When BFR is implemented correctly and for appropriate participants, the likelihood of adverse events is low. Minor side effects can include muscle soreness in the days following a workout, sensations of numbness and coldness in the limbs, light bruising at the sight of cuff application, and some light-headedness. The rates of more severe and dangerous complications (e.g., venous thrombosis, rhabdomyolysis, etc) are low.

To increase the safety of BFR training, participants should initially be screened for medical conditions to determine if this training method is appropriate. The BFR training should then be gradually introduced by a trained practitioner, with care being taken to stop training if any adverse responses are noted.

Applying BFR produces a unique set of sensations, which can vary based on the individual and the specific protocol used:

1. Pressure: The most immediate sensation is the pressure from the cuff. It should be noticeable but not excessively painful.
2. Muscle fatigue: As BFR limits blood flow and oxygen delivery to the muscles, you may experience muscle fatigue more quickly than during traditional training.
3. Burning sensation: The accumulation of metabolites with BFR can cause a burning sensation, similar to that felt during traditional high-intensity training.
4. Swelling and pump: BFR can cause noticeable swelling and a “pump” in the muscles, due to the pooling of blood in the restricted area.
5. Numbness or tingling: If the cuff is too tight, you might experience numbness or tingling. This may indicate that the cuff pressure requires adjustment.
6. Relief after release: Once the cuff is released, some may notice a rush of blood flow back into the muscles, which can cause a temporary sensation of warmth.

Exercise with BFR partially restricts blood flow to and from the muscles during exercise, leading to a unique physiological stimulus that can enhance adaptations to low-load or low-intensity training.

Greater vascular resistance from BFR limits oxygen delivery to the muscles, creating a localised hypoxic environment in the muscle and increasing reliance on anaerobic metabolism. For resistance exercise, the production and accumulation of metabolic byproducts which can cause fatigue (e.g., hydrogen ions) is increased, resulting in increased muscle activation for a given exercise and load. A series of anabolic pathways promoting muscle protein synthesis are also activated, ultimately causing muscle growth. For aerobic exercise, BFR increases heart rate to offset reductions in stroke volume (due to blood pooling in the limbs) and maintain cardiac output. In simple terms, this provides a more substantial central stimulus for cardiovascular adaptation. Alterations also occur in the vasculature to increase the capacity to deliver oxygenated blood to the muscles.

It is important to recognise that while BFR can enhance adaptations to a low mechanical stimulus (i.e., lifting light weights or slowly walking), it is not a “free lunch” – this technique simply upregulates some physiological responses which promote our body to adapt.

Training with BFR can benefit a wide range of individuals, particularly those who might find traditional high-load resistance training or high-intensity conditioning too challenging or impractical.

1. Load-compromised individuals: Those recovering from musculoskeletal injury or dealing with joint or soft tissue pain (particularly if aggravated by high loads).
2. Healthy individuals: Those looking to add variety to their workouts and stimulate adaptation with lighter weights or lower-intensity conditioning. This may also be a time-efficient workout, appealing for those with limited opportunity to exercise.
3. Competitive athletes: Athletes can use BFR to maintain muscular or cardiorespiratory fitness during periods of reduced training (e.g., travelling for competition), with some emerging evidence for use during sport-specific training.

Setting the pressure correctly for BFR training is crucial to ensure safety and effectiveness. The appropriate pressure can vary based on factors like limb size, cuff width, and individual tolerance. The best approach to setting the BFR pressure is based on an assessment of each participant’s arterial occlusion pressure; the lowest pressure at which there is no blood flow. This process requires the cuff to be gradually inflated to the point at which blood flow is stopped (often measured via a hand-held Doppler probe). During BFR exercise, cuffs should be inflated to a relative pressure of between 40% and 80% of resting arterial occlusion pressure. This ensures that some arterial blood flow is always going into the muscle.

More information on how to set the BFR pressure can be found HERE.

The most common application of BFR is during low-load resistance training, where it can cause substantial muscle growth and strength improvements. Interestingly, there is some evidence that while only the limb muscles are under restriction, muscles of the trunk may also benefit from BFR. Resistance exercises such as leg extensions, leg presses, bicep curls, and bench press are commonly examined in research.

Low-intensity conditioning exercise (e.g., walking, stationary cycling, ergometer rowing) have been shown to cause some improvements in cardiovascular fitness and functional abilities (particularly in older adults), and even some increases in muscle strength.

When purchasing BFR cuffs, there are several factors to consider to ensure you choose a safe, effective, and suitable product:

1. Type of cuff system: Inflatable cuffs allow more precise control of pressure and usually come with a pump and a pressure gauge. Premium cuff system will autoregulate the pressure to accommodate fluctuations in limb circumference during exercise. Elastic bands may be cost effective, but do not allow for precise pressure control.
2. Single- or multi-chambered cuff bladder: Some cuff systems utilise a multi-chambered inflatable bladder, which can make obtaining the arterial occlusion pressure at baseline difficult. Single-chambered cuffs may better allow for exercising BFR pressure to be relative to arterial occlusion pressure.
3. Size and width of cuffs: Ensure the cuffs are appropriately sized for the limbs you intend to train (upper arms or thighs). Some products offer different sizes for different limbs, with wider cuffs generally recommended for the legs and more narrow cuffs for the arms.
4. Ease of use: Cuffs should be easy to apply and adjust independently. Features like quick-release mechanisms or easy-to-use buckles can be beneficial. The product should come with clear instructions or guidance on how to use it safely and effectively.
5. Material and durability: Look for cuffs made from comfortable materials to minimize irritation and discomfort during use. Ensure the cuffs are made from durable materials that can withstand regular use without wear and tear.
6. Safety Features: Some cuffs have built-in mechanisms to prevent over-inflation and ensure pressure remains within safe limits.