Objective: Core muscles exercise has been recommended as an effective means to improve core stabiltiy and strength among healthy individuals and those with musculoskeletal complaints.However,many compensatory actions will happen to impair the effect of core exercises.The dynamic feedback which can efficaciously display muscle activation while performing core exercises is beneficial to instruct the trainer and avoid unnecessary activation of other muscles.Rehabilitative ultrasound imaging(RUSI)and surface electromyogram(sEMG)can efficiently evaluate the multifidus which is closely related to the progression of low back pain.Thus,in this study,RUSI combined with sEMG were used to monitor the performance of multifidus thickness and detect sEMG signal characteristics in real time in order to form correct muslce activation pattern in the core muscles dynamic feedback training.Methods: 42 healthy volunteers were randomly allocated into two groups: dynamic feedback group(22 cases)and control group(20 cases).During the core exercise,the dynamic feedback group were monitored by real time RUSI and sEMG while the control group recieved only traditional core muscle exercise without dynamic feedback.Both groups completed the specific core muscles exercise 2 times a week for 4 weeks totally in the same place.In the late 2 weeks,participants received advanced training.RUSI and sEMG signal were collected to record the thickness and activation of multifidus before and after the core muscles strength dynamic feedback training in two weeks and four weeks.The multifidus thickness value and root mean square(RMS)value were then extracted from the raw data for analyses.Results: The baseline show that there was no difference in thickness value and RMS value of lumbar multifidus between two groups(P >0.05).After 4 weeks training,the thickness value and RMS value of lumbar multifidus in both groups were higher than that before training with significant difference(P <0.05).After the same core muscles training,the thickness value and RMS value of lumbar multifidus in dynamic feedback group were statistically significant greater than control group(P <0.05).Conclusion: The core muscles strength dynamic feedback training using RUSI combined with sEMG can obviously increase multifidus thickness and RMS value in healthy adults.Meanwhile,the effect of dynamic feedback training is better than the effect of same training without dynamic feedback,providing a more effective method to maximize the effect of core muscles training.