Flexible but stable – impossible but possible

Our bodies are a puzzling kind of thing: we can be flexible, but we can also be stable. We can’t be both at the same time, though. We can be stable enough to push a  heavy door open in one moment, and then be flexible enough to bend down to tie our shoe-laces, in the next moment.

This can be explained in terms of soft matter physics, and in plain English best thought of in terms of Bio-Tensegrity.

But still, we are not too far from hard matter physics either: momentum, torque, distance, trajectory, rotational inertia, acceleration, displacement, weight, pressure, counter-weight, resistance, friction, … we can think in these terms too. They can help us to some degree, while learning, sensing, moving and improving.

Two important questions persist.

As physical beings we are not indestructible: material fatigue, structural damage, stress intensity, fracture toughness, yield strength, sheer stress, dislocations, overloading, … these terms apply to us just as well. And we can think in these terms too. They can help us to some degree, while learning, sensing, moving and improving.

The two question:

How long can we safely remain in any of the two opposites: how long can we safely remain stable, how long can we safely remain flexible?

How fast can we safely transition between the two opposites, or in other words: how and how long should a transition between these two opposites be?