Effects of Postural Change of the Shoulder on EMG Reaction Time of Triceps Brachii

Abstract

Postural dependence of electromyographic reaction time (EMG-RT) of triceps brachii in normal subjects was examined at neutral (N) and facilitating (F) positions. EMG-RT was faster at F than at N; moreover, the slower one''s EMG-RT, the larger the difference of EMG-RTs. F position of arms causes the shifting of EMG-RT through two biasing systems. The action of one system arises from either arm and acts on both arms, as the facilitation and its intensity depend on one''s EMG-RT. The other system arises from one arm, and facilitates the ipsilateral arm but inhibits the contralateral arm; its intensity is independent of one''s EMG-RT. The amount of the shift is determined by the added contribution of those two actions.

Arousal response induced by postural changes in patients with subacute myelo-optico-neuropathy, "SMON".

“…However, the ratio of RTs between the two positions is constant in normal subjects so that the smaller ratio corresponds to the larger effect of facilitating positions on behavioral alertness or arousal in each subject (Nakamura et al 1979 ;Taniguchi et al 1980). Thus, the main findings in this study were that the effect of the facilitating positions on the shortening of RTs was similar in both the normal and the SMON group when applied to the upper extremity but was different when applied to the lower extremity ; the patients without dysesthesia performed so well as the normal subjects and the patients with dysesthesia showed a large amount of RT shortening.…”

“…Recent studies have shown that changes of the proprioceptive input lead to shift of arousal and thus to variation of RT (Maria 1970;Nakamura 1983). The difference of RTs between two postures is definitely related to one's RT, so that it is possible to compare the arousing effect of postural changes among subjects using the ratio of RTs between two postures as a variable (Nakamura et al 1979;Taniguchi et al 1980). If physical stimuli such as muscle stretch cause dysesthesia or paresthesia, they should be accompanied with abnormally high arousal response.…”

Optimal Vibration Stimulation to the Neck Extensor Muscles Using Hydraulic Vibrators to Shorten Saccadic Reaction Time

“…Possible physiological factors accounting for this shortening may be ascending brain activation mainly from the brain stem, which contains the reticular formation, or descending activation from the cerebral cortex in accordance with neck muscle action (Taniguchi et al, 1980;Grantyn and Berthoz, 1987;Vallar et al, 1995;Berthoz, 1996;Shimura and Kasai, 2002).…”

The effect of PNF position of the upper extremity on rapid knee extension.

“…behavioral alertness ; force output ; PNF position ; reaction time It is empirically known that facilitating positions utilized in proprioceptive neuromuscular facilitation (PNF) technique make it easy for a subject to start and carry out patterned movements. Recent studies indicated that facilitating positions induced behavioral alertness, since premotor time (PMT) of the triceps brachii muscle, a latency from a response signal to the onset of EMG activities of the muscle, was short at the facilitating position compared to neutral or kinesiological reference position (Nakamura and Viel 1974;Taniguchi et al 1980), and also indicated that vocal reaction time was faster at facilitating position of the upper or the lower extremity than at the neutral position (Nakamura 1983). Although facilitating positions generally decrease PMT, their effect on force output in a reacton time study has not been examined.…”