At the University of Florida, rehabbing athletes can be found lifting low loads with a tourniquet fastened around their injured limbs. Called blood flow restriction training, this method is getting them back to activity faster and stronger.
This article first appeared in the July/August 2016 issue of Training & Conditioning.
By Paul Silvestri and Johnny Owens
Paul Silvestri, MS, LAT, ATC, is Associate Director of Sports Health and Head Athletic Trainer for Football at the University of Florida. He can be reached at: PaulSi@gators.ufl.edu.
Johnny Owens, MPT, is Medical Director of Owens Recovery Science, Inc., and a Clinical Researcher at the San Antonio Military Medical Center (SAMMC). Previously, he was the Chief of Human Performance Optimization at the Center for the Intrepid in the SAMMC. Owens has been practicing blood flow restriction training since 2011.
Blood flow restriction (BFR) training, or “tourniquet training,” first came to my attention while I was watching ESPN in November 2014. A segment was highlighting the eye-popping results BFR training was producing for wounded soldiers at the Center for the Intrepid in the San Antonio Military Medical Center. By lifting low loads with a tourniquet applied to their injured limbs, the soldiers were able to promote muscle hypertrophy and function. The technique had been implemented by Johnny Owens, MPT, then the Chief of Human Performance Optimization at the Center for the Intrepid, and the co-author on this article.
Not long after, I again heard about the positive outcomes seen when using BFR—this time in reference to injured elite athletes. In early 2015, the Houston Texans became the first NFL team to adopt BFR training, and rehabbing players like Jadeveon Clowney and Brian Cushing were the beneficiaries.
Once I saw the dramatic impact tourniquet training made on both wounded soldiers and NFL athletes, I contacted Johnny about bringing it to the University of Florida. The UF Sports Health staff strives to stay on the cutting edge of medical care, and BFR would allow us to further our mission of offering innovative treatments.
After researching the technique and getting trained by Johnny, we became the first college athletic department to implement BFR training with Delfi Medical’s PTS Personalized Tourniquet System in August 2015. Since then, it has become an integral part of our rehab approach. In this article, Johnny will cover the science and methods behind tourniquet training, and I’ll outline how we use it at UF to minimize strength losses in athletes’ injured limbs.
During the quiescent period of recovery, athletes are susceptible to anabolic resistance in their injured arm or leg because the limb isn’t being used. As illustrated in a 2013 study in The Journal of Clinical Endocrinology & Metabolism, local protein synthesis within the limb can decrease by as much as 30 percent during this time, correlating to a 350-gram loss of muscle tissue and a 30 percent decline in muscle strength.
Traditional resistance training guidelines recommend lifting loads greater than 65 percent of a one-rep max over 12 to 16 weeks to regain this lost strength. Obviously, serious injuries prevent athletes from doing this. However, using BFR, athletic trainers may be able to manipulate an injured athlete’s muscle protein synthesis into a positive state without compromising their vulnerable joints or soft tissue.
For instance, a 2007 study in the Journal of Applied Physiology demonstrated a 46 percent rise in muscle protein synthesis three hours post-BFR training for injured athletes. A work-matched control group without occlusion saw no change. Similarly, a 2010 study in the same journal revealed a 56 percent rise in muscle protein synthesis three hours after BFR training.
Improved muscle protein synthesis can correlate to increases in muscle girth and the amount of work a muscle can perform in an injured limb. To illustrate, a study in the Journal of Special Operations Medicine found muscle power grew by 50 to 80 percent in injured athletes after they practiced BFR.
So how does BFR training work? The first step is securing a pneumatic tourniquet (similar to those used during surgery) at the most proximal point of an injured leg or arm. Vascular flow is then detected via a Doppler-like system to determine the necessary occlusion pressure for the limb, which is defined as the amount of pressure needed to completely eliminate blood flow into the limb. Eighty percent pressure in the lower extremities has demonstrated the highest muscle recruitment, while 40 to 50 percent in the upper extremities has shown similar results.
