By Brent Brookbush DPT, COMT, MS, PES, CES, CSCS, H/FS
The DLS is comprised of muscles with a propensity to act synergistically; rarely do these muscles act as prime movers. This subsystem plays an important role in motion of the tibiofibular joints, hip joints, sacroiliac joints and spine, and may aid in proprioception by altering recruitment strategies based on the load and stretch imparted on the system during heel strike. The DLS is active during gait, forward bending (more so when knees are near full extension), and lumbar extension, and eccentrically decelerates spine flexion, hip flexion, and ankle inversion. Over-activity of the DLS may contribute to the following signs on the Overhead Squat Assessment: shoulders elevate, excessive lordosis (anterior pelvic tilt), knees bow in (functional valgus), feet turn-out and feet flatten (pronation). The DLS works synergistically with the Posterior Oblique Subsystem (POS).
The communicating fascial structures of the DLS are the deep laminae of the posteriorlayer (DL) of the thoracolumbar fascia (TLF), the sacrotuberous ligament, and the fascial continuity between the biceps femoris and fibularis muscles at the fibular head.
The anatomy of the DL is the fascial link between the upper body muscles of the Deep Longitudinal Subsystem (DLS). The DL runs from the splenius capitis and splenius cervicis, to the superficial fascia of the rhomboids, envelops the erector spinae (investing-in and reinforcing the paraspinal retinaculum) and is continuous with the sacrotuberous ligament (2-4). This implies that the DL has fascial continuity with structures from the hip to the skull. Further, the DL and the middle layer of the TLF fuse to posture for a given exercise.
© 2017 Brent Brookbush">formthe lateral raphe. Note, the middle layer of the TLF is a fusion of the fascia of the Anterior Oblique Susbystem (AOS), and deep fascia of the latissimus dorsi of the Posterior Oblique Subsystem (POS) (5). This both thickens the middle layer of the TLF to reinforce muscular attachments, and it may serve to ingrate the DLS, AOS and POS (2, 4). The idea of POS and DLS integration is reinforced by study by Kim et al. demonstrating synergistic muscle activity during gait (8), and DLS and AOS integration is reinforced by a study by Stevens et al. which demonstrated the co-contraction of various muscles investing in the DL and middle layers of the TLF during a “quadruped” exercise (9). The similar behavior of all muscles that invest in the DL may have been what inspired this myofascial synergy, and the interaction between the layers of the TLF inspires consideration of core subsystem integration.
The DL may also serve as an important mechanical function by enveloping and reinforcing the paraspinal retinaculum; a sheath of fascial tissue wrapping the erector spinae horizontally, from the tip of the spinous processes to the tip of transverse processes (6, 10). Schuenke et al. demonstrated that inflation of the retinaculum by extensor muscles altered the moment arm and load angle of muscles investing in the superficial posterior layer and middle layer of the TLF (6). This may imply that optimal function of the abdominal tourniquet muscles, the Intrinsic Stabilization Subsystem and AOS, are dependent on inflation of the extensor retinaculum; and therefore, optimal function of the DLS. Further, Huskins et al. proposed that reinforcement of the externsor retinaculum may increase force output of the erector spinae by up to 30% by restricting radial expansion (10). Last, inflation of the extensor retinaculum has been hypothesized to stiffen the DL aiding in eccentric deceleration of flexion forces (3, 4). This reinforcement of the extensor retinaculum by the DL may aid in optimal function and integration of subsystems, lumbar extensor force production and stabilization of the lumbar spine.
Note: A study by Levangin et al. demonstrated a reduction in For example, the glide of facet joint in the spine during spinal flexion and extension, or the posterior glide of the humeral head that must accompany anterior roll to maintain congruence with glenoid fossa during shoulder horizontal adduction.">shear
For example, the glide of facet joint in the spine during spinal flexion and extension, or the posterior glide of the humeral head that must accompany anterior roll to maintain congruence with glenoid fossa during shoulder horizontal adduction.">shearstrain between the posterior layers of the TLF (superficial and deep laminae) in those with a history of low back pain (11). Further, a study by De Coninck et al. demonstrated good inter-rater reliability for assessing disorganization of thoracolumbar fascia fibers via ulatra-sound in those with low back pain (12). How this may affect the optimal recruitment of subsystems, in particular the DLS and Posterior Oblique Subsystem (POS) has yet to be researched, but it may be reasonable to consider potential alterations in practice. Research has shown that direct pressure to the thoracolumbar fascia will increase extensibility, either manually (13) or with a foam roll (14). However, stretching the TLF via a latissimus dorsi stretch will not effect extensibility (15). This may imply that for addressing fascial dysfunction, direct manual pressure is effective and stretching is not. Research is needed on "fascial shear" techniques like Instrument Assisted Soft Tissue Mobilization, Pin and Stretch and Myofascial Release.
