Health & Safety ReportWildland FirefighterWildland FirefighterWildland Firefighter

Fall 2000 Missoula Technology and Development Center No. 2

TT he National Wildfire Coordinating Group (NWCG) coordinates firefighting efforts amongFederal and State agencies. As part of the NWCG’s mandate to ensure current, shared

information, a report on Wildland Firefighter Health and Safety issues will be published twiceeach year by the Missoula Technology & Development Center (MTDC). It will include activitiesrelated to the MTDC project on firefighter health and safety, including summaries of research,abstracts of related reports, articles, and field notes. Practical approaches to manage fatigue,environmental stress, and other factors that compromise the health and safety of wildlandfirefighters will be reported, and upcoming events will be announced.

0051-2855-MTDC

BackgroundThe NWCG assigned MTDCthe task of coordinatingthe WildlandFirefighter Healthand Safety projectand serving as thefocal point forongoing andfuture studies.MTDC hasconducted manyresearch anddevelopmentprojects related tothe health, safety, andproductivity of wildlandfirefighters. The WildlandFirefighter Health and Safetyproject will focus on threemain areas and goals:

Work/Rest Issues—Development of an objectiveapproach for thedetermination of work/reststandards, and recommendedassignment lengths for crewsand overhead.

Energy and Nutrition—Improvement of the energyintake, nutrition, andimmune function of wildlandfirefighters.

Fitness and WorkCapacity—Implementationof medical screening andwork capacity standards, andimprovements in the health,safety and productivity offirefighters.

Fires of 2000

As this report goes to press, the2000 fire season ranks as the

worst in 50 years. Withthousands of fires and

over 6 million acresburned, the

season hasstrainedhuman andphysicalresources.While helphas comefrom Army,

Marine, andNational Guard

units, and fromCanada, Mexico,

Australia, and NewZealand, the fires may

continue until rain or snowaids suppression efforts.Subject departs field lab on Storm King

Mountain during a simulated escaperoute evacuation (see page 6).

• Immune Function• Escape Route Evacuation• Human Factors• Fitness and Injury

In this Issue:

2

Table 1: Delayed-Type Hypersensitivity (DTH), infection, and death rate.

Infection Death RateRate of infected patients

(percent) (percent)

Reactive 7 19

Relative Anergy* 16 32

Anergy 25 51

*Anergy, the lack of response, indicates impairment of the immune system. Based on skin testing of 4,289 hospitalized patients (Christou and others, 1995).

Wildland Firefighting and theImmune ResponseSteve Wood, Ph.D., R.D.

Wildland firefighters performtheir jobs in a number ofconditions that may suppressthe immune system andincrease the risk of illness.This paper examines theinfluences of physical andpsychological stresses onimmune function and presentsa military model, containingmany of the stresses found inwildland firefighting, of a fieldnutrition study where immunesuppression was minimized.

The Immune System—Theimmune system is an intricatesystem of organs, tissues, cells,and molecules that maintainbalance between theenvironment and the body.Stresses such as physicalexertion, sleep deprivation,malnutrition, extremetemperatures, smoke,psychological pressures, andendocrine changes influencethe body’s defense system andalter its equilibrium. Theenvironment we live in has avariety of infectious microbes(viruses, bacteria, fungi,parasites, and protozoa). Ifthese multiply unchecked, theycan cause sickness, disease,and death. Our bodies combatthese microorganisms throughimmune responses. The skin isthe first line of defense. Whilefew infectious agents canpenetrate intact skin, they maygain access across epithelial

tissues, or through thegastrointestinal or urogenitaltracts. Once an organism hasgained access, the immunesystem must recognize thepathogen or foreign materialand mount an attack (immuneresponse).

Immune responses arecoordinated primarily by whiteblood cells (leukocytes). Oncethe white blood cells identifythe foreign material, theimmune system mounts anattack to bind and destroy it(phagocytosis). The immuneresponse is much like anorchestra. When cells andorgans are working together,the immune system functionseffectively; however, if cells andorgans are not workingharmoniously, the risk ofdisease and illness increases.

Energy and sleep deprivation,mental stress, and intensephysical exertion affect theimmune system. It is possibleto measure overall immunesystem effectiveness by usingclinical measures such asdelayed-type hypersensitivity(DTH), the rate of infection orresponse to pathogen orvaccine. DTH tests can beadministered easily by placingsmall amounts of proteins thatcause a reaction (antigens) intothe epidermis and superficialdermal tissue (Table 1).

