The influence of walking speed and gender on trunk sway for the healthy young and older adults.

SIR—Falls are a major problem for the elderly and others prone to fall [1–7], occurring frequently during walking [8, 9]. Maki et al. [10] suggested that the ‘cautious’ gait pattern, characterised by reduced walking speed and shortened step length, is adopted by older people to minimise the risk of falling. Somewhat paradoxically, these changes may predispose to trips and slips [11, 12]. Step width and length are influenced by walking speed [13]. It is difficult, however, to define stability during walking with thesemeasures. Trunk swaymay provide alternativemeasures as increased trunk sway is associated with an increased risk of falling [13–15]. Increased trunk sway occurs in the young when they walk slower or faster than normal [13], indicating that preferred walking speed is the most stable. A different conclusion was reached for older persons who show reduced sway velocities and angles with slower walking speeds [14]. Greater variability in trunk roll and pitch angle was observed at all speeds for older adults compared to younger people [16]. However, the effect of speed, on the amplitudes of trunk roll (side-to-side) and pitch (fore–aft) angle and angular velocity for both groups, has not been reported. In addition, there is a gender difference between the walking styles and the gait parameters [17–24], possibly for trunk sway too, at different walking speeds. In order to provide more complete data, the current study investigated the influence of age, gender and walking speed on balance measures in the form of trunk sway angles and velocities. It was hypothesised that these measures increase across walking speeds for both young and older people with larger values for the elderly. This hypothesis was verified except that trunk sway angles were not less for slower walking speeds than the preferred.