Watching a gymnast demonstrate their acrobatic ability, or a parkour cruise effortlessly over urban obstacles, or a martial artist maneuver around opponents as if dancing always leaves a spectator amazed at the range of human athleticism. But imagine if an individual, never having trained or practiced any of these skills, suddenly was able to perform any of these things after watching someone else do it…
The concept of being able to immediately replicate any physical movement after a single observation is colloquially known as muscle mimicry. As fantastic as this skill may sound, it would require the co-ordination of several superhuman abilities, namely eidetic memory, heightened strength, agility, and flexibility with the possible inclusion of increased visual acuity.
A large component of muscle mimicry would be an increased capacity for neuromuscular adaptation. In the context of muscle training, neuromuscular adaptation refers to the ability of the human body to “program” muscles to remember a movement, or series of movements through repetition and practice. While the muscular component is inherently understood in this process, the neural role, i.e.- which components of the nervous system are recruited and activated for a particular physical activity, is equally as important. Together, these factors create muscle memory, where an action that has been trained repeatedly can be performed without conscious effort. This can be readily observed in well trained athletes and performance artists such as dancers.
So while the individual instances of eidetic memory, neuromuscular adaptation and muscle memory occur occasionally for the former, and as a part of normal human existence for the latter two, the integration of superhuman versions of all these would be necessary for muscle mimicry to occur.
That said, there is a fascinating type of synesthesia that some humans are born with that approach a muscle mimicry phenomenon. Mirror synesthesia refers to the human ability to observe the physical contact that another human being occurs and experience it on their own body. For example, some mirror synesthetes will see someone across the room grabbed by the elbow, and they will feel as if their own elbow has been grasped. Such an ability has complications, however, as mirror synesthetes cannot watch violent movies, for example. The pain that they see inflicted on characters in the movie is not just observed but felt, and most of these individuals cannot tolerate watching such films without literally feeling injured.
From this perspective, if the human capacity for a physical empathic ability such as mirror synesthesia exists, muscle mimicry remains probable, not impossible. A lack of documented evidence does not mean proof of absence, particularly in light of the fact that precursor abilities are demonstrated as regular components, or variants, of normal human neuromuscular physiology. Perhaps integration of these skills into a phenotype of muscle memory is part of the next step in human evolution… or maybe it remains an existent skill that just needs to be nurtured.