Validation of a Cardiorespiratory Fitness Assessment for Firefighters.

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VALIDATION OF A CARDIORESPIRATORY FITNESS ASSESSMENT FOR FIREFIGHTERS ANTHONY T. DELISLE,1 ANNA K. PIAZZA-GARDNER,1 TIFFANY L. COWEN,1 MONA B. SAYEDUL HUQ,1 ALEXIS D. DELISLE,1 CHRISTINE B. STOPKA,1 AND MARK D. TILLMAN2 1

Department of Health Education & Behavior, University of Florida, Gainesville, Florida; and 2Department of Kinesiology & Health Promotion, Troy University, Troy, Alabama ABSTRACT

Delisle, AT, Piazza-Gardner, AK, Cowen, TL, Huq, MBS, Delisle, AD, Stopka, CB, and Tillman, MD. Validation of a cardiorespiratory fitness assessment for firefighters. J Strength Cond Res 28(10): 2717–2723, 2014—Currently, a submaximal protocol is used to measure cardiorespiratory fitness in firefighters by esti_ O2max); however, this submaxmating their true aerobic capacity (V imal test has not been cross-validated among firefighters. Thirty firefighters (85% male, 15% female), completed the submaximal protocol and the maximal (Bruce) treadmill protocol on separate occasions. Pearson’s correlation analyses between the submaximal and Bruce protocol revealed a significant moderate positive corre_ O2max values lation (r = 0.635, p = 0.005). The range of mean V and SDs produced from the submaximal and maximal protocols varied greatly (35.4–50.9 vs. 28.6–58.4 ml$kg21$min21, and SD _ O2 test underof 3.91 vs. 7.22, respectively). The submaximal V _ estimated the true VO2max in the majority of firefighters (72.4%) _ O2max in the remainder of firefighters. and overestimated the true V Participants with a higher body fat percentage were more likely _ O2max than those (p = 0.0157) to have an overestimated true V with a lower-body fat percentage. Our results indicate the current _ O2 test used to measure cardiorespiratory fitness in submaximal V firefighters is an improvement over previous protocols. However, our findings also show that the accuracy of this submaximal test for _ O2max in firefighters is questionable, and may predicting the true V not identify firefighters who possess substandard cardiorespiratory fitness, particularly in those with a higher percentage of body fat. Thus, the results of this study indicate that improvements to the current Fire Service Joint Management, Wellness & Fitness _ O2 assessment is still needed to accurately reflect Initiative (WFI) V _ O2max of individual firefighters. the true V

KEY WORDS physical fitness, aerobic capacity, V_ O2max, cardiovascular disease

Address correspondence to Christine Stopka, [email protected]. 28(10)/2717–2723 Journal of Strength and Conditioning Research Ó 2014 National Strength and Conditioning Association

INTRODUCTION

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ardiovascular disease (CVD) is the leading cause of on-duty death and disability in firefighters, contributing to 45% of all on-duty fatalities annually (6,7,17). The majority of fatal and nonfatal CVD events in firefighters occur during prolonged bouts of strenuous exertion and during high-intensity emergency situations, including suppressing a fire (32.1%), performing physically demanding nonemergency duties (15.4%), responding to an alarm (13.4%), and performing training exercises (12.5%) (14). A high level of physical fitness during these on-duty tasks is essential because they require firefighters to achieve near-maximal heart rates for sustained and prolonged periods of time, while using heavy equipment, and are often performed in extreme temperatures (8,12,23). Therefore, the relationship between physical fitness and CVD during the performance of firefighting duties has received considerable attention among concerned firefighters, public health officials, and researchers (7,15,17,20). Components of health-related physical fitness include cardiorespiratory fitness, body composition, muscular endurance, muscular strength, and flexibility (21). Among these, cardiorespiratory endurance is proving to be one of the most important in terms of safely performing the on-duty activities associated with CVD events in firefighters (9,15,22). Cardiorespiratory endurance, also known as “aerobic capacity” is the ability to perform dynamic exercise involving large muscle groups at moderate-to-high intensity effort for prolonged periods of time _ O2max is the maximal rate of aerobic metabolism to (21). V transport and use oxygen during maximal or exhaustive exercise _ O2max classification (based on age and sex) is (21). A low V associated with premature mortality and morbidity due to CVD (10,18,27,28). Substandard cardiorespiratory fitness levels are prevalent among the firefighter population, as studies show 25% of firefighters fail to achieve the minimum recommended _ O2max standard of 42.0 ml$kg21$min21 for firefighters V _ O2max is associated with the presence (9,16,22). A substandard V of CVD risk factors in firefighters such as hypertension, dyslipidemia, and obesity (4,20). To address the health needs of firefighters, the International Association of Firefighters and International Association of Fire Chiefs developed the Fire Service Joint VOLUME 28 | NUMBER 10 | OCTOBER 2014 |

