You can stretch your IT Band - you just can't lengthen it.
Confused? My apologies. Ten years ago I wrote a blog post (here) saying that foam rolling can’t stretch (i.e permanently deform or lengthen) your ITB. I stand by it. Its not some dough that you can kneed into some new shape and you sure aren’t “breaking up adhesions.
BUT, you can transiently “stretch” your ITB. This means that when you put tension through your ITB part of it will undergo strain. This means it lengthens will force is applied to it. The same thing happens to a tendon when you contract a muscle or move towards end ROM. Tensile force (tension) is applied to the tendon and it undergoes strain of about 6% for 85-90% max effort. And it seems like you need about 4.5% strain to catalyze increases in stiffness (see Bohm S on pubmed).
This also happens when you stretch a ligament. It will lengthen and undergo strain when you are applying force to it - you could call this a stretch. The ITB will do the same if you move your pelvis and femur into different positions - see here. Dr Carolyn Eng has argued that the role of the ITB is to store and release elastic energy when we run. This means that the ITB will stretch (i.e undergo strain) when the hip goes into adduction (a classic ITB stretch) and then release that stored “stretch energy”. And other researchers have modelled strain in the ITB and even suggested the rate of that strain is a risk factor for running injury. To be fair, that study just assumed that the ITB experienced strain based on the kinematics of running - they could have just been modelling the kinematics and calling it “strain”. Sorry, tangent - another blog sometime.
When I wrote that first blog post 10 years ago we did not have this information. The studies at the time suggested that the ITB did not undergo any significant strain (Falvey 2010 here) when you try to stretch. However, more recent work (e.g Dr Eng’s study) and Wilhem’s work suggest that the ITB is just like other connective tissue in that it can undergo strain (i.e a stretch).
Can you lengthen the tissue?
I don’t think so. But, I actually don’t think that any connective tissue can be lengthened or have its stiffness decreased outside of immobilization or injury. So, the ITB can undergo strain just like a tendon or ligament and this will lead to transient decreases in stiffness due to viscoelastic effects (and other stuff) but this does not lead to an actual decrease in the stiffness of the connective tissue in the long term (i.e permanent deformation or elongation). This actually a good thing. It means that we probably can’t create structural laxity in a joint through repeated end ROM loading. You can increase your mobility but you probably aren’t “loosening” up connective tissue.
How can I say that?
Good question. I’ve said it for years based on the research of both Kubo (here) and Blazevich (here). Have a read of this old blog post as well. Remember, applying tensile force to a tendon with strength training tends to make the tendon stiffer. So, why would applying tension to a tendon via a stretch cause the exact opposite effect (e.g decreased stiffness)? The quality of the input (tension) for mechanotransduction is the same. Just because there is a short term decrease in stiffness doesn’t mean that this is what mechnotransduction will create. It’s like strength training - in the short term it makes you fatigued and weaker but in the long term it makes you stronger. We shouldn’t judge an intervention that relies on mechanotransduction but its short term effects.
As far as I know, there is not a single study that shows that stretching will lead to decreases in tendon or connective tissue stiffness in the long term. Thus, we can hypothesize that stretching would not lead to a decrease in stiffness of a relative in the connective tissue world - the ITB. Specific support for that is seen in this recent study by Friede - where stretching did not lead to a decrease in stiffness but actually lead to an increase in stiffness of the ITB (but TBH, I’m not very familiar with the measurement technique so its hard for me to compare across studies).
Summary
Applying a stretching a maneuver to ITB (e.g hip adduction) can lead to strain in the ITB. This is technically a stretch. But this will not lead to permanent lengthening or long term reductions in stiffness of the ITB just like other connective tissue.