Fitness professionals are well aware of the importance of assessing their clients to identify postural alterations, range of motion, regions of strength and weakness, as well as determining functional capacity for performing a certain type of workout. However, it is important to understand that there is a major difference between looking at assessments that provide general information on muscle length, range of motion, and strength versus assessments that evaluate for the loss of stability. This article will define stability and illustrate how to use common assessments, such as posture and single-leg stance, to identify signs of stability loss in clients. Understanding and identifying the key regions of stability loss will then enable fitness professionals to institute a more accurate corrective and progressive exercise strategy for their clients in order to help them accomplish functional goals.
- Fitness professionals will be able to define stability and why it is important to assess for the loss of stability in their clients.
- Fitness professionals will be able to identify key strategies and compensatory patterns to suggest loss of stability during performance of a postural and dynamic assessments.
- Fitness professionals will be able to distinguish between general assessments, such as range of motion and muscle length, and assessments for loss of stability.
- Fitness professionals will be able to use their findings from their stability assessments to institute appropriate corrective exercise strategies.
Assessments are an essential component to a well-rounded training program and are as important to a client’s training program as the corrective exercise or progressive training component. While there are many types of general assessments, such as range of motion and manual muscle tests, as well as functional tests such as squatting and lunging, very few of these tests directly determine an individual’s level of stability. Rather, the majority of these tests provide us general information about the length of the myofascial structures (range of motion), the strength of the muscle (manual muscle test), or whether a client can or can’t perform a test (functional movement test). Therefore, it is important to include assessments for stability since the loss of optimal stability can lead to biomechanical changes, compensations, and is very often a precursor to injury (Osar, 2012).
To establish consistency in evaluating for stability, we must identify a definition of stability so that we are interpreting similar components during our assessments. In the strength and conditioning industry, stability is commonly referred to as joint stiffness or resistance to movement. This has lead to the development of many stabilization strategies that are designed to stiffen or brace regions of the trunk, spine, or peripheral joints. While this is an effective strategy for high level activities such as barbell squatting, kettlebell swings, or lifting heavy boxes, chronic use of this strategy tends to over-compress certain joints, creates hypermobility of others, and compromises respiration. Over time, this can lead to a reduced efficiency of motion and ability to perform even low-level tasks such as walking and performing activities of daily living. Additionally, it has been demonstrated that very little muscle activation is actually required to stabilize our joints (Richardson et al., 2004; Lee & Lee, 2013). The benefits to utilizing lower levels of muscle activation and a more efficient stabilization strategy is that it enables us to maintain optimal axes of rotation, ideal respiratory patterns, and efficient, less effortful movement.
While there are many literature references on the concept of stability, individuals researching the effects of different strategies on stability don’t agree upon a uniform definition (Lee & Lee, 2013). In an effort to present a clear and uniformed understanding, Hodges and Cholewicki have defined stability as the, “ability to maintain the desired trajectory (task goals, and encompasses static tasks) despite kinetic, kinematic or control disturbances” (Lee & Lee, 2013). It has also been suggested that stability includes robustness which has been defined as the ability to, “maintain stable behavior for both small and large perturbations” (Reeves et al., 2007).
This definition of stability suggests that we need to control our joints regardless of the task we are performing. Not only should we be able to control our joints but we should do it in a manner that is efficient or ‘robust.’ In other words, we need a different level of stability for the task at hand. For example, we require hip stability to remain in an upright standing posture without compromising the integrity of the soft tissue or osseous structures of the hip joint. Similarly, we require stability or ‘robustness,’ albeit a higher level, while walking up the side of the mountain that has an uneven terrain.
In the following stability assessments, clients will be evaluated for their ability to maintain the right amount of control for the task at hand. What tests should be included as part of an effective assessment for stability? There are numerous assessments that can be utilized to assess a client’s stability strategy. However, rather than assessing whether or not a client can perform a particular test, we are looking for the quality or efficiency of the client when performing the test. In particular, we are going to consider the client’s symmetry (or asymmetry), breathing, and ability to maintain joint centration during their tests.
