Olympic Athlete Amy Hastings Cragg resting after winning the 2012 Olympic 10K trials. If you watched the 2016 Olympics this summer, you most likely observed many runners resting on their backs/ resting their psoas muscles following their race.
A good article to read regarding taking care of your prime running muscles, your psoas, is linked below:
http://runningmagazine.ca/rest-release-stretch-psoas/