Persons who are DTH reactivehave a much lower rate ofinfection than those who areanergic (not responsive). Ifpersons who are anergicbecome infected, they have apoor prognosis. A reduction incell-mediated immuneresponses can limit thedevelopment of an effectiveimmune response againstintracellular pathogens,including viruses, bacteria,fungi, and protozoa. DTH hasalso been used to evaluate theimmune function of patientswho are malnourished, whoseimmune system is suppressed,or who have experiencedtrauma.

Firefighting Stress—Wildlandfirefighters are exposed tomany stresses that can affecttheir health and influence theirimmune systems. In addition tothe psychological challenges offirefighting, a number ofphysical challenges (such asenvironmental toxins, injuries,smoke inhalation, and burns)could cause the immunesystem to be suppressed.Although many studies haveevaluated the effectiveness ofequipment for wildlandfirefighters, none has focuseddirectly on the health of thefirefighter’s immune system.Therefore, we will examineresearch conducted in similarsituations to evaluate factors

Featured Topic

3

Immune function

infe

ctio

n

Risk of

Sedentary

Belowaverage

Average

Aboveaverage

Moderate High

Physical Activity

Figure 1—The relationship of physicalactivity to immune function and risk ofinfection.

that may influence the wildlandfirefighter’s immune system.

Stress and Infection—Whathappens to the immune systemas a result of stress? Dochanges in the immune systemtranslate into increasedsusceptibility to disease? In1991 Peterson and othersreviewed stress and thepathogenesis of infectiousdisease. The authors reviewedmany studies in whichstressors (exertion, electricshock, isolation or crowding,and exposure to coldtemperatures) were imposed onanimals.

Several epidemiological studieshave documented an increasedincidence of upper respiratorytract infection after strenuousexercise. On the other hand,individuals who exercisemoderately have a lower risk ofinfection than those who aresedentary. Regular moderateexercise appears to conveyenhanced immunologicalresponses. More chronic andsevere stress, such as thatexperienced by persons trainingin the U.S. Army Special ForcesAssessment and SelectionSchool (SFAS), decreasesimmune function and increasessusceptibility to environmentalpathogens (Figure 1).

Ambient conditions also caninfluence immune function andsusceptibility to infection.Animals maintained at lowtemperatures experience higherrates of infection. Animalstudies found females moreresistant to the effects ofcrowding. Lack of sleep hasbeen shown to reduce immunefunction. Rats that are deprivedof sleep drastically increasetheir food consumption(hyperphagia) but they loseweight (malnutrition-likesymptoms) and may succumb tolethal systemic infections.

Readiness and Impact onTime Lost—The effect ofdecreased immune function onfirefighter readiness and lostwork hours has not beenreported. However, corollariesfrom military studies can beused to establish the effects.For example, in several majorU.S. military conflicts diseaseand nonbattle injuries (DNBI)have accounted for significantloss of manpower.

Exposure to pathogens fromenvironmental factors andcrowded living quarterscontribute to diseasesusceptibility in military unitseven during routine peacetimeoperations. Seay and othersfound that 777 cases ofgastroenteritis were reportedafter a 10-day port visit. Theillness affected 15 percent ofthe work force and cost 462days of lost work. Seay stated,“Lost duty days, and the burdenof providing medicalconfinement may be morecritical than fatal illnesses.Fatalities may be replaced butsick soldiers continue tooccupy positions, decrementperformance, and consumelarge quantities of medicalsupplies.” While many factorsmay contribute to

susceptibility to infection anddisease during militaryoperations, the effect ofphysical and psychologicalstress undoubtedly have asignificant impact.

Physical and NonphysicalStresses—Stressors, such asexertion and extremeenvironmental temperatures,can affect the immune system.The changes are similar tononphysical stresses (such asisolation). In human studies,nonphysical and physical stresscan produce immunologicalchanges.

Chemicals in the smokewildland firefighters may beexposed to can affect theimmune system. Smokeexposure has been a recognizedhealth issue for many years. Afew studies of firefighters inthe 1970’s hinted that smokeexposure contributed to fatigueand injury. The main inhalationhazards are carbon monoxide,aldehydes, benzene, acrolein,and particulate matter smallenough to reach the lungs.

