Effects of step length on stepping responses used to arrest a forward fall

Age-related differences in kinetic measures of landing phase lateral stability during a balance-restoring forward step

“…This finding, along with our observation that age does not affect step width or stability measures, suggests that older adults maintain stability by increasing strength usage when using a single step balance recovery maneuver. This phenomenon may be unique to single step balance recovery, since multiple steppers demonstrate altered kinematics, a strategy that likely involves smaller strength requirements [13,14,25]. Although we are not aware of previous work quantifying lateral ground and ankle reactions during stepping, our findings may be associated with age-related increases in utilization of sagittal plane ankle power during a similar single-step balance recovery task [22,26,27].…”

“…Integration error was minimized by ensuring the participant remained still immediately before and after stepping and assuming zero initial and final velocity. Initial COM position was calculated using a static equilibrium analysis about the ankle joints [13]. To quantify lateral stability, COM lateral position (d COM,land ) and velocity (v COM,land ) were computed at step foot landing time.…”

“…Each participant was released from a static forward lean position using a tetherrelease mechanism attached to a waist harness, approximately at the midpoint between posterior superior iliac spines [13,14]. The lean angle was adjusted until 20% body weight was supported, representing a large enough disturbance to require a step response for balance recovery.…”

Kinematics of the threshold of balance recovery are not affected by instructions limiting the number of steps in younger adults

“…Therefore, it is not response initiation but rather response execution that affects balance recovery from an initial lean. Do et al [18] and King et al [19] explored the effect of instructions to take a shorter, longer or faster step. At fixed initial lean angles below the maximum lean angle, they showed that reaction times, weight transfer times and step velocities were not affected by these instructions whereas step times and step lengths were affected.…”

“…Indeed, while several studies limit balance recovery to only a single step [4,6,12,14,16,19,20], some studies impose no limit on the number of steps [13,15,17,18]. Moreover, even when there is no limit on the number of steps, only data on the first step are reported.…”