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Blood flow restriction training is quickly gaining popularity in the United States. However, it is not without controversy. While there are many reported health benefits, there are equally as many risks. Most concerning is the lack of industry standardizations regarding cuff size and pressure. There is no required training to implement blood flow restriction training, which can be problematic when people with little knowledge practice this type of exercise. When blood flow is restricted, there is an impact on the cardiovascular system, nervous system, and muscular system. Damage can be done when blood flow is restricted with too much pressure or too long of a duration. This paper provides a systematic review, including a comprehensive overview of the literature, regarding blood flow restriction exercise.
Blood flow restriction exercise, or blood flow restriction training, is rapidly gaining popularity among bodybuilders and exercise enthusiasts. This type of exercise can be used within a wide range of exercise modalities, including walking, cycling, and resistance training. It works by placing cuffs or wraps around a limb with the goal of maintaining arterial inflow while occluding venous return during exercise. The cuffs are wrapped at a perceived tightness of seven out of ten, and when used as a part of resistance training, low loads of 20%-30% of 1 repetition maximum (RM) should be used . This type of exercise stems from Kaatsu training, which was developed by Yoshiaki Sato, who in 1994 applied for a patent for his Kaatsu bands. He created these bands by experimenting on himself with bicycle tubes, ropes, and bands on various parts of his body. Kaatsu is a patented training approach developed by Dr. Sato specifically using the Kaatsu Master Device. Blood flow restriction training or exercise is the term used when apparatuses are used that are not the specific Kaatsu Master Device. Often the terms are used interchangeably. Also used interchangeably with blood flow restriction exercise is the term “occlusion training.” Blood flow restriction training is believed to cause a localized hypoxic effect which is the condition of low oxygen in the body’s tissues . Blood flow restriction exercise is reported to increase growth hormone, muscle hypertrophy, and muscle strength.
This condition is due to the inability of the blood to escape so
that metabolic stress and cellular swelling are increased. This restriction exercise training allows a person to achieve strength and muscle growth without having to use higher loads and in a much shorter time frame. This situation is especially useful when it comes to rehabilitation, as rehabilitation can begin much sooner, and this prevents atrophy as well as facilitates a faster return to normal functioning compared to traditional approaches . It is also suggested that blood flow restriction training positively affects circulating hormone levels. By using blood flow restriction before intense exercise, ischemic preconditioning can occur, which results in less damage and shorter recovery time after exercise. There is also the potential for this type of exercise to benefit those with chronic pain who desire to be more active . The research into blood flow restriction exercise often lacks details regarding how much pressure should be used for specific outcomes. This lack of detail is an area of concern in that too much pressure can increase the associated risks. However, not enough pressure can cause no benefits to occur . The aim of this review was to conduct a comprehensive review of the literature to determine the efficacy and safety of blood flow restriction exercise.
For the purposes of this literature review, the definition of blood flow training is exercise completed by placing a cuff proximally to the muscle being exercised through low-intensity
exercise with the purpose of recreating a hypoxic environment.
Data from the included studies was evaluated regarding
commonalities and areas of uniqueness to develop themes
related to the research aims of efficacy and safety of blood flow
restriction exercise. The requirement for informed consent was
waived given the retrospective nature of the review. The study
design was approved by the appropriate ethics review board.
A comprehensive search for research-based articles
published in a peer-reviewed journal within the years 2014–
2019 was conducted. The following electronic databases were
searched: PubMed, SPORT Discus, SBRnet, and Sports Medicine &
Education Index. The keywords blood restriction exercise, blood
restriction training, occlusion training, and Kaatsu training were
used. Abstracts were read to determine relevancy and adherence
to the inclusion criteria. Reference lists of relevant articles were
also reviewed to locate additional publications not included in
the online databases.
