Chapter 4—Wildland Firefighting
"In order that people may be happy in their work, these three things are needed: They must be fit for it. They must not do too much of it. And they must have a sense of success in it."
John Ruskin
Many factors can make work
difficult and stressful, such
as the concentration
required of air traffic controllers, the
balance and agility required of steelworkers,
or the ability to withstand the
endless repetition required of assembly
line workers. Energy expenditure and
muscular requirements define physically
demanding occupations, such as
forestry field work and wildland firefighting. The energy demands of
these occupations are classified as hard,
very hard, or extremely hard work (table
4.1).
See table 4.1 for the energy requirements of firefighting tasks.
The muscular requirements of firefighting, as defined by the National Wildfire Coordinating Group (2009), include lifting more than 50 pounds. Firefighters carry loads up to 45 pounds (hose packs, water bags) and loads over 50 pounds (pumps). Smokejumpers may have to carry loads heavier than 100 pounds. The muscular demands of firefighting range from heavy to very heavy (table 4.2).
Long work shifts and the demands of the working environment combine to make wildland firefighting an extremely demanding occupation.
Hats or Caps
Hats or Caps During the catastrophic fires of 1910, a seasoned ranger phoned Elers Koch in Missoula to request some firefighters. When Koch asked how many, the ranger replied:
"Send me 10 men if they wear hats, and if they wear caps, I'll need 30."
The respectable lumberjack always wore a felt hat, whereas the pool hall boys and general stew bums (hobos) usually wore caps and shoved their hands deep in their pockets (from "Year of the Fires" by Stephen Pyne 2001).
In 1960 men averaged 5 feet 8 inches tall and women averaged 5 feet 3 inches tall. Today, men are 1½ inches taller on average and women are 1 inch taller. The average weight of men increased from 166.3 pounds in 1960 to 191 pounds in 2002. The average weight of women increased from 140.2 to 164.3 pounds during the same time period. The average Body Mass Index (BMI), a ratio of weight to height, increased from 25 in 1960 to 28 in 2002. A BMI higher than 25 is considered overweight. A BMI higher than 30 identifies obesity, unless the waist measurement is under 40 inches for men and 35 inches for women. Recent data shows that 66 percent of adults over 20 years of age are overweight or obese. (National Center for Health Statistics: http://www.cdc.gov/nchs/nhanes.htm).
Also called maximal oxygen intake or VO2 max, aerobic fitness is defined as the ability to take in, transport, and use oxygen. It can be reported in liters of oxygen per minute (liters per minute) or as milliliters of oxygen per kilogram of body weight (milliliters per kilogram/minute). Table 4.3 shows the average aerobic fitness for men and women.
Fitness Testing—Since 1975, wildland firefighters and fire managers have been required to pass a work capacity test before the fire season. The current test is the Pack Test, a 3-mile hike with a 45-pound pack, which predicts aerobic fitness. Performance on the test is also correlated with muscular fitness. Firefighters must complete the hike in 45 minutes, predicting an aerobic fitness score of 45 milliliters/kilogram minute. The energy demands of wildland firefighting exceed the capacity of the average man or woman. Applicants for firefighting jobs must be above average in aerobic fitness to meet the job requirement or they must train to improve their fitness by up to 25 percent or more.
Factors That Influence Aerobic FitnessSeveral factors influence aerobic fitness, including heredity, age, gender, and training.
HeredityStudies indicate heredity accounts for half of the variance in maximal aerobic fitness among individuals. The remaining variation is accounted for by environmental factors such as training and nutrition. The capacity of muscle to respond to training is also inherited, with improvements in aerobic fitness ranging from 5 percent to more than 30 percent for a given amount of training. Other inherited factors such as physique and body composition influence the potential to perform. Genes influence potential, but they don't assure it. The 30,000 genes that form the blueprint of the human body are subject to the influence of the environment and behavior. Genetic potential can only be realized when genes are switched on by training. The only way to realize your aerobic potential is to engage in training.
AgeTable 4.3 shows the decline in aerobic fitness with age. At age 60 the VO2 max is about 75 percent of the level at age 20. The rate of decline approaches 8 to 10 percent per decade for inactive individuals, regardless of their initial level of fitness. Those who decide to remain active can cut the decline in half (to 4 to 5 percent per decade). Those who engage in fitness training can cut that rate in half (to 2 to 3 percent per decade, see figure 4.1).
