The SEBT was first described in 1998[5].The SEBT has ability to detect postural control deficits between lower limbs. Additionally, between healthy controls and injured populations. The SEBT can also be used to compare balance ability among different sports and its performance. Research has suggested to use this test as a screening tool for sport participation as well as a post-rehabilitation test to ensure dynamic functional symmetry. 


The SEBT was originally described as a rehabilitation tool consisting of a patient balancing on one leg and repeatedly performing single leg squat movements to use the non-stance leg to reach maximally along one of eight diagonal lines, each at 45 degree intervals from each other [5]. Participants are instructed to touch all 8 lines 6 times before measurements were made.


In general, 4 trials are now recommended in both clinical and research settings, to allow for the learning effect to occur and measurement error to be reduced [5].Researchers have also found that there was a huge amount of  variance between all 8 lines. It indicates that meaning that an individual’s ability to reach in one direction was highly correlated to another[10].Due to its variability now the test has now been simplified to 3 directions – anterior, posteromedial, and posterolateral – and this test can be referred to as the modified SEBT or Y balance test.


Technique:


Standardised testing [1,5]


• Anterior (ANT), posteromedial (PM) and posterolateral (PL) lines.
• Stand on the central point.
• Hands on hips. 
• Reach as far as you can along the line and gently tap the line.
• Do not come to rest on the line.
• Do not transfer your body weight onto the reaching leg.

The thing that interests us is that the research trials strongly emphasise standardisation of testing, to create a reliable measure and interpretation of the reach/distance outcome. This is fair and probably results in a more accurate measure of distance.

What are the FACTORS AFFECTING PERFORMANCE 


It is commonly understand that reach distance is going to be impacted by size, limb length and sex too.There aren’t too many studies telling us how far someone should be able to reach. Below are two additional considerations which impact performance on this test.


Foot placement:


Keeping the heel or toes on the central point will change the outcome of the test. Be mindful about consistency in foot placement. You should not focus on results only. Foot alignment is also important. Only consideration of results without considering foot alignment may lead to misinterpretation of the findings, especially for anterior reach scores” [4]. 


The foot placement may affect the results but there are no significant reaching differences that have been detected when researchers looked at arch control. In some cases having a flat foot or loss of arch control allowed one to reach further in the PL direction but no conclusive results were found. Research states that it is not recommended to control for foot type. However, rather It is to be consider the arch control as dynamic balance performance of that stance limb[1]. 


Let`s focus on Muscle activation patterns:


A study was conducted in 2001 by Earl & Hertel and later summarised in the systematic review by Gribbel et al, found that:


• Vastus medialis is most active in anterior reach. 
• Vastus lateralis is least active in lateral reach.
• Medial hamstring is most active during anterolateral reach.
• Bicep femoris was most active during posterior and posterolateral reach. 

It is always great to come across studies like this. That helps us to guide our clinical reasoning. This gives us an idea or guide us that if we want to train specific muscles, we can use targeted reach directions to bias them. 

WHAT DOES THE SEBT TELL US?


The most significant change to the structure of the SEBT is reducing 8 lines to 3 lines. Here are  few condition that consistently appear in the research across different patient populations:

CHRONIC ANKLE INSTABILITY (CAI):

In CAI, all three directions have the ability to identify reach deficits in participants.The shorter reach distances can be a combination of different factors, either mechanical or sensorimotor in nature [1].These authors found that with CAI, different directions require different physical demands. 


Anterior reach is limited, think about mechanical restrictions and sensory deficits impact this movement. The dorsiflexion ROM is best evaluated with the knee to wall test.[3]. 


Posteromedial and posterolateral reach is more impacted by eversion strength and balance control.  The Author studied the movement pattern differences in trunk rotation.[9] They found that CAI patients are more likely to use increased trunk flexion during anterior reach which suggests a compensation strategy for reduced ankle control is to manipulate the pelvis and trunk. 


ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION (ACLR):

The authors also studied trunk movements in ACL patients and found that following an ACLR, when reaching forward, patients are more likely to rotate their trunk away (backwards) from the reach leg and externally rotate the pelvis on the stance leg[9].. 


