What Is Blood Flow Restriction Training?
Blood flow restriction training involves wrapping an inflatable cuff or tourniquet around the top of a limb — the upper arm or upper thigh — and partially restricting blood flow during exercise. The restriction is applied to venous return (blood leaving the muscle) while arterial flow (blood entering the muscle) is maintained.
The result is that blood and metabolic by-products accumulate in the working muscle, creating an environment that triggers significant muscle adaptation — at loads far lower than what would normally be required.
In traditional resistance training, meaningful muscle hypertrophy generally requires working at loads above 65% of your one rep maximum. With BFR, similar adaptations can be achieved at just 20 to 30% of one rep max. For someone who cannot safely load a joint or limb heavily — due to surgery, injury, tendon irritation or pain — this is a significant practical advantage.
How Does It Actually Work?
The physiology behind BFR is genuinely interesting and worth understanding if you're considering using it.
Under normal training conditions, heavy loading causes an inflammatory response in muscle tissue that drives adaptation — bigger, stronger muscle fibres. This is also what causes delayed onset muscle soreness (DOMS) and limits the ability to train again the next day at high intensity.
BFR bypasses the need for heavy loading by exploiting the relationship between oxygen availability and muscle fibre recruitment. Here's the simplified version:
Oxygen is required for the development of Type 1 (slow twitch) muscle fibres — the endurance fibres that are recruited first during low-intensity exercise. Type 2 (fast twitch) fibres — the larger, more powerful fibres that drive strength and hypertrophy — are normally only recruited at high loads or intensities.
By restricting blood flow and reducing oxygen delivery to the muscle, BFR forces early recruitment of Type 2 fibres even at low loads. The metabolic by-products that accumulate — particularly lactate — act as cellular signals that stimulate muscle protein synthesis and growth hormone release.
Research has shown that BFR training can increase growth hormone secretion by up to 170% compared to traditional exercise — without the inflammatory effects of heavy loading. This has protective effects on tendons and muscle collagen, which is particularly relevant in the rehabilitation setting.
Where BFR Is Most Useful in Rehab
BFR is not a replacement for traditional strength training in most circumstances. But it fills a genuinely important gap for people who cannot train at the loads required for conventional hypertrophy and strength gains.
- Post-surgical rehabilitation
After ACL reconstruction, joint replacement or other orthopaedic procedures, the affected limb is typically restricted in how much load it can handle. Muscle atrophy begins almost immediately after surgery and is one of the primary barriers to full recovery. BFR allows meaningful muscle stimulus at the low loads that post-surgical protocols permit, reducing the extent of atrophy and speeding up the return to higher load training.
- Injury and reduced weight bearing
For someone managing a stress fracture, tendon injury or other condition requiring load reduction, BFR allows continued muscle training during the relative rest period. Maintaining muscle mass and strength during forced rest significantly improves outcomes when full training resumes.
Heavy loading is a key component of tendinopathy rehabilitation — but in the acute or irritable phase, the tendon may not tolerate the loads required. BFR can provide a meaningful training stimulus at loads the tendon can handle, maintaining muscle capacity while the tendon settles.
For athletes in structured periodisation programs, deload periods are important for recovery but can involve significant reductions in training load. BFR can help maintain muscle stimulus during deload phases without the systemic fatigue of heavy training.
- Older adults and clinical populations
For people who cannot safely perform high load exercise due to cardiovascular conditions, joint pathology or general deconditioning, BFR offers a lower-load pathway to meaningful strength gains that would otherwise be inaccessible.
What a BFR Session Looks Like
A typical BFR session involves applying a cuff to the upper arm or thigh at an appropriate occlusion pressure — which should be individually determined rather than guessed. Too little restriction produces minimal effect. Too much can be unsafe.
Exercise is then performed at low load — typically 20 to 30% of one rep max — for higher repetition sets (commonly 30 repetitions, then three sets of 15 repetitions) with short rest periods of 30 to 60 seconds between sets. The short rest is important — it maintains the metabolic accumulation that drives the adaptation.
The session typically feels more challenging than the load would suggest — the metabolic accumulation creates a significant burning sensation in the working muscle. This is normal and expected.
Who Should Not Use BFR
As with any training modality, BFR is not appropriate for everyone. Contraindications include:
- Known circulatory issues or clot risk including DVT history
- Heart disease or cardiac insufficiency
- Severe uncontrolled hypertension
- Diabetes with vascular complications
- Sickle cell anaemia
- Varicose veins
- Pregnancy
- Open wounds, incisions or active infection in the affected limb
- Active cancer
- Lymphoedema
- Under 12 years of age
If you have any of these conditions or are unsure, discuss with your physiotherapist or GP before attempting BFR training.
Getting Started
The occlusion pressure, load, repetition scheme and exercise selection for BFR should be individually prescribed rather than self-directed — particularly in a rehabilitation context. Getting the pressure wrong can reduce effectiveness or, at the extremes, create safety issues.
At Active Balance, our physiotherapists can assess whether BFR is appropriate for your situation, prescribe the right parameters and supervise your initial sessions to ensure you're getting the most out of it safely.
Book online or call us on (08) 7123 4148 to find out whether BFR training could be useful for you.
