Hazel McFarlane, 46, from Troon, will take part in the event on April 6, when she will be one of 150 runners.
It starts from Ruchill Park and participants will run mainly along canal towpaths.
Hazel said: "I will be supported by a team, each running with me for approximately 14 miles. To remain in the race, you must finish within 13 hours.
"I have been running 20 miles on Saturday mornings and 10 on Sundays, with two club training nights during the week. I would love to finish within the 13 hours"
She is aiming to raise funds for an Ayrshire service that supports sight loss victims.