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STUDY REALIZED ON PRE-ADOLESCENT GREEK GYMNASTS CONCERNING KINEMATIC PARAMETERS INFLUENCE OVER RINGS LANDING TECHNIQUE
DALLAS, G., Kapodistrian University of Athens, Department of Physical Education and Sport Science
KIRIALANIS, P. , Dimokrition University of Athens, Department of Physical Education and Sport Science
MELLOS, V., Teacher of Physical Education, High School of Karthitsa
GOUGOU-GRAMMATOPOULOS, B., Kapodistrian University of Athens, Department of Physical Education and Sport Science
SATRATZEMIS, I., Kapodistrian University of Athens, Department of Physical Education and Sport Science
Key words: artistic gymnastic, rings, pre-adolescent gymnasts, dismount, technical instructions, kinematic analysis
Introduction
One of the main purposes of gymnasts in artistic gymnastics is to learn the correct technique of skills. For this reason, the trainers in order to teach the technique of the skills are based in knowledge of biomechanical parameters that originate from analysis of technique and the provision of augmented feedback according performance's mistakes. This analysis is based in method of kinematic patterns, which is related with provision of information related with time and velocity of performance, angles of various segment of the body or the centre of gravity in various phases of the skill. This type of approximation has direct informational influence via kinematic feedback that provide to the gymnasts in order to fulfil the learning of complex motor skill (Newell, Morris, & Scully, 1985; Newell & McGinnis, 1985; Newell, Quinn, & Carlton, 1987; Newell & Walter, 1981; Schmidt, & Young, 1991).
Especially in artistic gymnastics where gymnasts from the early ages must teach the correct technique of basic skills, provision of kinematic feedback is essential in order to learn these skills (Newell & McGinnis, 1985; Newell, Quinn, & Carlton, 1987) as well as in dismounts from the rings. Related literature according the analysis of dismounts is referred to high-level gymnasts (Borhard, Chapman, 1979; Cheetham, Sreden & Mizoguchi, 1987; Nissinen, 1983; 1992; Vallier, 1973). Research data form gymnasts of early ages are characterized by smaller amount of parameters of forces, velocity in relation to the greater gymnasts (Bouchard, Malina, 1991) are restricted and referred to foreign high level gymnasts aged 10-14 gears old during the performance of dismount backward somersault with straight body (Satratzemis, 1990). On the contrary, there is little information according the performance of Greek gymnasts from the parallel bars (Stefanidis, et al, 2004). So, provision of kinematic parameters from high-level gymnasts to gymnasts of early ages is questionable. Also, it is not clear if kinematic parameters are differentiating according position of the body (tuck-straight) as well as if kinematic parameters of straight body can apply in teaching procedure of dismount with tuck position. Backward somersault with straight body as a dismount on the rings is an element of difficult A-part (FIG, 2005) and included in the compulsory programs of gymnasts aged 8-11 (E.G.O., 2002). It is well known that the rotation from lateral axis of straight body position has greater difficulty (10.5-13.0 Kgm2) than tuck body position (4.0-5.0 kgm2) (Hochmuth, 1984). For these reason trainers in early stage of practice during new skills, prefer to perform skills with tucked position in order to facilitate rotation because of the great amount of rotation.
The purpose of this study was the analysis and comparison of kinematic parameters of dismounts with tucked and straight body from the rings by high level young gymnasts aged 10-11 in order to ascertain if there are significant differences between these parameters in order to has the possibility to provide information's to the gymnasts irrespectively from the amount of inertia of the body. Furthermore, a second purpose of the study was the applications of technical guides from tuck position to the teaching procedure with straight body. Also, an additional purpose, according results of this analysis, is the construction of structural pattern in order to clarify the technical information for the body position in various phases and the more important mistakes of performance to correct the technique of this dismount.
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Material and Method
Eight gymnasts aged 10-11 (10.50±0.38) with competition experience 3-4 years, which are stand out in individual level on the rings as well as in all around competition participated in this study. Gymnasts volunteered to participate in this study and they informed consent before this study. Somatometric characteristics of these gymnasts are presented in table 1.
