Paramagnetic response of muscle-type systems

We provide a prototypical description of mechanically-induced collective conformational change (folding), relevant in a variety of biological contexts from muscle contraction to hair cell gating and integrin binding. Our study is inspired by the seminal Huxley-Simmons (HS) model which we reinterpret from the perspective of stochastic dynamics involving rigidly coupled bi-stable elements. In this interpretation the HS model can be mapped to a paramagnetic Ising model, however, the equivalence is not complete due to the presence of elastic elements responsible for negative susceptibility and quasi-critical behavior. We go beyond the conventional chemo-mechanical description of such systems, revealing both its strengths and its limitations.