If you thought Lance Armstrong was tough, consider this: Hotshot firefighters require nearly the same amount of energy as the Tour de France champion just to do their job.
Unlike in professional sports, where an athlete's calorie and water input and energy output are carefully recorded and charted in training logs, a wildland firefighter's progress is usually gauged by where fire lines remain at the end of the day.
But researchers at the University of Montana and Montana University have been using high-tech gadgets and sophisticated science in recent years to measure the physical strains on elite fire crews. The hope is by measuring how much energy these crews use to battle wildfires, their supervisors can support them better with adequate food, water supplies and rest schedules.
The results also interest researchers in the U.S. Department of Defense, which, along with the Forest Service, has provided funding for the studies.
"I think the attractiveness of the firefighter model is we're not faking anything," says Brent Ruby, an exercise physiologist at the University of Montana in Missoula. "That means you get a non-simulated combat field-like environment — physical and psychological stress included."
An Elite Fleet
The Montana researchers selected the toughest of the tough — hotshot firefighters — as their test subjects.
There are now a total of 1,360 hotshot firefighters in 68 crews nationwide, according to the Interagency Fire Center. The crews are assigned to the most difficult part of wildfires and are trained to work in all phases of wildland firefighting, including building fire lines, setting backfires and mopping up.
To measure the energy output of these crews, Ruby and Steve Gaskill, also an exercise physiologists at the University of Montana , used a testing device known as doubly labeled water. This water solution is packed with tracers in the form of isotopes — elements that are naturally heavier or lighter in mass.
The harder a person works, Ruby explains, the more calories a person burns and the more tracer isotopes leave the body. To measure calorie output, Ruby and Gaskill had men and women hotshot firefighters drink small cups of the water solution every morning for a week and took urine samples each morning before they set off to work.
His results, published in the journal Medicine & Science in Sports & Exercise, showed that among 17 subjects, daily energy expenditure ranged from about 4,000 to 8,000 calories a day. In comparison, Tour de France trainers have reported their cyclists in the three-week race typically burn about 6,500 calories a day.
"It's staggering," he says. "This is one of the highest values in an occupational setting."
The Montana team also found that women firefighters burn an equivalent number of calories on the job as their male counterparts when figures were adjusted for weight differences. The results were collected for the Department of Defense in considering female soldier's roles on the battlefield.
Different Test, Same Results
Although Ruby and Gaskill's results were illuminating, they were also expensive. Each dose of the tracer solution costs about $1,000 for five days. As an alternative, Dan Heil, a professor at the Human Performance Lab at Montana State University in Bozeman, recently published results of similar tests using a cheaper instrument.
Heil used a physical-activity monitor — a beeper-sized instrument that slips easily into a breast pocket — to measure the exertion of hotshot firefighters. The device, which is available in sports stores for about $1,000 each, records movement and translates that into energy expenditure in calories per minute.
Heil added a computer chip technology to the activity monitors to collect and organize the data, which he published this month in the journal Applied Ergonomics. His results, like Ruby's, showed hotshot firefighters are relentless athletes.
"These people not only fight fires, they do it in heavy gear at a high rate all day long," he says. "It's an incredibly demanding job and they do it for weeks at a time."
Now that researchers like Heil and Ruby have determined how much energy hotshot firefighters use, the next step is to plug those numbers into meal plans to make sure they're adequately fueled.
"We can't control a wildfire," says Heil, "but we at least can try and reduce factors like fatigue and dehydration so these people, at any given moment, can run for their lives."