Objective:To explore the safety and effectiveness of medium-frequency electrotherapy for increasing the volume of the latissimus dorsi muscle.Methods:Fifteen adult New Zealand white rabbits were randomly divided into three groups, namely group A, group B, and group C, with 5 rabbits in each group. This was a self-control study, with the right latissimus dorsi muscle as the experimental group and the left latissimus dorsi muscle as the control group. The three groups corresponded to three different current intensity levels: 7.062 mA for group A (6th gear), 10.593 mA for group B (9th gear), and 14.124 mA for group C (12th gear). After the 12th, 24th, and 36th sessions of the experiment, ultrasonography was used to collect the thickness of the latissimus dorsi muscle. After the 36th electrostimulation, the latissimus dorsi muscle samples were collected to measure their in vivo muscle thickness and wet weight and were then sent for HE and MASSON staining.Results:After the 12th, 24th, and 36th electrostimulation sessions, ultrasonographic sampling in groups A and B showed an increase in the thickness of the right latissimus dorsi muscle compared to the left; for example, the thickness on the right of group B increased by 37.8%. The wet weight data collected after the 36th electrostimulation in groups A and B showed an increase in the right latissimus dorsi muscle compared to the left; for example, the wet weight on the right of group B increased by 5.04%.Conclusions:Different electrostimulation modes of medium-frequency therapy technology can induce muscle fiber thickening or atrophy. In this experiment, the 9th gear (10.593 mA) of medium-frequency therapy technology may be a suitable choice for inducing muscle fiber thickening, and the 12th gear (14.124 mA) may be a suitable choice for inducing skeletal muscle thinning.