and analyzed for MFA, myonuclei, satellite cells and capillaries. Cross-sectional areas (CSA) of VL and m. rectus femoris (RF) were measured by ultrasonography. Strength was evaluated by maximal voluntary isokinetic torque (dynMVC) in knee-extension and 1RM in front squat. RESULTS: With the first block of BFRRE in Study I (paper I), satellite cell number increased in both fiber types (70-80%, p<0.05), while type I and II MFA decreased by 6±7% and 15±11% (p<0.05), respectively. No significant changes were observed in number of myonuclei or strength during the first block of training. With the second block of training, muscle size increased by 6-8%, while the number of satellite cell (type I: 80±63%, type II 147±95%), myonuclei (type I: 30±24%, type II: 31±28%) and MFA (type I: 19±19%, type II: 11±19%) peaked 10 days after the second block of BFRRE. Strength peaked after 20 days of detraining (6±6%, p<0.05). Pax7- and p21 mRNA expression were elevated during the intervention, while myostatin, IGF1R, MyoD, myogenin, cyclinD1 and -D2 mRNA did not change until 3-10 days post intervention. In paper II of Study I, αB-crystallin was reported to translocate from the cytosolic to the cytoskeletal fraction after Acute1 and Acute2 (p<0.05), and immunostaining revealed larger responses in type 1 than type 2 fibers (Acute1, 225±184% vs. 92±81%, respectively, p=0.001). HSP70 was increased in the cytoskeletal fraction at Day4 and Post3, and immunostaining intensities were more elevated in type 1 than in type 2 fibers (Day4, 206±84% vs. 72±112%, respectively, p<0.001). Glycogen content was reduced in both fiber types; but most pronounced in type 1, which did not recover until the Rest Week (-15-29%, p≤0.001). Intramuscular macrophage numbers were increased by ~65% postintervention, but no changes were observed in muscle neutrophils. Both protocols in Study II increased myonuclear numbers in type-1 (12- 17%) and type-2 fibers (20-23%), and satellite cells in type-1 (92-134%) and type-2 fibers (23-48%) at Post10 (p<0.05). RF and VL size increased by 7-10% and 5-6% in both legs at Post10 to Post24, whereas the MFA of type-1 fibers in Failure was decreased at Post10 (-10±16%; p=0.02). Echo intensity increased by ~20% in both legs during Block1 (p<0.001) and was ~8-11% below baseline at Post24 (p=0.001-0.002). IsomMVC decreased by 8-10% in both legs and 1RM by 5% in the failure leg after Block1 (p=0.01-0.02). IsomMVC and 1RM were increased in both legs by 6-7% and 9-11% at Post24, respectively (p<0.05). In Study III, BFRRE in powerlifters induced selective type I fiber increases in MFA (BFRRE: 12% vs. Con: 0%, p<0.01) and myonuclear number (BFRRE: 17% vs. Con: 0%, p=0.02). Type II MFA was unaltered in both groups. BFRRE induced greater changes in VL CSA than control (7.7% vs. 0.5%, p=0.04), and the VL CSA changes correlated with the increases in MFA of type I fibers (r=0.81, p=0.02). No significant group differences were observed in SC and strength changes. CONCLUSIONS: High-frequency low-load BFRRE in Study I and II induced pronounced responses in satellite cell proliferation, delayed myonuclear addition and increases in muscle size, concomitantly with delayed increases in strength in untrained and recreationally trained individuals. While the gains in satellite cell and myonuclear numbers as well as muscle size and strength were similar between non-failure and failure BFRRE protocols in Study II, perceptions of exertion, pain and muscle soreness were lower in the non-failure leg. Hence, nonfailure BFRRE may be a more feasible and safe approach. However, we report that short-term strenuous high-frequency BFRRE can induce elevations in multiple markers of cellular stress and damage in non-strength trained individuals. We showed that low-load BFRRE stressed both fiber types, but the fiber type-specific HSP-responses and prolonged glycogen depletion strongly indicated that type 1 fibers were more stressed than type 2 fibers. It appears that the first block of unaccustomed BFRRE exceeded the capacity for recovery in both Study I and II, and may have induced muscle damage in some of our participants. In accordance with our hypothesis, our participants seemed to recover during the rest week and to respond well to the second block of BFRRE. It is intriguing that BFRRE induced preferential type I hypertrophy after the second block of training in Study I. This indicates that although the initial stress may be too high (and cause damage), adaptive responses will occur and later the same exercise stress will be the important stimuli for adaptation. Our findings from Study I and II may provide insights into some of the physiological mechanisms underpinning overreaching and subsequent recovery and supercompensation after periods of very strenuous exercise. Finally, in Study III, two one-week blocks with high-frequency low-load BFRRE implemented during six weeks of periodized strength training induced a significant increase in muscle size and myonuclear addition in elite powerlifters. Preferential hypertrophy and myonuclear addition of type I fibers appears to explain most of the overall muscle growth. Intriguingly, these responses are in contrast to heavy-load strength training, that typically induces a greater type II fiber hypertrophy. Consequently, BFRRE appears to have complementary effects to heavyresistance training and the combination of these two methods may optimize adaptations of both fiber types in highly strength-trained individuals. However, despite the increases in muscle size, we could not observe any group differences in maximal strength.
