"In soccer, the game is with the ball. So, the whole time spent playing is a regression from your movement patterns. So you’re never going to reach the hips in the mechanics of absolute speed and acceleration because the ball is taking you to a pattern that is not functional. So we see the difficulties present in the switch, such as in Roger Federer when he switches his grip from forehand to backhand, he doesn’t even know, but the soccer players, they have a hard time because they are with the ball the whole time so we need to teach that, and that is movement skills. And we need to go backwards to teach them what it means to have the hip at 85 or 90 degrees, and for the ankle to be in a particular position to perform the pattern, so for that we need to know how the parts are moving themselves and how they integrate into the brain so they can change when they need to, when they change from passing the ball to running to space, and that is switching the mechanics. And some players don’t know that they don’t have that capability. (15:15). So when they are starting to learn that, they develop it in the mind, and mindset, to change that, and they don’t know they are doing it, then that is when the magic happens. And that will be the ultimate challenge, so they can switch from passing the ball to running really fast in a good manner of movement mechanics to fill an empty space and recover the ball. And it is something you can sometimes see in English Premier League but harder to see in youth mechanics in soccer. 
 
Rodrigo asked for my opinion so I started with reflecting Rod's question to him, about "How do you get that buy-in?"

The answer is two fold: because we will never forget the skills of football because we started this game playing with the ball and we won’t lose the skills. And we probably won’t lose the technical and tactical understanding of the game. But we will often forget the core fundamentals which include movement, mindset, recovery and nutrition. So if you don’t implement a movement philosophy, you’re at a risk of losing the core fundamentals, and then be prepared to answer the question – Convince me why these core fundamentals are so important? And the answer relates to some longevity, but it also relates to the main point – that great players are built from a solid foundation of core fundamentals and they have longevity that repeat those core fundamentals across years. So the answer to the question, Why is a movement philosophy so important at a club that is very skilled at football? The answer is that you’ll always remember how to play football but you’ll probably forget core fundamentals and the great players who play in the game longest respect those core fundamentals and that’s why its important. So eventually they’re going to ask you, “what about the players who don’t respect the core fundamentals who are no longer present?” Someone like LeBron James. I’ve heard a story that he scores 9 on the FMS and you could argue he doesn’t need any corrections because he’s possibly the greatest player of all time because if you just give him the ball he’ll score 40 or 50 points. And he is someone that we would say has movement dysfunction on a movement screen, and we would also say that he is very good at functioning with his dysfunctions – he’s a functional dysfunctional. And he has been able to stay in the game for a long time functioning with that dysfunction. Or he has a 14, 15, or 16 on the FMS which is part of the reason he is able to stay so good so long. Or he’s an outlier and he is one of those people that with all the problems he has, just give him the ball and he’ll shoot from anywhere. The interesting thing about this one outlier who can defy all of the higher risk and still be present in the game is that most organisations don’t have a LeBron James and need to be supported by the depth of players and you need to bring the weaker players up to a higher level and what is important about that is that when you work in a market, like a football league, that is very competitive and your resources are stretched thin, the edge you will have when you can’t spend any more money is to keep your players on the pitch. So the movement philosophy is important because you’re saying, we can’t buy a Ronaldinho, or a Fabinho or a Virgil Van Dijk, so we have to keep our players on the pitch so they can develop their technique and tactics and the least time they spend working on problems, the more time they can spend working with the head coach, and he or she can do things that they want to do.
 
​

Have you ever noticed how the gut affects neck movement? Me neither, until the past couple of years. So I tried to figure it out with my patients. And it's simple. 

The more someone has spine movement problems beneath the neck, the more the neck has difficulty moving. Further, the way the abdominal and even thoracic viscera behave interferes with spine movement. Ipso facto (I know, good use of Latin), gut misbehaviour interferes with the neck. But how? 

Think of this. The connective tissue that wraps around your abdominal organs is strongly attached to the front of the spine around the 1st lumbar vertebra. If and when this connective tissue increases its tension, there's a tension pulling on the L1 towards the front, ie increasing lordosis and/or joint/tissue pressure. Further, the connective tissue attachment is biased towards the right side of the spine, from L1 towards the sacroiliac joint. So, an increase in connective tissue tension pulls on the lumbar spine towards the front and right. This can create rotation of the lumbar vertebral bodies. Since the thorax sits on the lumbar spine, the thorax can flex and rotate in response to the lumbar spine - either way. And since the cervical spine sits on the thorax, it too can respond with increased mid-cervical lordosis and segmental rotation. 

Imagine this - a misbehaving batch of abdominal organs pulls your spine forward and your neck reacts, interfering with how the neck moves. 