In a different study following ACLR, researchers found that when looking above the ankle and at the knee, patients with reduced quadricep strength have reduced reach capacity in the anterior directions [2]. Additionally, found that hip abductions strength impacts all 3 directions. This helps  us to guide treatment directions for retraining dynamic balance control. This test needs to be incorporated earlier into our treatment plans to best help patients prepare for the next stage of their recovery.

PATELLOFEMORAL PAIN SYNDROME (PFPS):


Anterior reach involves a higher quadricep contraction, more ankle DF and greater loading on the patellofemoral joint. This reach direction is commonly the most limited in PFPS – which functionally impacts a patient’s ability to walk down slopes and stairs.


Implementation in rehabilitation programe:


The SEBT to assess dynamic balance then designing an exercise to address dynamic balance from the trunk, hip, knee, ankle etc. The one above is a great for a top-down training approach. 


Finally, When we went through all these studies about different body parts and patient populations we didn’t read a lot about what are normal ranges for distance and cut off scores for injury risk. This test is multifactorial and not injury specific. We can be used to assess athletes, active individuals and occupational workers.


The SEBT  helps us guide our rehab programs and focus on quality of movement. The SEBT requires strength, flexibility, neuromuscular control, core stability, ROM, balance, and proprioception. The SEBT is a great tool which helps us tailor our rehab programs to address the specific mechanical, sensory and functional impairments. 

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REFERENCES:


1. Gabriner, M. L., Houston, M. N., Kirby, J. L., & Hoch, M. C. (2015). Contributing factors to star excursion balance test performance in individuals with chronic ankle instability. Gait & posture, 41(4), 912-916.
2. Clagg, S., Paterno, M. V., Hewett, T. E., & Schmitt, L. C. (2015). Performance on the modified star excursion balance test at the time of return to sport following anterior cruciate ligament reconstruction. journal of orthopaedic & sports physical therapy, 45(6), 444-452.
3. Dill, K. E., Begalle, R. L., Frank, B. S., Zinder, S. M., & Padua, D. A. (2014). Altered knee and ankle kinematics during squatting in those with limited weight-bearing–lunge ankle-dorsiflexion range of motion. Journal of athletic training, 49(6), 723-732.
4. Cuğ, M. (2017). Stance foot alignment and hand positioning alter star excursion balance test scores in those with chronic ankle instability: What are we really assessing?. Physiotherapy Theory and Practice, 33(4), 316-322.
5. Gribble, P. A., Hertel, J., & Plisky, P. (2012). Using the Star Excursion Balance Test to assess dynamic postural-control deficits and outcomes in lower extremity injury: a literature and systematic review. Journal of athletic training, 47(3), 339-357.
6. Gribble, P. A., Kelly, S. E., Refshauge, K. M., & Hiller, C. E. (2013). Interrater reliability of the star excursion balance test. Journal of athletic training, 48(5), 621-626.
7. Earl, J. E., & Hertel, J. (2001). Lower-extremity muscle activation during the Star Excursion Balance Tests. Journal of Sport Rehabilitation, 10(2), 93-104.
8. Hyong, I. H., & Kim, J. H. (2014). Test of intrarater and interrater reliability for the star excursion balance test. Journal of physical therapy science, 26(8), 1139-1141.
9. De La Motte, S., Arnold, B. L., & Ross, S. E. (2015). Trunk-rotation differences at maximal reach of the star excursion balance test in participants with chronic ankle instability. Journal of athletic training, 50(4), 358-365.
10. Hertel, J., Braham, R. A., Hale, S. A., & Olmsted-Kramer, L. C. (2006). Simplifying the star excursion balance test: analyses of subjects with and without chronic ankle instability. Journal of Orthopaedic & Sports Physical Therapy, 36(3), 131-137
11. Olmsted LC, Carcia CR, Hertel J, Shultz SJ.Efficacy of the star excursion balance tests in detecting reach deficits in subjects with chronic ankle instability. Journal of athletic training. 2002 Oct;37(4):501.
12. Image courtesy : Relationships among the Y balance test, Berg Balance Scale, and lower limb strength in middle-aged and older females Dong-kyu Lee et.al Brazilian journal of physical therapy