Inside a warehouse-style gym, a mid-20s woman of pure muscle hoists more than 100 pounds above her head and then sprints to the horizontal bars for pull-ups. Nearby, a newcomer does a tamer version of the same workout, relying on a thick elastic band to help him raise his chin above the bar.
This is CrossFit, a style of working out that has swept the nation.
Bleeding hands and sore muscles are the norm but CrossFit, launched from Santa Cruz, Calif., a dozen years ago, is being sold to the masses on the notion that they, too, can do things they never dreamed possible. Each day, participants perform an ever-changing but always grueling sequence of exercises dubbed the Workout of the Day, or WOD.
The intensity of their effort is offset by the fact that the WOD is short -- generally less than 20 minutes. Trainers offer modifications for those who are injured or not yet strong enough to complete the workout as prescribed.
"You will do things here that you never thought you could do, and people are cheering you on to reach your goal," said Christian Norgaard, owner of the American River (Calif.) CrossFit. "You're going to hurt, but it's fun when you're done."
Since founder Greg Glassman posted the first workout of the day (WOD) online for his Santa Cruz gym in 2000, the business has expanded to more than 3,600 global affiliates. Each affiliate pays licensing fees to the parent, CrossFit Inc.
CrossFit has also become a presence on sports television in the form of the recent ESPN3 competition for the title "Fittest on Earth."
Norgaard and his wife, Kathleen, have watched the continued development of the industry since they opened a "box," as CrossFit gyms are called, in their garage in Sacramento, Calif., in April 2008. The Norgaards have gone from business rookies to successful entrepreneurs in just four years.
"We never could have expected this," said Kathleen Norgaard.
Each CrossFit gym has considerable autonomy. As an affiliate, the Norgaards pay $1,000 to Washington, D.C.-based CrossFit Inc. each year. They set their own membership prices, create their own workouts and decide on their own what equipment to buy.
Typically, a CrossFit gym includes rowing machines, lots of weights, bars for pull-ups, wooden boxes to jump on, balls to throw, sandbags to carry and maybe some sleds to pull.
"You don't need fancy stuff," Christian Norgaard said, pointing toward the sand-filled ammunition can boxes that served as the weights for the original classes in their garage.
While the workouts vary from gym to gym, there are some classic routines -- such as the Fran and the Murph -- that are considered must-do benchmarks for CrossFitters. Murph is named for Navy Lt. Michael Murphy who was killed in Afghanistan in 2005 and is one of 83 "Hero Workouts" that honors fallen soldiers.
Growth in the CrossFit industry is occurring outside the box as well, with enthusiasts developing nutrition, clothing and equipment companies.
David Shanahan, the 21-year-old president of FitAid, has been doing CrossFit for eight years and owns the CrossFit Maxim gym near Santa Cruz. He said the CrossFit community prefers to grow from the inside, with products launched by people who are already involved.
"A lot of larger companies have tried to infiltrate the CrossFit market, but a lot of the industry growth is coming from within," said Shanahan, whose nutrition beverage is now sold in 120 CrossFit gyms across the nation.