The Regulation Of Acupuncture On Exercise-induced Fatigue:A TMS Study

Objective:Exercise-induced fatigue is a kind of self-protection response after the body bears a large exercise load.It can be divided into central fatigue and peripheral fatigue,which not only affects the sports performance,but also is related to the occurrence of sports injuries.Acupuncture is a kind of traditional Chinese medicine therapy,which has been used as a common intervention to regulate and relieve the occurrence and development of exercise-induced fatigue.Despite numerous studies suggesting that acupuncture can be therapeutic by stimulating the meridians and collaterals to send messages to specific organs or brain centers.But the mechanism is still controversial.Currently the research on acupuncture regulation of exercise-induced fatigue mainly focuses on the mechanism of peripheral fatigue,and the research on the mechanism of central fatigue is relatively few.Therefore,the purpose of this study was to explore the regulation effect of acupuncture intervention on motor cortex in different states,and to provide theoretical basis for acupuncture to promote the recovery of exercise-induced fatigue.Methods:In this study,20 participants were recruited in resting state and 20 participants in exercise-induced fatigue state.Acupuncture intervention and sham acupuncture intervention were randomly performed in each state,with a one-week washout interval.Motor evoked potential（MEP）and heart rate changes were measured in 30min before and after intervention at resting state.Immediately after acupuncture,participants were instructed to fill in Massachusetts’s acupuncture sensation scale（MASS）.In the state of exercise-induced fatigue,after measuring baseline MEP,heart rate and blood lactic acid,fatigue modeling was performed on participants using the power bicycle with progressively increasing load,and Rating of perceived fatigue（RPE）was used to assess the fatigue of the participants.Intervention was performed immediately after exercise-induced fatigue,MEP,heart rate and blood lactic acid indexes were collected within 30 min.SPSS 26.0 was used for statistical analysis of the data,which were presented as Mean±SD.Two-factor repeated measurement analysis of variance（acupuncture method×acupuncture time）was used to compare whether there were differences in MEP,heart rate and blood lactic acid among different acupuncture methods within a short period of time.Bonferroni post-hoc tests were conducted to compare the specific difference.P<0.05 indicates that the study index was statistically significant.Results:1.Resting state experiment（1）It was found that MEP amplitude had a significant interaction between acupuncture method and acupuncture time(F_（1,38）=3.79,P=0.003,η²=0.09).In terms of acupuncture method,MEP amplitude was significantly increased after acupuncture intervention compared with sham acupuncture intervention（P=0.002,MD=0.44,95%CI=0.18-0.71）.In terms of acupuncture time,MEP amplitude after acupuncture intervention was significantly higher than baseline.For the latency period of MEP,there was no significant interaction between acupuncture method and time,and there was no statistical difference in the results of post-examination.（2）The frequency and intensity of acupuncture sensation showed that sore,pain,deep pressure,dull sensation,swelling pain,tingling,numbness,sharp pain,dull pain and pulsation were significantly higher after acupuncture intervention than after sham acupuncture intervention（P<0.001）except warmth and cold.In addition,the MASS score after acupuncture intervention was significantly higher than that after sham acupuncture intervention（P<0.01）.（3）The results of heart rate showed that there was no significant interaction between acupuncture method and acupuncture time（P=0.187）,and no statistical significance was found in the results of post-examination.2.Exercise-induced fatigue state experiment（1）MEP results showed that the amplitude and latency of MEP interacted with acupuncture method and acupuncture time(F_（1,38）=5.40,P<0.001,η²=0.12,F_（1,38）=3.78,P=0.008,η²=0.09).In terms of acupuncture method,MEP amplitude after fatigue-acupuncture intervention was significantly higher than that in the fatigue-sham acupuncture intervention（P<0.001,MD=0.46,95%CI=0.31-0.61）,there was no significant difference in the latency of MEP between the two groups.In terms of acupuncture time,MEP amplitudes at 15 min and 30 min after fatigue-acupuncture intervention were higher than baseline,and MEP latency at 30 min after intervention was significantly lower than baseline（P<0.001）.（2）The frequency and intensity of acupuncture sensation showed that other sensations after fatigue-acupuncture intervention were significantly higher than those after fatigue-sham acupuncture intervention（P<0.01）except for warmth,cold and pulsation.The MASS score was also significantly higher than that in the fatigue-sham acupuncture intervention（P<0.01）.（3）The heart rate showed an interaction between acupuncture method and acupuncture time(F_（1,38）=2.85,P=0.029,η²=0.07).At 30 min after acupuncture,the heart rate after fatigue-acupuncture intervention was significantly lower than that after fatigue-sham acupuncture intervention（P=0.049,MD=-6.00,95%CI=-11.97--0.03）.（4）Blood lactic acid results showed that there was no interaction between acupuncture method and acupuncture time.Post-test results showed that there was significant difference in the change of acupuncture time(F_（1,38）=529.11,P<0.001,η²=0.93).Blood lactic acid levels were significantly higher than baseline after exercise(（P=<0.001,MD=9.50,95%CI=8.74-10.26）and decreased significantly 30minutes later（P<0.001,MD=-6.88,95%CI=-7.63--6.12）.Conclusion:1.Acupuncture intervention in resting state promoted the excitability of motor cortex,and the effect was related to the intensity of needle sensation,but had no significant effect on the change of heart rate.2.Exercise-induced fatigue inhibited the excitability of motor cortex.Acupuncture intervention improved the decrease of motor cortex excitability caused by fatigue,promoted the increase of MEP amplitude,shortened the latency of MEP and the recovery of heart rate,which played an important role in the recovery of exercise-induced fatigue.However,it had no significant regulatory effect on the change of blood lactic acid.