Why are people going uphill at Bloomington's Hyland Hills Ski Area all summer long?

Sisyphus, according to Greek mythology, was forced to spend eternity rolling a boulder up a hill in the afterlife.

Something like that is going on right now in Bloomington.

Every weekend during much of the year, people labor for hours on end, repeatedly going up and down a steep hill in the suburb, wearing heavy backpacks or carrying sandbags or lugging buckets of rocks.

They're not being punished by the gods. This pain is self-inflicted by people who are in training, typically for something exotic or extreme: a trail ultramarathon in the Colorado Rockies, running to the top of Pikes Peak, climbing Mount Kilimanjaro.

Compared with those places, the Bloomington hill, located at Three Rivers Park District's Hyland Hills Ski Area, isn't very grand. Dubbed Mount Gilboa, it's described as having only about 180 feet of vertical climb from the base of the hill.

But as one of the highest natural points in Hennepin County, it's all that we've got in the otherwise flat Twin Cities area.

Some of the fittest people in town — from senior citizens to high school athletes — regard this as the best place to do hill training in the metro area.

Johnny Surprise, a 49-year-old Minneapolis man, spent Saturdays in summer running up and down Mount Gilboa with four friends to prepare for the Grand Traverse, a 40-mile mountain run from Crested Butte to Aspen, Colo., followed by a 40-mile mountain bike race in the other direction the next day. "This is really the only place in the area to get any altitudinal training," he said. "As the training progresses, we're going to be pretty much living here, going up and down, up and down."

His 17-year-old son, Dylan Surprise, also sprinted up the hill this summer to get ready to compete on the cross-country team for Southwest High School in Minneapolis.

"We come here because most cross-country races have a big hill at the beginning or the end, and these hills make those hills look tiny," Dylan said.

A sort of camaraderie develops among the dozens of people on the hill during weekends. "There are people training for all kinds of stuff," said Phil Robinson, a 67-year-old Prior Lake man who was training for a one-day, rim-to-rim hike at the Grand Canyon. "You need a big hill. You need to train as close to the actual environment as you can."

Sitting only about 1,000 feet above sea level, the Bloomington hill will never be mistaken for a Colorado peak. But resourceful Minnesotans have found ways to make the most of Mount Gilboa.

Marsha McDonald, 63, of Edina, carried a backpack filled with 45 pounds of kitty litter up Mount Gilboa to train for a rim-to-rim hike of the Grand Canyon two years ago. Now she's preaparing for a 25-mile hike on the Superior Hiking Trail.

Obstacle course racers Sid and Darcy Geldmeyer came from Baldwin, Wis., to hike up and down the hill carrying 45-pound sandbags on their shoulders. "This is good. It's bad, but it's good," Sid said.

Hopkins resident Jadde Rowe, another obstacle course racer, went up and down the hill lugging a 5-gallon bucket filled with 65 pounds of rocks.

Some people bound up and down the hill using ski poles as dryland training for cross-country skiing.

"This hill is legendary for a lot of Birkie skiers," said Eden Prairie resident Joe Mundenar, referring to the Birkebeiner cross-country ski marathon in Hayward, Wis. "This is the place that got a lot of people fit quick."

"It's hard and challenging, but it's beautiful," said Michael LeMair, a trail racer from Richfield. "Not only do you see the edge of the city and the cityscape, but there's vast beauty here."

Runners and hikers also have to be on the lookout for flying saucers and wedding parties.

When the hill isn't being used for downhill skiing in the winter, the area becomes a 27-hole disc golf course. The ski chalet at the bottom of the hill is frequently rented for weddings.

The golfers and wedding parties pay a fee to use the area, and during the summer the hill is maintained to support those activities, said Andrew Berns, operations supervisor of the ski area.

The endurance athletes are accepted by the park as long as they don't cause turf damage or interfere with disc golf or outdoor weddings.