An Experimental Study On The Effect Of 12-week Strength Training On Achilles Tendon Stiffness

Research purposes:From the perspective of sports training and biology,this paper explores the influence characteristics of different strength training methods on subjects’ Achilles tendon stiffness.Through the effect comparison,further explore and clarify the（most）optimization mode of the adaptability of Achilles tendon tissue to strength training.Research objects and methods:48 male college students from the track and field and physical fitness special team of Xi’an Institute of Physical Education（randomly divided into 4 groups with 12 students in each group,i.e.high-intensity strength training group,low-intensity strength training group,fast strength training group and control group）were selected as the research object.The experimental methods,testing methods and mathematical statistics were used to collect and analyze the relevant data of Achilles tendon before and after 12 weeks of experimental training.Based on the data of human tendon（Achilles tendon）measured by ultrasonic diagnostic instrument and isokinetic muscle strength tester,the elastic modulus and stiffness parameters of Achilles tendon are calculated respectively,and the results are further verified by three-dimensional dynamometer test.Research result:（1）12 weeks of strength training had different effects on the stiffness of Achilles tendon.Compared with the control group,the cross-sectional area,elastic modulus and stiffness of Achilles tendon in the three different forms of strength training groups were higher than those in the control group（P < 0.05）.（2）After 12 weeks of strength training,the change of Achilles tendon cross-sectional area was not related to height,but there was a positive correlation between Achilles tendon cross-sectional area and body weight.（3）After 12 weeks of high-intensity strength training,the elastic modulus of Achilles tendon increased from 623.5±90.6mpa to 648±102.3mpa（an increase of4%）,and the stiffness increased from 176.9± 23.8n/mm to 208.9± 30.6n/mm（an increase of 18%）.There was significant difference before and after training（P < 0.05）.（4）After 12 weeks of rapid strength training,the elastic modulus of Achilles tendon increased from 613.2±123.5mpa to 657.4±103.6mpa（an increase of 7%）,and the stiffness increased from 186.2±29.1n/mm to 234.4±39.3n/mm（an increase of 26%）.There was significant difference before and after training（P < 0.05）.（5）After 12 weeks of low intensity strength training,the elastic modulus of Achilles tendon increased from 645.8±103.6mpa to 655.9±121.8mpa（an increase of 2%）,and the stiffness increased from 198.6±23.8n/mm to 217.6±18.6n/mm（an increase of 10%）.There was significant difference before and after training（P < 0.05）.Analysis conclusion:（1）Among different strength training methods,fast strength training has the most obvious effect on Achilles tendon stiffness,followed by high-intensity strength training group and low-intensity strength training group.Without strength training intervention,there was no significant adaptive change in Achilles tendon stiffness.（2）Compared with high-intensity and low-intensity training,fast strength training has the most obvious effect on vertical jump performance,followed by high-intensity strength training group and low-intensity strength training group respectively.There was no strength training intervention,and the vertical jump performance did not change.（3）Fast strength,high-intensity and low-intensity strength training can cause the changes of elastic modulus and stiffness of Achilles tendon,and there are differences in the degree of improving the mechanical properties of Achilles tendon.（4）The change of Achilles tendon stiffness is closely related to the training mode.Enhanced fast strength training can more effectively change the mechanical properties of Achilles tendon and improve the elastic potential energy reserve of Achilles tendon,so as to promote the performance of bouncing movement.