Available online at www.pelagiaresearchlibrary.com European Journal of Experimental Biology, 202, 2 (4):88-92 ISSN: 2248 925 CODEN (USA): EJEBAU Effect of athletes level of proficiency in coordination stability during in-phase and anti-phase movements Negar Arazeshi, 2 Pouneh Mokhtari, 3 Mohammad Vaez Mousavi Department of Physical Education, Boukan Branch, Islamic Azad University, Boukan, Iran 2 Department of Physical Education, Tehran Central Branch, Islamic Azad University, Tehran, Iran 3 Department of Psychology, Exercise Physiology Research Center, Baqiyatallah University of Medical Sciences and University of Imam Hossein, Tehran, Iran ABSTRACT Although in-phase movement patterns are performed more stable than anti-phase movement patterns, the recent evidences suggested that stability during anti-phase movements are affected by the athletes level of proficiency. Therefore, this study targets the effect of athletes proficiency in stability of bimanual coordination movements. The performance of 30 novice and expert athletes of hip hop during two selected in-phase and anti-phase movement patterns was recorded using six, 00 Hz cameras in 3D format. Data was being processed using MATLAB software and analyzed afterwards. The results of two-way factorial analysis of variance (ANOVA) with (α 0.05) showed that stability during in-phase movement pattern is identical in both groups of novice and expert athletes. It is also noted that novice athletes movement is more stable during in-phase pattern compared to anti-phase pattern, which had no change during in-phase and anti-phase movements in expert athletes. The result of this study discusses the effect of practice on acquiring proficiency in performing anti-phase movements. Keywords: bimanual asymmetric coordination, hip hop, in-phase movement pattern, anti-phase movement pattern, level of proficiency INTRODUCTION Coordination of various body organs is needed to perform too many skilled movements successfully in daily life. Running, driving and manipulating objects are being done with maximum precision and harmony by human beings everyday [2]. Harmony and coordination is one of the essential and coherent elements of movement. These harmonious sophisticated performances require organized body muscles to direct the performed talent in fulfilling the desired goal [2]. The study of performing and controlling the coordination movements as well as the effective factors in controlling and performing such movements showed the existence of general rules and principles in performing all types of coordination movements [7, 9, 2]. Talented movements which have been performed coordinately during in-phase and anti-phase states using symmetrical organs are also among the mentioned movements. In-phase movement is a movement which happens synchronously in two symmetrical organs such as hands or foots with identical spatial and temporal characteristics in which, the same muscles in two symmetrical organs contract synchronously. Contrary to this, an anti-phase movement pattern is intermittent contraction of two identical muscles in two symmetrical organs with different spatial or temporal characteristics [6, 24, 25]. The difference between temporal characteristics of movement is being defined by relative phase. The position of an organ during a movement cycle compared to other organs in the same cycle is being defined by relative phase. Therefore, it is zero during in-phase movements and is variable from 30, 45, 90 and 80 degrees during anti-phase movements [8]. The timing of the movement in performing a movement pattern would remain constant as long as 88
the relative phase of that movement is constant. Any increase in rate or frequency may damage the coordination performance of a movement pattern and consequently transfer this pattern spontaneously to another coordination pattern. For instance, a parameter such as rate may decrease the stability of an anti-phase movement pattern and modify the movement to in-phase movement pattern. A more stable performance is acquired when a movement pattern is being performed longer with less error and the relative timing of the movement lasts longer [7, 2, 6]. Stability confirms the consistency of the movement while the performance becomes more consistent by more practice, i.e. more practice makes the performances of an individual more identical. While the skill consistency increases, specific features during a performance become more stable, with which any minor change in personal or environmental characteristics does not easily affect the learned behaviors [2]. Bogaerts and Swinnen (200) has concluded that performing most bimanual coordination patterns in which the two limbs have more spatial orientation is easier and more stable, while performed by the participants. Therefore, in-phase tasks are being performed more stable than the anti-phase tasks. Mulvey et al. (2005) findings showed that even a different spatial