Optimal Neuromusculoskeletal Mechanics During Gait
Optimal neuromusculoskeletal mechanics is typically observed in a habitual barefoot environment. When barefoot, tactile stimulus from the ground is not dampened and the foot, ankle, and leg are free to dynamically respond to proprioceptive sensory input and can safely manage the forces generated throughout the demands of three-dimensional activities.
Neuromuscular Reflex-Activated Anticipation/Preparation Phase
Movement-generated proprioceptive sensory input and tactile stimulus from the foot’s ground contact initiates a protective reflex response during the skeletal swing phase (while the foot is off the ground) in anticipation of the next step's ground contact.
Neuromuscular Reflex-Activated Ground Contact and Propulsion Phases
The protective reflex response activates muscle contractions to optimally align and stabilize the bones of the foot, ankle, leg, and hip, in order to safely manage the forces anticipated during the next step's ground contact (skeletal heel stance phase).
The resultant optimal alignment and stability not only protect the structure, but also ensure optimal muscular efficiencies and performance capabilities.
The stressors that are generated are safely managed and, therefore, contribute to the neuromusculoskeletal structure becoming more robust (stronger and more flexible), significantly reducing the risk of injury.
In short, to paraphrase sports training concepts, the barefoot environment promotes proper technique.
Over time, with repetition, the body adapts to the diversified stimuli and optimal neuromusculoskeletal mechanics become the conditioned norm or ”Optimal Reflexive Condition." This can be “reconditioned” or “retrained" to become a Maladapted Reflexive Condition through Poor Technique activities of sufficient intensity and duration.
Maladaptive Neuro-Musculoskeletal Mechanics During Gait
Maladaptive neuro-musculoskeletal function and related maladapted reflex function are typically observed in shoe wearing or "shod" populations. In the shod environment, relative to the footwear's specific cushioning / restrictive / supportive characteristics:
- Proprioceptive sensory input and tactile stimulus is dampened,
- The natural dynamic movement throughout the feet, ankles, legs, hips, and lower back is restricted or encumbered, therefore,
- "safe" force management capabilities of these areas is impaired throughout the demands of three-dimensional activities.
During maladaptive neuro-musculoskeletal function, the movement-generated proprioceptive sensory input and tactile stimulus from each foot’s ground contact is compromised by:
- Artificial cushioning, which dampens the tactile sensory input required to initiate an adequate protective reflex response during the Reflex Activated Anticipation/Preparation of the next step (while the foot is off the ground); and
- Artificial support and restrictions to musculoskeletal movement that impede the musculoskeletal structure's dynamic three-dimensional movement, leading to instability.
As a result, the following can happen:
- Muscles do not receive the signals required for effective alignment and stability of the bones in the foot, ankle, and leg (prior to ground contact).
- The bones of the foot, ankle, and leg cannot dynamically align and stabilize because of the “support” or “restrictions” (throughout all skeletal and neuromuscular gait phases).
Therefore, the neuro-musculoskeletal structure becomes incapable of safely managing the forces generated and its performance capabilities are impeded by compensatory, imbalanced, and inefficient muscle use.
The stressors that are generated cause damage and contribute to a less robust neuro-musculoskeletal structure (weaker and less flexible), significantly increasing the risk of injury.
In short, the shod environment promotes Poor Technique.
Over time, with repetition, maladaptive neuro-musculoskeletal mechanics become the ”Maladapted Reflex Condition," which can be “reconditioned” or “retrained” to become the Habitual Optimal Functional Condition by employing Proper Technique activities of sufficient intensity and duration.
For example, the Maladapted Reflex Condition is observed when a limb is put in a splint or a cast. Even after a relatively short period of two weeks, atrophy, joint stiffness, loss of soft tissue resiliency, and diminished protective reflex capabilities will be noticeable. In these instances, rehabilitative therapies (exercise programs) are commonly employed to retrain optimal function.
The Neuromuscular System's Adaptation Processes
The Proprioceptive System
Nerve endings that relay information about where different parts of the body are in relation to each other and how fast these parts are moving are called proprioceptors. The proprioceptive system supports muscle tone, spatial orientation, and control of effort, all of which provide the foundation for learned motor patterns that become the skilled movements that make up “coordination.”