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Fitness Assessment for Firefighters Management, Wellness and Fitness Initiative, or WFI (13). The WFI is a system wide approach to promote the physical fitness of firefighters because it reaches more than 300,000 full-time professional fire fighters and paramedics who protect 85% of the nation’s population. The WFI provides fire departments with resources for the development of comprehensive physical fitness programs and highly encourages the use of specific assessments to evaluate the physical fitness and performance of firefighters. Among these fitness assessments, the WFI currently endorses a submaximal treadmill test based on the time to reach 85% of age-predicted maximal heart rate to estimate the true peak V_ O2max of firefighters. Previous to this test, the WFI recommended a submaximal V_ O2 test that was shown to overestimate the true V_ O2max of firefighters (16). It is critical to evaluate the accuracy of the current WFI test to predict the true V_ O2max of firefighters given the strong relationship between V_ O2max, CVD risk factors, and the performance of on-duty firefighter tasks (4,5,9,20). Furthermore, it is important to assess the accuracy of the WFI V_ O2 test because the recommendation for its use is wide spread among professional firefighters. Thus, the purpose of this study was to evaluate the ability of the current WFI submaximal treadmill test to accurately predict the true V_ O2max of firefighters obtained from the maximal Bruce protocol test. We hypothesized that the WFI submaximal V_ O2 protocol would under-predict the true V_ O2max in more fit firefighters and over-predict the true V_ O2max in relatively less-fit firefighters. Our hypothesis is based on anecdotal evidence obtained from firefighters who use the WFI submaximal test annually to assess maximal aerobic capacity within their fire department. Before the study, these firefighters disclosed to investigators the WFI test frequently predicted a lower V_ O2max for firefighters who are well known to participate in regular aerobic activity compared with firefighters who do not participate in regular aerobic exercise.

METHODS Experimental Approach to the Problem

_ O2 test to predict the true We examined the ability of the WFI V _ O2max of firefighters by comparing it with the Bruce V_ O2max V protocol. Participants first completed the WFI submaximal test, followed by the Bruce maximal protocol during the fol_ O2max protocol was selected as the lowing week. The Bruce V standard for obtaining a true V_ O2max firefighters because it is widely used and accepted in the field of exercise and sport science, especially in cardiac rehabilitation (1,8,16,18). Thus, the basis for determining whether the WFI is a valid test or _ O2 values correlates not is dependent on how well the WFI V _ O2max values. We used the Bruce protocol with Bruce V because it is the gold standard test (especially because it is so widely used in cardiac rehabilitation testing, and that CVD is the number one cause of death and disability in firefighters), and therefore, this was the rationale for using this test.

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Subjects

Thirty firefighters, aged 21–46, from a North-central Florida fire department voluntarily completed a direct assessment of _ O2max, and the WFI submaximal test was used to predict V _ O2max. The sample comprised 85% male and 15% female V (department-wide average of 89% male and 11% female); thus, the sample population accurately represents the sex of the department tested. Participants first completed the WFI submaximal test, followed by the Bruce protocol during the following week. Institutional Review Board approval was obtained for this study. Subjects completed the informed consent process before testing, wherein the protocols, risks, and benefits for the study were disclosed. No incentives were provided for participation. All the participants completed health screenings before aerobic testing, including height, weight, body mass index (BMI), percent body fat, blood pressure, and pre-exercise heart rate. The 3-point skin fold test the WFI recommends for firefighters was used to measure the percentage of body fat in participants (males: pectoral, subscapular, and triceps; females: suprailiac, abdominal, and triceps). In addition to the health screenings, participants also completed a survey on information, including age, sex, frequency, intensity, and the duration of weekly physical activity. Level of participation in weekly physical activity was assessed to better understand the physical fitness of the participants. We anticipated our sample would be physically active and relatively fit because no incentives were offered to participate in the study. There was no attrition or dropout from the sample tested, however, one of the participating firefighter’s results was discarded because of mechanical issues with the equipment that arose during testing. Thus, the final sample size was 29 participants. Participants completed the testing between 8:00 AM and 12:00 PM. Participants were instructed not to eat 2 hours before testing, not to exercise before testing, and not to consume caffeine before the study. Participants were screened for these behaviors, and no participants reported violating these requirements. No participants reported being sleep deprived or having been up late at night running calls. Procedure WFI Submaximal Test

