Wolff's Law: If You are Alive, You are Adapting.
- Jul 18, 2023
- 7 min read
Updated: Jul 24, 2023
Nature's Amazing Ability to Adapt to Stressors
My favorite theory over the past 30 years in working both as a physical therapist and wellness provider is, without a doubt, a theory developed in the 19th century by the German surgeon Julius Wolff (1836–1902) . Wolff's law states that "bone in a healthy animal will adapt to the loads under which it is placed. If loading on a particular bone increases, the bone will remodel itself over time to become stronger to resist that sort of loading." (Wikipedia). In other words, bones will adapt to STRESS!!
One of the health challenges related to astronauts going up into space and spending time in a gravity-free environment is that the body will adapt to the absence of that stressor (gravity): Without the mechanical stress of gravity on the bones, the body will cease to reinforce and rebuild them. Instead, it will use its resources other places, and the density of the bones will decrease while an astronaut remains in space. Similarly, if an individual fractures their leg and has to undergo an orthopedic surgical repair, the surgeon will generally have their patient begin by limiting or totally avoiding weight bearing to that leg (because at that time, weight bearing might disturb the stability of the surgical repair). However, surgeons will then attempt to progress their patients to some degree of weight bearing as soon as possible, because they understand that the "stress of weight bearing" will promote increased healing and remodeling of the bone (as it then acts as a positive stressor).
This type of adaptation to stressors is not only relevant for creating strong bones. Wolff's law explains our body's response in every imaginable scenario: "The body responds and adapts to the stresses placed
upon it. " We can tend to think of any stressor, or anything that makes us uncomfortable, as negative aspects of our lives, but the reality is, stress is not only "normal" but stressors can trigger positive adaptations! Many stressors are not inherently bad. Some are. And some stressors can be positive stressors in one scenario and negative in another scenario. In general, stressors can either lead us toward helpful adaptive responses and wellness, or adaptive responses that move us away from good health. (We will discuss positive and negative stressors in an upcoming blog).
Plants and Adaptation
I have recently run across several bits of research that show that even plants (much simpler organisms than ourselves) have the ability to adapt to stress in order to ensure survival. "Plants need to cope with changing environmental conditions, be it variable light or temperature, different availability of water or nutrients, or attack by pathogens or insects. Some of these changing conditions can become stressful and require strong countermeasures to ensure plant survival." The below-referenced National Center for Bio-technology Information article discusses the idea that plants have the ability to sense stressors, activate immediate stress-mediating responses, and ADAPT to create long-term, more functional, responses to each specific stressor! Some research even suggests that the parts of plants that are stressed are able to communicate warning signals to other adjacent branches or other neighboring plants in order to signal their adaptation to the stressor as well! And all of this is accomplished in plants with a very simple "nervous system of sorts"!
The Human Body and Adaptations
You can imagine that if a plant with a very simple nervous system can pull off that type of impressive adaptation, the adaptations of the human organism (and nervous system), have the ability to WOW you! Most scientists would agree, that the human organism is, unarguably, one of the most complex, adaptive systems in existence! The human body, in a much more complex fashion than plants, is also known to
SENSE->RESPOND->ADAPT-> and COMMUNICATE about stressors.
So, let's talk about some examples of how the human organism/nervous system adapts to stressors:
1. SENSING and RESPONDING to an immediate stressor:
Your tongue and upper palate house thousands of taste buds. Each taste bud consists of 50 to 100 cells known as taste receptors. These receptor cells are responsible for either SENSING different tastes like sweet, salty, bitter and umami, or for signaling and triggering biological responses following intense stimulation . For example, when you eat a sweet, sugary dessert, blood sugars rise (a stressor), causing the body to release insulin which allows the body to use up that glucose energy in the cell. In this way, the body is able to lower blood sugar levels.. This is an example of how we RESPOND to feedback when the body is stressed (in this case, by high blood sugar).
2. ADAPTING to a repeated stressor::
But human adaptations are even more complex than that! It doesn't take much exposure to eating foods that are very high in sugar and experiencing a resultant spike in blood sugar before the body makes this connection: sugary, sweet tasting foods = spikes in blood sugar! Soon, the body will ADAPT to PROACTIVELY begin to release insulin as soon as it tastes sweet or sees a sugary dessert that you plan to eat! The body basically learns from experience how it needs to respond and adapts to the stressor of experiencing a spike in blood sugar. (Research has indicated that one reason why artificial sweeteners might not be so healthy for us, is that when we taste sweet, the body anticipates that it should proactively release insulin to deal with the impending spike in blood sugar. Many artificial sweeteners, however, do not change blood sugar levels. This mismatch can lead to significant metabolic difficulty in stabilizing blood sugars).