- Table 1
Means, standard deviations and range of somatometric characteristics
in young high-level Greek gymnasts
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Apparatus
Recording of trials was done with a video camera JVC GR-Ax2 (25 frames/sec) in distance 5.80m and height 2.55m, from the nearest ring, with optical axis perpendicular to the vertical level of motion of gymnasts. Further analysis was done with a program analysis BIOKIN by Darras (1995) that referred in analysis of kinematic characteristics of athletic movement. For the purpose of this analysis video was connected with P/C with special connection. In order to determine the centers of joints of the gymnasts' different points were marked on gymnast's body to facilitate the analysis of movement (Plaegenhoef, 1971). For structure of stick figures 12 points were selected which correspond in different joints of human body. Analysis was done every second frame and analyzed 55-65 frames in every performance. First frame determine the instant that begin the downward swing of body, meanwhile the last one referred at the instant of first contact of the feet on the floor during landing.
Experimental procedure
Participants during practice sessions performed seven trials of backward somersault with tuck and seven trials of backward somersault straight body and the best trial of each type of dismount, according judges opinion, were selected for further analysis. Inter trial time was one minutes in order participants has time for rest. Three judges evaluated the qualitative performance according the code of point. The high level of performance of the skill verified with the opinion of three trainers which evaluated the performance according the range of the forward swing during release of the rings as well as the height and correct position of the body during flight phase and landing phase. Kinematic parameters are referred to temporal, velocity and angular characteristics of the dismount. For analysis purpose dismount was break down in four phases, which related wit dynamic and kinetic energy into these phases. First phase begin with downward swing from handstand until the instant gymnast pass vertical level from hang. Second phase referred the instant from hang until rings release and third phase involve flight phase. Forth phase is landing phase from first contact of the feet on the floor until maximum flexion of the knee. Statistical procedures were mean (X), standard deviation (CD), coefficient of variation (CV%), and t-student test for independent samples.
Results
Kinematic parameters, which presented characterize the technique of these dismounts. Statistical indexes are presented in table 2. Gymnasts showed variation in performance in many of the kinematic parameters. According to somersault with tuck position, gymnasts differentiate their performance only in velocity of the body when it pass the horizontal level during the downswing (CV%=15.56%). In contrary the dismount with straight body differentiate between gymnasts in flexion and velocity of the hips joint in the lowest vertical position (hang position) (parameter 7 & 8 respectively) (CV%=14.93% & 15.08% respectively) as well as in the flight phase time (CV%=43.20%) (Parameter 14).
Comparison of the means showed significant differences in most parameters between these two dismounts, with tuck and straight body position. These differences are referred in the time swing the instant that the body pass the horizontal level (p<. 05) and time of swing from the hang position until the time of release the rings (p<.05). The significant differences that appeared in hip's flexion (parameter 7) be due in the different body position in the dismounts (p<.001) which is depicted in the hip's velocity at the instant of flexion (p<. 001) and significant difference appeared in the velocity at the instant of release (p<.001). Significant differences appeared in the shoulder's and hip's angle during release (p<.001) as well as in the height of hips during flight phase (p<.01).
- Table 2
Structural pattern of dismount tuck back somersault on the rings
by young high-level Greek gymnasts
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Rings
Dismount back tuck somersault on the rings by young selected (high level) Greek gymnasts
State
Support Position Hang position
Flight phase
Landing phase
Phase
1est Preparatory phase
2nd Preparatory phase
Main phase of kinetic energy
Final phase
Actions characteristics
Concentration of kinetic energy of the body
Use of kinetic energy of the body
Performance of movement
Preparation for landing
Motionless of body
Technical characteristics
Downward swing
Upward swing
Rotation at the highest point
Opening tuck position of the body
Absorption of body's momentum
Until horizontal level
Until vertical level
From vertical until horizontal level
Angle of release
Basic technical body position
Informational components of the body during flight phase
Straightness of the body maintain until 50-62°
(zone 1)
Shoulders must be relax an6 their angle is greatest
Hips´ flexion and acceleration be done at zone 2, on 20-27°.
Angle of release is 73-87° before horizontal level
Height of the body in flight phase 28-38 cm above rings (head toward to the chest)
Full straightness of the body with this position to be maintain until the 1est contact of the feet on the ground
Landing in zone 5, in distance ±10 until ± 30 cm.