Nutrition—Starvation has beenshown to affect the immunesystem. Nutritional deficienciesor suboptimal nutrient levelscan be the result of eating toolittle food, decreasedabsorption of nutrients, orincreased use of nutrients.Many nutrients are required foroptimal functioning of theimmune system. The effect ofinfection on nutritional statusis characterized by wasting ofperipheral tissues, particularlylean body mass (muscle).Nutrients (vitamins andminerals) are used as substrateand cofactors for immune cells.Once an infection takes place,immune cells have a higherrequirement for nutrients.After infection, particularly of

4

The era of nutritionalmanipulation of theimmune system has

finally dawned and itbrings with it the

promise of using dietand nutrition as

innovative powerfultools to reduce illnessand death caused by

infection.R.K. Chandra, Proceedingsof the National Academy of

Science.

the gastrointestinal tract, thegut’s mucosal lining may bedamaged and the microflora ofthe gut may change, decreasingthe small intestine’s absorptivecapacity. The mucosal andmicroflora changes can also beinfluenced by antibiotics andmedications, further decreasingthe effectiveness of nutrientabsorption. An infection mayalso increase use of nutrients.Nutrient supplementation canprevent malnutrition andprovide the essential factors forimmune cells to functionoptimally.

before an ultramarathon. Sixty-eight percent of the runnerswho consumed the placeboreported upper respiratorytract infections compared with33 percent of those whoconsumed the vitamin C.

Giuliani and Cesaro report thatphysical activity raises oxygendemand severalfold, increasingthe formation of oxygen radicalspecies or free radicals. Asoxygen radical species areformed, they adversely affectimmune function.Theoretically, providingantioxidants in sufficientamounts during exercise-induced oxidative stress maymaintain the immune system.Several reviews have beenpublished on the importance ofdietary antioxidants and theirinfluence on the immuneresponse.

Army Special Forces andRanger Training—RossProducts Division of AbbottLaboratories has investigatedpotential benefits of nutrientsupplementation andnutritional strategies tominimize immunologic changesin a variety of conditions. Themilitary stresses (carryingheavy packs and equipment,strenuous physical exertion,exposure to extremetemperatures, andpsychological stress) seem tobe similar to those experiencedby wildland firefighters.

Historically, militarydeployment has been associatedwith an increased incidence ofinfectious diseases.Furthermore, soldiers inmilitary training have incurredmore outbreaks of infectiousdisease than would be expected,pointing toward an underlyingsusceptibility. The UnitedStates Army Special Forces

Assessment and SelectionCourse (SFAS) is highlydemanding, physically andemotionally. Fairbrother andothers documented a negativeenergy balance (1,379 kcals/day)in soldiers who participated inthe 21-day course; however, nosignificant clinicalmanifestations of vitamin ormineral deficiencies werenoted. One observation fromthat study was a reducedlymphocyte proliferationresponse. This observationsuggested that multiplestressors (negative energybalance, sleep deprivation,physical activity, andpsychological stress) may havenegative effects on immunefunction and the ability oflymphocytes to combatinfections. Bernton and othersfound that during Rangertraining DTH skin anergyincreased over time. Thosetrainees who did respond had adecreased response.

Nutritional intervention withthis group allowed for anevaluation of nutritionalsupplementation on immunefunction. Two hundred soldiersparticipating in an SFAS coursevolunteered to participate inthis prospective, randomized,blinded, placebo-controlledstudy. The test group (n = 100soldiers) consumed theirregular diet consisting mainlyof meals ready-to-eat (MRE)plus a novel ready-to-eattreatment product (8 oz twotimes per day) containingantioxidants, minerals, astructured lipid (from long- andmedium-chain fatty acids), andindigestible carbohydrates. Thecontrol group (n = 100 soldiers)was given a ready-to-eatproduct similar to thetreatment product in taste andappearance with a similaramount of energy but without

Nutrient supplementation canimprove immune function,counteracting the stress-induced immune changes.Supplementation to minimizeor prevent immune changes andprotect individuals who areundergoing physical stress hasbeen studied to a limitedextent. Nutrients such asvitamin C may play a role inimmune function and mayprevent immune suppression inphysically stressed individuals.Peters and otherssupplemented the diets ofrunners with 600 mg vitamin Cper day or a placebo for 21 days

5

Firefighter Immunity

Mark Vore of the Idaho Panhandle National Forests analyzed1994 Northern Rockies fire camp medical records. He foundthat 30 to 50 percent of the visits to medical tents were forupper respiratory problems, including coughs, colds, and sorethroats. Similar results were noted by a team investigatingfatigue and stress during the 2000 fire season. A number offactors in the firefighting environment influence immunefunction and the body’s susceptibility to respiratory and otherillnesses. Upper respiratory problems can be due to fatigue,stress, smoke exposure, inadequate nutrition, or a combinationof stresses. Rapid weight loss and sleep deprivation have alsobeen associated with decreased immune function.

