1. Introduction
imanual coordination is an important and challenging issue in motor learning needed in daily and recreational activities [3]. An important feature of performing bimanual skills is that both hands tend to do the same thing simultaneously. Sometimes the two hands do not necessarily do the same thing, and each hand acts separately, which is called asymmetric bimanual coordination [1]. Research shows that the central nervous system easily controls symmetrical movements but has limited control over simultaneous asymmetric movements [6].
Eye-hand coordination plays a significant role in bimanual tasks [20], and this role is more prominent in ball sports (due to constant contact with the ball, catching a ball, and multiple blows to the ball) non-ball sports. On the other hand, athletes in ball and non-ball sports experience various experiences, tools, and environments; therefore, one of the important questions of this study was whether the level of bimanual coordination skills between athletes in ball and non-ball sports is different.
No research has been done in this field so far. On the other hand, although most studies have reported gender differences in bimanual coordination skills in favor of girls, there are conflicting results in this regard [26]. This study aimed to investigate the asymmetric bimanual coordination differences in male and female athletes in a ball and non-ball sports.
2. Materials and Methods
This research was of an applied study with a causal-comparative nature. The number of samples was 30 people with a Mean±SD of 26.00±4.50 years of age from male and female athlete students of the Faculty of Physical Education, University of Tehran, who were randomly selected. In this study, to control the subjects’ level of experience, athletes active in the relevant sport at the semi-professional and professional levels were selected. Finally, the research samples were divided into two groups, with 14 people in the ball sports group (ball-related sports) and 16 people in the non-ball sports group (sports that do not require a ball or special tools).
It should be noted that ball sports included football, futsal, basketball, handball, volleyball, and table tennis, and non-ball sports included wrestling, karate, taekwondo, swimming, and track-and-field. Also, most of the subjects had a history of professional sports at the provincial and national team levels. To measure asymmetric bimanual coordination, the Vienna Test System was used, which was available in the “learning and movement control laboratory” of the Faculty of Physical Education, University of Tehran. All subjects completed the consent form for voluntary participation in the research and the physical health form. 
Kolmogorov–Smirnov (K-S) test was used for normal data distribution, and Levene’s test was used to assess the equality of variances of the groups. MANOVA statistical method was used to test the research hypothesis, and also Box’s M test was used to equalize the covariance matrix of the groups. A significance level of P≤0.05 was considered for data analysis.
3. Results
In Table 1, the performance time (speed) and error time (accuracy) of the research subjects were presented separately for male and female athletes in the ball and non-ball sports. 


These results confirm that ball sports athletes spent less total time on the task. Also, ball sports’ athletes had less total error time performing the task; that is, they had higher accuracy than non-ball sports’ athletes. Performance time by female athletes (with a mean of 28.83 seconds) and male athletes (with a mean of 38.94 seconds) indicated that girls had higher speed and better performance in performing the tasks. Also, in examining the female athletes’ error time (with a mean of 0.34 seconds) and male athletes (with a mean of 0.61 seconds), it can be concluded that girls had fewer errors and had a higher degree of accuracy in performing bimanual coordination task.
MANOVA statistical results indicated that there was a significant difference between girls and boys in the dependent variables of “performance time” (speed) and “error time” (accuracy) (P≤0.05). There was also a significant difference between ball and non-ball sports athletes in these dependent variables (P≤0.05). Finally, the statistical results of this study revealed that the interaction effect of the two variables of “ball and non-ball” and “gender” on the dependent variables of “performance time” and “error time” was not significant (P≥0.05). In general, the results of this study confirmed that in performing asymmetric bimanual coordination tasks, ball sports’ athletes performed better than non-ball sports’ athletes, and girls performed better than boys.
4. Discussion
One of the results of this study was that girls had a significant advantage over boys in performing asymmetric bimanual coordination tasks. It seems that one of the reasons for the superiority of girls’ performance over boys in this study was related to performing a delicate task that required the use of delicate muscles of the fingers with high accuracy. Also, the results of some studies by MRI showed that the area of the corpus callosum in girls was larger than boys, as a result of which the exchange of information between the two hemispheres of the brain was more accessible, which makes girls superior to boys in performing bimanual coordination tasks [30].
The better performance of ball sports athletes compared to non-ball sports athletes in performing asymmetric bimanual coordination skills was another result of this study, which can be related to years of practice and experience working with both hands and balls in the ball sports group. Also, the task arranged in this study required high coordination between hand and eye movements, which in various studies it has been confirmed that ball exercises have a positive effect on the eye and hand coordination [41]; therefore, one of the possible reasons for the superiority of the bimanual coordination skills of the ball group can be attributed to the stronger coordination between eyes and. Finally, due to the high importance of bimanual coordination skills in sports success [43], it is expected that sports coaches, especially in the education of younger ages, pay attention to this critical issue.

Ethical Considerations
Compliance with ethical guidelines
All ethical principles are considered in this article. The participants were informed of the purpose of the research and its implementation stages. They were also assured about the confidentiality of their information and were free to leave the study whenever they wished, and if desired, the research results would be available to them. A written consent has been obtained from the subjects. The study was performed in accordance with the Helsinki Convention.

Funding
The paper was extracted from a research project of the Dr. Yaser Khanjari & Dr. Elahe Arabameri, Department of motor behavior and sport psychology, Faculty of Physical Education and Sport Sciences, University of Tehran, Tehran, Iran.

Authors' contributions
All authors equally contributed to preparing this article.

Conflicts of interest
The authors declared no conflict of interest.

Acknowledgements
We would like to thank all the students of the Faculty of Physical Education, University of Tehran and the experts of the Learning and Movement Control Laboratory who helped us in this research.

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