Abstract: Purpose: To study the effect of repetitive training and the cross-transfer of repetitive training, to test whether the interval between two identical maximum eccentric training rests and the key to whether the neural adaptation mechanism can produce the cross-transfer effect is worthy of in-depth discussion.. Methods: A total of 23 healthy adult male college students were recruited and randomly divided into experimental group (12) and control group (11) according to grip strength. In order of balance (half of the left and right elbow flexors), 30 times of maximum centrifugal contraction training (30 degrees/s) were given to the unilateral elbow flexors first, and then the second round of maximum centrifugal contraction training was given to the contralateral elbow flexors after 3 weeks of interval. In the control group, two rounds of maximum centrifugal contraction training were performed with the same non-customary elbow flexors on the same side, and the interval time was the same as that of the experimental group. The peak moment, surface electromyogram (EMG) signal and muscle injury index were recorded. Result: 1)The recovery speed of muscle ache, elbow joint relaxation and maximum isometric muscle strength change rate of the experimental group and the control group after the second round of maximum centrifugal contraction training were significantly better than their corresponding values in the first round. There was no significant difference between the experimental group and the control group in the immediate performance of the three indexes in the second round;2) On the first day after the first round of maximum centrifugal contraction training, the experiment was carried out. There was no difference in muscle ache, elbow relaxation and maximum isometric muscle strength between the control group and the experimental group, but on the first day after the second round of maximum eccentric contraction training, there were significant differences in elbow relaxation and maximum isometric muscle strength between the experimental group and the control group except muscle ache;3)In EMG signals, the experimental group and the control group had significant differences after the second round of maximum eccentric contraction training. The average power frequency was significantly lower than the first round, while the root mean square of EMG showed no significant difference. Conclusion: After maximal centrifugal contraction training in the first round of unilateral elbow flexors, the same contraction training in the second round of contralateral elbow flexors can effectively produce RBE phenomenon, and RBE phenomenon may participate in maximal centrifugal contraction training in the second round of contralateral elbow flexors by recruiting more type I muscle fibers, thus producing cross-transfer effect of RBE, so as to reduce muscle injury.

Key words: repeated training effect, cross transfer, delayed muscle soreness, maximum isometric muscle strength, central nervous system, sports training, fatigue