The effect of a sensory perturbation on step direction or length while crossing an obstacle from quiet stance.
OBJECTIVE
The purpose of this study was to investigate the effect of a sensory perturbation on step length and direction while crossing an obstacle from quiet stance.


METHODS
Nine healthy adults were asked to step over an obstacle to land on a primary target (normal stepping condition). Following a light signal subjects had to respond as quickly as possible by stepping to secondary targets either forward or diagonal to the primary target.


RESULTS
Distinct changes in the slope of the anterior-posterior (Fx) and medial-lateral (Fy) ground reaction forces occurred 176 ms following the light signal. For diagonal stepping stance limb tibialis anterior (TA) and bilateral gluteus medius (GM) were responsible for directing the swing limb to the target. An increase in step length towards the long target was achieved primarily by activation of bilateral GM.


CONCLUSIONS
Both EMG and force plate changes suggest that diagonal stepping is a more complex and challenging task than long stepping.
Kim
Hyeong-Dong
HD
Department of Physical Therapy, College of Health Science, Catholic University of Daegu, 330 Geumnak 1-ri, Hayang-eup, Gyeongsan-si, Gyeongbuk 712-702, Republic of Korea. hdkimx0286@yahoo.com
Brunt
Denis
D
D000328:Adult; D000704:Analysis of Variance; D004576:Electromyography; D005260:Female; D005528:Foot / Q000502:physiology*; D005684:Gait / Q000502:physiology*; D006801:Humans; D008297:Male; D009068:Movement / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology; D004856:Postural Balance / Q000502:physiology; D011336:Probability; D011434:Proprioception / Q000502:physiology*; D011597:Psychomotor Performance; D011930:Reaction Time; D012494:Sampling Studies; D012680:Sensitivity and Specificity; D013647:Task Performance and Analysis; D055815:Young Adult