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The purpose of this study was to examine the effect of skill level on variability of
intra limb coordination and control variables in top spin strike. The 16 participants
of this study were divided into two groups of Skilled and Novice. The Skilled group
was consisted of players who ranked as 8 top in national ranking at their age stage
and the Novice group was consisted of players who recently learned the top spin
skill. They performed 10 top spin strikes with emphasis on speed and accuracy.
Movement kinematics were recorded and analyzed. There was a difference
between these two groups in variability of intra limb coordination (p<0.05) and the
Skilled group performed more consistent. However, there was not any differences
between these two groups in movement control variables (all p>0.05). This study
showed that the skilled performers have more consistency in their movement
patterns, while it could be no difference with novice performers in control variables
as cause of task constraints.

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The purpose of this study was to investigate the effect of practice variability in physical compared with observational practice on golf putting performance. To this end, 50 male right-handed students (25±3.7 years) of the Ferdowsi University of Mashhad participated in this study. Participants were randomly divided into 5 groups (physical constant, physical variable, observational constant, observational variable, and control). During acquisition, the physical variable group randomly performed 50 trials from 5 different starting points to 2 different targets, but the physical constant group performed 50 trials from one starting point to one predetermined target. The observational variable and constant groups observed the performance of the physical variable and constant groups, respectively. The control group just participated in pre-and post-tests and did not practice any trial. Participants performed a test just like the pre-test 10 minutes and also 24 hours after practice. Putting accuracy was measured as the dependent measure. Results showed that variability of practice had a positive effect on participants’ performance than constant practice in physical and observational conditions (all P<0.05). Maybe the similar underlying mechanisms and also the similar feedback effects resulted in the higher performance of the variable group than the constant group in physical performance and action observation.

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The aim of the present study was to investigate the effect of inducing positive stereotypes on perceived competence, interest and motor learning in adolescent girls. Therefore, among all of the adolescent girls in Shiraz, 30 adolescent with the age range of 10-13 years were selected by convenience sampling. Participants performed 10 trials as a pre-test and afterward, they were randomly divided into two groups  . The acquisition phase consisted of 50 trials (5 blocks of 10 trials), and the task required participants to perform inside kicks at targets area attached to a wall and touching the ground. Twenty-four hours after the acquisition phase, participants attended retention test (with 10 trials) to check learning effects on them. The participants were asked to answer the questions related to perceived competence and interest before pre-test, after the acquisition phase, and before the retention test. To analyzing data, one way and Mix ANOVAs analysis and Independent T test were conducted using SPSS21 at significance level P≤0.05. The results showed that in the acquisition phase, all groups significantly increased their accuracy, though difference among groups was not significant. Also, the results showed that the induction of positive stereotypes led to higher perceived competence and motor learning in adolescent girls