Skeletal muscle is a dynamic tissue that responds to changes in its environment. When it experiences stress, such as during physical activity or exercise, it triggers a process of muscle growth and development. On the other hand, when it is not being used or immobilized due to injury or orthopaedic procedures, it can undergo a process of atrophy or wasting away. This can lead to a loss of muscle strength and size, which is a common consequence of disuse. To prevent this, it is important to encourage early return to physical activities and exercise after injuries or procedures, as this can help stimulate muscle growth and prevent muscle atrophy.
Traditional training routines usually involve lifting weights that are more than 70% of an individual's maximum weight that they can lift for one repetition. This is also known as their one-repetition maximum (1RM). The purpose of using this heavy load is to stimulate muscle growth and development. This type of training is often referred to as "resistance training" or "strength training". The idea is that by gradually increasing the weight lifted over time, the muscles are forced to adapt and grow stronger, which can lead to improved athletic performance and overall physical fitness.
While traditional training routines involving heavy weights can be effective in stimulating muscle growth, they may not be suitable for all patients, especially those recovering from an injury or surgery. In such cases, a low-load resistance routine may be more appropriate. This type of exercise still activates anabolic pathways, which stimulate muscle growth, but without the added risk of injury. This approach can be especially beneficial for those who are unable to tolerate high-impact or high-load exercises, such as older adults or individuals with pre-existing conditions.
Blood flow restriction therapy (BFRT) is a technique that was first created in Japan during the late 1970s and was called KAATSU training.5 The therapy uses both metabolic and mechanical stress to promote muscle growth, strength, and angiogenesis. Metabolic stress is achieved through the use of a tourniquet applied to the upper or lower extremity, which partially restricts the blood flow. This causes the muscles to work harder and leads to an accumulation of metabolic by-products, such as lactic acid, which triggers a cellular response that stimulates muscle growth and hypertrophy. The mechanical stress is produced by performing low-load resistance exercises with the restricted blood flow, which further enhances the growth and strength of the muscles. By combining these two types of stress, BFRT is believed to produce results similar to those seen with high-load resistance exercises, but with less joint stress and a lower risk of injury.
Blood flow restriction (BFR) has become a popular method for treating tactical injuries and has gained a lot of research attention in recent years. This technique involves placing a pneumatic cuff, similar to a tourniquet, on the upper or lower extremity proximal part, followed by applying pressure to restrict blood flow to the limb's proximal area. The patient then performs resistance exercises at around 20% to 30% of their one repetition maximum. This modification to traditional exercise has shown promising results in improving strength and muscle hypertrophy with lower resistance loads.
Implementation & Results
Research on the optimal use of blood flow restriction therapy (BFRT) in training routines is still ongoing, but current programs have shown promise in both athletic and rehabilitation settings. BFRT can be used in combination with different types of exercises such as walking, cycling, body weight training, and low-load resistance training.
A recent review by Scott et al. recommends a training protocol that involves one set of 30 repetitions followed by three sets of 15 repetitions, each with 30-second breaks in between sets. Blood flow restriction is maintained throughout all sets to ensure adequate venous pooling. This routine is to be performed 2 to 3 times per week. While this protocol has been used in several investigations with positive results, it may need to be altered to best suit each individual's needs and abilities.
As research on BFRT continues, it is likely that more specific protocols will be developed to maximize its effectiveness in various settings. In the meantime, it is important for individuals considering BFRT to work with a qualified healthcare provider or exercise specialist to ensure safe and effective implementation.
As people age, they may experience a decrease in skeletal muscle mass, which can lead to a decline in their physical function and ability to perform daily activities. Studies have consistently found that strengthening the quadriceps muscles can reduce symptoms of knee osteoarthritis, a common condition among the elderly. Blood flow restriction therapy (BFRT) has shown promise in increasing muscle cross-sectional area and strength in older adults. Therefore, BFRT may be a useful tool in improving the physical function and quality of life of elderly persons who experience muscle loss.