Administering pressure to the limb reduces vascular inflow and completely occludes venous outflow, creating a hypoxic environment within the target muscle. Exercising at light loads (20 to 30 percent of one-rep max) in this state produces a significant hypertrophy effect.
WHY IT MAY WORK
Although the exact mechanism behind the gains seen with BFR training is still not fully understood, several theories have been presented. One prevailing hypothesis is the recruitment of larger, fast-twitch motor units during the hypoxic state created by the tourniquet. Several papers supporting this idea have demonstrated higher intramuscular electromyographic signal output when performing exercise under vascular occlusion compared to low-load training without a tourniquet.
Another hypothesis is that as the muscle utilizes the anaerobic pathway during resistance training with BFR, its metabolic accumulation may trigger hypertrophic changes. This was seen in a 2014 study in Clinical Physiology and Functional Imaging that compared the accumulation of substances such as lactate—a byproduct of anaerobic metabolism—between BFR, high-intensity training (HIT), and standard low-load training. The BFR group demonstrated a significant rise in lactate and similar levels of metabolic stress as the HIT group. The systemic response from this metabolite accumulation with BFR has also been shown to include significant increases in substances such as growth hormone, insulin-like growth factor, and myogenic stem cells.
A third theory is that the muscle pump effect seen after tourniquet training may play a role in hypertrophy gains. BFR produces muscle swelling and a plasma volume fluid shift. As shown in a 2006 study published in Acta Physiologica, these effects could help augment muscle size by activating the protein synthesis pathway via MTORC1.
Other studies have supported this theory by demonstrating the ability of occlusion alone to mitigate atrophy compared to controls. The cellular swelling created by a tourniquet in the absence of exercise was enough to induce muscle protein synthesis. This phenomenon has been observed in subjects after an ACL repair, as well.
Since BFR is still a relatively new rehab tool, some athletic trainers are skeptical about it. One concern is the safety of tourniquet training.
Numerous studies have analyzed this topic, including a recent investigation that surveyed Japanese institutions about observed side effects with BFR training. The most commonly cited risk was temporary bruising around the tourniquet site (reported by 13 percent of patients). A dull pain or discomfort due to the tourniquet was reported in nine percent of patients, while transient numbness of the treated extremity occurred in 1.2 percent of the population. Other side effects included lightheadedness, a temporary cold feeling in the extremity, venous thrombus, and pulmonary embolism, but these were all experienced in fewer than one percent of patients.
Due to the nature of the technique, there is a theoretical possibility of developing compartment syndrome or deep venous thrombosis with BFR. However, previous studies have shown no increased risk of either when comparing BFR therapy to other exercise and rehabilitation regimens. In addition, investigations measuring clotting factors from the European Journal of Applied Physiology and the Journal of Bone and Joint Surgery did not find any increase after BFR. In fact, fibrinolytic (anti-clotting) factors were demonstrated to increase after tourniquet training.
The easiest way to ensure safety when practicing BFR is to acquire the correct equipment and operate it properly. It is critical that clinicians use a classified and regulated Class I FDA-approved device when introducing BFR. Don’t use a device that has not been listed with the FDA as appropriate for occluding blood flow. For example, utilizing items like knee wraps and blood pressure cuffs may cause injury and leave the clinician susceptible to liability.
At UF, we use the PTS Personalized Tourniquet System for BFR. Third-generation tourniquet systems like the PTS incorporate advanced safety features to minimize complications, including personalized limb occlusion pressure, automatic shut off if pressure gets too high, the ability to ensure blood flow is not completely restricted, and sensors to monitor ongoing pressure changes. Furthermore, the system’s wide tourniquet cuffs have a variable contoured fit that increases their surface area and significantly reduces pressure gradients, which has been demonstrated to reduce the potential for skin or nerve injury.
APPLICATION AT UF
Before we could start incorporating BFR at UF, our Sports Health staff underwent an eight-hour education and training session with Johnny. The first half of the day covered the science and history of BFR, while the second half addressed its application and general use.
