Interesting Sports Medicine Article
 

In the New York Times, by Gretchen Reynolds, it focuses on former elite athletes (gymnasts, swimmers, divers) trying out for Cirque de Soleil. But it addresses research correlating attitude and injury.

Here is an extended quote from the article I found very apt to aikido or to any physical art or endeavor:
"'How do you differentiate someone who has appropriate self-efficacy because they are not actually as good as others" from those who lack confidence despite being better', asked Dr. Ian Shrier, an associate professor in the department of family medicine at McGill and lead author of the Cirque study.
"The distinction matters, he continued, because interventions designed to prevent injury would almost certainly need to differ, depending on whether someone's perceptions of his or her abilities and risks were accurate. If you're correct that you're not physically ready to perform a skill, then the best intervention is going to be augmented coaching and physical training. But if you have the ability but simply don't believe that you do, intercessions should probably focus on building psychological coping skills, rather than physical technique."