Yeung wrote:Have a look at: Chan S. P., Luk T. C. and Hong, Y, Kinematic and delectromyographic analysis of push movement in Tai Chi, British Journal of Sports Medicine, 2003, Vol. 37, pp. 339–344
This a qualitative study of a long time practitioner and instructor of Taijiquan in Hong Kong, and they got interesting electromyographic reading but they do not know why because they fail to standardize the input variable.
Well, since their stated purpose was to “START” an analysis..., I guess it is OK, but a sample size of one with no control subject(s) and no tested variables does not provide anything that can provide conclusions. Still, what they observed is unsurprising, so it is probably fine for one data point. This study merely serves as a descriptive analysis of one person doing one version of TJQ, with no variables being examined for comparisons.
They seem to assume that the TJQ push movement that they present (as well as peng, lu and ji, which they also recorded but did not present data on) are special to TJQ because they are a part of the shisanshi, and the eight jin as defined by the art. But they do not establish that they are special relative to anything else, since they do not compare this one master to anybody else (sample size of one with no control subjects).
They did not compare the slow form push with the same master doing the move at application speed. They did not have the master do the push slowly against resistance. They did not have the master push fast (application speed) against resistance. They did not have a novice try to imitate the master for comparative purposes. They did not have a professional dancer try to imitate the master for comparison. They did not compare the eccentric data to someone just walking slowly down stairs. They did not compare this Yang style to Chen style, or Wu style, etc. pushes. They did not compare the TJQ push with pushes from other styles of martial arts, or even pushes by non-martial artists. Etc., etc., etc...
They erroneously state that “The path of the CG [center of gravity] during the retracting and pushing movements was unique, and the sway or deviation from this path was small.” Since they did not study anybody else’s movements, they CANNOT establish the “uniqueness” of the movement! It MAY be unique, but this study cannot establish this.
They discuss potential health benefits without having used any control subjects:
“...may help to increase the strength of the lower limbs.”
“Lower limb strength has been shown to affect balance.”
“”Several other studies have shown impaired balance to be associated with falls in this [elderly] age group.”
And then state “Therefore, if tai chi directly increases the strength of the lower limbs and improves balance, it may be a good form of exercise to use for health maintenance and fall prevention.”
This study, however, does not establish anything other than there being the expected concentric and eccentric contractions, and cannot provide evidence for their speculations since no comparative subjects were studied! They cannot even establish that TJQ improves strength (even though it most likely does) since they do not conduct any before and after comparisons of individuals being taught TJQ...
To be useful therapeutically, one needs to establish that the proposed treatment is in some way superior to whatever else is available to patients. Is TJQ better at strengthening the lower limbs and improving balance (and preventing falls) than having untrained patients merely walk slowly downstairs, for example? There is no way of knowing from this study since no control subjects were used.