Assessing for asymmetry in movement or control is one means of determining stability in clients. Asymmetry in motion has been identified as a potential risk for the development of injuries (Cook, 2010 ; Osar, 2012) and will be evaluated by observing the left and right sides of the trunk as well as the extremities. Loss of stability will be identified by the degree of asymmetry in maintaining the optimal biomechanics during the assessment. There are three specific findings that can lead us to conclude there is loss of stability:
- the client demonstrates over-contraction of certain muscles to stand on one leg versus the other leg (example: the client over-contracts the hip muscles to stand on one leg);
- the client demonstrates loss of range of motion on one side versus the other (example: the leg doesn’t flex as high on the right as it does on the left in single leg stance;
- the client demonstrates instability in completing the required task (example: the client is unable to efficiently hold herself supported on one leg).
A client can demonstrate any of these findings bilaterally. In this situation, you will be looking at the side of greater compensation to determine the location of loss of stability.
During the dynamic stability tests, the client must be able to maintain optimal three-dimensional breathing during their assessment without a change in the rate or ease of breathing. Breath holding and/or a chest dominant breathing over an abdominal/back strategy are signs of over-bracing and the loss of optimal trunk stability.
The ability of your client to maintain joint centration or an optimal axis of rotation during their assessments is a cardinal sign of an optimal stability strategy. If the client loses the ability to centrate their joints either in the postural or dynamic assessment, they have demonstrated a lack of stability as they have demonstrated their need to alter the axis of rotation to establish an optimal level of control.
While virtually any functional assessment can be utilized, we look at an individual’s ability to stabilize in static or standing position (postural evaluation) and during a more dynamic or functional movement (single-leg stance). Both optimal mechanics and signs of loss stability will be discussed.
The Postural Assessment
Although the postural assessment does not provide specific answers regarding whether a client is stable or not, it will provide information about robustness. In other words, it will tell us how efficient a client can maintain the upright position. A stable client should be able to hold themself in the upright posture without much effort. Another component that will be evaluated during standing is how committed the individual is to the particular strategy. In other words, evaluate the degree of effort utilized to hold upright posture. Is the client over-activating functional synergists (muscles working together to maintain optimal joint centration) to hold a particular posture, or is the client able to hold his or her posture lightly and efficiently? You can lightly palpate the rib cage and gently move it front-to-back and side-to-side to see whether or not the client is mobile, or functionally locking himself or herself into that position. Similarly, you can palpate the quadriceps, gluteals, and erector spinae to determine how much resting tone is present within these muscles. Also, try and move the client’s patella and flex the knee. If your client is using an efficient strategy, you will be able to easily move the patella and flex the knees.
Additionally, you will look specifically at how the client maintains joint centration of the spine and lower extremities. Are the joints centrated and stacked over top one another, or are they hanging off of the soft tissue structures? Palpate the hip position and determine if the client is optimally stabilizing her hip. Place your fingers in front of and thumb behind the greater trochanter. It should be positioned approximately half way between the anterior superior iliac spine and posterior superior iliac spines (image to right). If it is positioned anteriorly because of over-activation of the gluteus maximus or hip external rotators, there will be a palpable ‘fullness’ in the front of her hip and a divot, or hollowing, will be present behind her greater trochanter.
Other signs of inefficient levels of postural stability:
- The trunk is not positioned optimally over the pelvis (sternum is not positioned vertically aligned with the pubic symphysis);
- The pelvis is not held in a neutral position (anterior superior iliac spines are not vertically aligned with the pubic symphysis);
- There is loss of neutral spinal curves;
- The center of mass is not held symmetrically between the two legs;
- The hip, knee, and ankle/foot are not optimally aligned;
- There is loss of the foot tripod.
