Blood Flow Restriction Training: an Overview
Updated: Aug 3, 2022
The worlds of exercise and injury rehabilitation are constantly evolving. Athletes adopt new training methods, diets, and accessory tools in pursuit of greater strength, muscle mass, and speed. While, healthcare professionals help injured people by implementing new rehab strategies and utilizing the latest rehab tools.
One such tool, Blood flow restriction (BFR), has been gaining popularity in the world of exercise and rehabilitation. BFR is the process of restricting blood flow by wrapping a tourniquet-like device around the arm and/or legs. These devices allow blood to get to the limbs (arterial inflow) while preventing blood from leaving the limbs (venous outflow) (1). In other words, it lets blood carry oxygen to the muscles, but prevents it from returning to the heart. When done during exercise BFR has been found to improve strength, muscle size, cardiovascular endurance, and injury recovery (6,7,8,9,10,11,12,13)
What does BFR do?
BFR can help you get stronger (6,7) and gain muscle (11,12,7,13,10). Normal exercise will give you the same results, but BFR allows you to get these results while using lighter weights and performing less intense exercises (1). For example, gains in muscle and strength have been seen at 20% of 1 repetition maximum (1RM) with BFR training; this is one third of the minimum load (60% of 1RM) the American College of Sports Medicine (ACSM) recommends for muscle and strength gain (14). These benefits are not limited to resistance training; muscle size and strength increases have been seen with BFR plus walking (15) and BFR plus cycling (11). It is also worth noting that positive benefits are not limited to the arm and leg muscles. For example, doing a push up with BFR causes hypertrophy (gaining muscle) of the chest (pectoralis major) which is proximal (before) and the back of the arm (triceps brachii) which is distal (after) the occlusion site (16)
In addition to improving strength and hypertrophy, BFR can help with cardiorespiratory fitness (1,17). A study by Abe et al (11) showed that an 8 week program of 15 minutes of BFR cycling 3 times per week improves VO2 max (a measure of cardiovascular fitness) by 6.4% and time to exhaustion by 15.4%. A control group did the same cycling routine without BFR, but they did it for 45 minutes instead of 15 minutes; this group saw a slight decrease in VO2 max and only a 3.9% increase in time to fatigue. The BFR group did one third the work, and saw much better results! BFRs cardiorespiratory benefits have even been seen in extremely fit college basketball players (17).
Why might BFR improve hypertrophy, strength, and cardiovascular fitness with such low intensity?
Increased cell swelling (18).
Increased tissue oxygenation plus higher reactive oxygen species production (19,20).
Quicker recruitment of fast twitch muscle fibers (21).
Increased growth hormone release (22,23,24,25).
Improved glycogen stores (26).
Is BFR Safe
The short answer is yes it is safe for most people. A 2006 study surveyed 100 facilities and 13,000 BFR users ages 20-80 (27). They found the rate of serious events to be very low: cerebral anemia (0.277%), venous thrombus (0.055%), pulmonary embolism (0.008%), rhabdomyolysis (0.008), and deterioration of ischemic heart disease (0.016%). Less serious temporary side effects were a bit more common: bruising (13.1%), numbness (1.297%), and a cold feeling (0.127%).
Research has shown that BFR training is a safe method for training athletes, healthy persons (28), and potentially those individuals with varying comorbidities (27). However, if you have a history of heart disease, vascular disease, cancer, neurological conditions, hormonal conditions, musculoskeletal pain/injury, uncontrolled arthritis, or any other serious health conditions, you should consult a licensed medical provider before performing BFR training.
Who Would Benefit from BFR
Injured “Load compromised” athletes
The ACSM states that in order to increase strength and muscle size, loads should meet or exceed 60% of somebody’s 1RM (14). However, there are times when heavy lifting is not possible (for example, sprains, strains, and post-surgery). The goals of rehabbing an athlete or anybody who is active is allow their injury to heal while preventing loss of strength, muscle mass, and overall fitness. The dilemma is that exercise needs to be a part of their rehab, but loading too much puts the athlete at risk of further injury.
This is where BFR comes in; BFR allows athletes to maintain their strength, muscle mass, and cardiovascular fitness while using as little as 20% of their 1RM while weight training and performing low intensity cardiovascular training (6,7,8,9,10,11,12,13) . For example, during the first few weeks of a knee injury (such as an ACL reconstruction or meniscus tear), athletes often perform straight leg raises, mini squats with bodyweight (BW), and leg press at very low-loads (29) When these exercises are done with BFR, they go from easy to difficult; for example, the body may react to a 50lb leg press like it is a 200lb leg press. Thus, BFR allows an injured athlete to stay in shape without reinjuring themselves (5).
