Purpose：By means of a wireless MEMS sensor system, the purpose of this study was to analyze the differences of the seven main limbs, and the acceleration and angular velocity of the rackets between elite and sub-elite badminton athletes. Method：With the wireless MEMS sensor system composed of a three-axis accelerometer and a gyroscope, four elite and five sub-elite athletes’ seven limbs and the acceleration and angular velocity are captured while they are jump smashing. And then these data are analyzed by the MS Excel and MatLab softwares.
1. Elite athletes have longer duration in the air than sub-elite athletes because they better use their knees.
2. Elite athletes have longer duration in the air because they better use their waists.
3. The differences in the acceleration and the angular velocity of the shoulder between two groups are slight, but sub-elite athletes longer use their power and have more total acceleration power
4. Elite athletes swing their arms more obviously than sub-elite athletes. And there is much difference in the total power of the angular velocity, existing 10 times differences in three axes.
5. A large gap of the average maximum acceleration exists between two groups because the wrist of elite athletes can better accumulate the strength from the proximal limbs. And there is much difference in the maximum and the total power of the angular velocity, existing 12 times differences in three axes.
6. Elite athletes’ palms can instantly burst out their power of the whole body and they have better performances on acceleration. And there is much difference in the total power of the angular velocity, existing 11 times differences in three axes.
7. The kinetic chain is insignificant between two groups, and the sub-elite athletes’ palms can’t accumulate the strength from all the proximal limbs because their timing of turning around and flexing their wrists is not fixed.
8. Elite athletes have better motion stability in the proximal limbs (such as arm, shoulder, waist) because of relaxing and have worse motion stability in the distal limbs (such as palm,wrist) because of more average acceleration. Of all elite athletes, E athlete has better motion stability of all limbs while he is jump smashing.
9. From the vibration spectrum analysis of the racket, there is much difference in three axes in the full and low frequency, while a large difference in Y and Z axes in the high frequency, a slight difference in the middle frequency.
10. The average maximum acceleration of the racket in Z-axis is the most obvious. Of all elite athletes, D athlete has the most average maximum acceleration in three axes.
11. There is much difference in the negative maximum acceleration of the racket in Z-axis.
12. Sub-elite athletes have more total power of the racket vibration, which means they give more power to the racket. This is the same as the minimum analysis.
13. Sub-elite athletes have longer vibration of their rackets because they longer use their power.
Conclusion: From the data analysis of the acceleration and angular velocity, there are small differences between two groups in the proximal limbs (such as knees, waist, shoulders), but a large gap in the distal limbs (such as arms, wrists, palms ). In order to compete in a high-intensity badminton tournament, the athletes must try to save energy as much as possible even though they have to swing back and forth for thousands of times. Thus, the biggest differences between elite and sub-elite athletes are that elite athletes can move with little action and relax soon after they smash.
Suggestions: 1.From data analysis of this study, it can be clearly found that the biggest differences of elite and sub-elite athletes are in the wrists and palms. So these two parts of the body can be assessed for further understanding of the movements. This can allow tennis athletes and coaches to improve the performance of their techniques. 2. As for sub-elite athletes, D athlete can be chosen as a model for strength training, while E athlete, a model for motion stability.
Keywords: badminton smash, angular velocity, accelerometer, gyroscope,
motion stability, spectrum analysis