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BFR for triathletes: it’s time to recover smarter

Triathletes train hard to build strong bodies that perform consistently across the three elements of their sport. BFR offers these competitors an effective training tool, but perhaps more importantly, an extremely beneficial recovery tool. Dr Emily Jevons, Triathlete and Exercise Physiologist, explains why triathletes need to incorporate BFR and how it can work for them.

Dr Emily Jevons swim training for a triathlon

Triathlon training can be intense, time-consuming and highly physically demanding. We swim, cycle and run, often multiple times a week at a variety of intensities with the training load varying drastically depending on which distance triathlon you are training for. As triathletes we ask a lot of our bodies, pushing ourselves to perform day after day, hunting down those marginal gains. Whether it be pushing for a faster pace in the pool, trying to increase your FTP on the bike, or taking valuable seconds off your run time. Training can be rigorous and repetitive, so to optimise our body’s ability to perform well, we also need to consider how we can recover optimally to maintain and excel our performance.


No training plan is complete without a good recovery plan, but as triathletes, we’re known for sometimes neglecting true rest and recovery. It can be very easy to fall into the mindset that if you’re not training, you’re not improving, and ignoring signals that our bodies might need a bit of R&R. Rest and recovery doesn’t always have to mean doing nothing, you can use both active and passive modalities to improve your recovery. For example, an active recovery session may involve a short low intensity swim/bike or run, whilst passive recovery could simply involve ‘putting your feet up’. Taking a proactive approach to recovering from training can help with injury and burnout prevention, whilst also helping you reach your physical potential.


One powerful recovery aid is known as Blood Flow Restriction (BFR), but what is BFR? BFR is a technique used to artificially stress the muscles while performing low intensity exercise, or when recovering, to increase performance adaptations1-4 and accelerate recovery.5-7 It involves the application of a strong circumferential pressure at the very top of your arms or legs, while either performing exercise at a low intensity, or sitting back and recovering passively. When BFR is applied, it partially restricts the return blood flow to the body, causing the muscles to swell and become stressed. This may not sound that pleasant but stay with me to hear the benefits.


So how does BFR work?

The benefits of BFR start by the creation of a hypoxic environment, simply meaning there is a lack of oxygen in the muscle. This occurs since the restricted blood becomes deoxygenated as the oxygen is used up for energy, leading to blood pooling and swelling in the muscle cells. This stressful environment in the muscle is the precursor for all BFR protocols (Strength, Endurance and Recovery BFR), artificially stressing the muscles prior to performing your chosen protocol to enhance the desired outcome.

Dr Emily Jevons competing in triathlon (running)

Strength BFR

By adding BFR to your strength training, you can significantly lower the loads used (just 20-30% of your 1 rep max) and achieve similar strength adaptations to heavy load training, without loading the joints.1 When training with light weights, the body will recruit predominantly slow twitch fibres to complete the exercise. Since our slow-twitch muscle fibres rely on oxygen for energy production, they fatigue very quickly under the hypoxic environment created by BFR. The body is forced to recruit fast-twitch muscle fibres to help perform the exercise (usually recruited for power and speed),2 causing all muscle fibres to undergo a training stimulus at the same time. This is a unique feature of BFR Training, forcing the body into adaptations that would only normally occur by working harder at greater intensities. At the same time, lactic acid and other stressful metabolites build up in the muscles causing stress. The body responds to this stress by releasing hormones that increase muscle protein synthesis (MPS), leading to strength adaptations.2 Once the BFR is removed, the hormone rich blood flushes around the entire body providing a systemic training effect.


Endurance BFR

By adding BFR to your endurance work, you can create muscular adaptations that are usually only associated with longer more intense endurance sessions. By training aerobically with BFR applied, low oxygen availability (due to BFR) limits the muscles ability to receive and produce energy. The body responds with incredible adaptations – it extends its capillary networks (blood vessels) within the working muscles, increasing the surface area of vessels that deliver oxygen and glucose to the muscle cells3. This process is called capillarisation and will ultimately lead to increases in how effectively you can get your blood to your muscles when you’re exercising, thus improving performance.4

Secondly, there is an increase in the number of mitochondria in the muscle cells (the battery of our muscle),1 improving the muscles ability to create energy from the improved capillary network. Together, this makes the muscle much more efficient at producing and using energy, improving endurance and fitness capacity.