Should our capacity to gather information about our surroundings via this system be compromised, we will likely be predisposed to poor assessment and response in the face of threat. This can lead to poor protective reflex development that impairs our ability to choose appropriate defensive strategies, and the combination of impaired orienting and poor defense response dramatically increases likelihood of injury. Injury disrupts orienting and defensive responses further, injury results, and so on. After each cycle, the capacity for healthy function diminishes further. It only stops if proper orienting and defensive responses are restored.
Because physical repair of the orienting systems is a common focus in body therapy modalities, it is standard practice to address proprioceptive repair and retraining in classical physical therapy treatment by using hands-on techniques, balance boards, and movement exercises.
"Serving to protect the body or one of its parts from disease or injury a protective reflex". Merriam-Webster
A reflex is an unconscious, involuntary, or automatic action in response to stimuli. There are many types of reflexes and everyone has them. They protect the body from harm.
For example, if you touch a hot pot handle, your hand immediately withdraws before the thought itself reaches your brain. Similarly, when the body trips and begins to fall, the hands reflexively reach out to cushion impact with the ground. All protective reflexes involve the body’s proprioceptive reflex mechanisms.
Wolff’s Law of Bone Transformation (Julius Wolff 1836-1902)
Wolff’s Law states that bone in a healthy person or 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.
Trabeculae are the meshwork of interconnecting sections of a bone, which give strength to the bone without the added weight of being solid.
The internal architecture of the trabiculae undergoes adaptive changes in response to increased stress loads but the reverse is true as well: If the loading on bone decreases, the bone will weaken due to the absence of stimulus required for the continual remodeling necessary for the maintenance of bone mass.
The Mechanostat Model
This is a refinement of Wolff’s Law that describes bone growth and bone loss. It was promoted by Harold Frost and described extensively in the Utah Paradigm of Skeletal Physiology in the 1960’s.
According to this model, bone growth and bone loss are stimulated by the local mechanical elastic deformation of bone, which occurs under peak forces caused by the muscles (measurable via mechanography). Adaption (feedback control loop) of bone is a life-long process. Hence the mechanical properties of bone are always adapted according to the needed mechanical function. Bone mass, geometry, and strength adapt according to everyday usage. (Refer to Stress Strain Index, SSI).
In the healthy body, there is a linear relationship between a muscle cross sectional area, as a surrogate for maximum forces the muscle is able to produce under demanding physiological conditions, and the bone cross sectional area, as a surrogate for bone strength. These relationships are important, particularly in bone-loss conditions such as osteoporosis, since adapted training that utilizes the required maximum forces on the bone can be used to stimulate bone growth, hence preventing or minimizing bone loss. Vibration training is an example of effective adapted training.
Davis' Law is used to describe how soft tissue will model (adapt) along imposed demands. It is the corollary to Wolff’s Law and used, in part, to describe muscle-length relationships as well as to predict rehabilitation and postural distortion treatments.
Davis’ Law does not necessarily describe myohypertrophy, which is the shortening of muscle as it grows in response to resistance. Because most major muscle groups are composed of protagonistic and antagonistic muscles and their related synergistic groups of muscles, there is a reciprocation of strength. For instance, a strengthened but inflexible (shortened) gastrosoleus complex (of the calf) will result in a weakened but flexible tibialis anterior (of the shin).
The origin of the name, Davis’ Law, remains unclear, but may be in reference to Nathan Smith Davis who was the first editor of the Journal of American Medical Association.
Tendons are soft tissue structures that respond (adapt) to changes in mechanical loading. Bulk mechanical properties such as elastic modulus*, failure strain, and ultimate tensile strength decrease over long periods of disuse as a result of micro-structural changes of the collagen fiber level.
*When an electrical excitation takes place within muscle fibers, a mechanical response in the form of shortening, in addition to a modification of the mechanical properties, in the form of hardening, takes place. Understanding muscle mechanical properties is essential in clinical diagnosis and research on musculoskeletal injuries and movement-related disorders, and the application of this knowledge to patient care is central to rehabilitation.
