Figure 1: As we age, our posture becomes increasingly more stooped (yellow arrows) leading to a reduction in hip angle (orange lines) and corresponding joint movement, and a shortened stride length
Walking is an essential motor skill used during the activities of daily life. There are factors that can affect an individuals’ stability during locomotion and should be considered when determining the risk and probability of sustaining an injury due to a slip, trip or fall. The mechanisms of walking and gait control can be disrupted by certain neurological diseases or aging, resulting in increased gait unsteadiness and risk of falling.
Every year, over one-third of adults over the age of 65 fall. Trips and slips are the most common causes of falling, accounting for up to 60% of all falls. Research has found that as we age, our gait changes, wherein older people reduce their speed and stride length, increase their step width, reduce the joint range of motion and typically walk with a more stooped posture (Figure 1). It is generally assumed that these changes are adaptive and lead to an increase in stability during walking. Additionally, older individuals may experience reduced vision, increased reaction times and other cognitive impairment, all of which increase the probability of slipping or tripping.
In humans, recovery from a loss of balance due to slipping or tripping relies on a rapid and effective protective step either behind or in front of the center of mass in order to recover balance. People tend to increase the step length and generate a strong push off in the recovery foot order to recover balance after a trip and avoid falling, while fall avoidance after a slip is dependent upon arresting motion of the slipping foot and rapidly lowering the non-slipping limb to the ground behind the center of mass. Recovery of balance after a slip or a trip becomes more limited as we age. Initially, people tend to be leaning forward due to the stooped posture and have a reduction in joint movement which further decreases their ability control to swing the recovery leg in order to take a large step. Additionally, decreases in muscular strength and delayed responses in generating adequate muscular forces to push off the recovery foot contribute to the overall increased risk of falling as we age.
In light of the increased risk of falling associated with age, it is important to examine the conditions in which the fall occurred and keep in mind that older individuals are more susceptible to slips and trips, and are less likely to recover their balance which ultimately results in a fall. Furthermore, older individuals are more likely to sustain a severe injury when compared to a young individual due to increased fragility and reduced elasticity of bone, muscle and ligament in an older individual.