The sacrotuberous ligament is a complex structure that plays a significant role in sacroiliac joint (SIJ) function, and serves as an attachment site for several muscles. Research has demonstrated that the biceps femoris and gluteus maximus may increase tension in the sacrotuberous ligament (16, 17, 105), further, the piriformis, semitendinosus, semimembranosus, obturator internus and multifidus have been implicated by researchers due to their attachments (18), and the Brookbush Institute considers the ichiocondylar (posterior) head of the adductor magnus part of this group despite a void in the research (other than reference to its attachment in various anatomy textbooks). Studies by Vleeming et al. have shown that contraction of these muscles may increase tension of the sacrotuberous ligament, which may contribute to Vleeming, A., Pool-Goudzwaard, A. L., Stoeckart, R., van Wingerden, J. P., & Snijders, C. J. (1995). The Posterior Layer of the Thoracolumbar Fascia| Its Function in Load Transfer From Spine to Legs. Spine, 20(7), 753-758.
">force closure and stiffness of the sacroiliac joint (SIJ) (16, 19, 20, 105). Further, studies have demonstrated that increased tension of the sacrotuberous ligament via muscular contraction can resist nutation (17, 20). The contribution to force closure, stiffness and resistance to nutation may imply important roles in both stabilization and dysfunction of the SIJ, specifically contributions to Lumbo Pelvic Hip Complex Dysfunction (LPHCD), Lumbosacral Dysfunction (LSD), and Lower Extremity Dysfunction (LED). The research by Vleeming et al., the common attachments on the sacrotuberous ligament, as well as the common behavior relative to dysfunction contributed to the hypothesis of this myofascial synergy.
The gluteus maximus does not behave like other muscles investing in the sacrotuberous ligament, and is excluded from the DLS. While most muscles of the DLS have a propensity toward over-activity, the gluteus maximus has propensity toward under-activity. Further the gluteus maximus is a prime mover, where as most of the muscles of the DLS are synergists. The gluteus maximus invests heavily in the superficial laminae of the posterior layer of the TLF, and plays a larger role in the POS. The relationship between the gluteus maximus and DLS at the sacrotuberous ligament and SIJ may have important implications related to integrated functions of the DLS and Posterior Oblique Subsystem (POS) such as gait, jumping and lifting.
Muscles investing in the sacrotuberous ligament:
The erector spinae fills the majority of the cross-sectional area of the extensor retinaculum, is invested in the extensor retinaculum and DL from cranium to sacrum, and invests in the common fascial sheath (composite) of the sacrum running continuous with the sacrotuberous ligament. Although more research is needed investigating the relationship between erector spinae activity, DL tension/stiffness and recruitment of the DLS, there is a fair amount of research on erector spinae function and compensatory behavior.
The erector spinae is the primary lumbar extensor, especially the iliocostalis thoracis which may produce 70 - 86% of total extensor torque (21, 22). The erector spinae also contribute to frontal plane stabilization (23), can rotate the spine ipsilaterally (24), contribute to anterior shear of the lumbar vertebrae (more with increased lordosis) (22, 25), and may have an effect or be effected by the ribs and costovertebral joints (26). The iliocostalis has a higher muscle spindle density than the multifidus, demonstrating that muscle spindle density increases from the most medial fibers to the most lateral fibers of the lumbar extensors (26, 27). Unlike the multifidus, asymmetrical activity of the iliocostalis is common when challenged by asymmetric loads (128, 129). For example, holding weight in the right hand increases left iliocostalis activity, but bilateral multifidus activity. This behavior implies that the erector spinae behaves more like a prime mover or large force generator, and the multifidus more like a segmental stabilizer.
The behavior of the erector spinae relative to dysfunction is complex, but is similar to other muscles categorized as "short/over-active". In those exhibiting signs of chronic low back pain the erector spinae exhibit less activity in lumbar extended positions (30), produce less torque and fatigue faster during isometric extension (31-33), are more active during static standing (34 - 36), peak higher during flexion, spontaneously discharge around hypermobile segments (34, 36), and remain active for longer after a lift (37). Further, changes in motor behavior include delayed activity during lifting tasks (28, 38) and trigger point development (39, 40). Additional findings that may have implications for practice include a study by Renkawitz et al. that showed an imbalance in EMG activity between right and left sides in those exhibiting low back pain (41), Nourbkhsh et al. found that extensor endurance had the highest correlation with low back pain when compared to 16 additional mechanical factors (other variables were also strongly correlated) (42), and Cooper et al. found erector spinae atrophy in those with chronic low back pain (43). Based on these findings the BI recommends treating the erector spinae similar to other muscles of the DLS, using release, mobilization and lengthening techniques to address increased activity and reductions in mobility. Core integration and subsystem integration techniques should be relied upon to address atrophy and core muscle endurance. It may also be prudent to assess prior to any sign of injury (prehab), as a study by Lee et al (1999) demonstrated that imbalance between spine flexors and extensors was a risk factor for low back injury in a 5-year prospective study (44).