Only research studies using the above definition of blood
flow exercise were included. Additionally, only articles that
contributed data regarding the efficacy and safety of blood
flow restriction exercise were included. This included research
specifically on the Kaatsu training method. While abstracts were
used to narrow down relevant articles, only those with full text
were considered. All types of research studies were evaluated for
inclusion which included experimental/control group studies,
pilot studies, case studies, and systematic review
All publications before 2014 were excluded. Publications
written in languages other than English were also excluded.
Given that the specific focus of this work was to explicitly
investigate the safety and efficacy of blood flow exercise, all
research focusing on other aspects of this exercise method were
 define blood flow restriction training as a “method
partially restricting arterial inflow and fully restricting venous
outflow in working musculature during exercise”. One primary
issue surrounding this type of training is safety. There is a lack
of standards and regulations for blood flow restriction exercise.
Therefore, as the name implies, blood flow is restricted, and
there is no required training for practitioners, so there is the
possibility of injury. The areas of concern in terms of health
are the cardiovascular response, central vascular response,
peripheral vascular injury, venous thromboembolism, the
fibrinolytic system injury, reactive oxygen concerns, and muscle
Research by Patterson & Bradner  found that with the
growing popularity of blood flow restriction training, there is an
increasing population of practitioners who lack the knowledge
regarding using and applying the exercise in a manner that is
following standards developed by research. It was found that the
primary concern is a significant range of pressure that is being
applied with the cuffs. Instances of too much pressure being
used has resulted in large numbers of exercisers experiencing
numbness following their exercise session. This concept is
supported in research . The researchers compared low-load
training, and low-load blood flow restriction training in clinical
musculoskeletal rehabilitation. It was found that blood flow
restriction training is more effective and more easily tolerated,
making it a potential clinical rehabilitation approach. However,
the researchers clearly stated that more research should be done
to create standards so that this type of training, or rehabilitation,
can be individualized to minimize risk to patients and ensure
the highest possible level of effectiveness. In a 2016 survey
conducted , it was found that blood flow restriction training
within facilities is used for a variety of purposes. Responses from
232 facilities employing this type of training revealed:
a) 87% use this training for health promotion.
b) 85% use it for diet.
c) 70% use it for beauty and anti-aging.
d) 71% use it for an increase in muscle strength.
e) 72% use it for muscle hypertrophy.
f) 72% use it for improvement of sports performance
g) 38% use it for rehabilitation.
h) 38% use it for helping with orthopedic disease.
i) 17% use it for obesity.
j) 12% use it for improving diabetes.
k) 11% use it for cerebrovascular disease.
l) 8% use it for cardiovascular disease.
m) 7% use it for depression.
n) 6% use it for treating infertility.
o) 5% use it for neuromuscular diseases.
p) 3% use it for treating immune diseases.
q) 53% use it for additional/other purposes.
Additionally, the survey found that 92% of the facilities found
at least .5% improvement in the areas of which they used this type
of training. Also reported was the presence of minor side effects
including dizziness, subcutaneous hemorrhage, drowsiness,
numbness, nausea, and itchiness. The researchers considered
these as minor side effects and reported no serious side effects as reported on the survey. The study concluded that when under the
care of trained professionals, blood flow restriction training can
be used safely with positive benefits with any person regardless
of age, sex, or physical condition. However, the study failed to
provide details as to what they considered a trained blood flow
restriction professional to be, and the results were self-reported
from a survey of facilities where this type of training comprised
a significant proportion of their provided training. In practice,
frequency, intensity, and duration are focused on postsurgical
rehabilitation when it comes to planning for and implementing
blood flow restriction exercise.  specifically investigated cuff
width, cuff pressure, and intermittent pressure application in
terms of effectiveness and safety. Practitioners typically use
40%-90% of a person’s arterial occlusion pressure. This span
is a broad range indicating that standardized safety measures
are lacking. When investigating the effectiveness and safety
of various cuff widths, it was found that in terms of the lower
body, wider cuffs had a lower absolute occlusion pressure than
narrow cuffs. Additionally, using the lowest possible pressure is
considered the safest as it is the least stressful and offers the
most therapeutic results.  also found that wider cuffs are
