Temporal changes of pelvic and knee kinematics during running

 Problem statement: Continuous running for a long duration during training and competition can lead to injuries due to changes in lower extremity kinematics particularly in pelvic tilt and rotation. These changes of pelvic kinematics  may  serve  as  a  warning  sign  of  instability  structures  and  present  an  injury  risk. Objective:  To investigate the change of pelvic and knee kinematics during running at different time points (1st, 10th, 20th, and 30th minute). Materials and methods: During the first visit, VO2max test was performed on twelve recreational runners. During the second visit, 3D motion analysis was performed, and kinematics data were collected while the  participants  ran  on  a  treadmill  at  a  speed  of  individuals’  70%  of  VO2max  for  30  min.  Pelvic  and  knee kinematics in all three planes (including pelvic range of motion, pelvic angles, knee angles) at the 1st, 10th, 20th, and 30th min of 5 running gait cycles were obtained and analyzed. Additionally, step and stride lengths were analyzed. Results: One-way repeated measures ANOVA revealed no significant differences in the kinematics of knee and pelvic angle and no significant differences in step and stride lengths at initial contact (IC) and toe-off (TO) during running for 30 min. Conclusion: It is possible that the runners are used to their own pace and have the ability to maintain a running pattern. Therefore, this work may be beneficial for the coaches, runners, and sports  scientists  to  understand  the  changes  of  the pelvic  and  knee  mechanism  during  running  overtime  to improve training and reduce injury risk. Additionally, this work provides a practical overview to observe the lower extremities of running mechanics during different time points.