Why should we lift?

Living an active life requires certain levels of strength. For example, when we walk we put 3.5 x bodyweight through our calf (soleus), whereas when we run this increases to 6.5-8x bodyweight^1-2. We could build the needed strength to deal with these loads by gradually building up the specific activity, but this still may leave us with limited margins  and increased risk of injury. It can also take a long time to build up your strength this way (at least in a way that doesn’t result in injury!) This is why I love strength training: it provides a way to efficiently and safely improve performance and reduce injury risk. No matter what type of activity or exercise you prefer, you can (and should!) use strength training to increase your ability to do it safely, well, and without pain. 

These are the typical bodyweight forces produced by the main muscle groups in running

What if we can’t lift?

The gold standard for strength training is to use 60-80% of a persons one repetition max (1RM= the most weight a person can lift for one repetition of the exercise) over 8-12 reps, 2-3 days a week. That is all well and good, but what if you have had an injury or surgery and cannot comfortably or safely lift these weights? It might be that you have torn a hamstring, you know you need to strengthen, but it is too painful. Maybe you have had a surgery such as an ACL reconstruction or rotator cuff repair and those heavy loads could damage the surgeons work. Historically, we would have had to stick with low load exercise and accept that it would take longer to build up strength. 

But now, new research has shown there is a way to get the benefits of strength training, while lifting much lower amounts of weight! If you’ve been following me for a while, you know that I’m a big fan of keeping things simple and not jumping on the bandwagon with lots of trends or gimmicks. And I try to keep the tools I use for treatment to simple things that my patients can replicate at home. BUT – I have been keeping a close eye on the research surrounding this technology, and I am pretty excited about what it can do to help my patients, especially in some special situations like injury recovery and post-surgical rehab. 

It is called Blood Flow Restriction (BFR) training (terrible name, I know…). Basically, it is a specialized tourniquet that provides a controlled way to allow some blood to enter, but restrict it leaving the area that we want to strength train (for instance, a leg or arm). Once in this state, the muscle becomes anaerobic (oxygen-deprived), and reacts to a low weight load in the same way that it would react to a much heavier load under normal circumstances. You are basically simulating what the muscle experiences under heavy load, but with a much lower load. This is great when the other structures around the muscle (bones, tendons, ligaments) are injured and can’t withstand the heavy loads; you can still train and do significant strengthening of the muscle without harming those injured structures. All of a sudden you can get significant strength gains in someone in pain or someone who is protecting a surgery! This is great news, especially for an athlete recovering from an ACL repair, for instance.

It can also help with injured muscles; it might be very painful to place the muscle under a heavy load, but we can use a lower load with BFR to begin building strength back while the muscle is still healing; research is even indicating that it may help the healing itself happen more quickly as we see increases in growth hormone for example!

This may sound like wishful thinking, a pipe-dream, a gimmick, but actually it is a reality! Interest in Blood Flow Restriction (BFR) training has been growing and the research is showing some awesome results. The results are so good in fact that we have to not get carried away with it – there are still some circumstances where it is not king!

The history of restricting blood flow

BFR training stems from the realization in the 1960’s by Japanese doctor, Yoshiaki Sato, that when meditating he restricted blood supply to his legs and that afterwards as he massaged them it gave the pumping experience you feel after strength training. Over subsequent years, he experimented with different compression and exercises and developed a product called Kaatsu bands. He used these bands following a skiing accident and instead of taking the expected six months to recover,he was better in six weeks. Not just relying on this experience, he started to produce further research on the effect of his Kaatsu bands, showing further positive results. In the west, researchers turned their interest to this approximately ten years ago with early work being done by the US military looking at the effect of BFR on soldiers coming back from Iraq and Afghanistan to help regain strength after amputation. As positive effects were seen, people started to look at how they could use this in the general orthopedic and sports medicine population. The more recent research has shown BFR can be used in many patients and scenarios. It has reached the point that several of the top ACL surgeons penned a review in the respected arthroscopy journal³ and it has been covered in Forbes. These same surgeons now expect their patients to receive it after surgery such as ACL reconstruction.