The Single-Leg Stance Assessment
The single leg stance (SLS) is one of the best tests for assessing your client’s ability to stabilize the trunk over the support leg, ability to maintain the femoral head centrated within the acetabulum, and relative alignment of the hip, knee, and ankle/foot complex. These components are required for efficient performance in the fundamental patterns of walking or running. Loss of control in SLS is a sign that your client will likely be unable to maintain a stable or efficient gait pattern and will develop compensatory strategies.
You will look for many of the same things you looked for in the postural assessment. The main difference is you will be able to determine how efficient the client is in controlling frontal and transverse plane rotations as they stabilize on one leg. Evaluate your client’s ability to transition weight onto one leg while maintaining a neutral pelvis and spinal curvatures. If the client possesses optimal levels of stability, there should be minimal weight shifting while transitioning weight onto one leg. It should be a relative ease of movement onto the support leg. The client should be able to maintain the trunk vertically over their pelvis, the pelvis in a neutral position, and alignment of the lower extremity. There should be no gripping or over-activation within the trunk, upper extremities, or stance leg. Your client should be able to maintain three-dimensional breathing as they are shifting and standing on one leg. You should be able to palpate for a centrated hip as you did in the standing assessment and there should be no compensatory gripping or bracing as she shifts onto one leg.
Once you have discovered some signs of loss of stability in your client, you can follow these tests with more specific tests to determine which soft tissues need to be released or where they require muscle activation or strengthening.
Video Demonstration of the Assessments
Watch the Author's video demonstration on how to perform these assessments with your client:
Interpreting The Results of the Assessment
Now that you have performed your assessment, where do you start your client’s corrective exercise training? During the assessment, you are essentially looking for the pattern where your client has the most compromised control and/or loses control first. One of the best places to begin a corrective exercise or rehabilitative program is by correcting the region that demonstrated the primary loss of stability or the most compromised movement pattern (Gray, 2010; Lee & Lee, 2013; Osar, 2012). Rather than randomly recommending release of some common soft tissue release or activation of commonly inhibited muscles, address the region of primary loss of stability or greatest compensation in order to make your approach highly specific.
For example, if you noted upper chest breathing strategy, a rigid or stiff thorax, and/or the client standing with a forward hip position in posture and then also translated forward in single leg stance, then you may begin your corrective exercise strategy by releasing any myofascial restrictions around the trunk and hip. You would follow that up by re-activating any inhibited muscles around the hip complex and work on helping your client establish improved breathing patterns and lumbo-pelvic-hip alignment. Next, you would help your client re-integrate more optimal trunk and hip positions into a fundamental pattern, such as the squat, and teach your client how to maintain a centrated hip position and connected core throughout the (squat) pattern. Once you have instituted your corrective and integrative exercise strategy, reassess your client in single-leg stance and determine if they are able to demonstrate improved stability.
Assessments are a valuable part of a well-rounded training program because the information gathered helps you identify your client’s functional capacity, as well as identify areas of potential risks that may interfere with achieving functional goals. In this article, we have defined stability and discussed how the lack of stability is one of the primary reasons for movement dysfunction and lack of optimal performance in our clients. By developing your skills so that you are able to identify regions of loss of stability during assessments, such as standing posture and single-leg stance, you will be able to institute an accurate and specific corrective training strategy that will enable your clients to reach their health and fitness goals.
- Cook, G. (2010). Movement. Aptos, CA: On Target.
- Lee D. & Lee L.J. (2013). The Discover Physio Series 2013 Part 1: An Introduction to Treating the Whole Person with The Integrated Systems Model. Vancouver, Canada: Course Handouts.
- Osar, E. (2012). Corrective Exercise Solutions to Common Hip and Shoulder Dysfunction. Chinchester, England: Lotus Publishing.
- Reeves, P. N., Kumpati, N. S., & Cholewicki J. (2007). Spine stability: the six blind men and the elephant. Clinical Biomechanics, 22(3), 266-274.
- Richardson, C., Hodges, P. Hides, J. (2004). Therapeutic Exercise for Lumbopelvic Stabilization. London, England: Churchill Livingston.