By Carl Valle

I’ve come to respect blood flow restriction (BFR) training and believe it has value in certain situations. I’m also critical because it’s not perfect and is dangerous for some athletes. A few years ago, BFR training accelerated in pro sports in the United States, a sign that it was about to hit the mainstream. I’m a late adopter of occlusion training, not taking it seriously until enough research demonstrated it had value. I encourage you to read the science to see where this method fits best in your program since it can help athletes in many different ways.

I’ve found this novel technique has value for athletes who are injured and desperate. BFR is interesting enough to pay attention to but too unstructured to include in everyone’s program. I tried it and found it was exactly as promised, but it’s not essential. It took nearly two decades before I was ready to make it a part of an organized plan, not because I was resistant to change but because I needed the right environment to employ it.

This article covers BFR training’s stark realities and new ways to use it in sports. While plenty of articles exist on this topic, this one is unique because it covers points that have not been discussed, such as how it may work holistically. For those who are curious and want to start BFR training, I share what you can do—not what you should do.

New Science and New Application

Doing your homework on BFR science will likely lead you into a rabbit hole that you may not escape. I started a few years ago and followed up with an interview with Chris Brandner in 2017 to get more coaches aware of the key benefits and expectations. Still, it wasn’t until 2018 that I chose to do some experiments and refinements that I consider useful to nearly all programs. I wouldn’t use this for every athlete, but I think it’s essential for anyone who’s pressed for time.

So we’re on the same page: BFR is simply creating pressure around the extremities, like with a mild tourniquet, while training and thus increasing the tissues’ local metabolic demand. Most studies use low-intensity training, meaning low-load or low-intensity training combined with BFR. Some practices use ischemic preconditioning, similar to BFR training but with more of a warm-up or potentiation effect. I’ll explore this practice later, but essentially its restricting blood flow slightly, not completely.

For safety purposes, it’s important to understand we’re not cutting off blood flow all together for extended periods of time, which is foolishly dangerous. For the most part, we’re applying heavy circumferential compression.

Blow Flow Infographic
Image 1. Modulating blood flow often is used to increase muscle growth with low-intensity training. Some research supports the idea that an immobile athlete may benefit aerobically if they use a passive system that challenges their oxygen transfer abilities.

The science of BFR training clearly shows it works. The questions are what its magnitude and practical value are. In simple terms, I find it’s a narrow solution that makes sense when necessary. It’s not a strong enough technique to feel you’re doing a disservice to your athletes if you’re not doing it.

Without trying to sound over the top, it’s perfect when things go bad and you need “Dark Magic,” meaning a solution that works really well when you need it. A few investigations of post-exercise restricted blood flow protocols with healthy subjects shows it’s a promising technique. But due to the small amount of research and incomplete evidence, I’m not covering it in this article, although I see it used in some circles.

Usually, I write an article that places the research in a confined section so readers can trust the applications presented after the evidence is in place. This time I’m infusing the science directly into every area of sports performance because the science overwhelmingly favors it.

Rehabilitation and Post Surgery Care

I hate to say it, but if you’re not using an array of techniques to accelerate the return to play rapidly, you will likely face complications down the road. I favor getting athletes to recover deeper, not faster. Even if you have time on your side, everyone is behind the eight ball after surgery and shotgun approaches work.

Including BFR in a post-surgical return to play program adds a major advantage because athletes will have only so much tolerance for eccentric training. Similar to polarized training with aerobic conditioning, going lighter and going harder can work, provided the athlete is monitored carefully.

Rehabilitation environments favor BFR training for a combination of reasons, but most of its popularity seems to be because low-load training uses rapid improvements without risks to the surgical site. If you can unload the body when it’s compromised and make gains that are similar to intense options, you have a winning ticket. High repetition approaches also are popular as they create a small lactate response that encourages a mild beta-endorphin response, which athletes crave and sometimes need when movement is uncomfortable.

Vascular Leg
Image 2. After ACL repair, many athletes use blood flow restriction training to rehabilitate an injured leg. A combination of conventional methods and progressive BFR techniques is very effective when sequenced right.

If you’re looking for one takeaway from this article, it’s this: while BFR is a narrow solution that targets the local muscles of the extremities, I don’t rule out remote adaptations. Some coaches have tried central or torso muscle training, but this is anatomically foolish and has not been researched.

BFR with muscles like the rectus femoris and upper arm (biceps and triceps) is interesting while wrist extensors and flexors is promising along with the plantar flexors of the ankle. There’s not much information on hamstring recovery outside of case reports, but I’m sure we’ll see more down the road.BFR with wrist extensors, wrist flexors, and plantar flexors shows promise. CLICK TO TWEET

Again, the best-studied tissues are the supervision muscles. I expect to see conflicting responses with connective tissues and bones because they tend to remodel better from mechanical stress than from metabolic strain. As soon as the body is cut, the clock starts ticking. BFR is great to help reduce atrophy and get athletes training again.BFR will help reduce atrophy and get injured athletes training again. CLICK TO TWEET

Of course coaches are going to eventually ask about stacking BFR and electrical muscle stimulation, as the combination sounds promising with animal models and is already in use. In my experience with knee and Achilles return to play, they help. But I haven’t read any studies that make a case for synergy or special sequences. With little research and studies that use very mild protocols, it will take years to figure this out.