How it works – The basics

BFR works by limiting venous outflow while allowing arterial inflow – So, using a tourniquet we allow blood to enter, but restrict it from leaving. This creates metabolic stress and hypoxia leading to increased fiber recruitment, cellular swelling, inflammatory and endocrine responses (Human growth hormone), and other cellular changes all of which have been shown to mediate muscle protein signalling⁴. The changes in this signaling lead to strength gains. If you want to understand this in more depth you can read more here.

The above cellular changes with BFR lead to superior strength gains at 20% of 1RM when compared to no BFR. It takes someone lifting at 80% of 1RM to get the same effect as BFR can get at only 20% of 1RM^5-9. There are plenty of other people in my field and others talking about the physiology, so I won’t go into any depth here, but this treatment can really be a game changer for the right patient. It is clear how this can help when in pain after injury or to protect a surgery, but there are also some other applications. 

BFR for quicker bone healing (and space travel?!)

People with osteoporosis are now recommended to do weight bearing exercises as it promotes healthy bones – I discussed this in this article about stress fractures. After a fracture, doctors have to balance the benefit of loading the bone and promoting bone growth with the risk of excessive motion and slowed healing at the fracture site. Normally this means that for a period after a fracture (traumatic or stress) there will be a period of immobilization (perhaps even surgical fixation), but at some point there needs to be a progression where the bone is loaded to complete healing and for the bone to strengthen fully. During this period of immobilization, perhaps in a cast, using crutches, people lose muscle mass and atrophy. BFR offers us a great opportunity as there are studies showing that with the cell swelling that increases load around the fracture site, there is a measurable increase in bone formation markers and a decrease in bone reabsorption markers¹⁰. This is important as in healing a fracture we are trying to make sure that bone reabsorption (osteoblastic activity – breaking down bone) does not exceed bone formation (osteoclastic activity). This research is still in it’ early stages, but the other benefit of using BFR in the fracture population is that we can do strengthening at low loads, protecting the fracture, but can get more significant increases in muscle mass! So, theoretically using BFR in a fracture population is win-win! 

And what about space travel? We know that prolonged periods of space travel result in loss of bone density and muscle strength amongst other physiological issues. They have tried to address these with things such as a cycle ergometer, and more recently the Advanced Resistive Exercise Device (ARED)¹¹. BFR has been touted as a simple solution to the needs of astronauts and may also provide a gravitation-like force on the cardiovascular system which could make the return to earth an easier transition! Remember how many pioneering technologies have been brought to us courtesy of space and defense industries (think GPS, LEDs, artificial limbs, more here); BFR might be one to add!

BFR to help the training cycle

Below are some videos of BFR being used with Cody, a senior US national team gymnast. He had been having some issues with his feet and ankles, and past surgery had not given the relief they expected, but we started heavy load strength training and it was helping. However, he was in the middle of his season which meant we had the challenge of building capacity (strength training) while at the same time as challenging capacity (competition). The balancing of building vs challenging capacity was compounded by competition being elsewhere in the US and overseas, where he could not always access good gym equipment (particularly overseas). For example, to compete overseas he had to travel (2+day totals) and could not strength train/build capacity, but was then competing/challenging capacity at a high level. During these competitions he had some recurrence of pain, while at competitions where there were good strength training facilities he had little pain. We decided to trial BFR with him and he was able to see how he could use lower resistance, find it challenging, and get good effect. Having tried it and seen the benefit he can get his own cuffs and take them on travel with him. On travel, he can use moderately heavy objects such as his suitcase to get the effect of lifting heavy. So, for example the standing heel raise weight that challenged Cody over 4 sets of 30, 15, 15, 15, using BFR was 25#. The weights for the other exercises were also significantly lower than those that he would use without BFR.

