Accessing Effects Of Bioelectricity Interference Current In Acute Fatigue Test

Purpose:To evaluate if bio-electric interferential current (a method to assess the physiological responses of sensory, motor and pain to certain stimulations) can be used to monitor the training and recovery of athletes.Method:thirty sprinters (aged18-22yrs) were asked to finish an acute explosive fatigue training session with bilateral dynamic knee extension consisting of five sets of ten repetitions at maximum load,they were allowed to have a two-minutes rest during each set, maximal voluntary contraction (MVC) and surface electromyogram (aEMG) of the thigh extensor muscle groups using a leg extension test device and MyOnWare short (Myotonic Ltd, Finland) prior to and immediately after training, and blood index(testosterone、cortisol、creatinekinase) were also tested.At the same time,Bio-electric Interferential Currents(ICs,mA) was tested pre and post fatigue test..During the FAM tests7responses were records by remote control of the current under the electrodes in the toes including7responses:3sensor responses (first sensation (tingling); clear sensation; and strong sensation),3motor responses (weak motor contraction (the first motoric movement e.g. in the small finger); clear motor contraction (repeated muscle contraction); and strong motor contraction such as bending of the ankle), and pain level (painful sensation such as unpleasant feeling). Agreement was analyzed using Bland and Altman plot.Resoults:1、The MVC decreaced from535.57±24.31pre fatigue to441.63±17.72post fatigue,(p<0.01),however,the EMG had no significant change(p>0.05). The difference was not statistically significant.2、ICs increased on average from25.5±9.1mA to30.8±6.8mA in sensory response at10Hz immediately post training but decreased at24-hr (p=0.008) post training and retained at pre-level thereafter. Motor (p=0.033and p=0.066) and pain (p=0.022and p=0.019) response patterns were similar to sensory response. The agreement of using ICs and aEMG/MVC ratio yielded similar results in indicating bio-signal changes after fatigue.And there was a time shift association that increased sensor responses at10Hz (r=-0.411, p=0.027),50Hz (r=-0.413, p=0.026) and100Hz (r=-0.369, p=0.049) from pre-to immediately post fatigue test were correlated with decreased aEMG/MVC ratio from immediately to day1post fatigue test.3、 Changes of sensor responses also inversely correlated with changes in testosterone level from pre to post fatigue test (r=-0.377, p=0.040) and positively with cortisol level from post to day1after fatigue test (r ranged=0.374to0.401, p<0.005).Conclusion:acute fatigue induced by the5*10sets knee extensions in male sprinters is mainly susceptible to impaired peripheral muscle function not the divergence of neuronal codingmechanisms inthe centralnervoussystem; Bio-electric interference current may be a useful tool for monitoring fatigue during training and recovery. However, further investigations are needed to verify the results and to explore the mechanisms.