more efficient than narrow cuffs and supports the concern of a
lack of training standards for blood flow restriction training. This
research also found that 28 of 30 studies reported an increase
in strength for both men and women; however, these studies
also clarified that the data for women and blood flow restriction
exercise is lacking . Also reported were positive outcomes
in bone health. Heitkamp states that an occlusion pressure of
150mm Hg with an intensity of 20% for 1RM with wider cuffs
should be the recommendation . Additionally, this research
stated that blood flow restriction exercise showed no correlation
with an increase in the risk of thrombosis. Specific areas of safety
concerns regarding blood restriction training were studied 
in the form of a comprehensive literature review. One area
of concern is thrombus, or blood clot, formation. Research in
this area conducted on healthy individuals and older people
with heart disease found no change in blood indicators for
thrombin development or clot formation . Considering the
results of 13,000 persons using blood flow restriction exercise
found that the rate of deep venous thrombosis was less than
.06% and the rate of pulmonary embolism was less than .01%
[10,11] conducted blood flow restriction research specifically
on elderly people with a mean age of 64.7 years. Participants
were assigned to a control group and experimental group who
engaged in blood flow restriction training focusing on aerobic
Fitness, muscle mass, and muscle strength. The exercise was
completed two days a week performing leg presses with one
set of 30 presses and three sets of 15 presses at 20%-30%
restriction. This process was performed for 12 weeks and then
compared to the health markers before beginning the program.
The cuffs used were those that are commonly found in fitness
centers. Muscle damage is also a safety concern with blood flow
restriction exercise. The literature finds that low-load blood
flow restriction training carries a low risk for serious muscle
damage. Muscle damage and delayed onset muscle soreness for
restriction exercise are comparable to any type of exercise in
which a person is unaccustomed to .
There are also cardiovascular risks associated with this
type of exercise. There is a concern that restricted blood flow
can result in cardiovascular changes while one is exercising.
This change comes from the autonomic nervous system. The
decreased blood flow to the muscles could cause excessive
pressure reflex resulting in excessively high blood pressure.
Although the risk is present in anyone using this method, those
with heart failure, hypertension, or peripheral artery disease are
at especially high risk . Numbness is also a safety concern
and is most often caused by band pressure that is too high which
results in peripheral nerve compression. However, the research
has shown that this has little chance of occurring with less
than 2% of those participating in studies on this issue having
experienced numbness. Having the appropriate size cuff and
correct placement are vital to prevent peripheral nerve irritation
. Jessee and colleagues also found a muscular benefit to
blood flow restriction training and recommended it for clinical
rehabilitation . These researchers also found little evidence
that this type of training is any more dangerous than other types
and that concerns over safety are unfounded . However, it
must be noted that in their research cuffs were only used at a
five to seven-centimeter overlap and higher pressure was not
studied . The researchers also used the concept that a wrap
was too tight if no pulse can be detected. If this occurred, then
the cuffs were loosened . Like the other research studies,
 suggested the need for more research and standardization.
Similarly, in another study,  found that the swelling of cells
and metabolite-induced fatigue produced through blood flow
restriction exercise resulted in stimulated synthetic pathways
leading to muscle growth. The researchers also determined
that this type of exercise was relatively safe, but the cuff size,
cuff width, and the limb circumference must all be considered
. However, despite the research concluding that blood flow
restriction training is safe, a study  found that there is a lack
of focus on personal, medical, social, and family history before
one engages in this type of training. The researchers found that
specific attention should be given to one’s medical conditions
and lifestyle activities to determine the safety of blood flow
restriction training . As a result, the researchers developed
a risk assessment screening instrument that they recommend
is used before engaging in blood flow restriction exercise .
The researchers created a list of absolute or relative categories
where the presence of any absolute risk factors should exclude
persons from participating in this type of training (Table 1). The
absolute risk factors are:
a) History or presence of clotting disorders (includes
systemic lupus erythematosus, hemophilia, and high platelet
b) History or presence of deep vein thrombosis, or
c) History of thrombotic or hemorrhagic stroke.
d) Presence of level 1 hypertension or higher .
 investigated participant muscular pain when
participating in blood flow restriction exercise using low-loads.