Due to the size and attachments of the erector spinae from cranium to sacrotuberous ligament, its function as prime mover in lumbar extension, and the significant research detailing the attributes of its compensatory over-active behavior, the erector spinae is thought of as a keystone structure in the DLS. Assessed alterations in activity in length of the erector spinae should be attributed to all muscles investing in the DL and treated accordingly.
The biceps femoris, adductor magnus and piriformis all have attachments to the sacrotuberous ligament. Their is a significant amount of research on the biceps femoris; however, research on the piriformis, and adductor magnus is lacking. Further, there is no research on the activity of the deep rotators which are presumed to behave similar to the piriformis. Clinically, it has been observed that these muscles behave similar to one another, in a manner congruent with the behavior of the DLS, and addressing all of these muscles together seems to improve outcomes related to DLS and sacroiliac joint (SIJ) dysfunction.
Several studies have demonstrated increased biceps femoris activity relative to decreased gluteus maximus activity in those exhibiting knees bow in (functional valgus), an anterior pelvic tilt, lumbar spine instability, sacroiliac joint dysfunction and/or low back pain (42, 45 - 49). These studies may be evidence of a relationship between the DLS and POS that results in POS inhibition and synergistic dominance of the DLS. Release and stretching may be effective ways to treat this change in activity. A study by Hasegawa et al. on the relative activity of knee musculature, demonstrated that stretching the biceps femoris resulted in a relative increase in vastus medialis obliquus (VMO) activity (49). This begs consideration of whether stretching resolved an over-activity of the biceps femoris that was reciprocally inhibiting its functional anatogonist (VMO), and whether similar changes in activity would be observed at the hip. Further, foam rolling the hamstrings has been shown to be an effective strategy for increasing extensibility (50). Note, based on the relative increase in length in static posture in those exhibiting an anterior pelvic tilt, the Brookbush Institute (BI) suggests that better long-term results may be noted with release techniques alone, despite stretching providing some short-term benefits.
Very few studies have investigated activity of the piriformis, and no studies exist investigating the deep rotators to our knowledge. This is likely due to their location deep to the thick gluteus maximus. It is hypothesized that the deep rotators and piriformis behave similarly. The piriformis has been shown to be more active during external rotation, abduction and extension of the femur, and increased tension will contribute to stabilization (compression) of the sacroiliac joint (SIJ) (51-54). Note, the piriformis is unique among DLS muscles due to its ability to compress the SIJ via muscular action, as well as increase tension in the sacrotuberous ligament. Based on function, over-activity and adaptive shortening of these muscles would contribute to the compensation patterns Knees Bow Out (Functional Varus), Asymmetrical Weight Shift to the opposite side, and SIJ stiffness. Clinically, palpation of the piriformis would imply this muscle is commonly over-active, even in cases of, LED and LPHCD resulting in Knees Bow In and a presumed increase in length. There is some research to support that piriformis (and perhaps deep rotator) trigger points are common, occurring in 25 - 50% of the population (49, 55). Release has proven clinically effective; however, do to a presumed increase in length in those exhibiting dysfunction, stretching is only recommended if release techniques do not return normal extensibility.
There is a void in the body of research regarding the activity of the adductor magnus. Three older publications, suggest that despite the adductor group being active during the entirety of the gait cycle, the posterior or "ischiocondylar" head of the adductor magnus has spikes and troughs in activity similar to the hamstrings (49, 56, 57). That is, the posterior head of the adductor magnus is an extensor, an external rotator, and is active during mid stance, push-off and the late swing phase of gait. Anatomically, this muscle does share an origin with the biceps femoris on the sacrotuberous ligament and has neural innervation from the sciatic nerve via the tibial nerve (much like the hamstrings). Throughout the Brookbush Institute content, the term "adductor magnus" is used to reference the posterior head of the adductor magnus, and this muscle is addressed in the same manner as the biceps femoris, as well as the piriformis and deep rotators). The BI most often recommends release techniques for these muscle.
