Abstract In contrast to many systems studied in the field of classical mechanics, models of animal motion are often distinguished in that they are both highly uncertain and evolve in a high-dimensional configuration space Q. Often it is either suspected or known that a particular motion regime evolves on or near some smaller subset Q 0 ⊆ Q . In some cases, Q 0 may itself be a submanifold of Q. A general strategy is presented in this paper for constructing empirical-analytical Lagrangian (EAL) models of the mechanics of such systems. It is assumed that the set Q0 ⊆ Q is defined by a collection of unknown holonomic constraints on the full configuration space. Since the ana- lytic form of the holonomic constraints is unknown, EAL models are defined that use experimental observations {z1,…,zN} ⊆ QN to ensure that the approximate system models evolve near the underlying submanifold Q0. This paper gives a precise characterization of a probabilistic measure of the distance from the EAL model to the underlying submanifold.