The WFI submaximal test predicts the V_ O2max of firefighters based on the amount of time it takes to reach 85% of estimated maximal heart rate (HRmax) during a graded treadmill protocol. This submaximal test uses an age-predicted estimation of HRmax (85% of HRmax = 208 2 [0.7 3 age] 3 0.85). The amount of time it takes to achieve 85% of HRmax (test time) and BMI are inserted into the following formula to predict true V_ O2max: V_ O2max = 56.981 + (1.242 3 test time) 2 (0.805 3 BMI) (13). The WFI submaximal test begins with a 3-minute warm-up at a speed of 4.8 km$h21 at a 0% grade, followed by 1-minute stages of alternating increases in speed and incline. For example, after the 3-minute

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instructions. A 12-lead ECG was used to monitor the subject’s TABLE 1. Sample demographics (n = 29). heart rate before and during testing, as well as 5 minutes after the Department Variable V_ O2 sample mean (SD) mean (SD) completion of the test. A standard mouthpiece and nose clip Sex (% male) 85 (male); 15 (female) 89 were assembled and secured to Age (y) 31.9 (6.4) 38.5 (9.6) the subject’s head using a face Body fat (%) 26.0 (6.4) 22.2 (6.5) mask. A spirometer was conBody mass index 27.2 (3.8) N/A Submax V_ O2 44.6 (3.9) 42.9 (5.4) nected and calibrated to the metabolic cart (ParVo Medics Metabolic Cart Model: MMS2400, ParVo Medics, Inc., Murray, UT, USA), to accurately 21 measure the amount of oxygen consumed and carbon dioxide warm-up, treadmill speed is increased to 7.2 km$h , at exhaled by participants. Each participant was connected to an 4 minutes, the incline of the treadmill is raised to a 2% grade, 21 ECG machine and monitored for ECG abnormalities during at 5 minutes, the speed is increased to 8 km$h , at 6 minutes, the assessment. Participants walked for 3 minutes at 4 km$h21 the treadmill is raised to a 4% grade. Each of the subsequent before administration of the Bruce protocol to familiarize themstages of the WFI protocol lasts 1 minute and continues to 21 selves with using the treadmill. Participants were instructed to alternate between a 0.8-km$h increase in speed and 2% exercise as long as possible during the Bruce protocol, which incline until 85% of HRmax is reached and maintained for involves successive 3-minute stages of increasing speed and 15 consecutive seconds. Afterwards, participants complete incline over time. Rate of perceived exertion (RPE), according a cool-down phase consisting of walking for 3 minutes at 21 to the Borg scale (3) was recorded twice during each 3-minute 4.8 km$h at 0% grade. Recovery heart rate was recorded stage (at the start and end of each stage). Criteria for terminating during the first minute of the cool-down phase. the test included: (a) voluntary termination by the participant _ O2, or (c) _ due to fatigue or any other reason, (b) plateau in V Bruce Protocol (Maximal VO2 Test) when 2 of the 3 following criteria were met per Institutional Before administering the Bruce Protocol (1), electrocardioReview Board recommendations: (a) reaching maximum heart gram (ECG) and metabolic cart gas exchange analyzers rate (HRmax = 208 2 [0.7 3 age]), (b) achieving a respiratory were calibrated to proper settings according to manufacturer exchange ratio greater than 1.15, or (c) reporting an RPE of 20. After completion of the Bruce TABLE 2. Correlations of predictor variables to the Bruce V_ O2max value.* protocol, participants walked for a recovery period of at least Variable Pearson’s correlation coefficient (r) p 5 minutes, while heart rate and WFI submax prediction test† 0.63 0.005 RPE were recorded at the 1-, 3-, Age 20.26 0.183 and 5-minute time points. Body fatz Body mass index† Body composition† Resting HR Recovery HR, 1 min† Recovery HR, 3 min Recovery HR, 5 min Resting systolic blood pressure Resting diastolic blood pressure† Exercise d/wk (mod-strenuous) Exercise duration (mod-strenuous) Strenuous days Strenuous duration Moderate days Moderate duration *HR = heart rate. †Significant at p # 0.05 level. zSignificant at p , 0.001 level.

