Boris A. Zelle (left), MD, FAAOS, a member of the AAOS Now Editorial Board, interviewed Gustavo J. Almeida, PT, PhD, about research focused on testing the feasibility of using BFRT preoperatively in older adults awaiting total knee replacement.


Published 6/20/2023
Boris A. Zelle, MD, FAAOS, FAOA

Study Explores Benefits of Blood-flow Restriction Training in Older Patients Awaiting Knee Replacement

Blood-flow restriction training (BFRT) has recently emerged as a way to improve rehabilitation in orthopaedic patients. Moreover, it has been utilized to optimize patients’ conditions prior to elective orthopaedic procedures (i.e., rehabilitation).

Gustavo J. Almeida, PT, PhD, from the Department of Physical Therapy (PT) at UT Health San Antonio, has more than 20 years of experience in sports and orthopaedic rehabilitation. His most recent research has focused on testing the feasibility of using BFRT preoperatively in older adults awaiting total knee replacement. Given the importance of this emerging field, Boris A. Zelle, MD, FAAOS, a member of the AAOS Now Editorial Board, interviewed Dr. Almeida about his research.

Gustavo J. Almeida, PT, PhD, demonstrates orthopaedic applications of blood-flow restriction training to physical therapy doctoral students.
Courtesy of Gustavo J. Almeida, PT, PhD
Gustavo J. Almeida, PT, PhD

Dr. Almeida: I completed my PT degree and training in Brazil and have more than 20 years of clinical experience with a focus in sports and orthopaedic rehabilitation. I obtained my PhD in rehabilitation science from the University of Pittsburgh and currently serve as an assistant professor in the PT department at UT Health San Antonio. My research focuses on interventions to improve physical function and activity in individuals with arthritis.

To date, I have treated and studied hundreds of individuals with musculoskeletal disorders, focusing on their functional rehabilitation and quality of life. My role is to keep individuals with musculoskeletal disorders physically healthy by using exercise-based approaches that are effective and tolerable to them.

What is BFRT?
BFRT was developed in Japan in the 1960s as “kaatsu training.” Kaatsu training was primarily used by rehabilitation professionals in Japan to help patients recover from injuries or surgeries, as it was thought to enhance muscle strength and promote tissue healing without putting undue stress on the injured area.

The technique involves applying a blood pressure cuff proximally to the limb being trained, which restricts blood flow to the muscles during exercise. The cuff maintains arterial inflow while obstructing venous outflow distal to the occlusion site. Cuff pressure for BFRT can be established with a portable Doppler monitor to capture auscultatory signal of the posterior tibial artery while inflating the cuff until full occlusion is achieved or using automated BFR cuffs.

Initial BFRT cuff pressure is set at 50 percent of the full occlusion pressure during the first few exercise sessions and then progressed in increments of 10 percent until achievement of 80 percent occlusion pressure. This progression is based on the participant’s tolerance and level of fatigue after a training session. If the participant feels too fatigued after a training session, pressure should not be increased.

BFRT has gained popularity in the fitness and sports-performance communities as a way to increase muscle strength and hypertrophy, improve endurance, and reduce the risk of injury. The benefits of BFRT as they relate to skeletal muscle were first published in 1998. To date, several research studies have arisen to investigate how BFRT might help several clinical populations.

What is the physiologic mechanism of BFRT that is triggered by exercise?
The restriction of blood flow creates an environment in the muscle that mimics that of high-intensity exercise, even though the actual intensity of the exercise is low. BFRT is coupled with low-resistance exercises (20 percent to 30 percent of one repetition maximum), thus reducing the load on the joints. The partially restricted blood flow generates an anaerobic environment that induces cellular and hormonal changes, which stimulate muscle growth.

What are common applications of BFRT in orthopaedic patients?
There are several trials currently going on regarding BFRT before and after anterior cruciate ligament (ACL) reconstruction and as rehabilitation for ACL injury, knee osteoarthritis, total knee replacement, meniscal tears, articular cartilage injuries, Achilles tendinopathy, and fracture surgery.

Tell us about your research.
My current research study is investigating the feasibility of BFRT preoperatively (i.e., prehabilitation) in older adults awaiting total knee replacement. We have a great collaboration with Frank Buttacavoli, MD, FAAOS, from UT Health San Antonio.

Participants are performing leg extensions, leg curls, and sit-to-stand exercises while wearing the BFRT cuffs. A session lasts for around 20 minutes, which is the maximum time recommended. Participants perform one set of 30 repetitions in addition to three sets of 15 repetitions with 30 seconds of rest in between sets for all three exercises. One minute rest is allowed between exercises. We are also measuring quadriceps muscle strength, physical function, physical activity, quality of life, and muscle composition (via dual x-ray absorptiometry) at three timepoints: baseline (before exercise program), follow-up right after the exercise program, and follow-up at eight weeks after surgery. We are grateful that this approach is showing gains in quadriceps muscle strength, physical function, and quality of life preoperatively, which have been carrying over postoperatively.

What evidence suggests BFRT may be beneficial?
Several studies have shown that in older adults, BFRT increases muscle protein synthesis, which is the process by which muscle fibers repair and grow in response to exercise-induced damage. Studies in healthy young adults have shown that BFRT downregulates pathways involved in proteolytic activities, which may also help with muscle gains.

Another important finding is that BFRT has beneficial effects on angiogenic gene expression as well as vascular endothelial function and peripheral blood circulation in healthy older adults. Furthermore, low-
resistance BFRT has been shown to improve quadriceps strength and volume comparable to high-resistance exercise training in healthy adults.

Where do you see this field going in the future?
Our group and several others have shown that BFRT is a very useful rehabilitative tool to be used preoperatively to prepare patients for surgery, during early stages postoperatively, and during early stages of rehabilitation after orthopaedic injuries. Recovery has been faster as compared with traditional rehabilitation programs, as BFRT has been shown to maintain or improve muscle function even when a person is exercising without additional resistance.

Boris A. Zelle, MD, FAAOS, FAOA, is vice chair of research and chief of orthopaedic trauma in the Department of Orthopaedics at UT Health San Antonio.


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  2. Nitzsche N, Stäuber A, Tiede S, Schulz H: The effectiveness of blood-flow restricted resistance training in the musculoskeletal rehabilitation of patients with lower limb disorders: A systematic review and meta-analysis. Clin Rehabil 2021;35(9):1221-34.
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