Habitual upright walking is a characteristically human trait that provides a challenging set of physiological challenges. When standing erect, two-thirds of the body’s mass is located two-thirds of body height from the ground, precariously balanced on two narrow legs with the only direct contact with the ground provided by the feet [1]. Such a structure challenges the basic principles of mechanical engineering and requires a highly developed postural control system to ensure that the body remains upright. However, in order to progress forwards, it is necessary to repeatedly initiate a forward fall and then ‘re-capture’ this momentum by the appropriate placement of the leading limb. The potential for a loss of balance when performing an apparently simple task such as walking is considerable. It is therefore not surprising that between 50 and 70% of falls in older people occur when walking [2–4]. The aim of this chapter is to provide an overview of the literature pertaining to gait patterns in older people and their relationship to falls. Specifically, this chapter will address gait characteristics during level walking, when distracted by secondary tasks, when stepping over, avoiding, and approaching obstacles, during turning, stair walking, and the ability to respond to trips and slips.

Postural stability can be defined as the ability of an individual to maintain the position of the body, or more specifically, its centre of mass, within specific boundaries of space, referred to as stability limits. Stability limits are boundaries in which the body can maintain its position without changing the base of support [1]. This definition of postural stability is useful as it highlights the need to discuss stability in the context of a particular task or activity. For example, the stability limit of normal relaxed standing is the area bounded by the two feet on the ground, whereas the stability limit of unipedal stance is reduced to the area covered by the single foot in contact with the ground. Due to this reduction in the size of the stability limit, unipedal stance is an inherently more challenging task requiring greater postural control.