Note: similar to labeling the erector spinae as the keystone structure relative to the DL, the biceps femoris is the keystone structure of the muscles investing in the sacrotuberous ligament. This is due to the muscles relative size, the attachments from sacrotuberous ligament to fibular head, the significant amount of research detailing the muscle's activity relative to the gluteus maximus, and the relative ease of assessing this muscle compared to other muscles investing in the sacrotuberous ligament. Assessed alterations in activity in length of the biceps femoris should be attributed to all muscles investing in the sacrotuberous ligament and treated accordingly.
The fibularis muscles extend the DLS from knee to ankle via fascial continuity with the biceps femoris at the fibular head. This may imply the DLS has an important role in core function, as well as knee, proximal and distal tibiofibular joint, and ankle function.
Unfortunately, activity and behavior of the fibularis muscles has not been well researched. Based on their moment arm and size, these muscles are the strongest evertors (pronators) of the ankle/foot, but are relatively weak plantar flexors (58, 59). This may imply that these muscles contribute more to adjusting the foot to accommodate uneven terrain and less to propulsion, and further, over-activity of the fibularis muscles may contribute more to feet flatten (functional pes planus) than to a loss of dorsiflexion.
The fibularis muscles are categorized as over-active based on the prevalence of feet flatten (functional pes planus) in those exhibiting Lower Extremity Dysfunction (LED). Studies have noted that the © 2017 Brent Brookbush">postural
© 2017 Brent Brookbush">posturalchallenges are delayed in those exhibiting dysfunction (chronic ankle sprains) (60 - 64). Although these traits would seem to indicate "under-activity" more research is needed to investigate activity relative to other musculature of the lower extremity during various functional tasks. Labeling and categorization is complex, and although labeling the fibularis muscles as under-active may seem easiest given the above research, these initial studies have similarities to the attributes exhibited by the more thoroughly studied (and over-active) erector spinae muscles. Until further research can address these gaps and compare interventions intended to address fibularis muscle dysfunction, the BI recommends addressing these muscles as short/over-active with special consideration given to "reactive activation" exercises (for the invertors and glute complex).
By Henry Vandyke Carter - Henry Gray (1918) Anatomy of the Human Body (See "Book" section below)Bartleby.com: Gray's Anatomy, Plate 409, Public Domain, https://commons.wikimedia.org/w/index.php?curid=527331
There is some disagreement regarding whether the rhomboid fascia is a separate epimysial fascial sheath, the posterior layer of the TLF runs underneath the rhomboids, or whether the DL and superficial layer of the TLF envelop and are continuous with the rhomboid fascia as described by Barker et al. and Vleeming et al. (2, 65 - 68). In this article the rhomboids are treated as if the rhomboid fascia runs continuous with the DL. The behavior of the rhomboids matches activity of the other muscles of the DLS, and the inclusion of this muscle inspires consideration of how subsystems may affect scapular motion.
The rhomboids behave as might be expected from a synergist for retraction, elevation and downward rotation. Their activation cannot be separated from other scapular movers, and their activity increases with less trapezius activity during arm elevation (70, 71). They play a role in positioning the scapula for optimal glenohumeral mechanics during arm motion, are more active during "rows/pulling" (retraction), and less active during arm elevation/overhead pressing or pushing (72 - 75). Rhomboid activity is likely important for stabilization as it was noted that activity increases with gripping (finger flexor activtion), and increased re-activity (decreased latency) was noted in the trained arm of pitchers and the dominant arm of untrained individuals (76, 77).
There are very few studies related to the rhomboids compensatory behavior in those exhibiting signs of dysfunction. This is likely due to their position deep to the trapezius muscles. Research does suggest that their behavior does not change in those exhibiting anterior shoulder instability; however, in a study by Yoo et al., pain pressure threshold decreased in those working at a computer for just 15 minutes and continued to increase for the 60 minute duration of the study (78, 79). This may imply that compensatory changes in activity and length of the rhomboids are more heavily influenced by changes in scapula and thoracic spine position (slouched posture), and less influenced by shoulder dysfunction. Further, studies have demonstrated that the rhomboids activity increases with inhibition of the trapezius muscles, and research has demonstrated a higher rate of perceived exertion when the rhomboids and other synergistic muscles were relied upon for movement (71, 80). The function and evidence of altered behavior suggests this muscle is likely over-active in those exhibiting dysfunction, acting as an over-active synergist for inhibition of the trapezius muscle.
The deep lamina of the posterior layer continues to become the investing layer of the cervical fascia, covering the paraspinal muscles including the splenius cervicis and capitis as it blends with surrounding cervical fascias; eventually fusing with the cranial base (70, 81). Some evidence exists that the DL is not well developed above the border of the serratus posterior superior, which would exclude the cervical musculature from the DLS (67). We have chosen to treat the splenius cervicis and capitis as members of the DLS due to the potential for fascial continuity and the propensity of these muscles to behave similar to- and in conjunction with the erector spinae.
