[Isometric forces generated by the human wrist: force trajectories with and without a visual target].
The force trajectories of isometric wrist flexor efforts and corresponding EMG activity of forearm muscles were studied in healthy subjects. A target effort of 50 N was developed after the sound signal: the target level and force trajectory were displayed on the TV indicator. Force trajectories under conditions of visual control, kinesthetic control (without a visual target) and with random alternation of these regimens were compared. Wrist flexor EMG latencies were approximately equal under visual and kinesthetic control and noticeably longer when these conditions were alternated randomly. Relative error of the target effort reproduction and duration of late components of force trajectories were higher in absence of the visual target. When visual and kinesthetic regimes were alternated randomly the delay between EMG onset and force trajectory initiation increased; its values correlated positively with the duration of the first force derivative increase. Formation of different strategies for force trajectory correction under different experimental conditions is discussed.
Piatigorskiĭ
B Ia
BIa
Ivanov
A E
AE
D000328:Adult; D004576:Electromyography; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology*; D007699:Kinesthesis / Q000502:physiology*; D008875:Middle Aged; D014796:Visual Perception / Q000502:physiology*; D014955:Wrist Joint / Q000502:physiology*
Izometricheskie usiliia, razvivaemye zapiast'em cheloveka: silovye traektorii pri nalichii i otsutstvii vizual'noĭ tseli.