orientation of two hands, makes one hand move slower than the other and as a result, modifies the performance. Lee, Swinnen, and Verschueren, (995) also performed another research and found that motor control system of the body tends to perform identical spatial patterns in performing coordination movement patterns and also prefers synchronous bimanual performance compared to different bimanual tasks. Generally speaking, most studies suggest in-phase movement pattern is more stable than anti-phase pattern [, 2, 3, 4, 5, 9,, 3, 9]. Rebecca and Richard (2007) research results show a strong relationship in bimanual in-phase tasks. This means body motor control system applies a single mechanism for controlling synchronous movements of two symmetrical limbs of body, which confirms the existence of a pre-determined movement pattern during in-phase coordination movements. Since the tendency of two limbs in performing an identical job at the same time is one of characteristics of the inter limb movement skills performance, therefore it is rational for two limbs to pre-struggle in order to create an identical spatial and temporal pattern [2]. One of the key factors in stabilizing these movements is the control of coordination movements. Some studies show that symmetrical limbs movements with different spatial and temporal pattern are being controlled in a parallel way [8]. Parallel process has a high tempo, does not need concentration, is spontaneous and can t be stopped after the process is being started [6]. As a result, if anti-phase movements are being controlled in a parallel format, increase in error and stability decline occurs in this pattern due to the interference which happens as a result of simultaneous process of two different movement programs in two symmetrical limbs. Despite the number of researches which support the upper theory [, 3, 5, 9] and show in-phase movement patterns are more stable than the anti-phase movement patterns and proofs mentioned in confirmation of these results [4,, 3, 5, 8], some finding have not confirmed the abovementioned theory and showed that stability of anti-phase and in-phase movement patterns may be identical [7, 7, 22]. The results of these researches are mainly explained from the dynamic systems point of view. From dynamic systems and coordination structure theory point of view, a group of muscles which are acting together as a single unit, create a coordination structure and are being controlled by single movement program. The muscles which are present in a coordination structure respond to the production of a coordination movement at the beginning of performing a movement program. Later, the individual s body motor control system re-organizes the coordination structure in order to control the various movements in symmetrical organs if performing different movements of two symmetrical organs with different spatial patterns or different temporal characteristics are needed. Consequently, anti-phase movement patterns are being formed [2]. One of these researches is being done by Dessing et al. (2007) which showed that the movement stability during in-phase and anti-phase patterns in jugglers is the same. This contradiction is being discussed by the researchers and some factors such as change in relative phase and location, velocity of tosses, as well as the use of oscillations of other parts of the body and the unconstrained nature of eye movement are being found as the possible reasons of these unexpected findings. Nonetheless, skill of the participant was their major factor which has been emphasized by the researchers as the reason of this paradoxical result [7]. This issue is still unclear due to the lack of supplementary studies to discuss the role of these factors in stability of in-phase and anti-phase movement patterns. The main reasons of carrying out the current research are the existence of two different theories in controlling antiphase coordination movements and the paradox occurrence in Dessing et al. (2007) results compared to other studies in this regard [, 3, 5, 8] and also the possible effect of practicing and rehearsal in stability of in-phase and antiphase coordination movements according to Wenderoth et al. (2003) and Smethurst and Carson (200) researches. This research seeks to investigate the pattern stability in both in-phase and anti-phase movements of novice and expert groups of athletes in order to compare the effect of participants level of proficiency in both in-phase and anti-phase movement patterns. MATERIALS AND METHODS Participants Fifteen healthy male athletes who were expert in hip hop (Average age: 24 ± 5, average aerobics experience: 5.8 ± 3 years) were chosen among final nominees of the national physical preparedness competition which was held in summer 2009 and formed the Expert group. Another 5 healthy male participants (Average age: 2 ± 4, average 89
