Measuring Thoracic Rotation

When screening for t-spine mobility what are the main differences in screening it seated with dowel behind back in crook of elbows vs. quadruped/sit back on heels one forearm on the ground/one hand either behind back or behind head?So we'll take the question first in a slightly different direction.  The reason for this is that the types of thoracic motion measures that the reader is questioning about do not appear to be as championed in traditional physical therapy as the inclinometer measures that we see below.I've made it clear before that I most use my occulometer, and with the tests mentioned above, we can still be objective in simply seeing ranges when in a situation where they have to be reported.When I see the inclinometer stuff, I honestly just don't get it.This study shows intra-rater reliability, which is all fine and probably what someone would predict.  But how this culls out thoracic-only motion much controls for hinging or motor strategy inefficiencies yielded by such things as stiff rib motion.The videos below show the strategies, and show the differences in terms of biomechanical perspective vs. the choices above using a neurodevelopmental perspective https://www.youtube.com/watch?v=T1_NDHeZnu4https://www.youtube.com/watch?v=t9JalxTSPtAFrom a literature review standpoint, positions marked with differences in loading, we have this abstract as well as this review on the alternate strategies.To answer the questions above more directly, here are my opinions further towards measuring in sitting or quadruped.Seated vs. QuadrupedI think the biggest difference between sitting and quadruped is the level of compression through the spine.  With this compression can come a wildly different motor strategy as the forces to buffer are quite different.  If there is an efficiency of buffering loads in one pattern, it stands to reason that we will see a more appropriate appraisal of thoracic motion.Through the classical charts we know from Nachemson, he actually did not study quadruped, so perhaps my above assumptions are not even correct.However, while I don't know the numbers, and I'm not terribly inclined to look them up, Dr. McGill chose affinity for his Big 3, the curl-up, side plank, and birdog because of the lower stressors to buffer along with increased outer core activation EMG readings.  In his mind, this is a matter of efficiency.  So we can use this efficiency in his model to support low compression in quadruped.This is actually quite sensible because the spine is not as combated by gravity in all 3 planes, and base of support and reflexive force closure appear more often with the 4/6 fixed points in quadruped.So, with the increased compression in sitting, how the individual strategizes to stabilize the compressed system, the muscular pattern may stiffen the t-spine, or it may allow for smooth motion.I don't think this is much of a reach.It is difficult to apply passive rotation in the seated position.  You can certainly do it in quadruped, and this becomes an effective mobilization strategy and also lends to Progressive and Regressive Angular Isometrics, other PNF, or DNS strategies.Both positions can minimize lumbar and hip contribution, but is clearly impossible to "lock out" any of these joints.  Keeping legs as close to together, crushing a pad, towel, yoga block can further show what the t-spine can do, but it also measures the ability to stabilize below through the lumbar spine and hips to a lesser degree.  It's may be a nitpicky dilemma, but it may make what you're looking for a cloudy, which is simply can the t-spine be coached for skills or fitness, or does it need joint mobility to efficiently get to to skills or fitness.Arm PositionIn the seated position, you can have the dowel..........,...behind your elbows with arms at your side, which may be the most authentic with the exception of those that are already very anteriorly glided....in a cross-arm front squat position, but the pitfall here is someone very protracted.  We might need more than 45 degrees....in high bar, back squat position, arms starting 90/90, which can show you the difference between JMD and TED of the gleno-humeral joint if there is a big difference between FSq and BSq positions.In quadruped, you can have the arm in internal rotation, which actually doubles as a gleno-humeral SMCD deeper screen.  Sometimes this will elicit pain that did not show up in the Screen, and this is good, as you learn more.  Other times with someone so stiff, you just can't see any motion, but the t-spine can still go.  In that case, switching the arm anteriorly across the body, hand covering the stabilizing side shoulder, arm ADDucted to the body.When you have the arm in external rotation, there is a demand of scapular control, and this is often when we will see a major loss of motion with arm ER vs. IR.  This tells us the rotation exists at the t-spine, but we should investigate lats and pecs as well as the shoulder capsule.  If all is clear, a scapular motor strategy can explain clear thoracic motion in isolate when test in a less mature position, but it is not present in the sitting, standing, more mature vertical positions.