I find that combination methods are golden but don’t expect athletes to receive more than a mild benefit nor get back on the field significantly faster or with greater preparation. Again, good training is the foundation, and adding BFR and EMS is a complementary option. It’s worth the investment to add these techniques since every day and week matter in winning.

Hypertrophy of Healthy Athletes

Most BFR adaptations are to hypertrophy, not maximal strength or power. Due to the nature of the training, BFR will not help performance changes to the tissue outside of small size changes. Although a review study found that athletes are potentially good candidates for BFR, I don’t support this. A healthy athlete has options, and when they can train without restriction, BFR provides little value.Most BFR adaptations are to hypertrophy, not maximal strength or power. CLICK TO TWEET

If an athlete combines low-load and low-intensity training to a conventional program, the differences are likely to be small and administering the training for groups is a big challenge. The research is immature; it will take another 5-10 years of research to form a strong opinion on BFR’s potential to help athletes regarding muscle size and functional outcomes.

BFR Chart
Table 1. Hypertrophy is a local benefit of blood flow restriction training, but keep in mind the central nervous system plays a part in the rehabilitation process. Adding occlusion training doesn’t need to be limited to leg extensions, it can be actual ground-based training.

Technically, BFR is a “reverse pump,” and athletes enjoy the feeling of low-load strength training because it creates a metabolic and immune system disturbance with a similar feeling. A muscular pump is local blood flow to an area that is working, which is an antithesis to BFR. Although the outcomes are similar, it’s an opposite approach that encourages more growth than isolated exercises with a similar effort.

Since athletes care about muscular performance and size is a secondary benefit or accepted adaptation, the question is: Is the new growth explosive or just an increase in slower fibers? A few studies have gone beyond size and dug deeper into mechanisms such as genes and cellular responses. I have seen low inertia flywheel training use functional electrical muscle stimulation and BFR, but this is way too experimental to recommend yet.BFR is best for complementary workouts and early stage return to play rehabilitation. CLICK TO TWEET

BFR is promising as part of a program but does not have a seat at the table of priorities. Since the training is limited to low-load and low-intensity work, the research does not indicate it will be more effective than maximal or high-velocity training. I don’t’ recommend BFR for muscle development outside of complementary recovery workouts and early stage return to play rehabilitation.

Local Muscle Conditioning

BFR’s physiological adaptations to local muscle oxidative capacity are tricky since there seem to be two influencers on conditioning the muscular system. Coaches always want to address the rate limiters because these bottlenecks make the most impact on transfer to the field. For example, a study that looked at BFR with field conditioning testing didn’t produce anything significant with aerobic adaptation when they followed up with a running bout.

The question is: How powerful are the effects of one modality to a cardiovascular system that needs a comprehensive approach? Theoretically, reducing local blood flow creates a strong hypotonic environment, sort of like altitude but more specific to the muscle rather than the entire body. It’s fair to ask whether the trade-off for short periods of intense environmental shock is equal or similar to the promise of altitude training. They are different mechanisms, but do they create potentially similar results?

A wide scan of the science shows that applying BFR to serious endurance training is not impressive. In fact, the number of properly designed studies showing chronic training effects with elite athletes in endurance or team sport is unavailable. Acute priming with ischemic preconditioning is encouraging but not exciting unless you’re in elite cycling. Although many great studies are fascinating, placing team sport athletes in anything beyond a uniform is not practical yet, though I expect wearables to be very comprehensive in a few years.

The answer is a wishy-washy “maybe,” meaning it’s a little early to start using BFR to train the next great marathoner or to use with teams to max out their conditioning tests. We do know that a lot of physiological tests are available, but field tests are areas that I trust outside lab evaluations. Regarding VO2 changes, a simple walk protocol research study showed no advantage over walking without restriction.

As with atrophy, I find compromised athletes are the ones who benefit the most. Studies of sedentary people and the elderly can be used to construct clever solutions for traumatized athletes, post-surgical patients, and for those with extended periods away from training, such as retirement or severe burnout. Local changes don’t provide a systemic advancement in the aerobic system, and extreme intensities are not realistic with BFR, so the potential for new studies to show a serious effect are small.

Speed and Power Sports Performance

Sprinting and jumping are performance qualities desired by coaches, and BFR training can augment them both directly and indirectly, though with real limits. I still have questions about general magnitude, as most of the research is not very clear about whether it works at all.

