Today’s guest blog comes from former Cressey Performance intern Eric Oetter. Eric was one of the best interns we’ve ever had, and writing like this is just one example of why.
In Thomas Myers’ groundbreaking work Anatomy Trains , several “lines” of fascially connected muscles are presented. Myers denoted these lines as “anatomy trains” (thus giving rise to the title of his now famous book). For those unfamiliar, fascia is a seemingly endless web of connective tissue, which envelops and unites the musculoskeletal, nervous, and circulatory systems of the body. Though manual therapists have treated the fascial system for centuries, Myers has played a pivotal role in introducing the concepts fascia and musculoskeletal tensegrity to the strength and conditioning community.
Tying the bottom of the foot to the scalp through fascial connections up the posterior surface of the body, the superficial back line remains the most referenced of Myers’ anatomy trains. While this line certainly has implications in extension (above the knee), propulsion, and full-body pronation, it’s far from being the only line yielding practical application and solutions for strength and conditioning coaches and movement therapists.
Patrick Ward wrote an excellent guest piece on Mike Robertson’s blog last year concerning the deep front line and its effect on diaphragm functionality. I’ll follow suit with some examples of how the functional back line can produce stability across the posterior lumbo-pelvic-femoral complex.
Functional Back Line Anatomy
Tying one humerus to the contralateral tibia, the two functional back lines take the following path across the dorsal surface of the body:
Shaft of humerus –> Latissimus dorsi –> Lumbodorsal fascia –> Sacral fascia –> Sacrum –> Gluteus maximus –> Shaft of femur –> Vastus lateralis –> Patella –> Subpatellar tendon –> Tuberosity of tibia
From behind, the lines look like a giant “X”, intersecting at the pelvis. The two key components in this discussion will be the latissimus dorsi and the glute max, as well as how their muscular actions can affect the sacro-illiac joint.
Sacro-Iliac Joint Stability: Form Closure vs. Force Closure
The sacro-illiac (SI) joint is comprised of the articulation between the illium and the sacrum and lies right in the middle of both functional back lines, deep to the lumbosacral fascia. Much like a crack in the sidewalk, the joint acts as a predetermined fracture to defer stress across the pelvis.
Viewed from the back, the SI joint resembles a key fitting into a lock– the grooves on either side of the posterior illium are congruous with the lateral sacrum. This “lock-and-key” structure can be described as an instance of form closure. Essentially, the innate stability of the joint is provided by bony approximation.
While form closure can create stability, it’s not truly authentic. For example, we can create stability in the lumbar spine by shearing it into extension and using bony approximation to prevent movement. I hope all reading agree that such a situation is less than ideal.
A superior option would be the force closure of a joint system. As opposed to form closure, where the morphology of the joint system creates stability, force closure entails the surrounding musculature dynamically stabilizing a joint by “pulling it tight”.
Relating to our previous example of the SI joint, imagine how much better it would be to stop relying solely on the ligaments that cross the joint andinstead employ the powerful glute max and lat, which cross superficially as part of the functional back line, as both become continuous with the lumbosacral fascia.
While using the functional back line to create force closure is useful in cases of general instability, it can be especially valuable in the instance of sacral torsion, where, as shown in the CT scan below, the sacrum rotates one way and creates strain on the contralateral tissues/ligaments as they are pulled taught.
Training this line in isolation can certainly provide benefit, but why not implement a big-bang strength exercise that integrates the entire line at once?
Here are two great examples of how to train the functional back line in a more dynamic fashion.
Split-Stance Low Cable Row
The split-stance low cable row provides an excellent presentation of shortening the functional line from both ends, thus force closing the SI joint. The latissimus dorsi aids in the horizontal pull while the contralateral glute max stabilizes the pelvis in the transverse plane to fight rotation. (Remember, any unilateral movement is inherently rotational.)
The split-stance low cable row can be a great horizontal-pull variation for any client, but especially for those experiencing lumbosacral instability. I’d recommend placing it as an accessory exercise on upper body days – 3-4 sets of 8-10 reps.
1-arm Cable Rotational Row
Serving as a progression to the split-stance low cable row described above, the cable rotational row is a fantastic movement to dynamically integrate the functional back line into a more advanced pulling variation with much greater demand placed on the glute max. I view this movement much like the horizontal pull version of a push-press – the lower body drives the action with the upper body coming along for the ride.
The benefits of the rotational cable row are numerous, but two stick out in my mind. First, it drives a powerful and dynamic contraction of the functional back line, which as we’ve seen can have ramifications for pelvic/SI stability. Secondly, this variation has huge carryover for some of our rotary sport athletes who rely on the connection between shoulder and contralateral hip to develop force.
As mentioned above, use this as a progression to the split-stance low cable row or with some of your athletic clientele – think in the range of 3-4 sets of 6-8 reps per side.
The functional back lines can be powerful players in creating stability across a region of the body that demands it. In cases of lumbo-pelvic-femoral instability, utilization of these lines can be as crucial for correction as they are for performance enhancement.
I hope the two exercises described above help give some practical application for the functional back lines in action – let me know in the comments!
About the Author
Eric is currently a senior at the University of Georgia majoring in Exercise and Sport Science, with plans to pursue a Doctorate of Physical Therapy. After concluding a Division-1 football career at the Georgia Institute of Technology, Eric has ardently pursued his passion for coaching, garnering experience with clients of all ages and ability levels through internships at both Indianapolis Fitness & Sports Training and Cressey Performance. He can be reached at firstname.lastname@example.org.
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