BFR Cuff Design FeaturesMay 21, 2023
The purpose of a BFR cuff is to restrict blood flow into the limb by applying uniform pressure around the extremity during exercise.
But contrary to tourniquet cuffs designed for surgery with the patient being immobilized, non-autoregulated BFR Cuffs need to have some flexibility/pliability to allow the muscles to expand underneath the cuff during training.
Though, if the cuff is too flexible it can be impossible to determine Limb Occlusion Pressure (LOP). So, it seems reasonable to argue, just as the discussion i.e., pros and cons concerning narrow VS wider cuffs, the degree of flexibility also comes with trade-offs.
If the cuff is rigid, it will be easy to detect LOP and often at a lower absolute pressure. On the other hand, unpliable cuffs will for most people, especially muscular individuals, feel more uncomfortable because of higher pressure gradients from relaxation to contraction. – More on specific tourniquet design considerations for muscular individuals later.
In order for the cuffs to be able to determine LOP, they will need some decent width as well as some sort of rigidness. But if the cuff is too stiff it will not be feasible to be used for BFR Training, as the set pressure will vary compared to actual interface pressure. Simply because the muscles will be squeezed during contractions which are both uncomfortable and can lead to excessive muscle damage, thus rarely, even muscle contusion-type injuries.
The shape of the cuff is also of importance as the evidence shows, the majority of people, though definitely not all, contoured/cone-shaped cuffs have a lower LOP compared with straight cuffs of similar width. Intuitively this seems common sense as most people have tapered thighs, at least in a relaxed state.
Though it might be true for most individuals looking at simple anthropometrics such as the circumference of the upper thigh vs mid-thigh but not present during contractions. This is pertinent to the arms’ biceps brachii, as you visualize the peak muscle belly..
But the change of limb shape from pre to intra-training also applies to the thighs. Thus, a thigh can appear to be tapered, this might not be the case during muscle contractions of the quadriceps or the hamstrings.
This relative change in limb shape seems to be related to the relative amount of muscle mass. Further explained, a muscular individual will have a much larger difference in limb shape from relaxation to contraction. Just think of a bodybuilder’s pose of a biceps or quadriceps VS your average Joe posing..💪🏼
All of the nerdy details are relevant when you’re considering what might be the right type of cuffs for you.
Fit Cuffs offers both straight/cylindrical cuffs (the V2s, are blue in the video) and adjustable contoured/conical cuffs (the V3s are black in the video).
The V3.1 probably fits a broader spectrum of people. So, if you’re applying BFR to various clients this might be the best match for you.
Contrary to many beliefs, muscular or long-limbed individuals can benefit from a straight-designed cuff. Inherently a cylindrical cuff has identical circumferences of the top and bottom, this allows the muscle to expand relatively more beneath the bottom part of the cuff where most people have their muscle belly peak.
Alex’s recent experience with the V2.1 cuffs is that they feel better, probably because of his relatively low body fat and continuously hypertrophic response to BFR Training.
FYI, his LOP of 179 mmHg vs 176 mmHg for V2.1 and V3.1, respectively, is almost identical even though the V2.1 bladder is about 2 cm narrower VS V3.1.
Disclaimer: Most of the arguments in this post have not been rigorously tested. That is because most research has been on the passive features of tourniquet cuffs. So, please let us know in the comments about your experience with different cuff designs.
Shout out to all of the BFR researchers out there, it’s about time more research is conducted on BFR cuffs design features! 👏
Rolnick et al. (2022) Beneath the Cuff- Often Overlooked and Under-Reported Blood Flow Restriction Device Characteristics and their Potential Impact on Practice