aerobics experience: 8 ± 4) also formed the Novice group of this study. This number of participants was sufficient to reach 80% of Statistical power. All the participants support leg was the right leg. Experimental setup Japanese Motion analyzer made by Vicon Co. which is located at Human factors engineering laboratory of rehabilitation and welfare department of Shahid Beheshti University was used. The main application of this device is to measure the kinematic data of movement (displacement, velocity, linear and angular accelerations) and consists of hardware and software parts. Hardware section consists of a calibrated area, cameras and markers. The calibrated area with 2.5 meter length, meter width and 7 centimeters height is the place to perform the movement tasks. Markers are small round shape tools which their outer surface is sensitive to infra-red beam and are applied based on the joint s size. Eight medium-size markers were used in this research based on the movement task and goal of this study. The cameras were equipped with diode lamps which emit infra-red beams. The markers are sensitive to this beam. After the marker detects the infra-red beam, its reflection is being detected by the camera and consequently the movement path is being recorded and transferred to the system. This camera is capable of analyzing 2D movements using one camera or 3D movements using two or more cameras. The applied device had 6 cameras and all the movements of the participants were recorded in 3D format and 00 shots per second. The software part of the device consists of a computer program which extracts the cinematic data of the movement by applying video synthesis on the acquired data from the cameras as well as following the movement path of the markers. Also, a questionnaire about the personal data of the participants such as age, support leg, doing sports years of experience, aerobics and hip hop years of experience, any previous injury or any fracture in hand or foot as well as their acquaintance of the current study s movement tasks was distributed and filled out by them. Procedure In order to respond to questions and obscurities of performing this research, a pre-research by participating 5 expert and 5 novice athletes was carried out. Complete analysis of pattern, direction, executor muscles and joints, contraction sequence, relative phase measurement and aerobic movement pace was performed in order to choose and determine the movement tasks of the research. Among the movement skills of hip hop, five specific skills of leg (2 in-phase pattern and 3 anti-phase pattern) and two specific skills of hand (one in-phase and one anti-phase pattern) were selected as the movement tasks of the research which were being done by all the pre-research participants. The pre-research row data analysis showed that examining angular changes in muscles during the movement can lead us to the goal of this research. Therefore, two specific coordination skills for leg (zigzag for inphase task and Jazz-square dance for anti-phase task) were selected as the two bimanual coordination tasks. The selected tasks had maximum compatibility with the research goal. The reliability of the applied devices based on the pre-research data process was (r=0.968) and its validity was (r=0.904). Some information regarding the goal of this research was given to the participants prior to the execution of movement tasks and each one of them performed the movement patterns in the calibration area for one time after filling out the questionnaire. Then, eight markers were installed on Distal Head of fifth Toe, lateral Malleolus, Lateral Epicondyle and posterior side of calcaneus on both right and left legs respectively. The markers were attached to parts of skin with minimal movement and slide on bones in order to prevent any irrelevant movement which may affect the research results. Each participant started his movement from the beginning of the calibration area and performed continuously each coordination movement task for six times. Internal and external femoral rotation was the in-phase pattern. In this task, both soles were horizontal and were abducting and adducting along the vertical axis (Femoral bone) simultaneously. Anti-phase pattern was rotational movement of each leg over the sagittal area along the frontal axis of the body. Naturally, while one leg was rotating towards the front, the other leg was moving toward the back. The main source of rotation on both legs was the femoral joint but the angular changes of right malleolus were different from the left malleolus during the movement. Cameras started to record from the start of each movement and transferred data to the system s software. Finally, data containing the position of each marker being placed on the participants joints in 3D format (X, Y, Z) and at every 0.0 second was acquired. Row data was analyzed using MATLAB software and desired joint s angular change, velocity and acceleration of the movement was obtained. Statistical Analysis Variable error of each six performances performed continuously by the athletes was measured for each in-phase and anti-phase tasks. Dependent t-test was used to compare the mean variable error of the groups in inter-group coordination movements and independent t-test was applied between two groups. The collected variable error data was analyzed using the ANOVA 2x2 which measures the in-phase and anti-phase patterns stability in novice and expert groups separately. Tukey test was also applied to identify the place of displacement. SPSS version 5 was used to carry out the statistical analysis with α 0.05. Matlab software was used in order to convert the row data into statistical data. 90