Fire managers and crew leaders should do all they can to avoidexhausting firefighters and exposing them to excess smoke.Managers can reduce stress by providing up-to-date information,by soliciting input from crew members, and by minimizingcrowding, waiting, and other factors that contribute to stress .They can enhance rest and recuperation by providing adequatetime and conditions for sleep. And they can ensure firefighterfitness with early-season conditioning and heat acclimatization.Firefighters are responsible for preseason conditioning andnutritional food choices. Fire camp meals provide adequateenergy and nutrients. Firefighters must consume adequatecalories to maintain energy, and eat adequate servings of fruitsand vegetables or consider multi-vitamin/mineral supplements.

antioxidants, minerals, and thestructured lipid. Dietary intake,body weight, and immunefunction were measured beforeand after the physically andpsychologically demanding 21-day training course.

Fifty percent of the soldiers inthe treatment group completedthe SFAS course compared to57 percent in the control group.Subjects lost about 6.4 poundsin 3 weeks. Combining thedietary intake with the weightloss data, soldiers had anestimated energy expenditureof 5,040 kcals per day. The DTHtest after training suggestedthat subjects consuming thetreatment product had a greaterresponse (P = 0.07). Fewersubjects in the treatment groupwere DTH anergic (18 percent)to the skin test compared tothe control group (39 percent),suggesting a lower risk forinfections in the treatmentgroup. Overall, the treatmentformula appeared to minimizethe immunologic changesassociated with the stresses ofSFAS training.

A similar 62-day study wasconducted during Rangertraining, in which traineesreceived a nutrition bar with anutrient profile similar to theready-to-drink formula used inthe SFAS study. The treatmentbar lessened some of theimmunological changes andappeared to help maintainweight better than the placeboproduct.

Conclusions

The immune system is anintricate and highly regulatednetwork of cells, tissues andmolecules that help ward offinfections and disease.Although the effectiveness ofthe immune response can beinfluenced by a number ofstressors, specialized nutritioncan help maintain the immunesystem.

No studies have been conductedto evaluate immune function inwildland firefighters; howeverit is likely that they experiencesome level of immunesuppression from the physicaland emotional stresses. If thereis an increased rate of

infection, it would be valuableto study strategies (such asnutritional supplementation)that might influence theimmune systems under theseconditions. Nutritionalformulations tested in militarytraining, where the physicaland psychological stress maybe similar to wildlandfirefighting, may also be ofvalue.

Steven Wood, Ph.D., RD, is seniorclinical project leader associated withRoss Products Division, AbbottLaboratories. The complete text ofthis paper may be found in WildlandFirefighter Health and Safety:Recommendations of the April 1999Conference, 9951-2841-MTDC. Thepaper contains references and a listof nutrients and their influence onimmune function.

6

Research

Subject nears end of simulated escaperoute evacuation.

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Wildland Firefighter LoadCarriage: Effects on TransitTime and PhysiologicalResponses DuringSimulated Escape RouteEvacuation.B. Ruby, University of Montana;G. Ledbetter, Mesa StateCollege; and D. Armstrong,National Naval Medical Center.

This investigation was todetermine the effects ofcarrying a load on the timerequired for evacuation along asimulated escape route (transittime). Subjects (eight males,weighing an average of 181 lbs[82.2 kg] and five femalesweighing an average of 145 lbs[65.8 kg]) completed two longfield hikes in random order ontwo successive days; one hikewith and one hike without afield pack. Field trials wereconducted on Storm KingMountain near GlenwoodSprings, CO (site of the 1994South Canyon Fire). The dirttrail was 2,172 ft (660.5 m) longwith a vertical gain of 450 ft(137 m), yielding an averagegrade of 20.75 percent. Subjectscarried a calibrated portablemetabolic system (Cosmed K4or Aerosport VO2000), a fireshelter, and a Pulaski. Duringthe pack trial, subjects alsocarried a 35-lb (15.9-kg) fieldpack. Blood samples collectedbefore and 2 minutes afterexercise were analyzed forlactate (Accusport lactateanalyzer). Data were analyzed

trials (19.6). Simple regressionanalysis revealed a significantnegative correlation betweenbody weight and the slowertimes during the pack trials (r= -0.64), indicating that largersubjects were less affected bythe pack. High correlationsbetween peak VO

2 and transit

rates were noted (r = 0.82 forthe pack trial, r = 0.87 for theno-pack trial), indicating thecontribution of aerobic fitnessto quick escapes.

These data indicate thatcarrying a pack significantlyimpedes ground travel during aforced evacuation. The elevatedblood lactate, heart rate, andratings of perceived exertionresponses coupled with thepeak VO

2 levels indicate near-

maximal effort and an emphasison glycolytic energyproduction (data werecollected at an elevationof about 7,000 ft). The

using a mixed-design ANOVA(analysis of variance) withrepeated measures and plannedcomparisons (Table 2).