Body position during various phases of the dismount
Rings must be removed further with straight body
Dynamic absorp-tion of pressure on the shoulder´ joint
Upward acceleration of swing must be done with hips´ flexion
Before flight: Elevation of the body with backward& down-ward pressure of the rings
Body in flight phase has a tuck or half-tuck position with rapid straightness after vertical level
Maintenance of straight body until the contact with mats
Energetic and elastic impact on the mats
Significant errors
During downward swing shoulders´ angle must be less and with hyperextension of the torso
Great
shock, reduce range of swing and the knee are bending
Knee are bend, body is low in relation to the rings and shoulders´ angle must be great
Body is low and feet are not move backward
a) Release of the rings is done early: Flight is untucked without backward rotation
b) Release of the rings is late: Flight phase has not height and body rotate very fast
a)Straightness of the body is late
b) Preparation for landing initiate very early
a) Hard landing with tuck body
b)Un-control backward rotation of the body
Instructions for correction of the errors
In low rings, downward swing with fall on the mats
a) Swings with great range
b)On the rings: Swing falling on the spotters´ hand
c) As b but without spotters
a) Upward swing with straight body and feet
b) Same as a but with tuck hips
From hang on bars: Elevation of the torso (head to the chest)
a) Stabilize body position before release
b) Swings with touch the shoulders during release
a) Rapid straightness of the body with acoustic cues
b) Jumps drop from height on the mats with flexion of the joints during this contact
a)Improve-ment of technique in the dismount
b)Control of the backward rotation of the body
Learning method for correct technique performance
- A. PREREQUISITES components
- Know swing and technique without errors
- Performance of the dismount on trampoline
- Performance the skill on floor with spotters
- Β. Progressive controlled training
- Swings with rapid elevation of the feet and with pressure
As in the 1est case but with orientation of the feet
Performance the skill in trampoline with spot or safety belt
Performance the dismount after adler
From analysis of dismount with tuck position constructed the structural pattern of the dismount (table 2). The structural pattern referred into the kinematics and technical characteristics in various phases of the dismount, informational guides for the body, the kinetic energy of various phases and into the significant errors and the correctness of these errors and the method that must follow in order to learn the technique of the dismount.
able 3
Comparison of kinematic parameters between back somersault with tuck and straight body position by young Greek high-level gymnasts on the rings (numbers in parentheses indicated coefficient of variation (CV%))
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A/A
Parameter
Backward somersault (η=8)
Backward somersault body straight (η=8)
P
1
Time of swing until horizontal level (sec)
0,89 ± 0,03 (3,37)
0,86±0,01 (1,85)
*
2
Straightness of the body (°)
57,75 ± 3,92 (6,79)
58,87±2,16 (3,68)
Ν.S.
3
Hip's velocity at the horizontal level (m/sec)
5,59 ± 0,87 (15,56)
5,43±0,47 (8,71)
N.S.
4
Time of swing from horizontal until vertical level (hang position) (sec)
0,24 ± 0,01 (4,17)
0,23±0,01 (5,93)
Ν.S.
5
Velocity of the body in vertical level (hang) (m/sec)
2,61 ± 0,18 (6,89)
2,97±0,18 (6,06)
**
6
Time of swing from down vertical (hang) until release (sec)
0,26 ± 0,01 (3,85)
0,28±0,01 (2,50)
*
7
Hip´s flexion in the lowest vertical position (hang position) (°)
24,12 ± 2,17 (8,99)
16,37±2,44 (14,93)
***
8
Hip´ s velocity at the instant of flexion in the lowest vertical position (hang position) (m/sec)
7,06 ± 0,41 (5,72)
3,31±0,50 (15,08)
***
9
Shoulders angle at the release (°)
88,25 ± 1,75 (1,98)
78,12±3,18 (4,07)
***
10
Hips angle at the release (°)
84,25 ± 1,48 (1,76)
143,25±6,41 (4,47)
***
11
Hips velocity at the release (m/sec)
4,79 ± 0,38 (7,93)
5,77±0,17 (3,03)
***
12
Angle of release (°)
80 ± 5,47 (6,84)
81,75±3,01 (3,68)
N.S.
13
Maximum height of the hips above the rings (cm)
32,75 ± 3,19 (9,74)
27,75±1,83 (6,60)
**
14
Time of flight phase (sec)
1,08±0,06 (5,55)
1,05±0,04 (43,20)
N.S.
Discussion
Dismounts performance by young high-level Greek gymnasts with straight body position, is characterized by homogeneity as they appear non-significant coefficient of variation (CV%=<10%). To the contrary hip's velocity in horizontal level with tuck body position (CV%=15.56%) and two parameters in dismount with straight body position (hip flexion in the accelerate phase of swing (CV%=14.93%) and flight time (CV=43.20%) have significant variation between gymnasts. This is also an indication that the seven trials are adequate to provide stability in their performance (Bates et al, 1983).