RESULTS Mean and standard deviation of the variable error in performing in-phase movements of expert athletes were 6.9 and respectively. These numbers for novice athletes were 6.22 and. This shows that stability of in-phase movement performance of both expert and novice athletes were almost the same. However, Mean and standard deviation of the variable error in performing anti-phase movements of expert athletes were 5.78 and.33 respectively which was more stable compared to the novice athletes data which was 8.5 and 2.66. Table- shows the summary of the ANOVA results. Table. Summary of ANOVA Source Movement pattern (A) Level of proficiency (B) Mutual effect (AB) Intergroup error Sum of square 3.4 28.43 27.6 26.4 DF 56 Mean square 3.4 28.43 27.6 2.25 F 5.84* 2.63** 2.07** Α α 0.05 α 0.0 α 0.0 Based on the finding in Table-2, F AB = 2.07 which was greater than F in Table 7.2 at α<0.05. Therefore, the mean differences of two participating groups and two different movement patterns were 95% significant. Significance of measured F also confirmed the mean difference of this study s elements. Results of Tukey s HSD test which were shown in table 2, confirmed that mean variable error of novice athletes in-phase movements was identical with the expert athletes but the mean variable error of novice athletes anti-phase movement was higher than the expert athletes. It also showed that mean variable error of novice athletes anti-phase movement was higher than their inphase movements. In expert athletes, however, the mean variable error of both in-phase and anti-phase errors were identical. Table 2. Tukey HSD test with critical range of 0.05 (* significance) Novice (in-phase) Novice (anti-phase) Expert (in-phase) Novice (anti-phase) 2.282* 0.00 Expert (in-phase) 0.0307 2.32* 0.00 Expert (anti-phase) 0.4407 0.853 2.72* 0 0.4 0.877 DISCUSSION AND CONCLUSSION Coordination is the necessary factor to reach the desired goal in most of the movements being carried out by the human beings. Among coordination tasks, bimanual coordination patterns are more important due to their common application in daily, sports and professional activities. Hip hop task is among the conceptual movement tasks which ordinary people are not able to perform them without practice. In this research, two movement tasks were chosen among the movement skills of hip hop and assessing the pattern stability of both in-phase and anti-phase movements of two novice and expert athletes was attempted. The results of this study showed that novice athletes are performing in-phase movement pattern more stable than anti-phase one. Expert athletes however, are performing inphase and anti-phase movement patterns identical according to this study. Conclusively, expert athletes stability of coordination movements was higher compared to novice athletes. As the first outcome of this study and in comparing the results of novice and expert athletes of this study, we found out that in-phase movement pattern stability of both groups of the study is identical. This result was according to the Zanone et al. (200) and Temprado et al. (2003) research results. These findings showed that it is not that difficult to perform in-phase movement pattern especially while relative phase of movement in two symmetrical limbs is identical and pattern stability during in-phase coordination movements can be maintained by applying minimal energy. Therefore, the ease of inphase movement performance is the most probable reason of its stability in both novice and expert athletes. The second outcome of this study was that the novice athletes are performing in-phase movement patterns more stable than the anti-phase movements. Research results of Puttemans et al. (2003), Bogaerts and Swinnen (200), Lee et al., (995), Swinnen et al., (99), Amazeen et al., (996), Kelso (995), Baldissera and Cavallari, (982) and Cohen, (97) support the results of this research. Performance errors increase at the time of performing anti-phase movement pattern due to the spatial and temporal interference and as a result, movement stability decreases. Therefore, in-phase movement pattern is more stable than anti-phase movement pattern. The last outcome of this study is that expert athletes perform the in-phase and anti-phase movement with identical stability. Although this result is against the results of Turvey (996), Baldissera, F., Cavallari (982) and Cohen (97), Swinnen et al. 9
