It was only a month ago that I wrote about the effect of fatigue on foot function and now there is another publication to add to the mix. The reason that the issue is important is that most biomechanical studies and clinical assessments are done when runners are fresh and not fatigued. When they are fresh, they may not display what are assumed to be risk factors for an injury that they may display when they are fatigued. Obviously, the later part of every run and race is done in a fatigued state! The previous article looked more at the affect on foot function, whereas this new study looked more at running kinematics and the effects of core endurance:
Kinematic changes during running-induced fatigue and relations with core endurance in novice runners
Ian F. Koblbauer, Kimberley S. van Schooten, Evert A. Verhagen, Jaap H. van Dieën
Journal of Science and Medicine in Sport; Article in Press
This study aimed to investigate kinematic changes experienced during running-induced fatigue. Further, the study examined relations between kinematic changes and core endurance.
Repeated measures and correlation.
Seventeen novice runners participated in a running-induced fatigue protocol and underwent core endurance assessment. Participants ran at a steady state corresponding to an intensity of 13 on the Borg scale and continued until 2min after a Borg score of 17 or 90% of maximum heart rate was reached. Kinematic data were analyzed for the lower extremities and trunk throughout a running protocol and, on separate days, core endurance measures were recorded. Changes in pre- and post-fatigue running kinematics and their relations with core endurance measures were analyzed.
Analysis of peak joint angles revealed significant increases in trunk flexion (4°), decreases in trunk extension (3°), and increases in non-dominant ankle eversion (1.6°) as a result of running-induced fatigue. Post-fatigue increased trunk flexion changes displayed a strong to moderate positive relation with trunk extensor core endurance measures, in contrast to expected negative relations.
Novice runners displayed an overall increase in trunk inclination and increased ankle eversion peak angles when fatigued utilizing a running-induced fatigue protocol. As most pronounced changes were found for the trunk, trunk kinematics appear to be significantly affected during fatigued running and should not be overlooked. Core endurance measures displayed unexpected relations with running kinematics and require further investigation to determine the significance of these relations.
The results show changes in kinematics after the fatigue protocol that are assumed to be associated with an increase in injury risk (ie ‘overpronation‘) and poor running form (the increased forward lean of the trunk).
The surprise finding of this study was the relationship between the changes in kinematics and core endurance. They found that “participants who displayed better core endurance exhibited larger trunk kinematic changes when fatigued“. This does raise some questions about the widely assumed importance of the core in running and also questions about the mechanism of the relationship between ‘core stability’ and running kinematics.
I not sure how to interpret this result as they are counterintuitive. I have no doubt about the importance of the core, but the results of the study above are the results of the study and we can’t just wish away studies that we don’t like the results of if they have no fundamental flaws in them (I can’t see any in this one). Somehow the authors did manage to conclude from this: “This may support core endurance training in runners“. I am not sure how the data in this study shows that, even though they are probably right about the importance of core endurance training!
As always, I go where the evidence takes me until convinced otherwise.
Koblbauer, I., van Schooten, K., Verhagen, E., & van Dieën, J. (2013). Kinematic changes during running-induced fatigue and relations with core endurance in novice runners Journal of Science and Medicine in Sport DOI: 10.1016/j.jsams.2013.05.013