Armed with this knowledge, we could then educate UF athletes about BFR one-on-one prior to using it with them. We explained the science and application process, benefits of BFR, and what they would experience before and after training. Since tourniquet training differs from other rehabilitation techniques that we have used, we felt it was important to lay out the basics for athletes who would be practicing it.
Some of our athletes were skeptical about using BFR at first, but because of the relationships we’ve built with them, they were willing to trust us and try it out. Occasionally, I would apply a tourniquet to my arm or leg and demonstrate the training to ease their concerns.
The protocol for BFR fits easily into our broader rehabilitation programs. In most cases, we begin BFR training after the initial inflammatory phase of injury is controlled. Athletes then do one five- to 20-minute BFR session a day, three to five times per week. There is no science-based consensus regarding how long each session should last. Rather, we base it on the organization of each rehabilitation protocol. For example, athletes might do BFR for a longer period of time on days when they don’t have any other weightlifting or conditioning scheduled.
Almost all of our standard rehabilitation exercises can be performed with the tourniquet applied. Athletes generally perform four sets of each exercise prescribed in a 30/15/15/15 rep count, with a 30-second break in between each set. The 30/15/15/15 rep count is based on research conducted by Johnny and his team—they found this is the optimal count for maximum benefits. Following the BFR training session, the athlete continues with the rest of their rehab plan for that day.
To date, we have successfully used BFR with a variety of injuries, including lateral ankle sprains, post-op meniscectomies, ACL reconstructions, AC joint sprains, and patella tendonitis. The overall feedback from athletes has been overwhelmingly supportive. Any trepidation went out the window once they started treatment and quickly saw results. Eventually, we had injured athletes asking to use BFR as soon as they walked into the athletic training room to start their rehab. This marked the first time in my career that a new training technique created such a widespread positive buzz among players. (See “Success Stories” below for examples of UF athletes who used BFR.)
Lately, we’ve started using BFR even more frequently, and we continue to see more rapid improvements in muscle size, joint range of motion, and overall function compared to using conventional treatments alone. In the future, we hope to utilize the science behind the technique to promote recovery and decrease stress in athletes who have a history of knee or shoulder injuries. For example, we could use it on athletes with chronic knee problems during the season to reduce the load on the joint.
In just a year, BFR has changed our approach to rehabilitation at UF. As the clinical research surrounding it grows more and more, we look forward to expanding our use of this unique treatment.
To view a list of references for this article, go to Training-Conditioning.com/References.
The first athlete to use blood flow restriction (BFR) training at the University of Florida had a high-grade tear of the biceps femoris. Like we do with all injuries, we incorporated conventional methods of treatment, including RICE, controlled range of motion, a progression to concentric and eccentric strengthening, and a functional return-to-play program. We estimated the athlete would return to play in four to six weeks.
However, by adding BFR into the regimen, we were able to return the athlete to full competition after only three weeks. This eye-opening result was backed up by systematic diagnostic ultrasound imaging (US).
In previous biceps femoris tears, US revealed slow integral changes (about 10 to 20 percent improvement) in the area of injury when examined on a weekly basis. With the UF athlete using BFR, we were able to document approximately 30 percent improvement in muscle tissue repair using the same parameters. Obviously, given our sample size of one, we couldn’t say that BFR was the sole reason for these results, but it was definitely encouraging.
Our excitement about the potential for BFR increased following the recovery of an athlete who had undergone an anterior Bankart repair in his right shoulder. This was his third shoulder surgery in three-and-a-half years, but the recovery was different this time because we added BFR.
Due to the low loads used during tourniquet training, we were able to introduce strengthening during the athlete’s six-week immobilization period. This, in turn, allowed him to progress to more advanced strength movements earlier in his rehabilitation.
Having gone through two shoulder rehabs previously, the athlete said he could tell the difference once he started incorporating BFR. He stated that his shoulder felt stronger than ever, and his confidence levels were high when he returned to play.