Now imagine this - what can cause the gut to misbehave? Well, even if a person doesn't have a macroscopically identified (colonoscopy) gut problem, the gut can still misbehave. And even if microscopically identified issues don't exist (blood or stool samples), the gut can still misbehave? Not sure how? Try dehydration. Try dominant apical breathing over diaphragmatic breathing. The abdomen holds about 30% of all fluid in the body, and it is pumped with each breath by the diaphragms action. If you dehydrate, and reduce the pumping output, you get reduce and/or stagnant (in some parts of the gut) behaviour. The result? A dried batch of organ sections, pulling on its attachment in the spine. 

And now imagine this - you have a stagnant section of the abdominal organs, dehydrated. Consider that the contents of the stomach and/or intestines, if stagnant, can lead to fluid flow difficulties upstream, in the tube or in the tissue fluid flow. Congestion. The large intestine is congested because of reduced diaphragm excursion. So the small intestine is backed up and congestion, affecting fluid flow in the duodenum, and the stomach, and the oesophagus tissue fluid, creating tissue tension in the oesophagus which is in the thorax and neck. And the thorax and neck don't move very well. And you improve hydration acutely, and reset diaphragmatic breathing, and do manual therapy to the viscera until an audible gurgle occurs to indicate restoration of fluid flow, and your re-assessment reveals improvement in lumbar, thorax and cervical movement. It's all connected. And health before function before performance. 

So a neck problem doesn't demand an evidence-based neck solution. A neck problem is the organism's most currently notable symptom, demanding of an evaluation of the system, an intervention that can be measurably seen to change the system, including the necks behaviour. The parts-based evidence-based demands are taking up too much attention. The alternative is an improvement in the attention to patterns-evaluation that honours regional interdependence. 

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.
 
 

I had a question recently, about manual therapy in the foot and why I often use an indirect technique. 
​
"It seems that in this case and others, even on yours and Rods online videos, that indirect techniques seem to be used for navicular? Does your experience show that it responds best to that?"

My answer: 

The key to accurate palpation of joint movement is first to identify barriers. 

Coach Larson and I collaborated to make athletes better in professional sport in China. We wanted to do a good job for two reasons – to get results and to keep our job. We had access to most of our athletes most days of the week, and at times twice each day. We could have been forgiven for expecting to be able to manage and monitor so many variables to create exceptional programming. However, the truth of walking into a team with long-established ways of training and behaving meant that we had to get buy-in before we could get close to doing a good job. Therein lies the simple truth of what Coach Larson said – if the local athletes didn’t enjoy the training, lots of events would conspire against us doing a good job.

​The consequences of athletes not enjoying what you provide include:
• Speaking negative comments to teammates about their experience with you;
• Speaking negative comments to other coaching staff about their experience with you;
• Limited in-session effort;
• Limited consistency of attendance.

Those four consequences will cost a coach clients, money and position. It is hard work getting a client, getting paid and advancing a career. The likelihood of a second chance at a client or a job position is zero percent which brings us to compromise.
To hear more about how Rett and I collaborate to get the best out of our athletes, check out our Warm-Up Masterclass below.
https://www.performancephysicaltherapies.com/courses/WarmUp

 This case study will suit the practitioner with SFMA level 2 experience, now available as an online course as a pre-requisite to a live course.  If you haven't heard of the SFMA, you can briefly watch an intro to it here.

A client returns with a recurrence of LBP. A history is taken. A previous neuro scan and respiratory scan has been done and there is nothing to indicate any change. It is appropriate to proceed with a review of her movement assessment, ie the SFMA top tier. 

Findings: 
Cx F DN
Cx E FN
Cx R FN Bilaterally
MSF FP
MSE DP
MSR DP Bilaterally, with right being less painful. 
SLS FN
ADDS DN

My entry breakout is the deep squat, which reveals bilateral ankle dorsiflexion MD's, eversion MD's, hip ER MD's bilaterally (with hips flexed), left worse than right. I'm cautious with the DP of MSR, but I want to know a little more about hip rotation with hips extended to help me understand if ER is restricted in two positions - this refines whether I'm biased towards checking tissue texture abnormality via the active tissue palpation taught in level 2, or for joint play reviewed in level 2. Prone hip rotations reveal MDs in ER bilaterally, but worse on the left (29 degrees), with IR of 25 degrees. 

While prone, I do a static palpation assessment of the lumbo-sacral region and observe her lower lumbar spine is subtly rotated towards the left.

My reasoning is to do LBE of hip and feet. 

