Back in 2006, Australian researcher Belinda Gabbe reported that in Australian footballers, "For each 1 degree increase on the Modified Thomas Test (i.e. decreasing hip flexor flexibility), the risk of hamstring injury increased 15%." (Gabbe et al., 2006). Of course, getting the technique correct, as we teach it at the SFMA level 1 course, is so important (Vigotsky et al., 2016). Consider also that if the MTT reveals a mobility dysfunction (MD) at the hip then it can effect the output of the hip extensors (Mills et al., 2015) ..... starting to ring important now with that hamstring pain or strain?
The MTT reveals something about the way the body is behaving, from lower abdomen, trunk, pelvis and lower quarter. But it doesn't tell us what is driving that behaviour. Let's keep the MTT finding to one side for one moment.
Now remember if you're performing the MTT it's because there was a dysfunction or pain in the Multi-segmental extension (MSE) top tier and you're breaking out that pattern, so you'll include the FABER(E) in your breakout. Have you ever noticed that a patients FABER(E) is usually lower, (less positive), when the foot is NOT on the knee, or it is lower than the knee? Why is that? it's the relationship of the knee flexion to the test result - the more knee flexion, the more restricted is the hip in the FABER(E). So, consider that the anterior lower limb soft tissue plays a role in tightening at the knee and the hip - as you flex the knee, the anterior lower limb tissue tightens. Now consider the anatomy of the rectus femoris - it has an insertion at the anterior inferior iliac spine (AIIS) and on the acetabulum. Let me simplify - a tight quad pulls the ilium forward and compresses the hip.
Now, who's to say that when an athlete performs a toe touch, a multi-segmental flexion (MSF) that the hip is compressed? After all, the knee isn't flexed, right? So the quad (you know I mean the whole anterior lower limb tissue) isn't on stretch so it shouldn't pull the hip into compression, right? Well, in my experience a compressed hip stays compressed unless it is de-compressed, so a MSF that reproduces hamstring pain can change when we do something to the same side quad, and especially when we find a positive MTT or FABER(E).
When you decide to trust the breakout findings of an MD in the FABER(E) and MTT that you found in a patient with hamstring pain and who had a dysfunctional top tier MSE, then it won't take you long in that treatment session to reveal whether the quad is a cause, contributor or complicating factor for that patients hamstring pain. And when it is, you'll have accelerated their recovery by removing a hand brake on their movement on, according to Mills et al (2015), their hip extension strength.
Now think of this - an athlete does a toe touch, or a kick, or is in swing phase of sprinting and they approach a range of hip flexion, with a compressed hip due to anterior lower limb tissue tension, that creates a reflex loop such that the nervous system doesn't want to flex any further - if I humanise the nervous system a moment - it asks, "is there anyone down there who can pull us out of hip flexion while we're trying to do hip flexion so we don't compress the hip?" The hamstring has a shot at it and gets strained or tired and fatigued and tightens up.
It doesn't matter that you believe me or not - it matters that when you find what I describe above, which happens a lot, and then you treat the quad, that you'll find the straight leg raise, seated toe touch and standing toe touch get better, not to mention the MTT and FABER(E) and if you did so, a hip extension strength test.
It doesn't even have to be THE SAME SIDE QUAD - just ask footballer Lachlan Wallace, @theexcellencecoach, of Virtus Performance whose hamstring was bothering him but who, when receiving treatment for an opposite side corked quad completely changed his hamstring pain.
If you want to go a little further away in regional interdependence and hamstrings, I wrote previously how the ankle can affect the opposite side hamstring - check the opposite ankle when it shows up in your top tier patterns and breakouts when someone has a hamstring pain - if you're just treating the hamstring, you're still doing rookie things.
Gabbe, B. J., Bennell, K. L., & Finch, C. F. (2006). Why are older Australian football players at greater risk of hamstring injury? J Sci Med Sport, 9(4), 327-333. https://doi.org/10.1016/j.jsams.2006.01.004
Vigotsky, A. D., Lehman, G. J., Beardsley, C., Contreras, B., Chung, B., & Feser, E. H. (2016). The modified Thomas test is not a valid measure of hip extension unless pelvic tilt is controlled. PeerJ, 4, e2325. https://doi.org/10.7717/peerj.2325
Mills, M., Frank, B., Goto, S., Blackburn, T., Cates, S., Clark, M., . . . Padua, D. (2015). EFFECT OF RESTRICTED HIP FLEXOR MUSCLE LENGTH ON HIP EXTENSOR MUSCLE ACTIVITY AND LOWER EXTREMITY BIOMECHANICS IN COLLEGE-AGED FEMALE SOCCER PLAYERS. Int J Sports Phys Ther, 10(7), 946-954.