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To investigate the effect of acute changes of extracellular osmolality on whole body protein and glucose metabolism, we studied 10 male subjects during three conditions: hyperosmolality was induced by fluid restriction and intravenous infusion of hypertonic NaCl [2-5%; (wt/vol)] during 17 h; hypoosmolality was produced by intravenous administration of desmopressin, liberal water drinking, and infusion of hypotonic saline (0.4%); and the isoosmolality study consisted of ad libitum oral water intake by the subjects. Leucine flux ([1-13C]leucine infusion technique), a parameter of whole body protein breakdown, decreased during the hypoosmolality study ( P < 0.02 vs. isoosmolality). The leucine oxidation rate decreased during the hypoosmolality study ( P < 0.005 vs. isoosmolality). Metabolic clearance rate of glucose during hyperinsulinemic-euglycemic clamping increased less during the hypoosmolality study than during the isoosmolality study ( P < 0.04). Plasma insulin decreased, and plasma nonesterified fatty acids, glycerol, and ketone body concentrations and lipid oxidation increased during the hypoosmolality study. It is concluded that acute alterations of plasma osmolality influence whole body protein, glucose, and lipid metabolism; hypoosmolality results in protein sparing associated with increased lipolysis and lipid oxidation and impaired insulin sensitivity.
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Blood flow restricted (BFR) resistance exercise has become a popular area of research. However, studies use a range of blood flow restriction and resistance exercise protocols. Objectives: To provide an overview of the methods used for BFR resistance exercise for individuals interested in utilizing BFR training and for researchers studying the acute and chronic effects of BFR resistance exercise. Design: A systematic review. Method: BFR resistance training studies with muscular strength and hypertrophy as main outcomes were identified. Resistance exercise protocol and blood flow restriction protocol were compared between these studies. Acute BFR resistance exercise studies comparing different BFR protocols were also examined. Results: Continuous, partial arterial blood flow restriction during resistance exercise appears to be tolerable and effective for increasing both limb and trunk muscle strength and hypertrophy. Compared to non-BFR exercise, blood flow restriction produces an additive effect when combined with resistance exercise loads of <50% one-repetition maximum. Optimal BFR resistance training frequency may be higher (2x daily) than high-load resistance exercise. Conclusions: Restrictive cuff size, pressure, and limb circumference affect the degree of blood flow restriction and should be carefully considered when performing or prescribing BFR resistance exercise. The volume and frequency of BFR resistance exercise may depend on the trainee&apos;s capabilities and goals.
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Resistance training in combination with practical blood flow restriction (pBFR) is thought to stimulate muscle hypertrophy by increasing muscle activation and muscle swelling. Most previous studies used the KAATSU device; however, little long-term research has been completed using pBFR. To investigate the effects of pBFR on muscle hypertrophy. Twenty college-aged male participants with a minimum of 1 year of resistance training experience were recruited for this study. Our study consisted of a randomized, crossover protocol consisting of individuals either using pBFR for the elbow flexors during the first 4 weeks (BFR-HI) or the second 4 weeks (HI-BFR) of an 8-week resistance training programme. Direct ultrasound-determined bicep muscle thickness was assessed collectively at baseline and at the end of weeks 4 and 8. There were no differences in muscle thickness between groups at baseline (P = 0·52). There were time (P<0·01, ES = 0·99) but no condition by time effects (P = 0·58, ES = 0·80) for muscle thickness in which the combined values of both groups increased on average from week 0 (3·66 ± 0·06) to week 4 (3·95 ± 0·05) to week 8 (4·11 ± 0·07). However, both the BFR-HI and HI-BFR increased significantly from baseline to week 4 (6·9% and 8·6%, P<0·01) and from weeks 4 to 8 (4·1%, 4·0%, P<0·01), respectively. The results of this study suggest that pBFR can stimulate muscle hypertrophy to the same degree to that of high-intensity resistance training.
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The purpose of this study was to investigate the effects of short-term KAATSU-resistance training on skeletal muscle size and sprint/jump performance in college athletes. Fifteen male track and field college athletes were randomly divided into two groups: KAATSU (resistive exercise combined with blood flow restriction, n=9) and control (n=6) groups. The KAATSU group trained twice daily with squat and leg curl exercises (20% of 1-RM, 3 sets of 15 repetitions) for 8 consecutive days while both KAATSU and control groups participated in the regular sprint/jump training sessions. Maximal strength, muscle-bone CSA, mid-thigh muscle thickness (MTH), and sprint/jump performance were measured before and after the 8 days of training. The muscle-bone CSA increased 4.5% (p 0.05) in the control group. Quadriceps and hamstrings MTH increased (p 0.05) in the control group. Overall 30-m dash times improved (p 0.05) for either the KAATSU or control groups. These data indicated that eight days of KAATSU-training improved sprint but not jump performance in collegiate male track and field athletes.
