Fatigue-muscle Tone Matching Method

Research object:Sports are ancient and traditional human activities and perform considerable role in the development of human civilization. As sciences and technologies evolve, we have more recognition about competitive sports, with a more quantitative, standard approach to arrange and study in sports training and recovering. In competitive sports, skeleton muscle plays an important role up to other muscle. Mechanomyogram (MMG) are mechanical vibration waves, produced by muscle contraction. Since it contains information about muscle’s physical and physiological alteration, we can research it to realize how muscles run. In this text, we researched the MMG produced by Biceps in standing calf raise, for finding characteristic parameters which can interpret the change of muscle in physical side and physiological side. During these work we can descript and learn more details about progression of muscle fatigue.Research content:10male university students and two athletes do standing calf raise with25kg load, and two other athletes with15kg load. The MMG during these actions are measured and analyzed by Matching Pursuit method.Result:During compare to the result of Wavelet analysis and The short-time Fourier transform, we found Matching Pursuit method obtain more precise, continuous performance in time-frequency analysis of MMG. While analyzed subject No.11’s single contraction process, it suggest the frequency bandwidth of MMG become wider (21.03Hz～29.41Hz) when the fatigue came deep. Most of energy distribute in4～6Hz. With this result, we extracted characteristic parameter called ’Pr’, and calculated Pr during all progression. And we found Pr became lower when progression elapsed. The range of10subjects’ Pr are below:0.265～0.0.134at start,0.300～0.134at maximum and0.134～0.045at minimum. We consider the maximum period is non-fatigue, the stationary period is under fatigue and the monotonic decreasing period is fatigue.While analyzed the energy of concentric contraction and eccentric contraction in a whole contraction, we extracted parameter called ’kcc/kec’. Calculated the subject No.11’s kcc/kec, we found the value of kcc/kec declined when the fatigue progression elapsed, which suggested the concentric contraction contribute more fatigue than the counterpart of eccentric contraction.We used Pr and kcc/kec to evaluate the latter half of subject No.11’s whole MMG, found that Pr and kcc/kec are both stationary in the under fatigue period, and have a significant lower in fatigue period.Compared the Pr and kcc/kec of same period between25Kg load and15Kg load, we found25Kg group is higher than15Kg group.Conclusion:the extent of frequency bandwidth in fatigue is due to the fatigue of Type-Ⅱ. The energy of higher frequency implies that the number of Type-II Motor Unit is changed. The alteration of kcc/kec can be interpreted as the different contraction pay different contribution to fatigue. If the higher frequency extent, Pr and kcc/kec both decrease, and we can consider the muscle is under fatigue.