Athletes are not the only population that gets injured. Sore knees, backs, elbows, and hips are common among the general population. Just like athletes, the injured non-athlete rehabilitation exercises should be part of their injury’s treatment plan. Unlike athletes, the average person does not exercise regularly, and being injured will make exercising even more difficult.
BFR can help solve this problem. Let's return to the example of a knee injury; BW squats are a staple of knee rehabilitation, but many sedentary people won’t be able to do a full BW squat without pain. Let’s say they could do ¼ BW squats without pain. Normally ¼ bodyweight squats would not be as beneficial as full BW squats, but with the addition of BFR the strength and hypertrophy benefits are more comparable.
It is common for athletes performing weight lifting to get shoulder, knee, back, and elbow pain. Oftentimes, these injuries are not a result of bad form but are caused by too much load accumulation (5). BFR comes into play by allowing athletes to train for strength and hypertrophy with lighter weights (6,7,8,9,10,11,12,13). Let’s look at a football player who can squat 350 lbs for 3 sets of 5 repetitions. His current program has him do this 3 times per week. So he squats 15,750 lbs per week. Let's say this football player has back pain and we think it is a loading issue. By replacing one of his workouts with BFR squats at half the weight, he reduces his weekly load by 2,625 lbs. If his pain is due to load management, this will allow his injury to heal without stunting his strength and hypertrophy gains.
Let’s face it, most people do not find lifting heavy weights and doing intense cardio fun. Most people probably prefer walking over jogging, short runs over long runs, and lifting a light weight thirty times rather than a heavy weight eight times. Unfortunately, intense exercise produces the benefits of increased muscle mass, strength, and cardiovascular fitness better than low intensity exercise.
Again, BFR can help. Let’s look at a mom who wants to start running, but like most moms she does not have a lot of free time. As discussed earlier in the article, 8 weeks of a 15 minute BFR cycle done 3 times per week improved cardiovascular health more than 8 weeks of a 45 minute normal cycle done 3 times per week (11). In other words, BFR can give you better results in less time than conventional cardiovascular exercise.
Implementing BFR Training
Now that we have talked about the effects of BFR and who would benefit from its use, let's discuss how to implement it.
Your first step in performing BFR is to decide what type of device you want to use. The traditional options are a tourniquet (2), pressurized cuff (3), or an elastic band (4). A pressurized cuff is the gold standard because it allows you to monitor how much pressure you are using. This lets you keep pressure constant between training sessions and drastically reduces the likelihood of cutting off arterial blood flow.
Elastic bands and tourniquets are much cheaper options, but it is difficult to apply a consistent pressure while using them. This will result in inconsistent workout sessions and will put you in greater danger of cutting off circulation. Taking this information into account, I recommend investing in a pressurized cuff BFR product, if you are serious about including BFR in your workout or rehab program.
If you choose to use a pressurized cuff, your next step is to figure out your limb occlusion pressure (LOP). To find your LOP, start by placing the inflatable cuff around your leg or arm in the desired position (as close to the joint as possible while still being comfortable) (5). For the leg, find the pulse of the posterior tibial artery; it runs just behind the bump inside of your ankle (medial malleolus). For the arm, find the radial pulse on the front side of your wrist towards the thumb (5).
Pump the cuff up until you feel the pulse go away. The pressure displayed on your pressure gage is your LOP (5). This LOP will be used to optimize your workouts, and more to give you the piece of mind that if you are below your LOP, your arteries are not blocked.
Steps If your are using a cuff
Loosely fit the cuff around your leg (1)
Pump up the cuff to the appropriate percentage LOP.
If you are below your LOP, your arteries should not be blocked, but double checking your posterior tibial and radial pulses is still a good idea.
Steps If you are using a tourniquet or band
Wrap the strap around your arm and/or leg.
Pull to a 7/10 tightness (5).
You cannot use LOP with a tourniquet or band; so, make sure your arteries are not blocked by checking your posterior tibial and radial pulses.
Now lets discuss some general guidelines of BFR. The resistance used for BFR should be 20-30% of your 1RM; in other words, ¼ to ⅓ of what you would normally use for a set of 8 reps. Your repetitions per set should be 15-30 and your rest periods should be short (20-45 seconds)1. For weight training, BFR may be performed 2-3 times per week for the same muscle or muscle groups. While higher frequencies (ex, up to twice daily) may be used for less intense exercise (ex, walking).