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The purpose of this study was to examine the daily skeletal muscle hypertrophic and strength responses to one week of twice daily KAATSU training, and follow indicators of muscle damage and inflammation on a day-to-day basis, for one subject. KAATSU training resulted in a 3.1% increase in muscle-bone CSA after 7 days of training. Both MRI-measured maximum quadriceps muscle cross-sectional area (Q-CSA max) and muscle volume can be seen increasing after the first day of KAATSU training, and continuously increasing for the rest of the training period. Following 7 days KAATSU resistance training, the increases in Q-CSA max and muscle volume were 3.5% and 4.8%, respectively. Relative strength (isometric knee extension strength per unit Q-CSA max) was increased after training (before, 3.60 Nm/cm2; after, 4.09 Nm/cm2). There were very modest increases in CK and myoglobin after a single bout of KAATSU exercise in the first day of the training, but the values were return towards normal at 2 days after the training. IL-6 remained unchanged throughout the training period. In conclusion, our subject gained absolute strength and increased muscle size after only one week of low intensity KAATSU resistance training. Indicators of muscle damage and inflammation were not elevated by this training. KAATSU training appears to be a safe and effective method to rapidly induce skeletal muscle strength and hypertrophy.
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SUMMARY In order to stimulate further adaptation toward specific training goals, progressive resistance training (RT) protocols are necessary. The optimal characteristics of strength-specific programs include the use of concentric (CON), eccentric (ECC), and isometric muscle actions and the performance of bilateral and unilateral single- and multiple-joint exercises. In addition, it is recommended that strength programs sequence exercises to optimize the preservation of exercise intensity (large before small muscle group exercises, multiple-joint exercises before single-joint exercises, and higher-intensity before lower-intensity exercises). For novice (untrained individuals with no RT experience or who have not trained for several years) training, it is recommended that loads correspond to a repetition range of an 8-12 repetition maximum (RM). For intermediate (individuals with approximately 6 months of consistent RT experience) to advanced (individuals with years of RT experience) training, it is recommended that individuals use a wider loading range from 1 to 12 RM in a periodized fashion with eventual emphasis on heavy loading (1-6 RM) using 3- to 5-min rest periods between sets performed at a moderate contraction velocity (1-2 s CON; 1-2 s ECC). When training at a specific RM load, it is recommended that 2-10% increase in load be applied when the individual can perform the current workload for one to two repetitions over the desired number. The recommendation for training frequency is 2-3 dIwkj1 for novice training, 3-4 dIwkj1 for intermediate training, and 4-5 dIwkj1 for advanced training. Similar program designs are recom- mended for hypertrophy training with respect to exercise selection and frequency. For loading, it is recommended that loads corresponding to 1-12 RM be used in periodized fashion with emphasis on the 6-12 RM zone using 1- to 2-min rest periods between sets at a moderate velocity. Higher volume, multiple-set programs are recommended for maximizing hypertrophy. Progression in power training entails two general loading strategies: 1) strength training and 2) use of light loads (0-60% of 1 RM for lower body exercises; 30-60% of 1 RM for upper body exercises) performed at a fast contraction velocity with 3-5 min of rest between sets for multiple sets per exercise (three to five sets). It is also recommended that emphasis be placed on multiple-joint exercises especially those involving the total body. For local muscular endurance training, it is recommended that light to moderate loads (40-60% of 1 RM) be performed for high repetitions (915) using short rest periods (G90 s). In the interpretation of this position stand as with prior ones, recommendations should be applied in context and should be contingent upon an individual's target goals, physical capacity, and training
Article
Vascular blood flow restriction (vBFR) training stimulates muscle hypertrophy by increasing muscle activation and muscle swelling. Previous studies used expensive pneumatic cuffs, which may not be practical for regular use. PURPOSE:: To investigate the acute effects of low intensity practical BFR (LI-pBFR) on muscle activation, muscle swelling and damage. METHODS:: Twelve trained male participants completed a 30, 15, 15, 15 repetition scheme at 30% of their leg press 1-RM under control and LI-BFR conditions. Under the LI-BFR trial, knee wraps were applied to the thighs at a pressure which resulted in venous, not arterial, occlusion. In the control trial, wraps were applied with zero pressure. Ultrasound determined muscle thickness was recorded at baseline, 0 minutes post with wraps, 0, 5 and 10 minutes post without wraps. Muscle activation was recorded during warm ups and on the final set of 15 repetitions. Indices of muscle damage (soreness, power, and muscle swelling) were also recorded. RESULTS:: There was a condition by time effect for muscle thickness (p < 0.0001, ES = 0.5), in which muscle thickness increased in the LI-pBFR condition 0 minutes post with wraps and through 5 minutes post without wraps. No changes occurred in the control. There was a condition by time effect for muscle activation (p < .05, ES = 0.2). LI-pBFR had greater activation than the control. There were no condition by time effects on indices of muscle damage. DISCUSSION:: Our data indicates that practical BFR significantly increases muscle activation and muscle thickness without increasing indices of damage.