It’s well known that as we age, our balance decreases 1, 2, 3. But when does this occur? Most people do not know that their balance has decreased until it it too late. There are also many balance disturbances in healthy young adults as well after musculoskeletal injures like sprains and strains of the lower extremity that have affected the body’s proprioceptors, strength, and reaction times. Almost on a daily basis I find myself explaining the basics of human balance to patients or their families, and I think that a general overview is needed.
Human balance is achieved through the integration of vision (eyes), the vestibular system (ears), proprioception (muscle/tendon/ligament/fascia/joints), and reaction times within the central nervous system. I can’t just say brain here, because there are certain reflexes that occur down in the spinal cord as well that keep us on our feet. As we age, vision becomes the predominant system that is used by our bodies to control balance, and unfortunately, our vision usually worsens as we age.
But, what is balance? Balance is really our ability to maintain our center of gravity over our base of support. Seems simple enough, right?
Center of Gravity: Basically the COG is the balance point of the body at rest. However, as we move, this center of gravity is always changing, and the systems above are always adjusting to keep that center of gravity over its changing base of support.
Base of Support: This is the area that the center of gravity is supported by. In standing the BOS is the area of both feet on the ground, when there is a cane involved, the BOS widens, and in single leg stance, the BOS is reduced by about half. Here is a great article on balance and there is a good schematic of changing bases of support as well.
Humans utilize three main strategies to maintain balance:
1. Ankle Strategy – If you look at someone who is barefoot in quiet stance, you will see the tendons in their ankle jutting out, or the muscles in their calves working. This is the body at work making miniscule changes in its center of gravity to maintain its position above the base of support. In healthy individuals, this is the most used method for adjusting the body’s position and balancing. The anatomy of the ankle allows this method to control all directions of movement.
2. Hip Strategy – Commonly seen with larger perturbations to the body, it is characterized by swaying of the hips. Think of a tight-rope walker losing their balance and their hips going front to back to maintain their balance. As we age this gradually becomes used more and more as smaller perturbations become more problematic as our balance decreases. In an injured athlete, you may see this strategy used because of deficient reactions within the proprioceptive system especially with ankle injuries. Just as with the ankle, the hip can control weight shifting in all directions of movement. This is likely why there is not a prominent knee strategy.
3. Stepping Strategy – This is the least used balance strategy (unless you consider walking to be controlled falling), and if it has become your body’s “go-to” method of balance recovery there are some severe problems within your balance systems. This strategy is exactly what it sounds like. You are knocked off-balance and you take a step. This is done to either side or front-to-back. This is to increase the size of the BOS allowing for the COG to be maintained within the BOS.
Some general rules about balance – and how to use them for training
- Wide base of support is easier to balance within than narrow base of support – think two feet vs. one foot
- Tandem stance is more challenging than feet-together stance
- Unstable surfaces are more challenging than stable
- Eyes closed is more challenging than eyes open
- Head moving is more challenging than head stationary
One thing to note is that with training on an unstable surface, global muscle maximum strength capabilities are reduced, so thinking that you’re going to do all your weight lifting on something like the BOSU ball, isn’t really a great idea if you’re looking to get stronger. But to gain balance, this may be an eventual progression to work up towards once balancing on a stable surface has become easy.
To train for better balance it’s easiest to start with internal perturbations such as lifting and reaching for objects and then progressing to external such as tapping from the therapist or ball toss where the perturbation timing is unknown. All of the general rules above can be applied to balance training such as closing eyes (obviously no ball toss with this one), narrowing the base of support, turning of the head, etc. All of these progressions should be coupled with strengthening movements that are needed as well such as hip abduction in closed chain resulting in a gradual progression back to previous activities such as athletics, or decreasing the patients fall risk.
Testing for Balance Deficiencies:
If you are currently in physical therapy or believe that you are in need of physical therapy to improve your balance, your physical therapist may put you through specific tests including the Berg Balance Test, The Timed Up and Go, The Dynamic Gait Index, and The Activities-specific Balance Confidence Scale. These tests are used to establish under what parameters training must be applied (dynamic balance vs. static balance, etc). Included in this study is a good summary showing that as we age balance norms decrease with eyes open and with eyes closed as we age, and therefore, comparing balance tests of all people of all ages is not practical. However, literature suggests that if an individual cannot perform a Single -limb Stance Test for 5 seconds they are two times more likely to be injured by a fall.
Hopefully not much of this was new news to you. Please feel free to contact me, or your local physical therapist for more answers and to find out if physical therapy may be the right treatment for you.
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