  • A study of semi-professional Australian football athletes did not demonstrate any positive impact, which is why most coaches don’t find BFR very interesting.
  • Another study found low-intensity sprinting, or tempo running with BFR, was superior to similar speed running without restriction. Not only did the running improve 100m sprint times, but the BFR test group also increased hypertrophy in their quads.
  • Japanese study of BFR and jumping was disappointing, meaning low-intensity training didn’t help subjects improve their jump performance; there was no influence on the performance of untrained athletes over ten weeks.

The question is: Are any of the studies designed to give BFR the best opportunity to be used by practitioners, or do they oversimply the process and expect it to work by simply adding the intervention to any training program?

Without getting too theoretical, BFR mainly provides an indirect solution that, in a comprehensive program, helps coaches with a small part of a program over time. And I believe short-term studies will always come back disappointing.

BFR is great for tissue adaptations, though it doesn’t allow for high-intensity elements that stimulate the nervous system. If a modality helps low-intensity and low-load training, don’t’ expect much to challenge the neuromuscular adaptations that usually drive performance up.BFR is great for tissue adaptations but not useful for elite high speed and power performance. CLICK TO TWEET

For the record, BFR is a complementary strategy that’s not useful for the direct performance of high speed and power activities with elites. Research on BFR and acute neuromuscular system adaptations is rather straightforward—BFR is great for low load and low intensity.

Ischemic Preconditioning

We know less about the performance benefits of ischemic preconditioning, as we have less information on this technique compared with BFR training. Ischemic preconditioning is similar to potentiation training, where BFR is used to warm-up the legs before performance.

A recent study on speed skating using NIRS technology found BFR did not affect performance. One study I found very intriguing looked at red blood cell deformability with ischemic preconditioning—a rarely talked about topic that has some merit. While the study on ischemic preconditioning didn’t show any performance benefits, it showed that a temporary change to the red blood cells is worth exploring.

For those unfamiliar with deformability of a red blood cell, it’s basically how flexible the membrane is to move through small capillaries. It may not help performance when using BFR, but some studies show it has an impact on world-class performance. Perhaps it’s a way to support recovery? Time will tell.

Recovery Circuits and Between Match Sessions

It may seem strange that BFR is considered a recovery method, which is why I explained the confusion of active recovery with cool-down science as well as regeneration methods earlier in the article.

I contend that BFR helps stimulate growth while avoiding collateral damage like eccentric damage and cardiovascular stress. Imagine a workout without baggage or exercise in pill form. While recovery is a very individual experience, I’ve found that light training stokes capacity and changes to heart rate variability (HRV), something far more interesting to the autonomic nervous system than most passive means.BFR helps stimulate growth while avoiding collateral damage. CLICK TO TWEET

The best way to help recovery is to raise the threshold of capacity. BFR is like a cheat code in a video game. It breaks the rules because it fools the body artificially. Peripheral stimulation of the extremities is extremely useful when an athlete is too tired to work out hard but needs the training. It’s like maintaining a bonfire; if you can toss in a log, a few branches and gasoline may help keep things going.

Aquatic BFR
Image 3. Deepwater running is low impact and so slow, it’s hard to make it challenging. BFR options are growing, and some companies are recommending aquatic solutions.

I’ve seen athletes so broken that walking on a treadmill was a challenge. Adding BFR turned simple wellness activities into tempo running replacements. It’s not a perfect exchange, but after a few weeks, the athletes built up a tolerance to start running again. I’ve learned that recovery training is more of an art in doing something now for future benefits, not expecting an acute benefit immediately outside of some brain chemistry changes or opiate responses.BFR turned simple wellness activities into tempo running replacements. CLICK TO TWEET

Those with orthopedic restrictions who can’t do much outside of concentric training can use circuits for resurrection purposes. Biohacking full body workouts are little too crazy for me, so I like to limit the training to lower body. I did mention an arm training circuit as a chance to get a pump in that will please the gym rats; some athletes do like training and this serves more as a treat than a recovery session.

We usually see benefits with HRV, similar to the research on leg training and post-session parasympathetic changes that are based on soreness mitigation. Recovery is a mystical realm, and if an athlete enjoys the process and scores high on metrics for willingness to train, I am a fan.

A Few Warnings on Blood Flow Restriction

Don’t add BFR without getting your sports medicine staff involved if you’re a coach. With the current risks and complications, adding BFR for the wrong athlete is a bad idea. Examples are athletes with concussions and deep vein thrombosis. We think of athletes needing blood flow for healing, and those with restrictions can be susceptible to circulatory problems immediately afterward.

Other risks and complications are known, and I recommend a formal screening process for legal protection and the athlete’s safety and wellbeing. Add BFR into a program slowly and don’t get too creative early, as simple strength training and conditioning can create enough benefits that ecstatic ideas are simply unnecessary. If you’ve done your due diligence and want to help your athletes improve, BFR is a tool that can work wonders if you use it at the right time and place.

A true love for sports

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