Blood Flow Restricted Training

Introduction to Blood Flow Restriction (BFR) Training

Blood flow restriction training is a method that involves restricting venous return from muscles during submaximal exercise, which leads to the stimulation of muscle, tendon, and vascular growth both locally and systemically. The technique enhances training effects and stimulates recovery, allowing athletes to attain increased results with reduced effort. The use of blood flow restriction gained popularity in recent years, particularly highlighted during the Tokyo Olympics, with elite athletes adopting this practice to improve their competitive edge.


  • Therapy: looking at BFRT from a rehabilitation POV

Why submaximal exercise?

- Lower load = greater volume

-Greater volume = greater muscle fatigue

-Greater fatigue = greater accumulation of metabolic byproducts (lactate, H+…)

-Accumulated metabolic byproducts + hypoxic environment = hypertrophic environment

  • During BFRT, a hypoxic environment in the muscle is created which stimulates muscle fibres to adapt similarly to high load training.

So, specifically looking at rehabilitation and physical therapy settings:

  • Patient/athlete/individual cannot perform exercise at such as intensity needed to stimulate adaptation due to whatever cause (injury/disease/weakness…)

  • We can stimulate high intensity training through the use of blood flow restriction

  • So not only do we get amplified results from the tissue swelling and accumulation of metabolic byproducts (more so than we would with regular training), the effort of performing exercises are also lower and it is a more safe method of training

Historical Context and Development

The concept of blood flow restriction training was popularized by a Japanese former power lifter named Yoshiaki Sato in 1966. At 73 years old, Sato has dedicated much of his life to developing and promoting this technique, which he refers to as Kaatsu. Sato emphasizes the importance of the technique, stating, “It was always just a matter of time,” acknowledging the delayed recognition blood flow restriction received until the present.

Mechanisms of Blood Flow Restriction Training - pressure and cuff

Limb Occlusion Pressure (LOP)

The effectiveness of blood flow restriction training relies on applying a pressure that occludes/blocks arterial blood flow without restricting it completely.

Limb Occlusion Pressure refers to the minimum pressure required to completely block arterial blood flow. Protocols typically recommend using 40% to 80% of the individual’s LOP. Individual variations dictate that protocols should not have a fixed pressure to account for limb size, tissue density, and blood pressure differences.

Why not a fixed pressure?

-Individual variability in limb size, tissue density, and BP

-Risk of over occlusion, nerve compression, or thrombosis

Cuff Widths:

  • Narrow cuffs (≤ 5 cm) require higher pressures for occlusion.

  • Wide cuffs (13 to 18 cm) cause occlusion at lower pressures but may lead to discomfort.

Common equipment includes pneumatic cuffs, elastic bands, and electronic devices like the Vasper System and Kaatsu Cycle.


Program specifics: pressure and tourniquet placement and width:

  1. Pressure: based on limb occlusion pressure (LOP): minimum pressure required to completely occlude arterial blood flow, protocols use 40 to 80% of person’s LOP

  1. Pressure ranges by limb:

  • Upper arm (lower pressure because arteries are smaller)

Typical LOP range (mmHg): 150 to 200mmHg

Recommended BFR pressure (% of LOP): 40 to 80%

Approximate working pressure (mmHg): 60 to 160mmHg

  • Thigh (lower limbs higher pressure due to larger circumferences and greater arterial pressure)

Typical LOP range (mmHg): 180 to 250mmHg

Recommended BFR Pressure (% of LOP): 40 to 80%

Approximate Working Pressure (mmHg): 72 to 200mmHg


Physiological Reactions

BFR induces physiological mechanisms both locally and systemically.

Local Mechanisms

  1. Muscles contract at a set load (20-50% of their one-repetition maximum, or 1RM).

  2. Intracellular phosphates and oxygen (O2) are utilized at a rate faster than the circulatory system can replenish it.

  3. Accumulation of metabolic waste products occurs, leading to loss of homeostasis within the active muscle due to a hypoxic environment.

  4. To compensate for this, anaerobic glycolysis increases to augment ATP production.

  5. An observable increase in intracellular and interstitial lactic acid (and H+) occurs, which prompts muscle adaptation and growth.

Systemic Mechanisms

  • A disturbance in muscle homeostasis and vascular congestion produces pain and activates group III and IV afferents, resulting in an increase in sympathetic nervous system output.

  • This response leads to heightened heart rate, respiratory rate, and blood pressure.

  • The consequent increase in growth hormone (GH) release promotes skeletal muscle repair and growth.

Applications of Blood Flow Restriction Training

Rehabilitation Potential

Blood flow restriction training shows promise in a variety of rehabilitation contexts:

  • Improved Strength and Aerobic Capacity: It demonstrates improvements in strength, aerobic endurance, hormonal responses, and overall cardiovascular function.

  • Target Population:

    • In-season and off-season athletes

    • Active adults aged 18 to 80, 2-5 days per week

    • Inactive/deconditioned adults, astronauts, and individuals recovering from ACL and Achilles reconstructions or surgeries.

Specific Training Protocols
Strength Training

  • Training Intensity: Utilize low load resistance training (20-50% of 1RM or 30% peak power).

  • Sets: 3-5 sets with 30-90 seconds passive rest between sets.

  • Cuff Size and Pressure:

    • Wide cuffs: 90-120 mmHg

    • Narrow cuffs: 160-180 mmHg

  • Gains Expected:

    • Acute increases in strength (7-16%).

    • Increases in limb circumference and cross-sectional area (CSA).

    • Enhanced recruitment of Type II muscle fibers and motor units.

    • Cross-over effects to other limbs.

Aerobic Conditioning

  • Training Intensity: Target low intensity or interval training (20-40% VO2 Max), with higher controls (75% VO2 Max) for aerobic work without BFR.

  • Walking Protocol: Engage in 20-40 minutes of walking, 5-6 days a week over 3-4 weeks.

  • Cycling/Rowing: Implement progressive sets over 3-4 weeks.

  • Cuff Pressures:

    • Transition from wide cuffs at 120 mmHg to narrow cuffs at 200 mmHg.

  • Gains Expected:

    • Increased metabolic cost and heart rate during activities, improved VO2 Max, and enhanced muscle strength.

Hormonal Responses

Blood flow restriction facilitates significant hormonal responses, as studies indicate various responses across different ages and exercise intensities. It elicits increases in:

  • Growth Hormone (GH)

  • Cortisol (Cort)

  • Insulin-like Growth Factor 1 (IGF-1)

  • Testosterone (T)

Side Effects and Considerations

While blood flow restriction training offers numerous benefits, it may also present side effects, such as:

  • Pain (from tightened tourniquet)

  • Numbness

  • Nerve damage

  • Bruising and subcutaneous hemorrhage

  • Syncope (fainting)

  • Rhabdomylosis (muscle damage due to exertion)

Conclusion

Blood flow restriction training is an innovative approach that maximizes training efficiency while minimizing stress on joints and tissues. With its application across various populations—from elite athletes to rehabilitation environments—BFR has opened new avenues for enhancing strength, endurance, and overall physical performance.