VIDEO: Blood Flow Restriction Training In Rehabilitation and Performance of USA National Team Gymnast:

BFR for endurance gains

A further, different, example of the use of BFR is in a high-level runner. Nick had been recovering from a knee injury that occured early in his senior year. The injury had robbed him of track time and as such, although he was recovering well from a pain perspective and was still very quick, he didn’t have as much aerobic capacity as he would have with an uninterrupted season. We used BFR to build his aerobic capacity, using a method called ischemic preconditioning (IPC)¹². IPC was initially used as a way of protecting against organ and cellular damage after events such as heart attacks, but subsequently people looked towards using the same effects in performance sports. There are various strategies that can be used, but in this case we used a 100% limb occlusion pressure to significantly limit arterial inflow (5-minutes), followed by reperfusion (allowing blood flow to resume) for 5-minutes, and to repeat this 3-4 times. This is then followed by a maximal intensity performance (In Nick’s case a 2-3km run). The research is in its infancy in this area and there are not clear guidelines, but using this method I have personally seen two distance runners see gains. However, don’t be surprised if you seek 6-months after this blog has been published and see our application/technique changing as new research is produced. In this case I do not have objective data showing the improvement in aerobic capacity, but Nick reported the running felt easier, and he went on to success in the state championships, with season PRs 1:55 at 800m, and 4:18 at the mile. It is a potential tool he can use as he moves into running at the collegiate level at Alabama.

VIDEO: Blood Flow Restriction Training To Improve Aerobic Capacity In Elite High School Runner

Are there cases where it isn’t useful?

Yes! I alluded to this earlier, BFR is not the be all, end all for all injuries! A great example is tendinopathy which we have blogged about before. Tendinopathy responds well to heavy loads – the heavy loading affects tendon structure and nerve function leading to pain relief and improved capacity.  BFR reduces the loading so we do not see those affects; This is not to say it couldn’t have use at times for tendinopathy patients, but it should not be the mainstay of treatment. A further example is a stress fracture that can tolerate load – in these cases, like in someone with osteopenia/perosis, we want to load the bone up to stimulate new bone growth. The key here, and also with tendinopathy, is the idea of tolerance – If someone can tolerate load there are great benefits from loading them up. However, when there is intolerance to load or there needs to be a break from loading BFR provides us with a great option!

Hopefully, you can see there are a multitude of possibilities for BFR and it may be of use to you! Let me know if you have questions!

References:

1. Gheidi N, Kernozek TW, Willson JD, Revak A, Diers K. Achilles tendon loading during weight bearing exercises. Phys Ther Sport. 2018;32:260-268.
2. Almonroeder T, Willson JD, Kernozek TW. The effect of foot strike pattern on achilles tendon load during running. Ann Biomed Eng. 2013;41(8):1758-66.
3. Dephillipo NN, Kennedy MI, Aman ZS, Bernhardson AS, O’brien LT, Laprade RF. The Role of Blood Flow Restriction Therapy Following Knee Surgery: Expert Opinion. Arthroscopy. 2018;34(8):2506-2510.
4. Rossi FE, De freitas MC, Zanchi NE, Lira FS, Cholewa JM. The Role of Inflammation and Immune Cells in Blood Flow Restriction Training Adaptation: A Review. Front Physiol. 2018;9:1376.
5. Lowery RP, Joy JM, Loenneke JP, et al. Practical blood flow restriction training increases muscle hypertrophy during a periodized resistance training programme. Clin Physiol Funct Imaging. 2014;34(4):317-21.
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8. Farup J, De paoli F, Bjerg K, Riis S, Ringgard S, Vissing K. Blood flow restricted and traditional resistance training performed to fatigue produce equal muscle hypertrophy. Scand J Med Sci Sports. 2015;25(6):754-63.
9. Fahs CA, Loenneke JP, Thiebaud RS, et al. Muscular adaptations to fatiguing exercise with and without blood flow restriction. Clin Physiol Funct Imaging. 2015;35(3):167-76.
10. Bittar ST, Pfeiffer PS, Santos HH, Cirilo-sousa MS. Effects of blood flow restriction exercises on bone metabolism: a systematic review. Clin Physiol Funct Imaging. 2018;
11. Trappe S, Costill D, Gallagher P, et al. Exercise in space: human skeletal muscle after 6 months aboard the International Space Station. J Appl Physiol. 2009;106(4):1159-68.
12. Incognito AV, Burr JF, Millar PJ. The Effects of Ischemic Preconditioning on Human Exercise Performance. Sports Med. 2016;46(4):531-44.