Ultramarathoner Dave Proctor was forced to end his bid to run from coast to coast due to a serious back injury.

Proctor planned to run 7,200 kilometres in just 66 days after dipping his trademark white cowboy hat into the Pacific Ocean last month. He was doing well, crossing the Rocky Mountains and hitting the halfway point across Canada just east of Winnipeg. But running an average of 108 kilometers per day took its toll.

"This project was no longer safe for me to do, and I've got a long life, I've got to support my family and I can't compromise my long term health,” he said.

Pain in his back was growing unbearable, so his medical team gave him a close examination and found a herniated disk in his spine. Doctors told the 37-year-old that he could end up with permanent damage to his spine and hips if he continued his trek.

Researchers from the University of Calgary also took the run as an opportunity to study the human body, giving Proctor an MRI and running several endurance tests. His pre-race data and information collected when he ran through Calgary will be part of the study.

The run could carry on with numerous runners offering to continue portions of the remaining stretch.

"Our website is just flooded with people wanting to donate and really we are changing our slogan to one country” said Proctor. “That's what this should be all about."

But there is also personal heartbreak for Proctor. He began the project with the goal of raising awareness and half a million dollars for rare disease research because his nine-year-old son suffers from a rare disease.

"I will run to the ends of the earth for my son Sam, I will move mountains for him and that's what this was really about,” he said, saying he will do something else for his son. "Knowing me it will be something bigger, something grander but right now I just have to get my head straight and my body straight and we will see what comes up."

If you want to continue following Proctor’s recovery and see what happens next with the project, log on to outrunrare.com.