Objective  To establish the lower-extremity movement model of shoulder tackle for female rugby players and understand its muscle strength characteristics, providing theoretical references for the specialized strength training and technique learning for shoulder tackle.

Methods  The impact force and biomechanics indexes of shoulder tackle and lower-extremity movement in eighteen Chinese elite female rugby players were synchro- tested by the impact testing system, force platform, sEMG and Vicon system, and lower-extremity movement model was established with OpenSim Static Optimization (OSO) software.

Results  ① The average force of shoulder tackle was 0.86～1.25 times of body weight. ② There was a significant difference between muscle strength of right side and left side of lower-extremity in the same position of shoulder tackle (P<0.05). ③ The average muscle strength of the same muscle groups of lower-extremity in different body positions were shown with significant differences between high and low body positions of right quadriceps, between high and middle body positions of left quadriceps, and between high and middle and low body positions of gastrocnemius, respectively (P<0.05). ④ There was a positive correlation between the muscle strength of lower-extremity and impact force of shoulder tackle.

Conclusions  ① Left-and-right-side lower-extremity extension were balanced to produce force in shoulder tackle, and the hip, the dominant knee and the non-dominant ankle of lower-extremity were the main exerting joints. ② The dominant ankle was a relatively weaker one in tackle techniques of lower-extremity. As the contractile strength of the dominant ankle gastrocnemius muscle was 0.26～1.45 times of the body weight on average and 1.20～3.08 times of body weight on the maximum, it proved to be a relatively weaker one in the muscle group chain of lower-extremity movement.