Recovery BFR

Recovery BFR is an underutilised yet extremely impactful recovery method. By locking deoxygenated blood in the muscles, the body will upregulate recovery hormones (MPS, growth hormone, IGF-1) that support muscle growth and recovery.5-7 In the case of Recovery BFR however, this can happen independently of strenuous exercise or passively, harnessing the hormonal pathways of the body to create internal environments conducive for recovery.5 A second way to enhance recovery with BFR, is by performing BFR training at very low intensities, providing you with two recovery BFR options; 1, Passive Recovery BFR,5 or 2, Active Recovery BFR.6,7 Both are effective and boil down to the user’s preference. The real power of recovery BFR however comes from a second very important second step, present within both Recovery BFR protocols.


By releasing the pressure applied by BFR, you cause a powerful flush of blood flow across the muscles and joints. This helps remove waste materials and inflammation whilst driving fresh blood and nutrients into the muscle and structural tissues such as tendons and ligaments.5-7 This is known as reperfusion and is an integral part of the benefits of BFR for recovery. This powerful flush also drives blood around the rest of the body, bathing muscles and structures in recovery hormones. For biggest impact, Recovery BFR requires three flushing events, usually split in to 3 x 5 minute rounds of BFR interspersed with 2 minutes rest between each round. This protocol can be performed passively, or actively with low intensity exercise.


What are the benefits of BFR for triathlon?

Although there are impressive training adaptations associated with BFR, for the purpose of this blog we are going to focus on the use of BFR for recovery. The physiological process’ mentioned above that can trigger muscle growth, also trigger muscle repair. Fundamentally BFR will enhance the body’s production of natural recovery hormones. But why is this important for triathlon training?


Well, faster recovery means we can keep swimming, cycling and running to the best of our ability, more regularly, and hopefully feeling less fatigue. The research on BFR demonstrates significantly accelerated recovery from exercise by enhancing the restoration of neurological and muscular function, whilst reducing post-exercise muscle soreness due to the removal of damaging waste materials.5-7

Dr Emily Jevons bike training for triathlon

What kind of sessions?

The primary aim of Recovery BFR is to achieve three flushing events in the muscle, whether than be a passive protocol (at rest), or active protocol (performing very light exercise). For example, if on the turbo, you can incorporate BFR into your recovery spin simply by strapping in and performing 3 x 5 minutes rounds of light exercise, with 2 minutes rest (unstrapped) between rounds. Similarly, if at the gym using a treadmill /rower /bike, you can also incorporate this protocol. Using this protocol during low intensity exercise will cause the exercise to feel more difficult as you are effectively putting your muscles under additional stress by increasing muscle fibre recruitment. Though you are doing so without the additional impact on the joints and without having to actually load the muscles as hard i.e. pushing lower watts on the bike but still getting the benefits of pushing higher watts, or walking on a treadmill instead of running but providing the same muscular stress without the additional impact of running on the joints.


You can also use BFR passively using the same 3 x 5 minutes, but this time as rest.  For example, pottering about the house doing day to day tasks or even putting your feet up watching TV. This is known as passive Recovery BFR. Athletes who use this form of BFR can still expect a significant boost to their recovery, without any time or energy burden since it slots seamlessly into daily activity. It can be done anytime, anywhere. Using the strap of the Hytro BFR wearables for even one round of a few minutes is enough time for the body to upregulate recovery hormones, remove waste products, reduce inflammation, and increase the uptake of nutrient-rich blood, though three rounds is recommended.


For maximum impact, passive BFR should occur immediately after exercise, if you’re someone who likes to sit down post-ride on the sofa, this is the protocol for you. However, if this isn’t possible, strapping in within 24 hours of exercise will still elicit an accelerated recovery response.


What should I expect?

