Many coaches try to improve the performance of their athletes by given them cues and instructions about the way they
act before, during, or after the execution of a motor skill. To give this information, they usually use Modeling, or
Feedback. Both of these methods effect the performance in different ways. The purpose of the present study was to
investigate the specific changes (1) in kinematic, and (2) kinetic characteristics of Forehand Clear Service if these exist,
after the use of Learning of Observation and Verbal Feedback as methods of information.

21 amateur badminton athletes participated in the study (Age 11.4 ± 0.3 years, body mass: 46±0.2 kg and height 155
±2.75 cm). They were separated in three groups of 7 individuals based in the accuracy of service:Learning of
Observation group (LOG), Verbal Feedback group (VFG) and control group (CG). The athletes followed an 8-week
program with 45 minutes sessions twice per week. 20 points in the kinematic system were totally studied based on the
principals of Kinematic analysis (Tsarouhas 1983, Hay and Reid 1988, Allard, Stokes and Blanchi 1995), as well as,
the pre-existing researches in the area of Athletic Biomechanics, that dealt with kinematic analyses of multi-joint tasks
(Wadell 2000). Variables related to displacement, velocity, angles, angular velocities, time, forces and vertical maximal
force was evaluated.

Repeated Measurements was applied to the pre training variables. Dynamic and kinematic variables are depicted on
table 1.
Table 1:Kinematic and Dynamic Variables.
Discussion / Conclusion: Results showed that there were statistically significant differences between the experimental
groups and the control group for the factor time. However there were not statistically significant differences for the
factor group. The LOG group presented the most changes in the kinematic and kinetic characteristics of the forehand
clear service.

[1]. Allard, P.,Stokes I.,& Blanchi, J.,(1995). Three dimensional Analysis of Human Movement. Human Kinetics.
Champaigh, 19-40
[2]. Wadell, D.B. (2000). Badminton Adapted for children. Badminton for children based on biomechanical and
Kinematic Variables
[3]. Τsarouhas Ε. (1983). Biomechanics of Athletical Movements.

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