Men were 21.5 percent fasterwithout a pack and women were26.3 percent faster. For themales, mean and peak VO

2 were

higher during the no-pack trial.The difference in blood lactate(at peak exertion and at rest)was significantly higher duringthe pack trial for the malesubjects. Similarily, ratings ofperceived exertion (RPE) weresignificantly higher for malesduring the pack trial (19.8)compared to the no-pack trials(18.7). In contrast there wereno significant differences inratings of perceived exertion forthe females (20.0) for the packtrial compared to the no-pack

Finger stick forblood lactateanalysis at endof simulatedescape routeevacuation.

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LactateTime Mean VO2 Peak VO2 Heart rate peak - rest(min) (mL/kg-min) (mL/kg-min) (beats/min) (mmol)

Pack

Male 10.7 41.1 48.6 181 9.8Female 13.7 32.5 42.5 188 5.8

No Pack

Male 8.4* 46.0* 52.1* 177 5.8*Female 10.1* 35.1 41.1 188 5.8

* The probability that the difference between carrying a pack and not carrying a pack is due to chance is less than 0.05.

Table 2—Pack and no-pack trials of escape route evacuation.

data also show that largerindividuals and those withhigher levels of aerobic fitnessare better able to negotiate theescape route. Finally, theresults support therecommendation that wildlandfirefighters should abandontheir packs during evacuationsalong emergency escape routes.(Supported by the MissoulaTechnology and DevelopmentCenter and a collaborativeresearch grant from Mesa StateCollege, Grand Junction, CO).

Note: This study supplementsprevious estimates of the effectof carrying a load on escaperoute evacuation. Earlier esti-mates based on moderate loadsand hiking speeds indicated a 15to 20 percent faster time with-out pack and tool. With higherspeeds or heavier loads, drop-ping the pack could increasespeed by up to 30 percent, basedon those estimates. Subjects inthis study on Storm King Moun-tain were instructed to hike asfast as possible. Results indi-cated they could travel 21.5 to26.3 percent faster without the35-lb pack, but with a tool thatcould be used to clear a site forshelter deployment. The dataalso provide clear support forrequiring firefighters to main-

tain a minimum level of aerobicfitness for safety reasons.

Analysis of Predictive Testsof Aerobic Fitness forWildland Firefighters.M. Strickland and S. Petersen,University of Alberta.

This study compared two fieldtests commonly used to predictaerobic fitness in wildlandfirefighters with directmeasures from laboratorytesting. Forty-five males(average age of 25.2 years with aVO

2 max average of 53.6 mL/kg-

min) completed a treadmill testfor ventilatory threshold (VT)and VO

2 max test, the Leger 20-

m shuttle run, and the packtest (3-mile [4.8-km] hike with45-lb [20.5-kg] pack) onseparate days. The meanhighest shuttle run stagecompleted was 9.5 sec and thetime to complete the pack testwas 41.6 min. Heart rate (HR)and blood lactate concentrationfrom the pack test weresignificantly lower than valuesobserved at the ventilationthreshold, but perceivedexertion ratings (RPE) weresimilar. The heart rate andratings of perceived exertion atthe end of the shuttle run were

not significantly different thanat the end of treadmill test, butpeak blood lactate wassignificantly lower after theshuttle run than after thetreadmill test. Shuttle runperformance was significantlycorrelated with both VO

2 at the

ventilation threshold (r = 0.69)and VO

2 max (r = 0.91). Lower

but significant correlationswere found between pack testtime and VO

2 at the ventilation

threshold (r = -0.47) and VO2

max (r = -0.65). While theshuttle run is a better predictorof aerobic fitness, the pack testinvolves other aspects of workcapacity (such as muscularfitness) related to wildlandfirefighting tasks. (This paper,supported by AlbertaEnvironmental Protection, waspresented at the annualmeeting of the CanadianSociety for Exercise Physiologyin 1999).

Note: Dr. Petersen reports thatwhen 22 female subjects wereadded to the sample, analysisconfirmed that a 45-min time onthe pack test was equivalent toa VO2

max (aerobic fitness) of 45mL/kg-min. The correlationbetween the pack test and VO2

max for this larger sample (n =67) was -0.7. The VO2 max is ameasure of maximum intensity.Wildland firefighting is anendurance event that demandsaerobic fitness (VO2 max),muscular fitness, and the abilityto sustain work output acrosslong work shifts.