The spleneii contribute to extension and ipsilateral rotation of the cervical spine and head (82 - 85). A study by Vasavada et al. reported the splenii among the cervical muscles with the largest extension moment arms (85). Unlike the larger upper trapezius muscles, the splenii do not appear to be inhibited by antagonist activity, as two studies demonstrate that resisted flexion (and diagonal flexion) resulted in a maintenance of low level activity throughout (86 - 87). These studies imply that the splenii can ipsilaterally rotate the cervical spine, but are likely more important as extensors and may play a role in stabilization of the spine during flexion.
Those with cervical dysfunction exhibit altered splenii activity. Two studies report a decrease in activity and force when pain is experimentally induced via injection (88-89). Although these studies may aid in our understanding of compensatory behavior relative to acute injury; this decrease in activity following injection is noted in similar studies on other muscles. This may imply that injection alone results in a decrease in activity. The behavior of the splenii relative to cervical dysfunction is more nuanced. Although chronic forward head posture results in a decrease in cervical muscle activity and force overall (90), an increase in splenii activity (and upper trapezius) is noted during protraction of the cervical spine, and/or when neutral posture is compared to forward head posture (91). Further, a study by Lindstrøm et al, demonstrated a strong correlation between cervical pain and an increase in splenii (and upper trapezius) co-activation during resisted forward flexion (92). Splenii trigger points are common, slightly more common in those exhibiting cervical radiculopathy, and may be related specifically to C4/C5 lesions (93, 94).
These traits imply that the splenii are commonly over-active; however, improving lower cervical extension strength is an important component of any program with the intent of reducing forward head posture. A study by Schomacher et al. demonstrated that during cervical extension exercise (DCF Activation), extensor activity may be higher at the segment resisted (95). It is recommended that release techniques are implemented first, to reduce activity and decrease trigger point sensitivity, followed by resisted cervical retraction with a band placed low on the neck. Note, studies have demonstrated that more reps at lower loads to fatigue increases activity more than higher loads with low rep ranges (96).
By Henry Vandyke Carter - Henry Gray (1918) Anatomy of the Human Body (See "Book" section below)Bartleby.com: Gray's Anatomy, Plate 384, Public Domain, https://commons.wikimedia.org/w/index.php?curid=561537
The Deep Longitudinal Subsystem (DLS) eccentrically decelerates leg swing during gait, and may act as a proprioceptive mechanism to rate heel strike force, and reflexively aid in recruitment of propulsion muscles. During the the swing phase of gait (hip flexion/knee extension), tension and activity increase in the lower extremity muscles of the DLS, peaking during heel strike and the initiation of propulsion (97 - 101). Research has also demonstrated that the stretch-shortening cycle (muscle spindle excitation) and afferentation (sural nerve, bottom of foot) at the end of swing phase alters recruitment of the biceps femoris (102-103). Do to a "law of parsimony" hierarchy in the body, lower level activities often rely on smaller synergists for motion, and larger prime movers are not recruited unless motion is resisted by an external force. In this way, the muscle spindle excitation and additional afferentation from structures of the DLS during heel strike, may be the difference between relying only on the DLS, or additionally recruiting larger muscles from the Posterior Oblique Subsystem (POS) during tasks like walking uphill or stair-climbing (101 - 104).
As mentioned above, increased activity of the DLS muscles increases tension in the sacrotuberous ligament, which may resist nutation, contribute to Vleeming, A., Pool-Goudzwaard, A. L., Stoeckart, R., van Wingerden, J. P., & Snijders, C. J. (1995). The Posterior Layer of the Thoracolumbar Fascia| Its Function in Load Transfer From Spine to Legs. Spine, 20(7), 753-758. ">force closure and increase stiffness of the sacroiliac joint (SIJ) (16, 17, 19, 20, 105). This may have important implications relative to SIJ stabilization for gait and other high intensity activities. For example, as the innominate posteriorly rotates on the sacrum (nutation) during the swing phase of gate, tension develops in the lower extremity DLS muscles increasing tension in the sacrotuberous ligament. The tension may aid in eccentrically decelerating nutation, and is highest around heel strike (97 - 101) when increased rigidity of the SIJ and pelvis would be most beneficial for transferring force from hip muscles to the lower extremity for the initiation of propulsion. This same mechanism would be beneficial for higher intensity tasks such as stair-climbing, sprinting, jumping, squatting or deadlifting when stability of the pelvis and SIJ may be essential for optimal performance and reducing risk of Lumbo Pelvic Hip Complex Dysfunction (LPHCD).
