This study was designed to improve the understanding of how standing at elevated surface
heights and the associated changes in the visual field affect human balance control.
Healthy young adults stood at four different surface heights (ground, 0.8, 1.6 and
3.2 m) under three different visual conditions (eyes open, eyes closed and eyes open
with peripheral vision occluded). Mean position, Mean Power Frequency (MPF) and Root
Mean Square (RMS) of centre of pressure (COP) displacements were calculated from 60s
standing trials, and psychosocial and physiological measures of fear and anxiety were
also collected. When standing at a height of 3.2 m, 10 of 36 participants reported
an increase in anxiety and a robust fear response while the remaining 26 participants
experienced only an increase in anxiety and no fear response. A between subjects analysis
of the effect of surface height on postural control revealed that fearful and non-fearful
participants adopted different postural control strategies with increased heights.
Non-fearful participants demonstrated a postural response characterized by increased
MPF and decreased RMS of COP displacements with increasing heights. In contrast, fearful
participants demonstrated both increasing MPF and RMS of COP displacements with increasing
heights. These findings demonstrate, for the first time, a direct relationship between
fear of falling and the strategies used for human postural control.