A verification of Shaolin and Wudang by Tang Hao (1930)

[LaoDan]

“Eccentric contraction occurred mainly in the anti-gravity muscles such as the rectus femoris and the medial head of gastrocnemius. Tai chi requires the lower limbs to move bent and in slow motion. This entails a considerable workload, especially for the lower limbs. The frequent bending of the hips, knees, and ankles by eccentric and concentric contraction of the muscles may help to increase the strength of the lower limbs” (S P Chan, T C Luk, Y Hong, 2003).

In this study, they examined the variables of anti-gravity muscles, eccentric contraction, and concentric contraction in a Taijiquan practitioner. The problem is that electromyography cannot differentiate between eccentric, concentric, and combined muscle actions. From Taijiquan, we do learn about passive action, stretching, no brute force, and double weighted.

Yea, since they differentiate between eccentric and concentric muscle contractions, they should have mentioned in the methods section how this was determined. But, since they took simultaneous measurements of joint angles, then they should have the information to know when the detected work was during lengthening or shortening of the muscles being measured. For claims to be made, the determinations should be clearly explained.

[Yeung]

There are technical difficulties to ascertain the difference between eccentric, concentric, and combined strengths with the electromyography, as it only shows the levels of muscle activities. The general findings are that eccentric strength has the lowest level of activity, concentric strength has lower activity compare to the combined strength used in controlling a weight; and the anti-gravity muscular activity is generally low and often absent. The method of uses muscle length to differentiate between eccentric and concentric is viable with very careful observations, as movements are multiple joint actions. Multi-joint kinetic chain analysis can interprets the range of motions of various joints and establish muscles lengths. The uncontrollable variable is contracting concentrically in an eccentric movement. In the case of Chan et al., (2003) the subject lowering his rear leg which is an eccentric movement but he contracted his muscles concentrically to perform a slow descent, and this is why there is a high electromyographic reading on the rectus femoris. This technique is the same as the overloading training in lowering a weight slowly to build up strength, thus it is reasonable to conclude that eccentric muscle contraction [with concentric contraction] of the lower limbs in the push movement of tai chi may help to strengthen the muscles from people knew very little about Tai Chi. From a practitioner’s point of view, this is a good example of double weighted.