Think of red as energetic. Think of orange as enthusiastic. Think of yellow as joyous. Think of green as comforting. Think of blue as calming. Think of purple as luxurious. Think of black as accentuating.
These colors, such as in the context of using them to paint a room, evoke reactions and can cause certain effects. Interior decorators would likely encourage one to consider what effects/moods are desired and create the environment accordingly (and stylishly).
Believe it or not, movement is not much different. As a movement practitioner, it is our job to create an environment where movement creates a desired result. All movement should be purposeful, not arbitrary.
Think of flexibility. Think of positioning. Think of load. Think of assessment and training.
When thinking of the above, consider how the proprioceptors – especially the Golgi Tendon Organs – are being turned on and how that information is relevant to the ultimate task.
Our knowledge of the proprioceptive information provided by the Golgi Tendon Organs, like all the other mechanoreceptors, continues to increase but still remains limited from a functional perspective. Historically, Golgi Tendon Organs (named due to their location in tendons) were thought to serve a protective function. This resulted from research that demonstrated when an extensor muscle-tendon unit (MTU) was lengthened; the Golgi Tendon Organs in that MTU sent an inhibitory signal to the spinal interneuron. This effect was called autogenic inhibition because this signal would inhibit the contraction of the same muscle. Essentially the MTU would inhibit itself. With greater levels of tension, the increase in inhibitory signals could substantially reduce the force of muscle contraction. For this reason, it made sense to propose that Golgi Tendon Organs would protect the muscle from producing excessive force that could injure the MTU.
As science has evolved with improved measurement techniques, it has become very clear that the function of afferent information from the Golgi Tendon Organs is much more complex. A review article by Windhorst summarizes much of this new knowledge gained by studying spinal reflexes. While providing tremendous insight into the influence of afferent signals from the Golgi Tendon Organs, all of these results must be considered with caution because most studies are performed on animals in conditions that are far from true function. This blog will focus on a couple of the findings that have direct relevance for movement practitioners.
Windhorst’s article makes the case for the influence of Golgi Tendon Organs afferent information as being “dependent on the context and task of motor acts.” As evidence, he cites the autogenic inhibition example described above. Where the lb afferents from the tendon organs inhibit the alpha motor neuron of the same muscle. The lengthening in these experiments occurred from a quiet state. However, when the extensor MTU is lengthened in the context of weight bearing, the same afferent impulses from the Golgi Tendon Organs become facilitating to the extensor muscle. The functional use of the information by the body is context-dependent!
The article builds the case for afferent complexity by listing numerous other neurons that are influenced by Golgi Tendon Organs information including gamma motor neurons in the muscle spindles and different spino-cerebellar tracts. Windhorst discusses in detail the interesting “convergence of spindle Ia and tendon organ Ib afferents” on spinal interneurons that result in a number of different excitatory-inhibitory combinations. Other studies have shown that Golgi Tendon Organs' afferent information improves the muscle’s control of joint position and movement.
So what, who cares, why is this information so important? Gray Institute® has coined many phrases, including the following statement: “Movement turns on proprioceptors, proprioceptors turn on muscles, and muscles control the movement.” The proper (functional) movement is key, which is why 3DMAPS® (3D Movement Analysis & Performance System) is so vital to any assessment and any progression/program.
So let’s restate the question above: What is a movement specialist to do with this new information?
- First, the results would suggest that passive stretching is not the best preparation for function. Dynamic functional flexibility, where the tendon is stressed and lengthened while the muscle is actively contracting seems like a much better choice.
- Second, the position of the body relative to gravity (context) seems critical. If our patient’s / client’s function is upright, then our training should be predominantly upright.
- Third, tendon lengthening under load will provide the authentic combination of afferent signals that can modulate the response at the level of the interneurons.
- Finally, assessment and training require movements in three planes of motion under external loads to provide the “neuro-perceptual experience” needed to improve our patient’s / client’s function.
While the load is one progression (mobility and stability emphasis) within the Performance System of 3DMAPS®, it is important to note that all progressions within/throughout 3DMAPS® can be “loaded.” In fact, asymmetries may surface quicker for the naked eye to see when a movement has an external load component to it. (Learn more at https://www.grayinstitute.com/courses/maps.)
Load is one of the important considerations in the Performance Movements of 3DMAPS®. Load will provide the physiological stimulus for increased forced production in the muscle. Load will promote tendon elasticity and energy return. Load will increase the discharge of Golgi Tendon Organs to complement all the other proprioceptive information. Load, whether body weight or additional external forces, should be used in ways to replicate the desired functional tasks of those who come to us for help.
- Windhorst U, Muscle proprioceptive feedback and spinal networks. Brain Research Bulletin, 2007, 73:155-202