Submitted by: Jeremy Nelson PT
14.0 Standing On One Leg
This final component of the Berg is not its most difficult as noted earlier. In regards to the hierarchy of critical tasks, this would be around 9 or 10 if the Berg was organized based on difficulty and complexity. The single limb pattern exists in other tests, albeit for shorter periods of time than will be tested in this component. What makes the scoring on this component worthy of being the last of tests is the duration of time each score. The goal requires the performer to be “able to lift leg independently and hold > 10 seconds”. To successfully complete the goal a number of critical tasks are required. The test examines first the weight shifting found in the asymmetrical stance critical tasks and progresses into the control of the center of gravity over a small base of support. On display are the extensors and hip abductors close kinetic chain performance.
What typically undermines the capacity of the performer to attain the test position as in “unable to try or needs assist to prevent fall” is the incomplete capacity at the level of the asymmetrical stance. At this level the weight shifting is inadequate. The critical task in asymmetrical stance as during ambulation from initial contact to midstance is to complete the weight shift on a diagonal. Performers that lose their balance during this position typically perform a weight shift anterior to posterior. In an asymmetrical BOS, this will bring the COG anterior of the BOS and result in the patient losing their balance to the trailing limb side. Once the performer is able to learn the weight shift from trailing limb to the forward limb on the diagonal they are well positioned to attempt the single limb position.
To be able to lift the leg off the ground during the “tries to lift leg unable to hold 3 seconds but remains standing independently” the weight shift has occurred, however the stance lower extremity is unable to maintain the COG over the small BOS. Typically the cause is at the hip, which demonstrates instability in various planes. If the mobility of the hip is adequate to attain the knee at extension and hip at neutral, then the next task is to coordinate the hip to position the COG over the BOS. Most often the performer fails to pass 3 seconds because they have returned to the start position by falling towards midline. In other words the initial weight shift was only to the medial edge of the stance LE. The lesson here is to promote greater weight shifting to the stance LE. Focusing on enhancing the power of the hip abductors and extenders to perform in a closed kinetic chain will increase the duration of the single limb stance.
As the performer is “able to lift leg independently and hold ≥ 3 seconds” and up to “able to lift leg independently and hold 5-10 seconds” conclusions regarding the safety on different surfaces during ambulation can be made. As uneven surfaces take a longer time for the step to take place and thus require greater time in the single limb position, the performer can be considered safer as the capacity for single limb stability improves. As was described in the picking off of the floor, there can be progressions within the scoring matrix, with the changes of the BOS surface. Moving from a firm tile surface to a more compliant carpet surface provides increasing challenges regarding the establishment of the BOS and the control of the COG over the BOS. As the challenges increase and the performer progresses through this component they will find that they are better able to be involved in life as they desire.