The young high-level Greek gymnasts, aged 10-11, performing these dismounts (backward somersault with tuck and backward somersault with straight body) differentiate in the velocity of the body in the hang position (accelerated phase of the swing). The greater amount of moment of inertia of the straight body has greater amount of velocity than the tuck position, in order to fulfill the rotation of the straight body (Hochmuth, 1984). This amount of velocity, in the hang position, verify the high level athletic ability of Greek gymnasts, which is in accordance with other data of foreign gymnasts aged 10-14 years (Satratzemis, 1990). Velocity of the hips at the instant of release is differentiating between Greek gymnasts in the dismounts with different body shape (p<. 001) with greater amount of velocity to be appear in dismount with straight body. This amount (5.77±0.17 & 5.80±0.13 m/sec) is in the same level with the results of foreign gymnasts (Satratzemis, 1990).
Shoulders´ angular data between two dismounts in the present study in Greek gymnasts are differentiating at the instant of release (p<.001) and they are reversing linear with the amount of moment of inertia (88.25° & 78.12° for tuck and straight body). The less angle of straight somersault of Greek gymnasts is the same with foreign gymnasts (77.66°) according other data (Satratzemis, 1990) and with this way verify the same angular position between Greek and foreign gymnasts. The fact that the different body position (tuck & straight) affects the technical guide in learning these two dismounts is in partial support in various phases in the present dismounts. Technical guides of trainers during practice procedure must be care according body shape. So cues like 'do faster the swing' or 'accelerate your swing at the release of the rings' are essential components in a successful performance between these two dismounts.
The greater amount of moment of inertia in straight body position affects significant velocity of the body in Greek gymnasts during the downward swing (p<. 05 and for this reason gymnasts wants greater amount of velocity at the instant pass the vertical level from hang position. The increased moment of inertia is verified by non-significant difference from duration of swing in the next phase, from the hang until the instant of release, despite the greater amount of velocity (2.61 & 2.97m/sec for the tuck & straight body position respectively). It is very characteristic that velocities of the hips until horizontal level during downswing in two dismounts are significantly different in the hang position (parameter 5) and at the instant of release (parameter 11) (schema 3). Differentiation of amount of velocity has as a target to resist the increased inertia of the body and this results the significant change of time in swing in various phases between these two dismounts. Finally, the moment of inertia is straight related with body shape position and has a direct affect in kinetic parameters which are relating with velocity of various segment of the body during performance of dismounts by Greek gymnasts, the high level of athletic technique is verified by the corresponding kinematic parameters by foreign gymnasts.
The fact that different position of the body (tucked-straight) affect technical instructions in learning these two types of dismounts has some support according the kinematics parameters that examined in various phases of these skills. The technical instructions by the trainers, during practice sessions, must provide under special condition with body position (schema of the body) (tucked-straight) as well the angular position of various segments of the body. This means that instructions as 'accelerate your swing near the hang position, or 'greater range of swing before apparatus release', or 'greater range of swing in order to increase shoulder's angle at the instant of ring release' are essential determinants to successful performance between these two dismounts. It is concluded that kinematic information feedback (Newell, Morris, & Scully, 1985; Newell, Quinn, & Carlton, 1987; Schmidt, & Young, 1991) must taken in account the schema of the body in order to facilitate the communication between gymnasts and trainers.
Abstract
The purpose of this study was to examine some of the kinematic parameters of two dismounts on rings apparatus: somersault backward tuck and somersault backward straight. Eight (8) gymnasts aged 10.32±0.32 years (mean + SD), performed 7 trials of the exercise during training courses and the best one, according to the opinion of 3 judges, was further analyzed. A video camera JVC GR-Ax2 (25 frames/sec) was used to videotape the trials of the gymnasts. Also, a motion analysis program (BIOKIN, Darras, 1995), which linked with PC, was used for the analysis of the movement. Temporal, angular and velocity parameters were analyzed and presented. The statistical analysis of the data included the means (X), the standard deviation (SD), coefficient of variance (CV%) and the student t-test for independent samples. Results showed that the subjects were characterized by non-uniformity in kinematic parameters, especially when the exercise performed with straight body. Between subjects there were some significant differences regarding the: a) temporal parameters and the velocity of the body in different phases of the dismount, b) angular parameters according to the position of the shoulders and the hips at the moment that the athlete releases the rings and c) height of the hips during the flight phase of the body. So the possibility, to differentiate technical instructions between these types of dismounts, increase as they affected from the moment of inertia in separate phases of the skill.
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