I find that despite the left hip displaying MDs of the physiological movements (ie limited osteokinematics), the right hip displays more restricted accessory movements (ie arthrokinematics or joint play). They are limited in multiple accessory planes so I perform a long-axis hip traction of the right hip with MET, 3 reps. 

Reassessment reveals the left hip physiological rotation is now in the high 30's for ER and IR. Treating the most limited joint play on the right hip changed the most limited physiological movement on the left hip that was revealed in the breakouts. I had come to that breakout because I chose a DN of ADDS and cautiously added breakouts of the DP pattern of MSR. By the way, in prone, right hip ER reproduced left low back pain pre-treatment, confirming the cautious approach and consistency with what was found in left MSR. 

I then went to the feet. Notable findings, left navicular was limited into pronation, medial-to-lateral glide and inferior-to-superior glide. There were restrictions also in midfoot joints at navicular-cuneiform and particularly at the medial cuneiform-to-1st-metatarsal which had very limited dorsiflexion but could plantarflex. 

I did an indirect technique, as a positional release, then with MET. Specifically, I mobilised the navicular where it was capable of going comfortably, ie into supination, lateral-to-medial glide. The superior-to-inferior glide was a trickier element to add in, so I just "stacked" two planes, to R1 - it took a lot of quieting to create motion and listen/feel for it. Then I had her cycle a breath. I released. I repeated, then added isometric ankle dorsiflexion, then released. I repeated a few times. 

Ankle dorsiflexion "let go" and increased, as did the 1st TMT joint into dorsiflexion, as did the subtalar joint. Both manipulated easily with a gentle direct oscillation technique. The left hip ER in extension went well past 40 degrees with R1 and beyond 50 degrees with R2. Hip IR was well beyond 30 degrees. The lumbar spine was neutral. MSR was DN bilaterally, as was MSE and MSF. No pain.

The Reinforcing and retraining drills were 1x1 figure 4 horizontal and vertical bridges, then 2x1 and 2x2 hip extension with ER and IR, then 3x1 tall kneeling rotations with KB and half kneeling chops and lifts (3x3). 

​Hit me up with questions. 

First of all - a 20 minute consultation is ridiculous unless you're simply strapping someone, checking an exercise and adjusting, or I don't know. This is therapy people, not a sheep pregnancy van where we shuttle people in for a feel and kick them out again. If I had a psychology counselling session and I was out in 20 minutes, I'd wonder what the point is. 

Nevertheless, you work for someone who wants you on those time slots. 

This post is following on from yesterdays blog post about how to implement the SFMA when you are new to it, in a 40 minute new patient consultation. 

Janice arrives a few days to a week after the first consultation. After initial greetings and chats, I ask her about compliance and symptoms. She says she's tried to do the hip mobilisation exercise as per the video but isn't sure if she's doing it right. And she doesn't know if she got the right band from Rebel sport.

J: It's green, "will that do?" 

"No" I say, it's too light - there isn't enough tension to distract the joint enough. "Don't worry,", I say, "you can keep green for other exercise, but you'll have to get the red one otherwise you'll be coming here all the time to get me to mobilise your hips." 

Ok, we have checked compliance but we have to see how she's doing it. 
I check her top tier MSF which is DP and her prone hip extension range, active and passively, and it has improved on last week's initial, but regressed from post-treatment, DP actively, FN passively. I check her exercise with a red band, how she's doing it - she had the band too distal to the joint and was breath holding and wasn't directing eyes and cervical flexion towards the foot she was reaching - missing out on the better part of the roll pattern. 

Once I correct it, I recheck her passive range and it's beyond 50 degrees, with no back pain. Active is FN at 45 degrees. Her MSF is DN. 

While I'm there, and knowing I am in a 20 minute session, I use the same red band and set her up for a band-assisted thoracic rib grab mobilisation, emphasising the lumbar-lock element of the drill, with bilateral hip flexion, plus the eyes and cervical rotation, and diaphragmatic breathing. I get hands on to facilitate the thorax rotation in addition to the band, to help her feel what the rotation should feel like. Her MSF is DN. I take a moment with her - the reason she came in was for back pain - we haven't treated her back yet and her back pain is gone by addressing her hips and thorax. That's an important moment. 

The plan now is to stress the importance of the red band, use eyes and cervical flexion and diaphragmatic breathing on the hip exercise, then add the band-assisted rib grab with eyes and cervical rotation and breathing - 3 to 5 breaths per movement. 

I'll see her next week. She is to do the exercises as often as she wants through the day. 

Next week I'm going to check compliance, top tier Cervical Extension, MSF, MSR, MSE and key breakouts from hip and thorax and plan from there. Time's up. Notes, breathe, smile. I wonder why I haven't done it this way up until now - I didn't know I guess, thanks uni. I wonder if there's evidence behind the SFMA approach - hey Greg, can you shed any light on that? (Am I talking to myself?) 

