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Excerpt
Since Weiss (1965) introduced the measurement of reaction time (RT) components with electromyography (EMG), pre-motor time (PMT) and motor time (MT) have been used to identify the central (cognitive) and peripheral (neuromuscular) components of voluntary movement initiation in human performance research (Adeyanju, 1982; Clarkson & Kroll, 1978; Ito, 1991). PURPOSE: To examine RT, PMT and MT for supination and pronation hand/forearm movements across four consecutive days.
METHODS: Sixteen right hand dominant college students volunteered for the study (8 male, 25.75 ± 4.23 yrs; 8 female, 25.50 ± 4.04 yrs). Based on the EMG activity of the pronator teres and biceps brachii, fractionated RTs of pronation and supination were measured for each hand for four consecutive days. A three-way (gender × day × movement) ANOVA with two repeated measure factors was the design used in the study. RESULTS: RT decreased significantly (p<0.05) from day 1 to day 3; no significant change was found between day 3 and day 4. PMT significantly decreased from day 1 to day 2, but not from day 2 to day 3 nor from day 3 to day 4; the PMT between day 2 and day 4 was significantly different (p<0.05). For MT, no significant differences were found among the days. Based on the trend analysis of the RT measures, the average RT, PMT and MT of day 3 and day 4 were used for further analysis. Significant RT and MT, but not PMT, differences were found between the pronation and supination movements (p<0.05). Males and female did not differ significantly on any of the measures. No significant differences were found between the right and left hands for any of the measures. Significant RT and MT differences were found between supination (RT = 228.19ms, MT = 60.49ms) and pronation (RT = 221.53 ms, MT = 55.32ms), but no difference was found for PMT (supination = 167.71ms, pronation = 166.21ms). CONCLUSIONS: RT is task related and the measurement schedule can affect RT and its fractionated components. At least 3 consecutive days of 20 trials per day is recommended for determining a reliable simple RT measure that reduces the effects of learning. The initiation of a pronation movement was faster than a supination movement, and the difference could be attributed to neuromuscular (MT) instead of cognitive (PMT) factors. The measures were not a function gender or hand differences.
