Featured Topic Shift Food
In cooperation with the University of Montana Human Performance Laboratory, MTDC has studied the effect of supplemental feeding strategies on self-selected work activity during wildland fire suppression. Firefighters from eight different interagency hotshot crews were studied during three fire seasons. During the first two seasons subjects consumed, in addition to a sack lunch, either a liquid carbohydrate drink or a flavored placebo every hour, or liquid carbohydrate every even hour and solid carbohydrate every odd hour, using counterbalanced crossover designs. During the third season, subjects consumed either their sack lunch halfway through their workday or shift food at 90-minute intervals after breakfast, in a randomized crossover design with similar caloric intake in sack lunch and shift food (1,500 kcal per shift). In all studies, work output was monitored using electronic activity monitors.
During the liquid carbohydrate trials, firefighters who consumed liquid carbohydrate drinks had significantly higher average activity for the entire day than those who consumed a placebo. For the liquid and solid carbohydrate trials, firefighters consuming carbohydrate had higher average activity 2 hours before lunch and during the last 4 hours of the workday, when compared to those who consumed a placebo.
For the sack lunch and shift food trials, firefighters eating shift food had higher average work activity during the final 2 hours of work when compared to those eating sack lunches. Liquid and/or solid supplemental carbohydrate and intermittent feedings rather than a single meal increased self-selected work rates during fire suppression, particularly late in the workday. Shift food items purchased at local grocery stores cost less than the sack lunch.
In related studies conducted in cooperation with the Army Research Institute of Environmental Medicine, we studied the effect of an experimental ration consisting of eaton-the-move items to promote snacking and provide caffeine during fire suppression activity. The eat-on-the-move ration, also known as a First Strike ration (FSR) (3,067 kcal/day) was compared to a Meal, Ready to Eat (MRE) field ration, (2,841 kcal/day), consumed whenever the firefighters wished over several days of work. Twenty-eight wildland firefighters received each ration for 2 consecutive days, with a 1-day break between trials. Firefighters ate significantly more frequently with the eat-on-the-move ration compared to the Meal, Ready to Eat ration. Salivary caffeine and total activity counts during fire suppression were significantly higher when firefighters consumed the eat-on-the-move ration rather than the Meal, Ready to Eat ration. Researchers concluded that delivery of energy and caffeine in a manner that promotes snacking behavior (intermittent feeding) helps increase work during arduous fire suppression.Conclusions
Wildland firefighters are endurance athletes who engage in arduous work throughout a long work shift. Athletes in prolonged endurance events, such as the Tour de France or the Ironman Triathlon, eat at regular intervals throughout the events. Our studies reviewed in issue 10 of this report indicate that intermittent feeding of wildland firefighters throughout the work shift maintains work output, especially during the latter hours of the shift. The studies also show that intermittent feeding helps maintain blood glucose, immune function, and a positive mood. The shift food used for intermittent feeding costs less than a sack lunch, and firefighters prefer shift food to a sack lunch.
Of the meals provided in fire camp, the sack lunch is the least well received by firefighters. Alternatives to sandwiches have improved the acceptability of sack lunches. Items in the traditional sack lunch can be consumed intermittently throughout the day, but bagged sandwiches dry out once they have been opened.Recommendation
MTDC recommends gradual implementation of the shift food system, as an option to or replacement for sack lunches. Either approach would require developing a shift food delivery system and educational materials that emphasize intermittent feeding throughout the shift. Shift food will improve day-long work output. Maintaining blood glucose also could contribute to improved decisionmaking and employee safety. MTDC recommends a pilot program in a fire camp setting that includes a full trial with shift food and firefighter education.
The trial program would identify shift food items suitable for intermittent feeding and develop a system that ensures delivery of adequate energy and nutrients. The trial should determine firefighter acceptance of shift food. The trial also should include participation of caterers and contract personnel to ensure successful servicewide implementation.
Slides from the presentation Eating for Health and
Performance: The Wildland Firefighter.