8

RiskManagement

The daily habits of peoplehave a great deal more todo with what makes themsick and when they diethan all the influences ofmedicine.L. Breslow, M.D.

The seven habits research hasassociated with health andlongevity, include: regularexercise, adequate sleep, a goodbreakfast, regular meals,weight control, abstinence fromsmoking and drugs, andmoderate use of alcohol.

In other words individuals areresponsible for their health.

Human Factors

The Wildland Firefighter SafetyAwareness Study identified anumber of strategies to addresshuman factors, including:prevention of fatigue, accurateassessment of fatigue andhealth, recognition of differingcapabilities of crews, andfostering physical fitness forthe job. A 1999 GeneralAccounting Office report onfederal wildfire activitiesidentified issues that couldaffect the agencies’ ability tomanage firefighting programs,including the shrinkingwildfire workforce. And aBrookings Institute study hasidentified physical fitnessreguirements as one of the

most important issues in itsstudy entitled, “Where Have Allthe Firefighters Gone?” Inaddition to a loss of expertisedue to the retirement of anaging workforce, fire managersare faced with a precipitousdecline in the fitness andhealth of the existing andprospective firefighters.

In recent years the UnitedStates has become the fattestnation in the world, with 55percent of the adult populationoverweight or obese! Adultonset diabetes is appearing inteenagers. When doctorsexamined teenage heartsdonated after accidental deaths,they found one in six alreadyshowed the blockages andplaque deposits of coronaryartery disease. These alarmingdevelopments cannot be blamedon genetics. Studies ofgenetically similar PimaIndians living in Arizona andMexico indicate a greaterincidence of obesity anddiabetes in Arizona. Obesityexpert Claude Bouchard blamesthe epidemic of obesity on anincrease in caloric intake and adecrease in caloric expenditure.In other words, Americans areeating too much and exercisingtoo little. The excess caloriesare stored as fat.

Toxic Food?—Americans areeating more fast food andprepared foods, with high levelsof fat and calories. Brownellhas coined the term “ToxicFoods” to describe the effectsof a steady diet of high-fatfoods. Schools are leasinglunch programs to fast foodoutlets, or kids go to the mallfor a burger, fries, and shake(1,500 calories and 50 grams offat). With both parents working,more meals are eaten out orordered in. The result is asteady diet of toxic food, high in

fat and calories, and low innutrients. In addition to theeffects of overweight oneveryday life, the excess fatinhibits the action of insulinand increases the risk ofdiabetes. The fat and excesscalories raise the blood lipids(cholesterol and triglycerides),leading to an increasedlikelihood of heart disease.This epidemic of obesity andinactivity will result instaggering health care costs inthe future. The immediateeffects include a decline infitness and work capacity.

Fit to Work?—Candidates forfirefighting jobs reflect thenational trend toward higherweight and lower fitness.Children, teens, and adultsspend their hours sitting inschool or at work, in front ofcomputers, TV’s, and videogame displays. No nationalprogram is in place to reversethe alarming decline inphysical activity. As aconsequence, few workers areequipped with skills andexperience in arduous work.Fewer still come to a job workhardened, or with effectivework habits. Overweight andinactivity combine to reducefitness and work capacity.Excess weight is a handicapthat increases metabolic heatproduction and heat storage,making the job tougher and theworker more prone to heatdisorders.

While lower levels of workcapacity may be accommodatedin jobs where mechanicalassistance is possible, theypose a risk to the health andsafety of wildland firefighters.Firefighters work in remotelocations whereaccommodations cannot beused. They must wearprotective clothing, and carry

9

gear, water, and tools weighingover 30 pounds. They mustnegotiate difficult terrain,under extreme environmentalconditions. And they areexpected to perform usefulwork. When emergencies arise,firefighters must be able totake care of themselves and tohelp others if necessary. Thosewho lack the capacity risk theirlives and the lives of those whostay behind to help (see theRuby, Ledbetter, and Armstrongstudy on safety zoneevacuation).

Participants at the WildlandFirefighter Health and SafetyConference (1999) made anumber of recommendations toimprove the health, safety, andproductivity of the work force.They endorsed the use of thework capacity test (pack test)for firefighters, andrecommended mandatoryparticipation in fitnessprograms for seasonal and full-time employees engaged inwildland fire suppression. Thepack test defines the minimallevel of work capacity forwildland firefighting. Higherlevels of work capacity areneeded to sustain work outputall day under difficultenvironmental conditions, tostand up under repeated days ofarduous work, and to meetunforeseen emergencies. Firemanagers have higherperformance expectations forType I crews. Yet current workcapacity requirements do notdifferentiate between thecapabilities of Type I and Type IIcrews. Participants at theWildland Firefighter Health andSafety Conferencerecommended the review andpossible improvement of crewstandards.