">force closure and increase stiffness of the sacroiliac joint (SIJ) (16, 17, 19, 20, 105). This may have important implications relative to SIJ stabilization for gait and other high intensity activities. For example, as the innominate posteriorly rotates on the sacrum (nutation) during the swing phase of gate, tension develops in the lower extremity DLS muscles increasing tension in the sacrotuberous ligament. The tension may aid in eccentrically decelerating nutation, and is highest around heel strike (97 - 101) when increased rigidity of the SIJ and pelvis would be most beneficial for transferring force from hip muscles to the lower extremity for the initiation of propulsion. This same mechanism would be beneficial for higher intensity tasks such as stair-climbing, sprinting, jumping, squatting or deadlifting when stability of the pelvis and SIJ may be essential for optimal performance and reducing risk of Lumbo Pelvic Hip Complex Dysfunction (LPHCD).
As mentioned above, many of the muscles of the DLS are synergists, acting to assist larger prime-movers. This is especially true of the extension mechanism that is essential for gait and lifting. Several studies have demonstrated a correlation between dysfunction, a reduction in relative gluteus maximus activity, and an increase in lumbar erector and biceps femoris activity (106 - 112). Visually, this may present as an increase in the lumbar lordosis during gait, and/or a reliance on lumbar flexion and extension (as opposed to hip flexion and extension) during bent-over lifting. Although it may be important to have an alternative movement pattern or set of motor units to maintain function during fatigued or dysfunctional states, research and practice imply that that dominance of one system results in a decrease in activity of the other. That is, targeting the muscles of the DLS with strengthening techniques is likely to increase reliance on the DLS, and reduce reliance on the larger more powerful muscles of the POS.
Clinically it has been noted that lifting nearer to full knee extension increases reliance on the biceps femoris, resisted adduction during squatting, stepping, and gait increases reliance on adductor magnus, and targeted interventions for any muscle of the DLS prior to functional tasks will increase the targeted muscles activity. To increase reliance on the gluteus maximus and POS, and decrease activity of the lumbar erector and biceps femoris, research suggests the following cues may be beneficial (113 - 117):
The DLS is prone to over-activity, specifically becoming synergistically dominant for an inhibited Posterior Oblique Subsystem (POS). Perhaps more than any other subsystem, all of the muscles in this subsystem exhibit the same compensatory behavior (over-activity), many of them also exhibiting a relative increase in length during postural assessments. In the Brookbush Institute's predictive models of Lumbo Pelvic Hip Complex Dysfunction (LPHCD), Sacroiliac Joint Dysfunction (SIJD), and Lower Extremity dysfunction (LED) this sub-system is categorized as long/over-active (playing no significant role in Upper Body Dysfunction (UBD)). The most common scenario may be described as: inhibition of the Intrinsic Stabilization Subsystem (ISS) followed by dominance and over-activity of the Anterior Oblique Subsystem (AOS), leading to altered reciprocal inhibition and under-activity of the Posterior Oblique Subsystem (POS), and compensatory synergistic dominance and over-activity of the DLS. Evidence of DLS dominance during an Overhead Squat Assessment, may result in feet flatten, feet turn-out, knees bow-in, knees bow-out, excessive forward lean, anterior pelvic tilt, and/or an asymmetrical weight shift (AWS). Dominance of the DLS (and under-activity of the POS) is generally most dramatic in those individuals exhibiting LPHCD, SIJD and LED.
Based on available research on individual muscles, the Brookbush Institute’s (BI’s) predictive modelsof postural dysfunction, and observations in practice, this subsystem is categorized as “long/over-active“. As subsystems are synergies, dynamic multi-segmental posture for a given exercise.
© 2017 Brent Brookbush">postural
Assessments used by human movement professionals can be divided into three broad categories:
Note: An assessment, or assessment result, may fall into more than one category. For example, although goniometry is an assessment most often used to Refine Exercise/Intervention Selection, if a range of motion is significantly altered, with an abnormal end-feel, and/or causes the patient or client/pain, the individual may need to be referred to a physician for further testing and Clearance to resume rehab activities. Further, that same patient may return to the human movement professional with a list of Contraindicated Activities from the physician. - "When in doubt, refer out!"">assessment is recommended for determining compensatory activity, muscles assessed as over-active are released, and strengthening/activation of individual muscles within the over-active subsystem is avoided. The BI uses the research and theory of subsystems as a means of refining core and integratedexercise selection. Note, the BI’s Corrective-Template addresses individual structures prior to addressing subsystems to reduce
Example: A reduction in hip extension range of motion may result in an increase in lumbar extension during gait.
">relative flexibility, synergistic dominance and compensatory patterns.
The Brookbush Institute's (BI’s) preferred dynamic posture for a given exercise.