In this study, researchers participated in blood flow restriction
exercise two times a day . Data were collected every five
training sessions for three weeks. Overall, participants reported
mild muscular discomfort while exercising . However, within
five minutes after exercise was completed, pain was reported to
be back to pre-exercise pain levels . Pain during exercise
ranged from 44-66 mm Hg which was significantly greater than
the baseline established both before and after exercise .
After the completion of three weeks of blood flow restriction
exercise, there was a reduction in muscular pain levels .
This data is represented in Figure 1 . Research has also been conducted regarding pain, particularly the influence of the type
of cuff material used, including elastic or nylon. In other research,
the cuff material was not explicitly discussed. However, 
studied how the cuff material affected both discomfort levels
and exertion levels from the patient perspective. The results are
shown in Figure 2 .
This review of the literature determined that there is a need
for standardization regarding blood flow restriction exercise.
There is a lack of guidelines in terms of cuff size, duration, and
pressure. Also lacking are standards to guide practitioners when
it comes to accomplishing specific outcomes. For example, for
building muscle mass, a user needs to use x amount of pressure
for x duration. This situation is also true for those using blood
flow restriction training for rehabilitation purposes. Guidelines
are needed that list the appropriate duration and cuff pressure
for accomplishing specific rehabilitation goals. Standards
for age, sex, and a variety of physical conditions and specific
illnesses/ailments are also needed for example, standards for
how a person with heart disease should use this type of training.
Having these guidelines will help to achieve individualized goals
and decrease safety risks. Currently, a set of standards would
require more specialized research and a compilation of already conducted research. Those already focused on researching blood
flow restriction exercise have called for standardization within
the field, yet none have taken on the task.
The literature also alludes to the training of blood flow
restriction training experts. The literature that mentions
professional training states that there is a need for training
standards and standardized requirements. However, the available
research does not include any standardization suggestions for
this training. Like standards for use, training requirements need
to be based on relevant research, so more research on this topic
should be undertaken. By having set requirements in terms of
knowledge and skill, blood flow restriction trainers can further
ensure that safety standards are implemented, thus lessening
the risk for those engaging in this type of exercise. Available r
esearch has shown consistency in terms of how blood
flow restriction functions and the benefits it brings in terms
of muscle enhancement and strength. No research studies
included in this review disputed the usefulness of this type of
training. Most research investigating blood flow restriction
exercise benefits also reported that this type of training would
be, or is, even beneficial for rehabilitation. While using blood
flow restriction for rehabilitation is not specified in the scope
of this paper, it is acknowledged that the literature does include
studies focused specifically on the use of blood flow restriction
for specific rehabilitation needs such as muscle weakness, joint
replacement, ligament/muscle injuries, etc. Even though the
research recognized its value in terms of rehabilitation, doctors
are seldom prescribing this type of therapy, and it is typically not
offered at physical therapy clinics . The included studies also
acknowledge that there are risks to this type of exercise. Only one
study stated that the risk is the same as other forms of exercise.
Research has found that primarily there is an increased risk of
blood clots, muscle damage, and nerve compression, but that
other physical damage can also occur. These risks, however, are
reported within the research to be minimal. Research also is clear
in that this type of training should not be undertaken without
the supervision of a knowledgeable professional. This situation
leads back to the concern that there is not a set of standards or
any documentation of professional training required for those
helping others implement blood flow restriction exercise.
It is expected that the trend of blood flow restriction
training will continue to grow and become a respected method
for muscle enhancement, rehabilitation, and sports endurance.
The available research indicates that there are many more
areas that need further investigation, along with a clear need
for standardization for being a trainer and for using blood flow
restriction exercise safely. Overall, it can be concluded that
blood flow restriction exercise is a safe form of training, leading
to increased muscle development, but it should be undertaken
with the guidance of a knowledgeable and experienced trainer.