The muscle spindle is a type of sensory receptor found in skeletal muscle, and it is responsible for detecting changes in the length and tension of the muscle. These receptors are located within the muscle tissue, and they contain specialized sensory cells that are sensitive to mechanical stimuli. When a muscle is stretched, it activates the muscle spindle, which fires a signal to the brain. The brain then processes this, and we experience the sensation of stretch.
As mentioned above, the sense of stretch allows the body to register the pulling of the muscles through muscle spindles. Like tension, it indicates an amount of stress on the muscle. Again, the stress can be distress, but it can also be a beneficial stress to improve the body and allow it to have knowledge of the body’s state. This occurs when the body is extending itself beyond a normal or minimal range. The sensor ensures no harm or annunciates any issues with the muscle. Because we are trying to use the senses to help design and not to injure, we will only look at the use of stretch and the muscle spindle for good within our frame of design. Like tension, we will explore stretch through the movement of the body across space. Unlike tension, the exploration will not be through typical use of the space and structure, instead it will be through exercise and pulling the muscles beyond a standard range. Some examples include reaching overhead for an object on a shelf or down over a guardrail. So, like tension, it is about the movement of the body through space, but instead, it is exploring the limits of the body in space as well as the limits of the space itself.
We can use the design installation to encourage the body to stretch beyond its normal limits. Again, this is not meant to be an exploration of pain, so it is a controlled extension. How do we make individuals exercise and stretch? We need to draw them toward attractions and those attractions should be near the limits of reach. Up, down, and beyond obstructions, such as gates, rails, and furniture. What are they reaching for? What do they want? Physical and social interaction, exercise, food and drink, and entertainment are all viable reasons, and this is likely where the designer should push the concept of stretch in a design installation.
As with tension, exploring design as only stretch is enticing and would rely on the limitations of motion. However, we would need to utilize tension and proprioception to reach those limits. Therefore, being strictly stretch is not likely possible, yet we should use these other senses to reach the limits and define a space as well as define the body within the space. The sense of stretch would be variable with a plateau which we would not want to meet, as this is the realm of overextension and pain. Using exercise, such as yoga to understand the limits allows the individual to know themselves physically, but it would also allow the one exercising to know how to index the limits of the body in space, defining the realm of use and the margins.
To design without the use of stretch would entail the lack of movement, and all dynamism in the project is lost. This is not ideal, and as mentioned in tension, we realize the use of space is not required, because there is no movement, and therefore the design would be flat, lacking depth and roundness. What is the purpose in such a space? Why would we do this?
Beyond the movement to the limits, stretch can also be used to communicate. To stretch is to provide a small amount of stress, and the stress can be coded as a signal or even a language to share information. One can use something like Morse code or the simple introduction of the sense to amplify other information or senses, such as using stretch to add import to aural information or to provide an announcement of danger or change. Although the experience of stretch is variable, we can treat it as binary, unless we can translate the extent of the sense. This variability adds one dimension which can provide the magnitude of the information. Otherwise, the coding will be simply off and on.
Using stretch in an existing space requires the designer to survey the space for the areas just out of reach, such as stairways, open expanses, and areas overhead. Pairing stretch with other senses to provide impetus to use the sense is a fine combination, complementing one sensory experience with another. Again, we must have attractions or moments of interest that encourage the user to stretch, and these are surely given through the use of other senses. Furthermore, interaction with others requires other forms of touch, hearing, and vision, beyond stretch. Exercise requires proprioception, multiple forms of touch, and often hearing or vision. Entertainment can use a large range of senses, but the question is what is the entertainment that requires stretch? A good precedent is seeing over others in a crowd during a presentation or performance. But, what are other examples we can use?
If tension is the motor for motion, stretch is the boundary of motion. Really, it is stretch that defines the space, when not relying on vision, and though tension through motion may create the space, it is stretch that sets the limits. With use, we are able to extend beyond the limits, and we grow and change, the index of these limits provides the definition of this growth and change.