Next we will discuss detailed programs for BFR training. The majority of this information is taken from Squat University’s blog on BFR training. Squat University is a leader in the strength and conditioning field, and I highly recommend checking them out if you are interested in getting stronger.
A warm up is a key part of a workout. It physically and mentally prepares the athlete for the day’s training, and BFR can be a good addition to this important part of training.
Squat Warm Up (5):
Dynamic Warm Up: A five minute walk followed by mobility work for the hips and ankles and the McGill Big 3 for priming core stability.
BFR Warm Up: 3-5 sets of 15 bodyweight “air squats” with 60% LOP with 30 seconds rest between each set.
Squat Workout: start with the open barbell and then add load.
The most commonly used routine to improve strength and hypertrophy with BFR is a 4 set protocol (5). The first set is 30 reps and the next three sets are 15 reps. Thirty seconds of rest is taken between (5). During the first set, aim for 60% LOP for the legs and 40% for the arms and lift 20-30% of your 1RM (5). As you get used to BFR, you can increase LOP and percentage of your 1RM.
Make sure you can complete all repetitions for all sets; the last set should be very difficult. If you cannot complete all repetitions, reduce the weight or occlusion pressure. If the last set is easy, increase the weight or occlusion pressure (5).
Example 1: Athlete with knee injury who cannot squat deep (5)
Exercise 1: Box squat using 20-40% of 1-rep max.
Exercise 2: Touchdown single leg squats off small box or single-leg leg press.
Exercise 3: Straight leg raise or bridge
Example 2: Athlete who trains heavy but supplements their heavy lifting with BFR training.
Exercise 1: Bench or Overhead Press with 20-40% of 1-rep max.
Exercise 2: Suspension Trainer Rows
Exercise 3: Triceps pull downs with 30% of 1-rep max.
The 30/15/15/15 protocol should be used for every exercise (5). Make sure you get through all four sets before deflating the cuffs (5). Rest for one minute before going to the next exercise (5).
As we discussed above, BFR can help build cardiovascular health and fitness using lower intensity exercises performed for less time. Here are some examples of how to do this. You can ride a stationary bike, rowing machine, or walk for 10-20 minutes a few times a week with the BFR cuffs on. The cuffs should be set between 60-80% LOP. Your pace should be just above a conversational pace (5).
Recovery is an important and often overlooked component of exercise. BFR can be used to enhance this important training variable.
While sitting in a relaxed position (or lying flat) increase the BFR cuffs anywhere between 80% LOP and full occlusion for 5 minutes (5).
Perform 10 isometric contractions of your quad muscles for 5 second holds every minute (5).
After 5 minutes, deflate the cuffs for 1 minute before reapplying for another 2 rounds (5).
This same protocol can be used after a post-surgery when the patient cannot use their arm or leg. During this time, the recovery BFR protocol we just discussed can be used to prevent or slow down muscle atrophy on the non-weight affected limb (5).
Frequency and Progression
BFR needs to be performed frequently (at least 2-3 days per week) to produce a maximum benefit (30). Going for a run once every couple weeks won’t make you better at running and the same principle applies to BFR.
Like any good strength and conditioning program, a BFR program has to progress. You can increase LOP, percentage 1RM, or total sets throughout the course of your program, but do not increase the intensity or volume of your workout by more than 10% per week.
BFR research provides some extra guidance for our program progression. When using light weights (20% 1RM), keep the LOP high (80%). When using heavier weights (40% 1RM), keep the LOP low (40-50%) (31). Having high LOP and high 1RM% will not get you better results (5). This can also be applied to cardio. If you are running at a fast pace, keep the pressure lower; if you are doing a long slow run or a walk, increase the pressure.
As you progress, remember that the goal of BFR is not to lift heavy weights or to sprint as fast as possible. The goal is to get the benefits of high-intensity exercise while doing less taxing versions of those activities.
BFR training is a great tool for a wide variety of populations: athletes, inactive people, healthy people, and those with injuries can all improve their health and fitness with BFR training. You should lift heavy weights and run without BFR, but it is a great addition to most people’s workout program.
Hopefully you now have a better understanding of what BFR is and how to use it in your workout routine. If you have any questions or want help integrating BFR into your exercise routine, feel free to contact us.
If you want to see how chiropractic can help with pain and injury, book an appointment with Chirostrength Twin Cities at 612-314-0268.
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