August 17, 2016
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 (also referred to blood occlusion 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: [email protected]
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.
Personalized 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 blood occlusion training, 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. Blood occlusion training 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 blood occlusion training 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.