Blood Flow Restriction Training - does it work for clinical conditions?
Blood flow restriction training (BFR training) also known as occlusion training, has become increasingly popular in recent years among physical therapists. This type of training involves restricting blood flow to a limb during exercise to enhance the muscle's training response. There are several clinical conditions that cause muscle mass depletion such as cancer, prolonged immobilisation, COPD and chronic heart disease, all of which, could potentially benefit from muscle strengthening and muscle hypertrophy but cannot withstand conventional high intensity exercises.
This article will look at the effectiveness of blood flow restriction training for several clinical conditions and cover the benefits and drawbacks of this training method which will help you make an informed decision as to whether you want to incorporate this treatment modality in your practice.
What exactly is Blood Flow Restriction Training?
Blood flow restriction training involves using a tourniquet or cuff to restrict blood flow to a limb during exercise. By reducing blood flow to the limb, the muscles receive less oxygen and nutrients, leading to an increase in metabolic stress and muscle activation. This type of training can be performed with lighter weights, making it accessible for patients who are unable to perform traditional strength training with heavier weights or higher resistance.
The idea is that the combination of metabolic stress from blocked blood flow and mechanical tension from physical activity or strength training leads to enhanced muscle growth and strength.¹ At the cellular level, a range of factors such as metabolic by-products, hormonal changes, communication between cells, cell swelling, and internal cell signalling pathways are thought to play a role.² These metabolic by-products, which accumulate during exercise and drive muscle growth, are heightened by the low oxygen and restricted blood flow of BFR training. This is thought to lead to earlier fatigue at the cellular level, which in turn causes greater activation of muscle fibers, as seen in studies where BFR with light weights produced similar muscle activation to high-weight resistance training.³
BFR training for post-operative rehabilitation
The rapid development and significant impact of muscle wasting after surgery or inactivity is well known as well as the harmful effect it has on recovery, overall mobility, and the risk of re-injury. In just a week, immobilisation alone can cause a 7% reduction in quadriceps muscle mass, and after knee surgery, this muscle wasting can be as much as 33% in three weeks.⁴ BFR training with low or no weights is ideal for this group, as it helps maintain muscle mass, causes less muscle damage after exercise, reduces pain sensitivity, and eases stress on joints.
Although BFR training has been proven effective in ACL reconstruction recovery, it may also be beneficial in cases of prolonged inactivity (such as meniscal repair, transplant, cartilage procedures, or osteotomy), multi-ligament reconstructions, or individuals with persistent muscle wasting.⁵ The growing evidence of BFR training's positive impact on muscles near the site of blood flow restriction has broadened its potential use in rehabilitation after shoulder and hip procedures as well.
BFR training for COPD
Current evidence shows that BFR training creates significant improvements in both functional and subjective measures of strength in COPD patients.⁶ BFR training has been shown to improve isometric knee extension strength, which is a commonly used benchmark for improvement in knee extension strength for COPD patients undergoing pulmonary rehabilitation. A recent meta-analysis found that combined strength and endurance rehabilitation programs can result in up to 32% improvement in isometric knee extension strength, whereas recent trials have shown that BFR training can improve isometric knee extension strength by 477% on average.⁷
BFR training for chronic heart disease
A recent systematic review showed that BFR training had promising results for individuals with chronic heart disease due to significant growth in the circumference of the quadriceps, hamstrings, and adductor muscles, significant enhancements in leg strength, as well as improvements in submaximal and maximal physical performance and cardiovascular endurance after 3 months of BFR training twice a week.⁸ The favourable results of this systematic review is applicable to patients with a variety of chronic heart conditions including CABG and valvular surgery, PTCA, non-ST segment elevation MI and ST-segment elevation MI, dilated cardiomyopathy, and heart failure. Importantly, BFR training in patients with chronic heart disease has not shown an increase in the risk of developing blood clots or inflammation.⁹
Criticisms and Concerns About Blood Flow Restriction Training
While blood flow restriction training has shown promise in some studies, there are also concerns and criticisms about this training method. This is especially true considering the uncertainty surrounding its effectiveness when pressure is applied through methods other than calibrated pneumatic tourniquets. Common side effects of BFR include temporary paresthesias, bruising, and delayed-onset muscle soreness. However, serious adverse events like rhabdomyolysis, prolonged pain, and fainting can occur from misuse, over-exertion, or in individuals who are not fit enough for moderate or intense physical activity. Although blood clots were once considered a risk with BFR, there is no evidence to support this claim. In fact, BFR may even have a protective effect against such events as it stimulates the fibrinolytic system. Provided that BFR is used within established guidelines, the risk of adverse events does not seem to be any higher than with other exercise methods.
Blood flow restriction training has the potential to be an effective tool for improving muscle strength, size, and endurance for patients receiving physical therapy treatment. Ultimately, the effectiveness of blood flow restriction training will depend on individual patient factors, such as rehabilitation goals, current physical capacity and their medical history. If you want to learn more about how to manage COPD, post-operative and chronic heart disease patients, head over to our intelligent question bank with case studies to learn more. Comment below if you have any thoughts on BFR training!
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Lu Y., Patel B.H., Kym C., et al. Perioperative blood flow restriction rehabilitation in patients undergoing ACL reconstruction: A systematic review. Orthop J Sports Med. 2020;8.
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Nakajima T., Kurano M., Sakagami F., Iida H., Fukumura K., Fukuda T., et al. (2010). Effects of Low-Intensity KAATSU Resistance Training on Skeletal Muscle Size/strength and Endurance Capacity in Patients with Ischemic Heart Disease. Int. J. KAATSU Ttaining Res. 6 (1), 1–7.
Madarame H., Kurano M., Fukumura K., Fukuda T., Nakajima T. (2013). Haemostatic and Inflammatory Responses to Blood Flow-Restricted Exercise in Patients with Ischaemic Heart Disease: A Pilot Study. Clin. Physiol. Funct. Imaging 33 (1), 11–17.