Arm Weights and Increased Cadence Improve Activation of Posterior Oblique Subsystem

Research Review: Arm Weights and Increased Cadence Improve Activation of Posterior Oblique Subsystem

By Stefanie DiCarrado DPT, PT, NASM CPT, CES, PES

Edited by Brent Brookbush DPT, PT, COMT, MS, PES, CES, CSCS, ACSM H/FS

Original Citation: Kim, T., Yoo, W., An, D., Oh, J., Shin, S. (2013). The effects of different gait speeds and lower arm weight on the activities of the latissimus dorsi, gluteus medius, and gluteus maximus. Journal of Physical Therapy Science 25:11 1483-1484 - ARTICLE

Posterior Oblique Subsystem

Why is this relevant?: Arm swing is an important component of gait that can minimize energy consumption and increase stability during ambulation. The link between the latissimus dorsi and gluteus maximus via the thoracolumbar fascia is often referred to as the Posterior Oblique Subsystem/Sling (POS) , and in previous studies has been found to stabilizes the sacroiliac joint (1, 2), which may be essential for proper dispersion of ground reaction forces. Proper activation may improve gait mechanics and allow for pain free motion during walking.

Study Summary

Posterior Oblique Subsystem: Latissimus Dorsi & Gluteus Maximus connected via Thoracolumbar fascia

Review & Commentary:

This study is of particular interest for its examination of a muscles synergy, specifically the link between a UE muscle (LD ) and its influence on LE muscles (GMax and GMed ) and visa-versa. The findings of this study may provide inspiration for clinicians to consider various options for increasing the demand on the LE or UE when the goal is improving gait mechanics and/or cadence via an increase in posterior oblique subsystem (POS) activity. The strength of this study is its simple methodology, requiring little equipment and employing a fairly simple methodology for testing the hypothesis. The authors provided clear descriptions of any software and equipment used, including EMG settings and electrode placement. Subjects walked on a treadmill barefoot for 30 seconds with and without a 1 kg sand weight on their L arm at 3.5 kmph and then at 5.5 kmph. The researchers collected EMG activity data from the L LD and from the R GMax and GMed , testing activation of the POS relative to increased demand. All testing occurred within the same session.

The study is not without limitations. The sample size examined in this study was small, but provided enough data to determine statistical significance, meeting research objectives and generating interest for future studies. The use of surface electrodes does risk interference from other proximal muscles; however, the muscles examined were superficial reducing this risk. The author's do not list inclusion or exclusion criteria, but mentioned that subjects were young and healthy. It is likely safe to assume they had no current pain or pathologies that would affect the study. Future studies should consider examining the differences in activation in individuals with a history of shoulder, lumbar, sacroiliac or hip pain/dysfunction, as studies have shown changes in fascia relative pathology - specifically the thoracolumbar fascia and low back pain (3). The researchers examined only the left (LD ) and the right (GMax and GMed ). This does leave the question of how the contralateral side may be affected by changes in load and pace, and whether dominant or non-dominant sides may be affected.

Why is this study important?

This study is important because it demonstrates the POS can be influenced by placing demands on either the UE or LE to influence the other and improve overall gait mechanics.

How does it affect practice?

In certain populations, increased cadence is not possible as an option for therapeutic exercise; for example, those post surgery or with neurologic compromise. This study demonstrates that a practitioner may activate and challenge LE musculature by imposing demands on the UE, which via the POS may help improve ambulation efficiency and stability.

How does it relate to Brookbush Institute Content?

Prior to this study, the Brookbush Institute hypothesized a possible contribution of the gluteus medius (GMed) in synergistic recruitment of the POS . This study includes the GMed in its examination of the POS, but found a minimal increase in EMG activity when an arm weight was added or speed was increased. This does not preclude a relationship between the gluteus medius and the POS , but is does imply that the gluteus medius is not an essential component of the POS as it relates to sagittal plane gait. Further research, is needed to provide a clear picture of this relationship.

As stated in the POS article: "The POS functions to stabilize the posterior kinetic chain, allows for efficient transfer of force between lower and upper extremities (UE, LE), and may decelerate total-body pronation… Every time we land from a jump, get pushed in the back, step off a curb, or bend over to pick something-up – it is this subsystem, along with the optimal function of our ISS (Intrinsic Stabilization Subsystem), that ensures optimal stability of our lumbo pelvic hip complex."

This subsystem is commonly under-active in all models of postural dysfunction: Upper Body Dysfunction (UBD) , Lumbo Pelvic Hip Complex Dysfunction (LPHCD) , Sacroiliac Joint Dysfunction (SIJD) , and Lower Leg Dysfunction (LLD) . Further, the Deep Longitudinal Subsystem (DLS) is typically overactive, resulting in relative synergistic dominance and inhibition of the POS . A more complete corrective intervention for addressing dysfunction of the POS , may also include release and lengthening of muscles and fascia associated with the DLS.

Relative to this study, the Brookbush Institute may need to re-examine the hypothesis that the gluteus medius should be included in the posterior oblique subsystem (POS) , and further consider options for gait training relative to POS integration.

The videos below demonstrate a progression of exercises for challenging and integrating the POS .

Squat to Row - Posterior Oblique Subsystem Integration

Step Up to Row

Static Lunge to Row

Reverse Lunge to Row

Squat to Row Sled Pull

Bibliography

1. Barker, PJ., Hapuarachchi, K.S., Ross, J.A., Sambaiew, E., Ranger, T.A., and Briggs, C.A. (2013) Anatomy and biomechanics of gluteus maximus and the thoracolumbar fascia at the sacroiliac joint. Wiley Online Library. DOI: 10.1002/ca.22233
2. Carvalhais, VO., Ocarino, Jde M., Araújo, VL., Souza, TR., Silva, PL., Fonseca, ST. (2012). Myofascial force transmission between the latissimus dorsi and gluteus maximus muscles: An in vivo experiment. Journal of Biomechanics 46. 1003-1007
3. Langevin, H., Fox, R., Koptiuch, C., Badger, G., Greenan-Nauman, A., Bouffard, N., Konofagou, E., Lee, W., Triano, J., Henry, S. (2011) Reduced thoracolumbar fascia shear strain in human low back pain. BMC Musculoskeletal Disorders. 12: 203

© 2016 Brent Brookbush

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