Pionnier R, et al. A new approach of the Star Excursion Balance Tests to assess the dynamic postural control in people complaining from chronic ankle instability. Gait & Posture, 2016, 40:97-102.

This article compared a group of individuals with complaints of chronic ankle instability (CAI) to a control group performing a series of movements where the subjects stand on one leg and reach for a target with the other foot. A battery of these “reach tests” in the 8 “compass” directions has become known as the Star Excursion Balance Tests (SEBT). The SEBT has been proven in previous research to be reliable, and valid for documenting deficits in lower extremity function. The authors looked at the traditional reach distance and error at hitting the target. They also used motion capture and force plate analysis to gain a greater understanding of these deficits.

This study confirmed differences in reach distance (CAI shorter) and target error (CAI greater). Some of the findings from the force plate data were that the center of pressure motion out to the limits of balance showed reduced velocity and less variation in the CAI group. When the motions of the lower extremity were compared, the CAI group had less motion of the foot, knee, and hip, particularly in the frontal and transverse planes. 

Lower extremity biomechanics provides a logical explanation for this. If lateral ankle sprains result in either decreased subtalar joint motion, or the fear of allowing this motion to occur, then the transverse plane motion at the knee and hip will be reduced. Whether caused by pain, fear, or incomplete recovery from injury, the CAI subjects may have “learned” to control the motion of the subtalar joint and ankle. At Gray Institute®, we would describe this as choosing stability over mobility. Lacking the proper blend on simultaneous mobile-stability during weight-bearing function will have a negative affect on the entire body during functional tasks. These balance reach test not only can identify functional impairments, but they serve as essential training movements for rehabilitation and performance training.

Most practitioners do not realize that these balance reach tests were designed, organized, and published in the early 1990s when Dr. Gary Gray convened two meetings of movement specialists from different professions to create a system of measurable tests. The initial publication was called the Lower Extremity Functional Profile. This original battery of tests was expanded into the Total Body Functional Profile. The Profiles went well beyond the balance reach tests, including hops and jumps. That these functional tests have subsequently been found to be reliable and valid is a testament to Gary’s vision regarding functional movement and the need to document functional limitations.

The balance reach tests have evolved into a foundational component of the 3D Movement Analysis and Performance Systems (3DMAPS®). Using lunges and arm swings, mobility (motion) is assessed in each of the 3 planes. Then the lunges in the mobility analysis are tweaked so that the reaching foot barely touches the ground, and then does not touch at all. These balance reach tests (combined with the arm swings) serve as the Stability (strength / control) component of the 3DMAPS® Analysis. These movements document if the body has the resources needed to control the motions. If deficits in the control of the motion exist, it is likely that the client lacks strength or neural control. 

Since at Gray Institute®, the test properly tweaked is the exercise, these testing movements become training movements. They identify the deficit, then populate training programs, and eventually document the improvement in function. The evolution of functional testing continues, and Gray Institute® is honored to be an essential resource for all the movement professions.