Figure 4.1—Age and aerobic fitness. Reprinted,
with permission, from B.J. Sharkey and S.E. Gaskill,
2007, Fitness & Health, 6th ed. (Champaign,
IL: Human Kinetics), 80.
The average aerobic fitness of young women is 10 to 20 percent lower than the average for young men. The VO2 max and performance of highly trained young female endurance athletes are only 10 percent below elite males. One reason for the difference between genders may be women's lower hemoglobin levels. Hemoglobin is the oxygen-carrying compound found in red blood cells. The average hemoglobin levels for women are 2 grams per deciliter of blood below those of males. Total hemoglobin is correlated to VO2 max and endurance. Other reasons for the differences between genders may be that women are smaller and have less muscle mass and more body fat on average than men.
A portion of the difference in fat between genders is sex-specific fat that is essential for reproductive function and health. For these and other reasons (such as the risk of developing osteoporosis), women shouldn't try to become too thin. We raise the issue only to explain why the average male has some advantage over the average female in aerobic fitness.
Studies and distance races show that women are well suited for fat-burning endurance events. Some women tolerate heat, cold, pain, and other indignities as well as or better than men. Although the average man has a small advantage in aerobic fitness, women can overcome that difference with training. The physical demands of wildland firefighting are not related to age or gender, so the work capacity requirement does not change for firefighters of different ages or genders.
Factors That Influence Muscular FitnessIn 1980, MTDC conducted a large field study to analyze the relationship between muscular fitness and performance of firefighting tasks. Measures of strength and muscular endurance, as well as lean body weight, were significant predictors of work performance. Factors that influence muscular fitness include age, gender, and lean body weight.
Age—Strength peaks in the early 20s and declines slowly until about age 60. The rate of decline usually accelerates after age 60, but it doesn't have to. When strength is used, it hardly declines, even into the 60s.
Gender—Until 12 to 14 years of age, boys are not much stronger than girls. Afterward, the average male gains an advantage that persists throughout life. Studies show that untrained females have about half the upper body strength and two-thirds the lower body strength of males. The average male has 10 times more testosterone, an anabolic (growth-inducing) steroid, than the average female. Testosterone helps muscles get larger and stronger.
Small but Fit
After several seasons on a district fire crew, Rebecca, a 40-year-old mother of two, earned a spot on a hot shot crew. She was 4 feet 10 inches tall and weighed 95 pounds. On one fire, when the wind picked up and the crew was ordered to a safety zone, she had to jog to keep up with her long-legged coworkers. Fortunately, her excellent aerobic fitness kept her from slowing the crew's escape to safety. A less fit worker would have slowed the crew and increased the threat posed by the fire.
Body Size—Body size is a factor in hard work. Physically demanding occupations often require absolute capacities and performances. Absolute demands, such as being able to lift and handle heavy loads, place someone with a smaller lean body weight at a disadvantage. In wildland fire suppression, no mechanical aids assist the worker. To perform effectively, smaller firefighters may have to work harder than a larger employee, leading to fatigue and the potential for injury. Firefighters must be able to meet the physical demands of their occupation in a safe, effective, and appropriate manner to avoid risk to themselves, coworkers, and the public.
Lean Body Weight—Lean body weight or fat-free weight is the body weight minus fat weight. Lean body weight reflects an individual's muscle mass. Studies of wildland firefighters indicate that lean body weight is positively associated with performance of firefighting tasks and is associated with performance in lifting tasks. Individuals with a lower lean body weight may have to engage in muscular fitness training before the fire season.
Body Fat—Two-thirds of the adult population is classified as overweight or obese. Excess body fat does not contribute to work performance or strength, and it decreases aerobic fitness, endurance, and heat tolerance. Lean body weight is significantly related to performance in lifting tasks. Those with more muscle can lift more. A weight training program will add pounds of muscle. Both weight training and aerobic training will help pare away excess fat.
The Available WorkforceThe energy and muscular demands of wildland firefighting exceed the capacities of many untrained individuals. The national epidemic that has left so many persons overweight or obese further narrows the pool of available workers. Some applicants have no experience in physically demanding work or sport. To qualify for firefighting positions, many applicants will have to engage in muscular and aerobic training, lose excess body fat, and become hardened to the rigors of this physically demanding occupation. Crew bosses will have to teach work skills and help new firefighters gradually adapt to long work shifts.
