ST. MARYS — Karl Joseph learned a lesson 10 months ago when he and two other ultra-marathoners left downtown St. Marys with the goal of running the entire 155-mile Coastal Georgia Greenway without stopping.

The thermostat rose to 95 degrees with a heat index of 103, forcing the runners to abandon their quest 75 miles into the run.

“Last year I experienced mind-numbing cramps but that was because I was dumb enough to try the run in June, because I had missed the official run, running the Boston Marathon,” he said.

Joseph said he an several other runners plan to leave Savannah 7 a.m. on April 7, with a goal of arriving in downtown St. Marys the following day by 9 p.m. The run is intended to generate support for completion of the Coastal Georiga Greenway.

A road crew will not accompany the runners this year, Joseph said. Instead, they have established three cache spots along the route for supplies.

“Other than that we will each rely on what we can carry and purchase along the way at convenience stores,” he said. “We have camel-backs which hold water.”

Runners stop briefly every six to 10 miles for a food break.

“As we have learned over the last couple of years, it is unwise to stop for very long, as lactic acid buildup is very uncomfortable,” he said. “Some of us are intending to break the record of 44 hours, by finishing under 40 hours which will necessitate minimal and very short breaks.”

Joseph said he hydrates with water 90 percent of the time, adding Gatorade or a power drink from time to time. They also take salt tabs. As for diet, it’s a matter of taste, he said. He eats avocados, bananas, nuts, seed, Cliff bars for protein and the occasional peanut butter and jelly sandwich.

He is running 44 to 60 miles a week, including speed work and tempo, which builds in mileage.

“I will probably get another 30 miler in at some point between now and April 7,” he said.

The biggest concerns are dehydration, over-hydration and traffic, he said.

“Sleep-deprivation is very debilitating, so we will limit our breaks,” he said.