You've just taken SFMA level 1 (and/or level 2) and you arrive at work to see a new client, your head is full, your brain is wondering how to get your clinical side of you to behave with this new person who wants your help. What do you do?

First, reset your own breathing. Then smile and check this example out: 

The appointment is 40 minutes long (a typical new consultation). They are late by a couple of minutes. Don't stress. Perhaps they completed a pre-appointment questionnaire. Read it and then spend some time filling in the gaps. Your primary aim is to find out if they have a medical diagnosis, or need one, and whether they are in the right room today. If they have a medical diagnosis, this will inform you about contraindications for moving, given the first principle is to protect. Let's assume you know how to take a history and it takes you up to 10 minutes. You have 30 minutes to go. Let's assume you want to wrap it up with 5 minutes spare so they can gather themselves, head out to reception and you can finish some notes. So you're down to 25 minutes. 

Second, reset your own breathing. Then smile again and proceed. 

Let's assume I'm making a lot of assumptions. 
Do an ortho-neuro screen of special tests - this helps you clarify the primary aim - do they have a medical diagnosis that needs referring out. 
​Screen their breathing. 
Do a top tier and proceed. 

For example, I'm 10 minutes into my consultation with Janice, a 43 year old who asked for help with left sided low back pain, no radiation, chronic. No red flags. No bowel or bladder signs. No paraesthesia. I have 25 minutes, probably, left over. 

I do a top tier. 3.5 minutes later I write down my top tier findings. 

I'm at about 15 minutes. 20 minutes to go. 

I remember that my SFMA instructor said, in the first week after taking the course, to top tier everyone (which I've now done), then pick one breakout to master that week. My instructor said I could pick any breakout, and there will be some information, but not a complete set of findings. Nevertheless, pick one. She also said to breakout the DN's before DP's, then FP's, and not to breakout the FN's. 

So, I see Janice has an FP for MSF. I won't break that out. I choose MSR which is DN. I could also have chosen MSE but Janice would have had to do cervical extension and that provoked pain so I leave that out. The MSR includes cervical rotation which was not painful. 

Her MSR breakout includes seated spine rotation which was dysfunctional. While she was seated I had her do active tibial rotations which were dysfunctional both directions on both sides. 
I note on her history that she's had bilateral knee ligament injuries and these still bother her, so instead of being in the lumbar lock position I keep her on the chair and ask her to do a modified lumbar lock test on the chair - it is dysfunctional bilaterally for thorax extension and rotation actively and passively so I know she has bilateral MDs. I don't have to test for prone-on-elbows lumbar extension and rotation. 

I put her on the treatment table and test hip rotations in prone and find that her hip internal rotations clear 30 degress actively, so I don't need to do passive. The range is in the vicinity of mid 30's degrees. Her external rotations, actively, are less than 40 degrees. Stabilised hip ER in extension does not become functional. Passive testing is also less than 40 degrees, at 35 degrees bilaterally, and both of them provoke low back pain at R1. 

In supine, her tibial rotations are bilaterally MD in both directions.

Her FABER(E) is bilaterally MD with provocation of low back pain. Stabilised FABER(E) does not change.

Her Modified Thomas Test is bilaterally MD with a lateral drift on the right side. 

Another 7 minutes has passed. I'm at 22 minutes and want to have her out at 35 minutes, that leaves 17 minutes. 

I write some notes on the above findings and take a moment to scan the findings. I know I haven't broken anything else out but I'm assured that my instructors have told me that in the first week I mustn't be tempted. 

She has multiple findings of MD's.
In the thorax both ways into extension and rotation, so thorax MDs are 2. 
The hips have MDs into extension showing up in two tests, on both sides, so that makes hips MDs for 4. Two of them provoke pain, and two don't. 

At this stage I can reason that with MDs above and below the low back, this is fitting the profile of the joint-by-joint-approach. I remember that instead of just jumping to a favourite technique, I have to do a local biomechanical examination (LBE), but I'm not as confident on the thorax LBE so I go to the hips. 

I test accessory joint play in supine, and find multiple direction restrictions, in posterior-anterior, and lateral-to-medial and medial-to-lateral. I'm not sure, but i'm going to make a call on my findings - multiple accessory plane MD's, thus a joint mobility dysfunction, bilaterally. I quickly check Obers test and it confirms a lateral chain MD, more so one side than the other. So, there's a tissue mobility dysfunction also. 

I have spent another 2 minutes figuring that out and I'm at 24 minutes. Shit. Only 11 minutes to go. 

