Older runners can compete in marathons without worrying about permanent cardiac damage, a new study has found. Headed up by Manitoba University professor Davinder Jassal, a team of researchers subjected a group of healthy volunteers from the 2010 and 2011 Manitoba Full Marathons to blood tests, heart ultrasounds, and CT and MRI scans. The group discovered that marathon runners over 50 had the same temporary cardiac abnormalities post-race as younger runners, but didn't incur any permanent damage. "What our study shows is that if you've trained well and you've done your homework in terms of keeping yourself hydrated, things will be OK," Jassal told the Canadian Broadcasting Corporation. The number of Canadians over 50 who run in marathons has doubled over the past two decades.