1. Introduction

The human body is exposed to mechanical loads throughout its life. Aside from forces deriving from ubiquitous and penetrating fields, such as gravity, or forces due to electromagnetic fields that are non-contact in nature and as such effective over distances, there is a great variety of forces acting on the human body from contact with the surrounding environment. In addition, numerous forces are generated in the course of physiological processes inside the body, in the different organs and tissues. Throughout evolution, all forms of life, including plants, animals and humans, adapted their physiology to mechanical interactions; some of them to the extent that proper function requires the influence of forces, for example bone remodelling. Mechanical forces are known to modulate cell development even in utero.