We studied the effect of concurrent tasks on motor control of gait wit
h dual-task methodology. Ten healthy subjects were instructed to perfo
rm different cognitive and motor tasks during gait on a conductive wal
kway. Footswitch signals were recorded and stride lime and double-supp
ort time were calculated. It was assumed that the former reflects gait
-patterning mechanisms and the latter relates to balance control. Stat
istical analysis showed an increase in double-support time when a memo
ry-retention task (digit-span) and a fine motor task (buttoning) were
executed simultaneously during gait. During gait performance of the co
gnitive task declined compared to baseline conditions. Attentional dem
and of concurrent cognitive and motor tasks appeared to force subjects
to modulate their gait strategy to ensure control of balance. Stride
time was consistent across task conditions except when subjects perfor
med fast finger-tapping during gait. Then all but one subject showed a
decrease in stride time and an increase in stride-frequency that was
repeatable on retest. Since different rhythmic movements are likely to
share common neurobiological networks, we assumed that the modulation
of stride-frequency was due to structural interference.