© 2017 Brent Brookbush">postural
Assessments used by human movement professionals can be divided into three broad categories:
Note: An assessment, or assessment result, may fall into more than one category. For example, although goniometry is an assessment most often used to Refine Exercise/Intervention Selection, if a range of motion is significantly altered, with an abnormal end-feel, and/or causes the patient or client/pain, the individual may need to be referred to a physician for further testing and Clearance to resume rehab activities. Further, that same patient may return to the human movement professional with a list of Contraindicated Activities from the physician. - "When in doubt, refer out!"">assessment is the Overhead Squat Assessment (OHSA). The DLS contributes concentrically to ankle eversion, tibial external rotation, femoral external rotation, relative nutation of the sacrum, extension of the spine and downward rotation of the scapula. Eversion and tibial external rotation may contribute to the signs feet flatten, feet turn-out, and knees bow in (functional valgus), relative nutation of the sacrum and extension of the spine may contribute to an asymmetrical weight shift and excessive lordosis (anterior pelvic tilt), and doward rotation of the scapula may contribute to shoulders elevate. Note, despite the inclusion of the rhomboids and splenii in the DLS, and the potential contribution to shoulders elevate, addressing the DLS in those exhibiting Upper Body Dysfunction (UBD) does not yield significant results. The BI recommends that DLS issues are considered a "less likely" potential contributor if addressing UBD is the intent.
As mentioned above, the muscles of the DLS have a propensity to become over-active. It is recommended that over-active muscles are released and targeting these muscles with strengthening exercise is avoided. There is some evidence to support that over-active synergist strength and function will improve more with exercise that attempts to correct alignment and targets commonly under-active muscles, when compared to exercise that specifically targets over-active synergists (118-122). Specific to the DLS, this may imply that exercise that targets the lumbar extensors, hamstrings or fibularis muscles should be avoided. Instead, focus on bridges, chop progressions, and single leg balance which may aid in improving posture for a given exercise.
© 2017 Brent Brookbush">posture, optimizing length/tension relationships, and improving posture
The BI suggests ending rehabilitation, corrective exercise and movement preparation routines with multi-joint exercise/activities (integrated exercise) to reinforce new motor patterns. The BI refines “integrated exercise” selection with research and theory on subsystems. As mentioned above, the muscles of the DL are over-active and should likely be addressed with in rehabilitation, performance, and manual therapy settings, generally refers to the feeling of a reduction in tissue tone, tension, density or activity. "Release techniques" generally accomplish this feeling via pressure, tissue stretch, vibration or specific positioning. The mechanism that results in a feeling of "release" is likely a complex set of neuromuscular reflexes (example, depicted below in the Schleip Model of Tissue Manipulation); however, it assumed that "autogenic inhibition" plays the largest role, as a result of stimulating golgi tendon organ, ruffini endings and/or pacinian corpuscles.
Tissue Manipulation Model - Schleip, R. (2003). Fascial plasticity–a new neurobiological explanation Part 2. Journal of Bodywork and movement therapies, 7(2), 104-116.
">releasetechniques and avoidance of targeted interventions. That is, the muscle and fascial structures that can be released are addressed, and exercises that place emphasis on the DLS are avoided until movement quality improves. Exercises that should be avoided:
">tension, enhanced For example, the glide of facet joint in the spine during spinal flexion and extension, or the posterior glide of the humeral head that must accompany anterior roll to maintain congruence with glenoid fossa during shoulder horizontal adduction.">shear and a reduction in cross-bridging between fascial layers, changes in both muscle ">tension (with sustained pressure), and/or altered transmission of force of multiple muscles acting to stabilize a joint (123-125). As mentioned above, some studies imply that direct pressure may increase thoracolumbar fascia extensibility, but stretching may not (13-15). IASTM of this fascial line is common practice, and practitioners report good efficacy; however, further research is needed on this and other fascia specific techniques to support these clinical findings. The BI recommends attempting fascia specific techniques for the structures of the DLS; however, since additional research is still in development, special attention should be given to assessment and re-assessment.
For example, the glide of facet joint in the spine during spinal flexion and extension, or the posterior glide of the humeral head that must accompany anterior roll to maintain congruence with glenoid fossa during shoulder horizontal adduction.">shear and a reduction in cross-bridging between fascial layers, changes in both muscle ">tension (with sustained pressure), and/or altered transmission of force of multiple muscles acting to stabilize a joint (123-125). As mentioned above, some studies imply that direct pressure may increase thoracolumbar fascia extensibility, but stretching may not (13-15). IASTM of this fascial line is common practice, and practitioners report good efficacy; however, further research is needed on this and other fascia specific techniques to support these clinical findings. The BI recommends attempting fascia specific techniques for the structures of the DLS; however, since additional research is still in development, special attention should be given to assessment and re-assessment.
