While only seven days after our submission to Nature the editor stated

We certainly have no doubt that your model will be of value to others seeking a deeper understanding of human gait; and we don’t question that the insights so obtained could be relevant in a variety of therapeutic and artificial contexts.

he also said

But as the broader implications of your findings have yet to be elucidated, we are unable to conclude that the paper offers the sort of striking advance that would be likely to excite the immediate interest of Nature’s broader audience.

and advised us to transfer the manuscript to Nature Communications. Which we did not do but instead transfered to Nature Physics first, hoping to receive feedback before Christmas. This did not happen and after 28 days the editor of Nature Physics told us

In the present case, we have no doubt that your mathematical description of the dynamics of human walking will be of inherent interest to fellow researchers working on this and related topics.

but at the same time stated

As you may know, in deciding which papers to publish we have to make an editorial judgement about the immediacy of interest to our readers and the degree and nature of the advance demonstrated.

and suggested to transfer to Nature Communications, which we ultimately did last week. We are still waiting for an editor to be assigned and meanwhile I am wondering who is this audience of Nature and Nature Physics (not to forget Science, of course)? Why are they reading these journals and what are they looking for? And how do the editors know, what this is? Very curious to me.