3. COMMUNICATING about CHRONIC ADAPTATIONS:
If an individual eats a great deal of sugar on a consistent basis and requires the body to ADAPT REGULARLY to stabilize blood sugar, the body will eventually learn and adapt a much more extensive, chronic, metabolic response. The body will COMMUNICATE extensively to insure that multiple organs and tissues participate in its efforts to manage this stressor. One part of this chronic adaptive response is referred to as insulin resistance. Insulin resistance is the body's adaptation which allows it to keep blood sugars low by immediately storing glucose away as fat instead of using it for energy in the tissues. Insulin resistance explains why individuals who are obese often cannot lose weight even though they are decreasing their caloric intake.
DISEASE=WHEN THE BODY CAN NO LONGER ADAPT
If an individual continues to expose the body to high levels of "negative" stressors, eventually, the body's adaptative ability will be exhausted. In the scenario discussed above, unmanaged insulin resistance, over time, will likely eventually lead to type 2 diabetes (an inability to stabilize blood sugars).
In order to understand more fully about how the body responds to stressors, it is important to know the difference between FEEDFORWARD and FEEDBACK loops. I think most people understand the nature of FEEDBACK loops and adaptation: If your boss is keeping track of productivity and gives you feedback about your performance, and you then modify your behavior or work processes in response, that is a good analogy of how the body uses its FEEDFORWARD response. In the above example, the body (like the boss) is keeping track of blood sugar levels. That feedback is communicated to the pancreas so that it can release the appropriate level of insulin in order to stabilize blood sugars. The body is using a FEEDBACK response in this scenario.
When a stressor occurs repeatedly (like we described above), the body's adaptation becomes more extensive, and its response is no longer based on sensing what is actually occurring in the moment, but rather on projecting the most reasonable response based on past experience. This is called a FEEDFORWARD response. So, when an individual eats a great deal of sugar and experiences consistent spikes in blood sugar, the body will begin to release insulin, not based on tracking the actual levels of the blood sugar in the moment, but on its best guess (based on prior experience) as to how much insulin or what kind of strategies you will likely require to keep blood sugars manageable in that moment.
Becoming insulin resistant is a good example of a feedforward response, but these feedforward responses also occur quite extensively for all of us. It makes more sense for our survival that the brain should project how to protect us based on what was needed consistently in the past versus waiting to respond in the moment after getting sensory feedback.
I want to sum this post up by recounting what I recall about a research study that demonstrates the body's amazing ability to sense, respond, adapt, predict and communicate. You will have to forgive me, but I have googled this extensively, and I cannot find the study, but I know that it goes something like this: They exposed a group up subjects to a series of red/hot probes. Some of the redder/hotter probes were hot enough to burn the skin and cause blistering and pain. They also exposed these same subjects to blue/cold probes that merely offered a cold or numbing sensation and caused no pain or tissue damage. After a period, they then placed a red/hot tip on a cold probe. The temperature being delivered should not have been painful or caused tissue damage, but the brain began using a feedforward response ("I know what happens with these red hot probes. They damage the skin, and I have to cause blistering and inflammation to begin protecting the tissues."). And many of the subjects experienced pain and blistering in response to a temperature/stimulus that never should have caused any tissue damage at all!!
Our ability to adapt is amazing! Look for another follow-up post on Wolff's Law and evaluating "positive" and "negative" stressors!
.
Disclaimer: This BLOG is for Educational Purposes, Only. This information provided is educational and informational in nature and is made only as general information. The information does not establish a patient-provider relationship, establish a standard of care, or offer medical, dietary, or therapeutic care, advice, opinion, diagnosis, or treatment. This information does not replace independent professional or medical judgment and should not be relied upon as medical, psychological, or other professional advice of any kind or nature whatsoever. This information should not be used for diagnosing or treating any mental or physical health problem or disease. You are solely responsible for any action taken based on your interpretation of this information and you are responsible for your own health care decision-making by obtaining any necessary consultations with appropriately licensed health care professionals such as physicians and psychologists.
Comentários