">tension (with sustained pressure), and/or altered transmission of force of multiple muscles acting to stabilize a joint (123-125). As mentioned above, some studies imply that direct pressure may increase thoracolumbar fascia extensibility, but stretching may not (13-15). IASTM of this fascial line is common practice, and practitioners report good efficacy; however, further research is needed on this and other fascia specific techniques to support these clinical findings. The BI recommends attempting fascia specific techniques for the structures of the DLS; however, since additional research is still in development, special attention should be given to assessment and re-assessment.
|Intrinsic Stabilization Subsystem (ISS)||Under-active||Transverse Abdominis (TVA) Activation||N/A|
|Anterior Oblique Subsystem (AOS)||Over-active|
Avoid: planks, crunches, resisted hip flexion
|Legs with Push|
|Posterior Oblique Subsystem (POS)||Under-active||Chop Progression and Bridge Progression||Legs with Pull|
|Deep Longitudinal Subsystem (DLS)||Over-active||Avoid: leg curls, lumbar extensions||Avoid: straight-leg deadlifts, kettle bell windmills, Nordic curls|
If movement assessment leads us to believe that the Deep Longitudinal Subsystem is over-active consider the following changes to your exercise programming.
Splenii Release Manual:
Rhomboid Manaual Release:
Erector Spinae Release (Not easily released using self-administered techniques)
Piriformis Self-Administered Static Release:
Piriformis Manual Release:
Adductor Magnus Release:
Adductor Magnus Manual Release:
Biceps Femoris Self-Administered Static Release:
Biceps Femoris Manual Release:
Fibularis Self-Administered Static Release:
Fibularis Manual Release:
© 2017 Brent Brookbush">Form
Giphart, J. E., Stull, J. D., LaPrade, R. F., Wahoff, M. S., & Philippon, M. J. (2012). Recruitment and activity of the pectineus and piriformis muscles during hip rehabilitation exercises: an electromyography study. The American journal of sports medicine, 40(7), 1654-1663.
Snijders, C. J., Hermans, P. F., & Kleinrensink, G. J. (2006). Functional aspects of cross-legged sitting with special attention to piriformis muscles and sacroiliac joints. Clinical biomechanics, 21(2), 116-121.
Grimaldi, A., Richardson, C., Stanton, W., Durbridge, G., Donnelly, W., & Hides, J. (2009). The association between degenerative hip joint pathology and size of the gluteus medius, gluteus minimus and piriformis muscles. Manual therapy, 14(6), 605-610.
Vleeming, A., Van Wingerden, J. P., Snijders, C. J., Stoeckart, R., & Stijnen, T. (1989). Load application to the sacrotuberous ligament; influences on sacroiliac joint mechanics. Clinical Biomechanics, 4(4), 204-209.
© 2017 Brent Brookbush">posturalmovements and in ambulation. American Journal of Physical Medicine & Rehabilitation, 49(4), 223-240.
Calatayud, J., Casaña, J., Martín, F., Jakobsen, M. D., Colado, J. C., & Andersen, L. L. (2017). Progression of Core Stability Exercises Based on the Extent of Muscle Activity. American Journal of Physical Medicine & Rehabilitation, 96(10), 694-699
Marshall, P. W., & Murphy, B. A. (2005). Core stability exercises on and off a Swiss ball. Archives of physical medicine and rehabilitation, 86(2), 242-249.
Kang, T., Lee, J., Seo, J., & Han, D. (2017). The effect of bridge exercise method on the strength of rectus abdominis muscle and the muscle activity of paraspinal muscles while doing treadmill walking with high heels. Journal of physical therapy science, 29(4), 707-712.
Yoo, W. G. (2014). Effect of the individual strengthening exercises for posterior pelvic tilt muscles on back pain, pelvic angle, and lumbar ROM of a LBP patient with excessive lordosis: a case study. Journal of physical therapy science, 26(2), 319-320.
Chang, M., Slater, L. V., Corbett, R. O., Hart, J. M., & Hertel, J. (2017). Muscle activation patterns of the lumbo-pelvic-hip complex during walking gait before and after exercise. Gait & posture for a given exercise.
© 2017 Brent Brookbush">posture, 52, 15-21.
Schleip, R. (2003). Fascial plasticity–a new neurobiological explanation: Part 1. Journal of Bodywork and movement therapies, 7(1), 11-19.
Schleip, R. (2003). Fascial plasticity–a new neurobiological explanation Part 2. Journal of Bodywork and movement therapies, 7(2), 104-116.
© 2018 Brent Brookbush
Questions, comments, and criticisms are welcomed and encouraged