It's a long way uphill from Phoenix to Lake Tahoe. Beth Dyer, a self-described amateur runner, is anxious about the climb up, and the jog down.
On Saturday, the 47-year-old Arizona woman will join hundreds of other athletes in the 10K portion of the Lake Tahoe Marathon, which goes downhill beginning at Emerald Bay.
It's something she looks forward to, but she knows 6,200 feet is 5,114 feet more than she's used to.
"I will start slow in a jog, drink lots of water and I'll walk when I feel the altitude is getting to me," Dyer said of her strategy for the race.
And that's a good way to go about it, according to sports medicine experts who know something about exerting the body in a high-altitude setting.
Essentially, regular activity increases the oxygen-carrying capacity of blood.
During exertion, the blood carries more oxygen and the body's endurance and efficiency are improved, said Terry Orr, a South Lake Tahoe sports medicine specialist and physician for the U.S. Ski Team.
"What high-altitude living does is stress the body, stimulates immature blood cells," he said. "Ideally you want to live high and train low. For the athletes who live here, they are getting the best workout. When they go down to sea level, they feel as if they can go on forever."
That's not necessarily the case for those who train low and come up high.
For example, someone who runs a 26-mile course in three hours at sea level can expect to add six minutes at Tahoe altitude, said Les Wright, director of the event. He said it would be 12 minutes for a four-hour marathoner.
"The sooner an individual gets to Tahoe, the sooner their body creates additional red blood cells to carry oxygen through the body, and the easier the run will be. But it will always be a slower run," Wright said. "The marathon is not a speed course, even without the 6,200 feet elevation."
Joe Pettit, owner of Sierra Athletic Club in South Lake Tahoe, knows what elevation does to some of his vacationing customers.
During peak holiday times in summer and winter, the Tahoe Keys gym is inundated with vacationers from the Bay Area who are, for the most part, surprised that their workout routines have suddenly become more difficult.
"The efficiency with which the body has the ability to process and utilize oxygen is diminished by approximately 15 percent up here," Pettit said. "This applies not only to cardiovascular work, but to weight/strength training as well."
For athletes participating in this week's events, the best defense against the slow burn is to arrive early.
It can take up to two weeks before a person's body can acclimate itself from, say sea level, to Lake Tahoe's elevation, Pettit said.
"If you're running in a competitive event like the marathon, the half marathon or the 10K you'd be doing yourself a great service if you got here a week prior to the event. And, depending on your level of competition, you may want to allow for even more time," he said.
The Lake Tahoe Marathon is several days worth of events, including a marathon on Thursday, Friday and Saturday as well as kayak, swimming and biking races.