Risk Management

• Maintaining Immune Function
• Before Fire Season
• During Fire Season

Maintaining Immune Function

Studies by the U.S. Navy indicate a significant increase in upper respiratory tract infections 9 d after sailors embark on a long deployment. Group living conditions, such as those experienced in military training and wildland fire camps, lead to similar trends in upper respiratory infections. In addition to the stress of group living, the arduous work of wildland firefighting has the potential to reduce the body’s ability to resist viral and bacterial infections. When arduous work is combined with insufficient rest, the immune system is more likely to be depressed. Studies of overwork and overtraining indicate a series of physiological, biochemical, and psychological changes that reduce immune function and work capacity. These changes may include:

• Muscle microtrauma, increased numbers of white blood cells, and the release of inflammatory interleukins, leading to systemic inflammation
  
  
• Elevated cytokines coordinating a whole-body response that
  
  
  • Induces mood and sickness behaviors
    
    
  • Breaks down tissue protein to produce blood glucose
    
    
• Increases in the stress hormone, cortisol, with the suppression of the immune function increasing the likelihood of infection

When muscle protein is broken down to provide energy, lean tissue is lost, compromising muscle strength and endurance. If illness occurs, recovery may take many weeks. Maintaining a healthy immune system makes good sense.

Maintaining Your Immune System: Before the Fire Season

Physical Activity/Fitness—One of the best ways to ensure a healthy immune response is to engage in regular, moderate physical activity. Studies show an “inverted U” relationship between activity and immune function (figure 6). Sedentary individuals have a reduced immune response compared to those who are more active. Immune function peaks with regular moderate activity, decreasing when activity leads to fatigue or exhaustion. Of course, the term moderate is relative. Moderate could mean a brisk 30-min walk for some individuals or a vigorous 3-h bike ride for an athlete. If you engage in moderate activity most days of the week, your immune system will function at an optimal level.

Figure 6—The relationship of physical activity
to immune function and the risk of infection.

Nutrition—Studies conducted on soldiers indicate that nutritional status should be optimized before deployment when the deployment has the potential to compromise immune function. One guide to adequate nutrition is maintenance of body weight. Recent weight loss could compromise immune response, as well as strength and endurance. Studies show that firefighters have a difficult time maintaining muscle mass during a long fire assignment.

It is unwise to begin any campaign in a compromised state. Firefighters should never attempt to lose weight while working on the fireline.

Good nutrition involves appropriate percentages of carbohydrate (60 percent of calories), fat (20 to 25 percent of calories), and protein (15 to 20 percent of calories). Carbohydrate should consist of complex carbohydrates such as beans, corn, rice, potatoes, and whole-grained breads and pasta. At least two to four servings of fruits and three to five servings of vegetables should be consumed daily (eat more when you’re on a fire). Fat intake should be low, because high-fat diets suppress immune function. No more than one-third of fats should be saturated and hydrogenated fats (trans fats in processed foods). Daily vitamin and mineral supplements may be useful during periods of weight loss or when you can’t get the recommended servings of fruits and vegetables.

Rest/sleep—Firefighters should be well rested before deployment. Sleep deprivation compromises immune function. Fire camp is not the place to catch up on lost sleep.

Maintaining Your Immune System: During the Fire Season

Once the fire season has begun:

• Avoid allowing fatigue and exhaustion to accumulate by interspersing days of lighter activity between days of hard work.
  
  
• Get 7 to 8 h of sleep each night.
  
  
• Use short (less than 20 min) and long (more than 90 min) naps when possible.
  
  
• Maintain body weight.
  
  
• Wash hands after using the toilet and before meals.
  
  
• Eat regular meals and use liquid and solid carbohydrate supplements.
  
  
• Maintain adequate hydration. Drink before, during, and after work.
  
  
• Use carbohydrate and electrolyte (sports) drinks for up to half of fluid needs.
  
  
• Avoid sharing water bottles except in emergencies.
  
  
• Consider taking vitamin, mineral, and antioxidant supplements during periods of hard work and stress.
  
  
• Try to avoid excessive exposure to smoke.
  
  
• Consider taking days off when upper respiratory symptoms are "below the neck" (fever, deep cough, muscle aches, nausea, and diarrhea).

Note: Do not adhere to a low-carbohydrate diet while engaged in arduous firefighting activities. High-protein and low-carbohydrate diets do not provide the energy needed for long shifts of arduous work. Muscle mass is lost when protein is broken down to form glucose for energy. In addition, a high-protein and low-carbohydrate diet increases fat intake, which can suppress immune function. Low-carbohydrate diets are only appropriate for individuals who intend to remain sedentary. These diets appear effective in the early stages because the low carbohydrate intake leads to a significant loss of water (carbohydrate). These diets lead to weight loss because they provide fewer calories than the average person burns. However, the long-term effects of such diets have not been studied. They raise concerns about increasing risks of heart disease, colorectal and breast cancer, impaired kidney function, and complications of diabetes.