With two joints having MDs, but one drifts laterally in the Modified Thomas Test, I choose to treat that one hip to start with. I tell Janice her hips are not accessing the movement they are supposed to, nor is the thorax, and the low back is probably the victim in the middle. The right hip has less movement so I'm starting with that. 

I position her in supine, legs out straight, I pick her up lower leg just above the ankle and position her into 20 degrees flexion, 20 degrees abduction, 20 degrees external rotation to loose pack the joint. I watch the ASIS and then gently traction until it begins to move. I have her cycle a diaphragmatic breath, then resist my pull, gently, for 5 seconds, then let go, then cycle a breath. This is a muscle energy technique with joint distraction at R1. I repeat 3 times. I re-check the hip acccessory glides and thank goodness they have demonstrated better movement. I check the Obers and it has released. Phew. The Modified Thomas Test also has improved. The prone hip ER has 47 degrees to R1 and is not provoking low back pain. The opposite hip also improved to 42 degrees. I ask her to stand up and her MSR has improved in range. Her MSF improves in range and is less painful. 

Another 3 minutes has passed. I'm at 27 minutes. 

I point out that the brief reset has made a difference to her hips and lower back and definitely hasn't made her worse. She acknowledges and is pleased. 

I get her back up, repeat the above treatment, then do it on the other side. I confirm bilateral improvement in FABER(E) and prone hip ER, plus MSF. Interestingly, Cervical Extension has improved but isn't pain-free. 

I have to give her a reinforce and retraining exercise so I have her do a superband assisted hip mobility drill, with the motor control option as per this video. That's her homework to do for 5 breaths in the mobility position, and 5 repetitions in position 1 and 2. I tell her she can get a red superband from Rebel Sport for $39.95 and she's happy because her back feels so much better. I give her the link to the video and ask her to return in a week to continue work on the other findings. 

I don't have time to reflect any further and I'm a bit stressed by what's just happened but the system seems to have given me a step forward. I make a note to check her exercise performance next week, plus symptoms, and breakout her thorax, in addition to repeat checking her Modified Thomas test, FABER(E), Obers, and hip ER in prone, plus hip LBE. 

Bye Janice. Time for a quick cup of tea before Joe comes in. 

You love a bench press. 
You love a back squat. 
You love to play sport. ​

Could the first two be hurting the third?
Yes. 
"Go on," I hear you think. 

The short term responses and long term adaptations, if left un-offset, will cause, contribute or complicate your ability to move well, move often and move fast. 

"Be specific," I hear you think. 

You bench so much that you have great bulk and tone in your pecs and anterior deltoid. Looks great, feels great. Except that tone creates an internal rotation at the glenohumeral joint. If the pec minor is tonic as well (and it will be), it creates anterior tilt and/or protraction at the scapulo-thoracic joint. 

So what, I hear you think?
Well, the now what is that now you can't externally rotate your shoulder enough to get under the bar comfortably in a back squat, particularly a low-bar back squat. Let me keep going before you feel the need for another "so what". So now you have to find another way to get your hands on the bar and you need more spine extension. Well, that weighted bar on your spine has been pushing your spinous processes down towards each other and they've responded and adapted to rest in an extended position so much that you are already extended at the thoracic spine. Plus, you remember you should lock your lumbar spine into extension when you squat heavy, so you do, and that means you also anterior tilt your pelvis. So now you go into loaded hip flexion where the hip was already pushed into flexion by the anterior pelvic tilt, and you load your quads, because, well, it's squat day and big quads matter, and that rectus femoris tone develops, and the deepest tendon attachment of the rectus femoris attaches at the ilium, across the hip joint, creating more hip flexion tone and hip extension restriction. 

So, now you're accelerating running, lack hip extension even though you've been training your glutes in the squat rack, lack shoulder extension because of the bench adaptations, and your quads are highly tonic. The leg swing is propelled by passive elastic tension in the quads and your hamstrings have to brake the tibia that is swung forward by a rampantly elastic set of hip flexors and quads. Ping. Hamstring tear. So, do more nordics, that'll fix it. 

Plus, as you swing the leg through, the opposite leg can't express hip extension range, because, (well, see above re effect of rectus femoris and anterior pelvic tilt and lumbar extension and restricted thorax and big chest), and so your ability to separate legs in acceleration is limited, and you're just not accelerating fast enough, despite doing "all the right strength training" and not enough of the offset training. 

Right. Ahhhh. So, what's the offset training?

Come on, weigh in, you're better than that. You come up with training, based on revealed limitations, to improve movement where you don't have it. Being strong matters, but how strong is strong enough and what are you doing to offset the negative adaptations?