In micro-gravity situations, human test subjects have experienced gastrocnemius tendon strength loss of up to 58% over a 90-day period. Test subjects who were able to engage in resistance training displayed a lower magnitude of tendon strength loss within the same micro-gravity environment, but modulus strength decrease was still significant.
Similarly, a tendon that has lost its strength due to long periods of inactivity can regain its bulk mechanical properties through gradual tendon re-loading. Biological signaling events (application of sensory stimulus) initiate growth at the site and mechanical stimulus further promotes rebuilding. It is generally accepted that it takes 6 to 8 weeks to properly restore a tendon’s mechanical properties via gradual re-loading, after which active rehabilitative re-training can begin.
It is important to note that excessive loading during this recovery process may lead to material failure, ranging from partial tears to complete rupture. Studies show that tendons have a maximum modulus of approximately 800 Pa (units of pressure or stress) and that additional loading will not significantly increase modulus strength. Therefore, aggressive re-training of the tendon cannot strengthen it beyond its baseline mechanical properties, and can make patients to tendon overuse and injuries.
BioPodsTM Variable Reflex TechnologiesTMBioPods foot insoles and footwear are designed to encourage healthy protective reflex function and work in harmony with the natural dynamic movement of the feet rather than attempt to artificially support, cushion, control, or restrict. When using BioPods arch insoles and footwear, your shoes should be loosely laced to allow room for adequate foot flexion.BioPods sports shoe insoles and footwear provide a safe “spring-like” variable stimulus under the center of your arches that continually engages and optimizes your body’s Protective Reflexes in the feet, legs, hips, and back when walking, running, or other weight-bearing movement.Regular variable stimulus challenges the body's natural proprioceptive and protective reflex mechanisms and causes them to adapt towards healthier function. Even though the stimulus is at the sole of the foot, it affects proprioceptive and reflex function in the feet, legs, hips, and back.With regular use, this variable stimulus challenges the body's natural proprioceptive and protective reflex mechanisms, causing them to adapt towards healthier function.
Soft and flexible for best resultsBioPods insoles for shoes and footwear work in harmony with the feet to provide the greatest therapeutic, performance enhancement, and comfort benefits. When using BioPods shock-absorbing insoles and footwear, your shoes should be loosely laced to allow room for adequate foot flexion.
Soft Tissue Adaptation PhaseWhen using BioPods running insoles and footwear for the first time, the body's neuromuscular systems will undergo a Soft Tissue Adaptation Phase as the feet, legs, hips, and back respond to the BioPods stimulus. As with any neuromuscular muscle training, the Soft Tissue Adaptation Phase takes approximately 6-8 weeks for most individuals but can take longer for those sufferers noted below. During this period, it is normal to experience transitory twinges or tightness in various areas at different times. It is during this period that latent historical scar tissue or fibrosis may become noticeable in the form of soreness. Seek advice from medical professionals who specialize in soft tissue mobilization, as noted below, if soreness persists.
BioPods over pronation insoles and footwear do not treat already damaged tissue, such as scar tissue or fibrosis that has been caused by trauma or maladaptation related degenerative stresses from poor foot mechanics and function. Damaged tissues can be treated by a medical professional with complementary conventional mobilization therapies such as ultrasound, deep tissue massage, A.R.T. (Active Release Technique), or Graston Technique, as appropriate.
RECOMMENDATION for sufferers of chronic myofascial pain, fibromyalgia, plantar fibrosis, or multiple trigger points:
It may take longer to adapt to the BioPods’ stimulus. It is possible that enough inelastic scar tissue or fibrosis has developed to cause transient pain or “sticking points” that will reveal themselves during the Soft Tissue Adjustment Phase. In these instances, a medical professional can apply a regime of complementary soft tissue mobilization therapies such as ultrasound, deep tissue massage, A.R.T. (Active Release Technique), Graston Technique, etc., to break down the scar tissue or fibrosis and restore elasticity to the soft tissues for full mobility.