Surface Emg Traditional And Wavelet Transform Parameters Applied To Monitor Changes After Exercise-Induced Muscle Damage

Abstract

Investigations have demonstrated that exercise-induced muscle damage can inhibit muscle performance post-exercise. However, to overcome the non-stationary condition and low sensitivity to muscle fatigue of the traditional parameters, some new techniques have been proposed to monitor muscle fatigue more accurately. PURPOSE: To correlate the traditional and stationary wavelet transform parameters which can explain peak torque output during maximal isometric contractions before and after exercise-induced muscle damage. METHODS: Thirteen resistance trained males (age: 23.9 ±5.2 years; body mass: 79.2 ±9.9 kg; height: 176.1 ±6.3 cm) volunteered to take part in this study. Subjects performed 4 sets of 10 unilateral maximal elbow flexion concentric/eccentric reciprocal actions with their dominant arm. They were seated in a chair with their arms draped over a “preacher curl bench.” All exercise was performed on a Biodex System 3 isokinetic dynamometer at 120°s-1 with one minute rest between sets. Maximal voluntary isometric contraction of the elbow flexors was measured at 90° of flexion for 3 seconds. Isometric peak torque (PT) and the surface electromyography (sEMG) of the biceps brachii were collected at baseline and immediately post exercise. Traditional parameters of amplitude (RMS) and frequency (MdF) of the sEMG signal were calculated with a specific routine written in Matlab (v 6.5, Mathworks, Natick, MA). The signal was also decomposed into five detail coefficients (D1 to D5) using the discrete wavelet transform (mother wavelet Daubechies 5). A Pearson correlation was used to associate the decrease in PT (ΔPT) with variations in RMS, MdF and energy of the wavelets details. RESULTS: Pearson’s r values were positive correlated between PT and all sEMG parameters. However, there was only a strong relationship between ΔPT and D3 (r=0.79). CONCLUSION: The energy of D3 from discrete wavelet transform used in the present study was more sensitive in assessing changes in muscle performance following exercise-induced muscle damage.