A research study conducted by Loenneke and his colleagues reviewed 11 studies that compared the effects of Blood Flow Restriction Training (BFRT) with low-intensity training. Their meta-analysis found that BFRT produced greater improvements in muscle strength (with an effect size of 0.58) compared to the control group (with an effect size of 0.00). Similarly, muscle hypertrophy was also observed to be more significant with BFRT (with an effect size of 0.39) compared to the control group (with an effect size of 0.01).
Blood Flow Restriction Training (BFRT) holds great promise in the recovery of injured and postoperative patients who typically experience significant strength deficits ranging from 10% to 30% due to disuse, immobilization, or casting. The primary objective of BFRT in rehabilitation protocols is to promote earlier increases in strength while minimizing potential damage to connective tissues and joints.9 Research by Takarada and his colleagues has shown that BFRT alone, without resistance training, can help reduce muscle atrophy postoperatively after an anterior cruciate ligament (ACL) reconstruction. In their study, patients who underwent BFRT experienced a 9.4% decrease in cross-sectional area (CSA) compared to the control group that had a 20.7% decrease. Ohta and colleagues conducted a prospective randomized control trial to examine the effectiveness of blood flow restriction training (BFRT) in individuals who underwent anterior cruciate ligament reconstructions. After completing a 16-week program, the researchers found that the BFRT group had significant increases in thigh cross-sectional area (101% compared to 92% in the control group) and maintained their strength better (84% compared to 63% in the control group, as indicated by the injured/healthy leg ratio).
Elite Training Program
The Blood Flow Restriction Training (BFRT) method has not demonstrated the ability to activate as many muscle units as high-load training techniques. Nevertheless, it has displayed potential as a supplementary method to traditional training regimes in various studies.
A review conducted by Scott et al analysed 12 studies on the use of Blood Flow Restriction Training (BFRT) in healthy athletes. The authors' findings indicate that based on current evidence, BFRT can improve muscle development in athletes and serve as a useful addition to high-load training programs.1 Yamanaka et al conducted a study to investigate the effects of BFRT in enhancing the off-season training of 32 Division IA football players. Both groups followed their regular off-season routine, but the BFRT group added four sets of bench press and squat exercises with the use of elastic bands on the proximal extremity (performed 3 times a week at 20% of 1RM). The results showed that the BFRT group had a significant increase in bench press (7% compared to 3.2%) and squat (8% compared to 4.9%) compared to the control group.
Despite the potential advantages of using Blood Flow Restriction Training (BFRT), concerns have been raised about its safety, particularly in relation to the cardiovascular system, due to the physical restriction of blood flow to an extremity. However, a national survey conducted in Japan in 2006 with 13,000 participants showed that the most frequent adverse effects were temporary and included subcutaneous haemorrhage (13%), sensory paraesthesia (1.3%), and light-headedness (0.3%). Despite the safety concerns, BFRT may still be a useful training method for athletes if implemented correctly and with appropriate precautions.11
Cardiologists have expressed concern about the possible impact of blood flow restriction training (BFRT) on the exercise pressor reflex (EPR), which is the body's natural response to physical exercise. During exercise, the EPR is activated by increased levels of metabolites such as lactate and hydrogen ions, as well as mechanical pressure. This response leads to increased sympathetic activity, resulting in elevated carbon monoxide, heart rate, contractility, and mean arterial pressure.
BFRT has been found to potentially intensify the EPR's reaction, which could lead to adverse cardiac events like arrhythmias, stroke, myocardial infarction, or sudden cardiac death. This concern is particularly significant in patients with cardiovascular comorbidities since they may have an already heightened EPR response at baseline.
Strength deficits are frequently observed after orthopedic operations, immobilization, and casting, particularly among older patients. This can lead to muscle atrophy, which can further exacerbate the problem and lead to a higher risk of injury and osteoarthritis. To avoid these negative outcomes, promoting muscle strength and hypertrophy is crucial for earlier rehabilitation and better outcomes. Blood flow restriction training (BFRT) is a promising method for enhancing muscle development and preventing postoperative atrophy. BFRT involves combining low-load resistance training with blood flow restriction to stimulate greater muscle strength and hypertrophy gains compared to low-load resistance training alone. Studies have consistently shown that BFRT is an effective method for promoting muscle development and can aid in earlier return to functional status after orthopedic operations or injuries.