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1.1 1 xml info:srw/schema/1/mods-v3.2 Liebermann D G author Hoffman J R author 2005 English This study investigated temporal patterns of EMG activity during self-initiated falls with different optic flow information ('gaze directions'). Onsets of EMG during the flight phase were monitored from five experienced volunteers that completed 72 landings in three gaze directions (downward, mid-range and horizontal) and six heights of fall (10-130 cm). EMG recordings were obtained from the right gastrocnemius, tibialis anterior, biceps femoris and rectus femoris muscles, and used to determine the latency of onset (L(o)) and the perceived time to contact (T(c)). Impacts at touchdown were also monitored using as estimates the major peak of the vertical ground reaction forces (F(max)) normalized to body mass, time to peak (T(max)), peak impulse (I(norm)) normalized to momentum, and rate of change of force (dF(max)/dt). Results showed that L(o) was longer as heights of fall increased, but remained within a narrow time-window at >50 cm landings. No significant differences in L(o) were observed when gaze direction was changed. The relationship between T(c) and flight time followed a linear trend regardless of gaze direction. Gaze direction did not significantly affect the landing impacts. In conclusion, availability of optic flow during landing does not play a major role in triggering the preparatory muscle actions in self-initiated falls. Once a structured landing plan has been acquired, the relevant muscles respond relative to the start of the fall. Adult Cues Electromyography Humans Male Movement/physiology Muscle Skeletal/*physiology Posture/physiology Psychomotor Performance/*physiology Vision Ocular/*physiology PMID:15642660 exported from refbase (https://refbase.nfshost.com/show.php?record=39), last updated on Mon, 31 Dec 2012 14:30:37 +0000 text http://www.ncbi.nlm.nih.gov/pubmed/15642660 http://www.ncbi.nlm.nih.gov/pubmed/15642660 10.1016/j.jelekin.2004.07.005 15642660 Liebermann+Hoffman2005 2005 continuing periodical academic journal 15 1 120 130 1050-6411 1