Wildland firefighting is toughwork, and it may be getting

tougher. Proposed increases inthe use of prescribed fire havethe potential to extend the fireseason to more than 6 monthsfor some workers. To maintainthe health and safety of thework force, fire managers needto resist efforts to lower workcapacity standards. They shouldmake the standards known topotential recruits and helpthem meet the standards. Fielddata and experience indicatethat high standards attract fit,motivated workers to firecrews. Low standards damagemorale, decrease productivity,and risk the health and safetyof the work force.

Fitness and Injury

A study of 861 male and femaleU.S. Army trainees indicatesthat the fittest workers(measured by pushups, situps,and 1- and 2-mile runs) havethe lowest injury rates. Womenrecruits experienced twice asmany injuries as men, with 57percent of the femalesexperiencing one or moreinjuries compared to just 27percent of men. The risk ofserious injuries was almost 2.5times higher for females thanfor males. The study’s authors,Hemenway and others,indicated that the gender-injuryrelationship appears to beexplained by physical fitness,especially aerobic fitness. Theslowest runners experiencedmore sports injuries and thefastest runners experienced thefewest, regardless of gender.This study agrees with a 1999study of Australian Armyrecruits by Pope and othersthat found a negativeassociation between fitness andinjuries. In another Australianstudy a modified physical

training program reducedinjury and medical dischargerates for male recruits, but notfor females. The authors,Rudzki and Cunningham,recommended fitness standardsfor recruits entering theservice.

Obesity and Asthma

As the prevalence rates ofobesity and asthma increase,recent studies have detected alink between the conditions.Using data from the NursesHealth Study, a cohort of85,911 female registerednurses, from 26 to 46 years old,researchers correlated asthmawith obesity as indicated by thebody mass index (BMI = weightin kilograms divided by thesquare of height in meters).The results showed a strongpositive association betweenBMI and the risk of adult-onsetasthma. Women who gainedweight after age 18 were atsignificantly increased risk ofdeveloping asthma during the4-year followup period.

Note: Obesity is defined as a BMIabove 29. See BMI chart inSharkey, B., Fitness and WorkCapacity, NFES 1596, 1997.

10

Field NotesThe pack test is usedto determine acandidate’s ability tocarry out the arduousduties of a wildlandfirefighter. The test,which replicates part ofthe firefighters’ job,requires the sameenergy expenditure ascarrying a pack whilefirefighting (7.5 kcal/min). The pack testhas been taken bythousands ofindividuals in Federaland State agencies in

Immune FriendlyNutrients

In addition to adequate energy,a number of nutrients havebeen found to enhance thefunction of the human immunesystem. They include:

Vitamin C-(citrus fruits,broccoli, peppers) enhancesimmune response.

Vitamin E-(whole grains,wheat germ, vegetable oil)stimulates immune response.

Beta Carotene-(carrots,sweet potatoes) stimulatesnatural killer cells.

Vitamin B6-(potatoes, nuts,spinach) promotes white-cellproliferation.

Folate-(peas, salmon,romaine lettuce) increaseswhite-cell activity.

Selenium-(tuna, eggs, wholegrains) promotesantibacterial action.

Zinc-(eggs, whole grains,oysters) promotes woundhealing.

Several of these nutrients(Vitamins C, E, and B-carotene)also serve as antioxidants.(From B. Sharkey, Fitness andWork Capacity, NFES 1596,1997).

Note: For a comprehensive listof nutrients that influence theimmune system see the com-plete text of Dr. Steve Woods’

article in the MTDC publicationWildland Firefighter Healthand Safety: Recommenda-tions of the April 1999 Con-ference.

Pack Test

The pack test is used todetermine a candidate’s abilityto carry out the arduous dutiesof a wildland firefighter. Thetest, which replicates part ofthe firefighters’ job, requiresthe same energy expenditurefirefighting tasks (7.5 kcal/min).

duty. Female Army recruitshave been trained to carry 75 lbat 4.4 mph. Marines routinelycarry 75 lb in awkward Alicepacks, even on snowshoes. Arecent article in the journalMilitary Medicine recommendsa backpack run test, a 2-milerun with a 66-lb pack, as “amodel for a fair andoccupationally relevantmilitary fitness test.”According to the authors, thebackpack run test usesstandard-issue equipment,eliminates body size bias, andmeasures work- and health-related components of fitness.

