Introduction
BFR training, formerly known as KAATSU training, was first created in Japan in the 1960s. It involves placing a pneumatic cuff, or a tourniquet, proximally to the target muscle. It can be used on the lower or upper extremities. The next step is inflating the cuff to a certain pressure to achieve total and partial venous obstruction. The following procedure is to have the patient execute resistance exercises at a low intensity of 20 to 30% of 1 repetition maximum (1RM), with high repetitions (15 to 30) and brief rest intervals (30 seconds) in between sets.
What Is Blood Flow Restriction Training?
Blood flow restriction (BFR) is a growing rehabilitation approach that employs a tourniquet to minimize arterial inflow while obstructing venous outflow during resistance training or exercise. Although this method was originally thought to promote muscular growth, a greater understanding of its physiological advantages and mode of action has made it possible for creative therapeutic uses.
BFR is a technique to reduce joint stress without sacrificing strength gains, whereas, for postoperative, wounded, or load-compromised persons, BFR represents a way to hasten recovery while minimizing atrophy. Additionally, there's increasing evidence that it improves cardiovascular health and reduces pain.
Blood flow restriction therapy promotes muscle growth through an integrated approach to metabolic load and mechanical tension, although there is still much to understand. It also has additional advantages for cardiovascular fitness and pain management. There is potential for accelerated healing with novel types of BFR and growing uses in athletes and postoperative patients. Sustaining adherence to rehabilitation protocols and investigating the physiology and many applications of BFRs will enhance their efficacy and prescription.
What Is the Mechanism of Action?
Though several theories have been put forth, the current consensus is that mechanical tension from exercise or resistance training combined with metabolic stress from vascular occlusion produces synergistic improvements in strength and muscle hypertrophy. Metabolites, cell-to-cell communication, cellular enlargement, hormonal variations, and intracellular signaling pathways have been linked at the cellular level. The comparatively ischemic and hypoxic circumstances of BFR enhance the effects of metabolites, which build up during exercise and are recognized mediators of muscle hypertrophy.
The fact that BFR at low loads has recruitment comparable to high load resistance training suggests that they cause earlier, peripherally mediated fatigue, which leads to increased motor unit recruitment. The increased muscular growth in low-load BFR compared to identical low-load exercise alone can be explained by the activation of type II fast-twitch muscle fibers, which are generally only selectively recruited at greater intensities at lower loads.
Greater motor unit recruitment, however, is not confined to muscles distant from the occlusion site. The gluteus maximus, shoulder (deltoid or rotator cuff), and pectoralis major are the more proximal muscles that have been demonstrated to have higher levels of recruitment in both upper and lower-extremity BFR compared to controls. It is believed that this happens due to the early fatigue of synchronous muscle groups distant from the occlusion site. This has significant consequences for using BFR following operations or injuries in which proximal tourniquet application is impossible.
A possible explanation for the supraphysiologic effects of BFR exercise is the proliferation of multipotent satellite cells within the connective tissue of muscles, which are responsible for the growth of muscles and regeneration. BFR enhances the proliferation of satellite cells even at modest loads, contrary to previous beliefs that they are only active during high-resistance training. This increases muscle protein synthesis, myonuclei content, myofiber size, and muscle strength.
What Are the Effects of Blood Flow Restriction?
The purpose of BFR training is to use a cuff to simulate a hypoxic environment to replicate the consequences of high-intensity exercise. After the cuff is positioned close to the muscle being worked, low-intensity activities can then be done. The low-oxygen blood that collects in the cuff due to blood flow limitation causes a rise in protons and lactic acid. As a result, low-intensity exercise and BFR training will cause the same physiological modifications to the muscle as high-intensity exercise, such as hypoxia, hormone release, and cell swelling.
When compared to standard low-intensity exercise, low-intensity BFR training increases muscle circumference. First of all
Cell swelling is the outcome of low-intensity BFR (LI-BFR), which causes a rise in the water content of the muscle cells. It also increases the rate of activation of fast-twitch muscle fibers. Furthermore, cuff removal is predicted to result in hyperemia or an excessive amount of blood in the blood vessels, which will inflate the cells even more.
It has been demonstrated that four to six weeks of brief, low-intensity BFR training can result in a 10 to 20 % gain in muscular strength. These increases matched the gains made from high-intensity exercise without BFR.
What Are the Safety Precautions to Be Considered?
Although the impact of scientific research on sports performance is remarkable, one should exercise caution due to the risks involved in using BFR improperly. This is particularly true considering the need for more assurance surrounding its efficacy when pressure is applied using less accurate techniques than pneumatic tourniquets with regulated pressures. Generally, using BFR may cause bruising, temporary paresthesias, and delayed-onset muscle soreness. However, improper use, overexertion, or use in people who are not well enough to engage in moderate-to-intense physical activity can cause serious adverse events, such as prolonged pain, rhabdomyolysis, and syncopal events.
Last but not least, even though blood clots were frequently mentioned as a problem in the early research and debate surrounding BFR, there is no proof to suggest a higher risk of thromboembolic events. Because BFR stimulates the fibrinolytic system, it may have the reverse effect, protecting against such occurrences. Despite these concerns, using BFR following consensus standards doesn't raise the likelihood of negative outcomes more than conventional exercise methods.
Conclusion
BFR therapy has additional advantages for pain and cardiovascular fitness and stimulates muscle growth through a synergistic response to metabolic load and mechanical tension. There is potential for accelerated healing with emerging types of BFR and growing uses in athletes and postoperative patients. Continued attention to rehabilitation standards and research into BFR physiology and uses will aid in optimizing the benefits and prescription.
