The National Safety Council listed falls as the third ranked cause (14.6%) of unintentional deaths in the general population of the US. It is postulated that an attempt to control the COM is employed to prevent falls during perturbed gait. The goal of this research was to gain an understanding of (1) the relationship between COM dynamics at slip initiation and slip severity, and (2) how individuals control their COM dynamics when warned about the possibility of slipping (anticipatory control). The dynamics of the body's COM during slips may reveal insights into the biomechanical reasons behind the high prevalence of slip-precipitated falls in the elderly. The findings may also be helpful in differentiating between postural strategies that successfully recover balance and responses that result in falls.Sixteen healthy young (20-35 yrs) and 11 older (55-70 yrs) subjects were exposed to an unexpected slip (no prior knowledge of the floor's contaminant condition), and alert slip (warned of the potential contamination), and known slip after two baseline walking trials. Body motion from 79 VICON markers attached to the body was sampled at 120 Hz. Segmental mass was generated using a segmental analysis. For an unexpected slip, maintaining the COM closer to the leading leg, an elevated COM position and fast medial-lateral COM transfers to the slipping leg at heel contact were associated with an increase in slip severity. For anticipation conditions (alert and known), COM placement and velocity was geared toward continuing the gait cycle. Age was significant in regards to COM position variables
