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In the present investigation we determined the time course of attention demands during the jumping service in volleyball by the dual-task paradigm. Fourteen voluntary junior elite volleyball players performed 60 jumping serve. Jumping-serve performance (JSP) as primary task and verbal reaction time (RT) to an auditory stimulus that was administered in four probe positions (PP), as secondary task was measured. Repeated measures analyze of variance (ANOVA) showed no significant effect of the PP on JPS, indicates allocating the most attentional weight to the JSP. In second analyze, effect of PP on RT was significant, so that all probes RT were significantly higher than the base line RT, indicates attention demanding of the JSP. Results also showed that pre-shot in run-up (PP1) and after the ball strike (PP4) had the greatest attentional demands respectively while per-jump stepping ahead (PP2) and just pre-striking the ball (PP3) had respectively the lowest needs of attention. The results indicate that attention follows a non-linear pattern, in the JSP.

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In the current research, the dual-task paradigm was used to examine the temporal distribution of attentional demands during a tennis serve. Twenty experienced tennis players to performed tennis serves. The participants were asked to respond verbally to an auditory tone presented at four probe positions (PPs) during tennis serves. The probe reaction time measure of attention was administered during four segments of a tennis serve including preparation period (PP1), from onset of backswing-loading (PP2), from onset of forward movement just before stroke in the exploding period (PP3), and after the stroke during follow-through (PP4). Reaction time was significantly longer when the probe stimulus was presented at PP4 than those of the other segments. Reaction time at PP2 was significantly greater than those of PP1 and PP3. The results showed a unique non-liner distribution of attentional demands for tennis serves. It appears that monitoring of proprioceptive feedback following movement begins, and that initiation of corrective sub-movements is necessary for skillful performance of tennis serves. So it is concluded that from a motor control perspective, PP2 is the most important segment during a tennis serve.

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Focus of attention instruction has a great influence on performance and learning. The purpose of this study was to examine the predicted constrained action hypothesis in badminton backhand serv. 30 women student participants from physical education classes of University of Kharazmi are selected as sample. Participants are tested in probe task at different stage of serve after identifying base of reaction time, and level of attention demanding of different parts was measured. Then participants divided into two groups (internal and external focus of attention) and they are tested with their specific instruction again. The results revealed that first stage of serve has the most attention need (p<0/001), but there is not any difference between two groups and different serve stage in the effect of focus of attention type. Accordance with these results the constrained action hypothesis at discrete skills is not confirmed.