Wildland firefighters are toldnot to run while taking thepack test. The pack test is apass/fail test. Running is notnecessary to pass: doing soincreases the risk of injury.

Candidates for the pack testshould be reminded of properlifting techniques and the needto warm up and stretch beforebeginning the test. Candidatesshould follow all safetyinstructions, wear acomfortable pack, hike with anupright posture, and avoidextreme body positions (suchas crouching or leaning).Finally, candidates should betold they are free to stop at anytime for any reason. Candidatesshould train before taking thetest.

Fitness forFirefighting

Like athletes, seriousfirefighters realize thatphysical activity and trainingare a year-round commitment.Job-specific training and workhardening should begin weeks

The pack test has been taken bythousands of individuals inFederal and State agencies inthe United States, Canada, andAustralia. Even though morethan 90 percent of thecandidates pass the test, it hasbeen criticized as too difficult,the pack (45 lb) as too heavy,and the pace (4 mph) as toofast. Smokejumpers carry 110lb for 3 miles to qualify for

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• Jog the flat course (without apack) to build aerobicfitness.

• Cross-train (mountain bike,lift weights) to build staminaand strength.

(For more information abouttraining, see B. Sharkey,Fitness and Work Capacity,NFES 1596, 1997.

TechnicalCommittee Meets

Members of the WildlandFirefighter Health and SafetyTechnical Committee met inIndianapolis during the Juneannual meeting of the AmericanCollege of Sports Medicine.They discussed currentresearch, recommendedresearch priorities, andplanned field studies. Inaddition, the committee willmeet by teleconference and mayhold a fall meeting to planFiscal Year 2001 field studies.

If you have comments,questions, or suggestions

about this report or projectsend them to

bsharkey@fs.fed.us.

before taking the pack test.Before training, candidatesshould complete the PAR Q oran equivalent health-screeningquestionnaire. They shouldconsult a physician if they areover 45 years of age or if thequestionnaire indicates thatthey should do so.

Begin specific training for thepack test at least 6 to 8 weeksbefore taking the test andreporting for duty. Train byhiking or power walking usingthe ankle-height footwear thatwill be worn during the test.Pack test candidates should:

• Hike a 3-mile flat coursewithout a pack. When theycan cover the course in lessthan 45 minutes, they shouldcarry a 25-lb pack ontraining hikes.

• Increase the pack weightuntil they can hike 3 milesin 45 minutes with a 45-lbpack.

Candidates can also:

• Hike hills (with a pack) tobuild leg strength andendurance.

Publications

Wildland Firefighter Healthand Safety Report: No.1. 2000.Missoula Technology &Development Center, (0051-2825, call 406–329–3978).

Coming up. . .

In the next Wildland FirefighterHealth and Safety Report:

• Heat Stress

• Hydration

• Uniforms and Heat Stress

• Drugs and Heat Stress

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The Forest Service, United States Department of Agriculture,has developed this information for the guidance of its employees,its contractors, and its cooperating Federal and State agencies,and is not responsible for the interpretation or use of thisinformation by anyone except its own employees. The use oftrade, firm, or corporation names in this publication is for theinformation and convenience of the reader, and does notconstitute an endorsement by the Department of any product or

service to the exclusion of others that may be suitable. TheUnited States Department of Agriculture (USDA), prohibitsdiscrimination in all its programs and activities on the basis ofrace, color, national origin, gender, religion, age, disability,political beliefs, sexual orientation, and marital or family status.(Not all prohibited bases apply to all programs.) Persons with

disabilities who require alternative means for communication ofprogram information (Braille, large print, audiotape, and so forth)should phone USDA’s TARGET Center at (202) 720-2600 (voiceand TDD). To file a complaint of discrimination, write: USDA,Director, Office of Civil Rights, Room 326-W, Whitten Building,14th and Independence Avenue SW, Washington, DC 20250-9410, or call (202) 720-5964 (voice or TDD). USDA is an equalopportunity provider and employer.

Additional single copies of this document may beordered from:USDA Forest ServiceMissoula Technology and Development Center5785 Hwy. 10 WestMissoula, MT 59808-9361Phone: 406–329–3978Fax: 406–329–3719Internet: wo_mtdc_pubs@fs.fed.us

For additional technical information, contact BrianSharkey at the address above.Phone: 406–329–3989Fax: 406–329–3719Internet: bsharkey@fs.fed.usLotus Notes: Brian Sharkey/WO/USDAFS

An electronic copy of this document is available onthe Forest Service’s FSWeb Intranet at:http://fsweb.mtdc.wo.fs.fed.us