As you can probably imagine, BFR is not the most comfortable, but it is precisely due to this intensified environment that BFR is so effective. As your muscles swell with blood, you should expect to feel skin tightness and slight sensations of tingling or numbness as the muscle oxygen levels drop, while your skin will become discoloured. This is completely normal and proven to be safe over thousands of research papers. As with any training, the more consistently you do something, the more normal the sensations become. It’s also important to note, for your muscles to repair effectively, regardless of BFR or no-BFR, protein and adequate nutrition is vital to ensuring your maximising your recovery and muscle repair.


In summary, Recovery BFR works by creating a hypoxic environment in the restricted muscles, causing them to swell with blood and become artificially stressed, forcing the body to adapt. BFR also increases the natural production of recovery hormones that enhance muscle growth and repair, impacting the whole body systemically. In addition to this, when unstrapped from BFR, waste products and inflammation are flushed from the joints and muscles, while fresh blood is driven into the tissues. Finally, BFR can be incorporated into recovery sessions in two ways; 1, Active Recovery BFR involves light cardiovascular exercise, on the turbo, treadmill or bike, using 3 x 5 minute intervals with 2 minutes rest unstrapped, or 2, Passive Recovery BFR following the same 3 x 5 minute protocol independently of exercise, while sitting back and relaxing.


Learn more about Blood Flow Restriction Training by reading the ‘What is BFR Training’ journal.

Read the journal

Photo credit: Two26 Photography



Hypoxic – A deficiency in the amount of oxygen reaching the tissues, in this case by using circumfixal pressure around the top of the limb using Hytro BFR wearables.

Slow twitch muscle fibres – Also known as type I muscle fibres, they contract slowly and are especially important for endurance exercise. They can sustain force for an extended period of time, but they are not able to generate a significant amount of force.

Fast twitch muscle fibres – Also known as type II muscle fibres, they provide bigger, more powerful force but they fatigue quickly so only last for a short duration.

Capillarisation – The process of new capillaries (small blood vessels) being formed which increases overall blood vessel surface area and can enhance oxygen delivery to the muscle.

Mitochondria – found in most cells, this is where energy production occurs, aka your muscles battery.

Re-perfusion – When blood flow is restored to the muscle.



  1. Groennebaek, T., Jespersen, N. R., Jakobsgaard, J. E., Sieljacks, P., Wang, J., Rindom, E., & Vissing, K. (2018). Skeletal muscle mitochondrial protein synthesis and respiration increase with low-load blood flow restricted as well as high-load resistance training.Frontiers in physiology9, 1796.
  2. Pearson SJ, Hussain SR. A review on the mechanisms of blood‐flow restriction resistance training‐induced muscle hypertrophy. Sports Med (Auckland, NZ). 2015;45(2):187–200.
  3. Ferguson, R. A., Hunt, J. E., Lewis, M. P., Martin, N. R., Player, D. J., Stangier, C., & Turner, M. C. (2018). The acute angiogenic signalling response to low-load resistance exercise with blood flow restriction.European journal of sport science18(3), 397-406.
  4. Christiansen, D., Eibye, K. H., Rasmussen, V., Voldbye, H. M., Thomassen, M., Nyberg, M., & Bangsbo, J. (2019). Cycling with blood flow restriction improves performance and muscle K+ regulation and alters the effect of anti‐oxidant infusion in humans.The Journal of physiology597(9), 2421-2444.
  5. Beaven, C. M., Cook, C. J., Kilduff, L., Drawer, S., & Gill, N. (2012). Intermittent lower-limb occlusion enhances recovery after strenuous exercise.Applied Physiology, Nutrition, and Metabolism37(6), 1132-1139.
  6. Fekri-Kurabbaslou, V., Shams, S., & Amani-Shalamzari, S. (2022). Effect of different recovery modes during resistance training with blood flow restriction on hormonal levels and performance in young men: a randomized controlled trial.BMC Sports Science, Medicine and Rehabilitation14(1), 1-10.
  7. Arriel, R. A., Rodrigues, J. F., Souza, H. L. R. D., Meireles, A., Leitão, L. F. M., Crisafulli, A., & Marocolo, M. (2020). Ischemia–Reperfusion Intervention: From Enhancements in Exercise Performance to Accelerated Performance Recovery—A Systematic Review and Meta-Analysis.International journal of environmental research and public health17(21), 8161.


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