| Taiji and social dancing are favorite exercises among the old in China. Many researchers had described their positive effect on our health condition using the psychology. Chinese medicine and balance theories. The movements of these two kinds of exercise are known to be smooth and full of stability, which is quite different from most of the other kinds of exercise for the shock attenuation and transmission. It had been reported that the shock and shock wave have been linked to degenerative joint diseases, stress fractures, osteoarthritis, low back pain and so on. If Taiji and social dancing can improve the function of body's shock attenuation, we can study these exercises in a rather new direction, and we can spread these exercises more easily and wider than ever.In this study, a Nation-M9500 normal speed camera and a uniaxial accelerometer (BK4393) were used to get the kinematics and shock test data. 49 retires in the BeiTi Jiashuqu were select as the subjects. They were divided into three groups: taiji group, social dancing group and control group. The aim of the study is to test and analyze the shock attenuation and shock wave absorption characteristics of the exercise group and control group, using the methods of kinetic and spectral analysis. The data were processed in the software of matlab and the results were statistical analyzed using SPSS. The conclusion was described as follows:a) The shock magnitude on tibia was significantly different between the taiji group and dancing group (8g and 4.6g), which could probably explained by their different patterns of touching the ground. The shock on the head was all below 3g for each group.b) The IA (impact attenuation) was 60%, 40%, and 55% respectively for the taiji, dancing, and control group.c) For the tibia shock wave components, the dancing group and taiji group were mainly covered by the frequencies below 5Hz, while the control group was mainly covered by 7 Hz or so; and there was significant difference between the exercise group and the control group. For the head shock wave components, all the three groups were mainly covered by the frequency of 4 Hz. That means the dancing group and the taiji group are unlikely to be harmed by the high frequency shock wave components.d) For the mean tibia MPF, the exercise group was lower than the control group; while for the mean head MPF, the exercise group was higher than the control group. There was only significant difference between the dancing group and the control group, and the same thing couldn't be found between others.e) As shown in the TF figure, the shock wave absorption of the control group was the highest for each frequency. And the frequency of the shock components of max absorption was rather wide for the control group, while an absorbing peakappeared for both of the taiji group and the dancing group.f) Their PSD figure indicated, the predominant shock components that transferred through the body of the dancing group and the taiji group are both of the low frequency. And the PSD of their high frequency component is very low. It seems the taiji exerciser has a function to avoid being hurt by the high frequency shock wave.g) By correlation analyzing, we assumed that the different shock attenuation and absorption between the exercise group and the control group were due to the effect on the ankle movements of dance and taiji practice. In addition, long term exercise will improve the function of the shock attenuation constructions such as bone, muscle, nerve and so on, which may lead to the difference of the shock and shock absorption between the exercise group and the control group.
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