[Quantitative analysis of patellar tendon elasticity of amateur marathon runners after a competition based on shear wave elastography].

To analyze the changes of patellar tendon elasticity quantitatively of amateur marathon runners by shear wave elastography (SWE) in a half marathon. A total of 47 amateur marathon runners (31 males and 16 females, aged from 20 to 44 years) were enrolled as the marathon group, and divided into dominant side (47 patellar tendons) and non-dominant side (47 patellar tendons). Grey-scale ultrasound and SWE were performed on the bilateral patellar tendons before and after the half marathon within 2 h and after a period of 1 week. Thirty healthy volunteers (18 males and 12 females, aged from 22 to 39 years) were enrolled as the control group, the SWE-values derived from the patellar tendon were collected and analyzed. Multivariate logistic regression was performed to analyze the relationship between the changes of SWE-values and running age as well as weekly amount of running. None of any runners showed knee pain and sports injury during the test. The dominant side had a higher SWE-values than non-dominant side in marathon group before running [(55.1±15.7) kPa vs (43.8±15.9) kPa, <0.05]. The marathon group had higher SWE-values than the control group both in dominant side [(55.1±15.7) kPa vs (18.5±3.7) kPa] and non-dominant side [(43.8±15.9) kPa vs (17.4±3.2) kPa], respectively, before running (<0.05). The SWE-values increased significantly both in dominant side [(80.2±23.2) kPa vs (55.1±15.7) kPa] and non-dominant side [(76.5±26.6) kPa vs (43.8±15.9) kPa] 2 h after running in marathon group. After a week, the SWE-values were not statistically different from those before running (>0.05). Multivariate logistic regression showed that running age and weekly amount of running were related factors leading to the increase of SWE-values after running. The patellar tendon of amateur marathon runners has higher SWE-values. SWE can dynamically evaluate the changes of patellar tendon during exercise and is helpful for runners in scientific training and avoiding sports injury.