(99), but was somehow according to the results of other researchers who have appointed the reorganization of coordination structure in muscles as the main factor of correct performance during anti-phase movement patterns [6, 0, 4, 7, 20, 22]. This research was completely in agreement with Dessing et al. (2007) research results. Considering the average experience of expert athletes in performing hip hop and especially the selected movement tasks of the current study, it can be concluded that motor control system of these athletes reorganize a new coordination structure in presence of increased rehearsal time and individual s level of proficiency. As a result, spatial and temporal interference doesn t affect the performance of anti-phase movement patterns. As the coordination structure is being formed, variable error of athletes performance declines and their stable performance capability during anti-phase movement pattern increases. Consequently, decrease in errors of anti-phase movement performance of expert athletes makes the in-phase and anti-phase stability of their movements almost identical. The abovementioned items express that athletes acquire stable inter limb coordination movement capability by practice and can perform continuous movements identical to each other, despite the spatial and temporal differences of coordination movement patterns. In this research, the novice athletes performed the in-phase movement pattern more stable than anti-phase movement pattern, as expected; However, expert athletes performed both in-phase and anti-phase movement patterns with identical stability. The current results can be explained in this way is that expert athletes perform anti-phase movement patterns more than in-phase movement patterns and their correct performance of anti-phase movements is due to their persistence in performing anti-phase movement patterns. Another explanation is that high accuracy and proficiency of expert participants of this study make them capable of correcting their possible errors during the performance in the next cycle of the movement and consequently, decrease their errors and increase their stability in performing the movements. In short, the results of this research showed that both novice and expert participants perform the in-phase movements with identical stability due to ease of in-phase movement patterns and common spatial and temporal features in performing this movement. Novice participant, however, perform the anti-phase movements with more errors due to presence of spatial and temporal interference in this pattern and consequently, their anti-phase performance is less stable. Expert athletes better performance of anti-phase movements is naturally related to their more practice. These athletes are capable of identifying and correcting their possible errors in next cycles of movement which makes their movement stability of in-phase and anti-phase movements identical. REFERENCES [] Amazeen EL, Sternad D, Turvey MT, Human Move Sci, 996, 5, 52 542. [2] Arne Ridderikhoff CE, Peper and Peter JB, Neurophysiol, 2005, 94. 32 325. [3] Baldissera F, Cavallari P, Civaschi P, Neurosci Lett, 982, 34, 95 00. [4] Bogaerts H, and Swinnen SP, Human Move Sci, 200, 3, 3-28. [5] Cohen L, Percep Motor Skill, 97, 32, 639 644. [6] Deborah JS, Neuropsychol, 2008, 46, 49 425. [7] Dessing JC, Daffertshofer A, Peper CE, Motor Beh, 2007, 39, 5, 433-446. [8] Kelso JAS, Am J Physiol, 984, 5, R000 R004. [9] Kelso JAS, Dynamic patterns: The self-organization of brain and behavior, Boston: MIT Press, 995. [0] Kim Y, MA thesis, (Texas, USA, 2002). [] Lee TD, Swinnen SP, Motor Beh, 995, 27, 263-274. [2] Magill RA, Motor Learning and Control, United States, ninth Edition, McGraw Hill, 997. [3] Mulvey GM, Amazeen PG, Riely MA, Motor Beh, 2005, 37, 295-309. [4] Murian A, Deschamps T, Bourbousson J, Temprado JJ, Neuroscience Letters 432, 2008, 64 68. [5] Rebecca MC, Richard BI, Human Movement Science, 2007, 26, 226-234. [6] Schmidt AR, Lee TD, Motor control and learning, Fourth Edition, Human Kinetics Publishers Company, 2005. [7] Smethurst CJ, Carson RG, Human Move Sci, 200, 20, 499-529. [8] Swinnen SP, Young DE, Walter CB, Serrien DJ, Exper Brain Res, 99, 85, 63-73. [9] Temprado JJ, Swinnen SP, Carson RG, Tourment A, & Laurent M, Human Move Sci, 2003, 22, 339-363. [20] Tsutsui S, Lee TD, Hodges N, Motor Beh, 998, 30, 5-57. [2] Turvey MT, The challenge of a physical account of action: Amsterdam, Free University Press, 990, 57-94. [22] Wenderoth N, Puttemans V, Vangheluwe S, Swinnen SP, Motor Beh, 2003, 35, 296-306. [23] Yamanishi JI, Kawato M, Suzuki R, Biolog Cyber, 979, 33, 99 208. [24] Zanone PG, Kelso JAS, Exper Psych, 992, 8, 403 42. [25] Zanone PG, Monno AB, Temprado JJ, Laurentb M, Human Move Sci, 200, 20, 765-789. 92