20.74 20.54 20.52 20.13 0.54 0.37 0.24 20.20 20.54 0.27 0.16 0.10 0.19 0.27 0.0004

,0.0001 0.003 0.008 0.518 0.004 0.060 0.247 0.316 0.004 0.210 0.447 0.651 0.379 0.194 0.999

Statistical Analyses

All statistical analyses were performed using SAS version 9.2 software (SAS Institute Inc., Cary, NC, USA). Mean differences between the fire department average and the sample for this study were analyzed with independent samples t-tests to check for equivalence between groups. Pearson’s correlation coefficients were calculated to examine the relationship between the predicted WFI submaximal values _ O2max values to the true V

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Fitness Assessment for Firefighters

TABLE 3. Mean values for the Bruce protocol vs. WFI submaximal prediction tests. Variable Bruce V_ O2max (mlO2$kg21$min21) Submax V_ O2 (mlO2$kg21$min21)

Min Mean SD value

Max value

45.7 7.2 28.6

58.4

44.6 3.9 35.4

50.9

obtained from the Bruce protocol. An a priori alpha level of p # 0.05 was used for determination of statistical significance. Additionally, Pearson’s correlation coefficients were obtained to determine whether relationships existed between demographic and physical fitness variables (body fat percentage, body composition, BMI, blood pressure, resting, and recovery heart rates), and the true V_ O2max values obtained from the Bruce protocol (a = 0.05). Additionally, participant results were divided into 2 categories as true V_ O2max being over- vs. under-predicted by the WFI test, and the hypothesized predictor variables of exercise frequency/intensity, BMI, and body fat percentage were tested as predictors for classification into either group.

RESULTS Table 1 compares the sample mean demographic and physical fitness variables of the subjects with those from the entire department they were sampled from. Overall, the subjects were, on average, 7 years younger, roughly equivalent in sex, slightly higher in body fat percentage, and slightly higher for submaximal predicted V_ O2max. The subjects reported an average of 4.6 days per week of moderate to strenuous physical activity lasting, on average, 40 minutes per session. All participants completed both the submaximal and maximal V_ O2 testing and achieved the criteria for maximal effort during the Bruce protocol. Pearson’s correlation analyses between the WFI submaximal and Bruce protocol produced a significant and moderate correlation coefficient

TABLE 4. Prediction error between WFI submaximal compared with Bruce V_ O2max protocol. Direction

N

Under-predicted 21 Over-predicted 8

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Mean SD 23.9 5.9

Min

Max

3.1 20.3 211.1 5.0 0.5 13.8

(r = 0.635; p = 0.005). True V_ O2max values were significantly and moderately correlated with percentage body fat (r = 20.7353; p = 0.0001), diastolic blood pressure (r = 20.541; p = 0.0035), BMI (r = 20.5445; p = 0.003), 1-minute recovery HR (r = 0.537; p = 0.0038), and body composition (r = 20.5178; p = 0.008) (Table 2). Mean values and SDs from the WFI submaximal and Bruce protocol are presented in Table 3. The estimated sample mean values for the submaximal V_ O2 and true V_ O2max values were similar (44.58 6 3.91 and 45.68 6 7.22 ml$kg21$min21, respectively, paired t-test p value = 0.2616). Although the mean values are similar, the ranges of mean values and SDs were smaller when comparing the predicted and true V_ O2max values (min–max: 35.4–50.9 vs. 28.6–58.4 ml$kg21$min21, and SD of 3.91 vs. 7.22, respectively). Additionally, the WFI submaximal test underpredicted the true V_ O2max in 72.4% of firefighters and over-predicted the true V_ O2max in 27.6% of the firefighters tested (Table 4). Further analysis showed the group whose V_ O2max was over-predicted by the WFI submaximal test had a significantly higher mean body fat percentage compared with those who were under-predicted (p = 0.0157).

DISCUSSION The primary purpose of this study was to evaluate the validity of the current WFI submaximal treadmill test to accurately predict the true V_ O2max of firefighters obtained from the maximal Bruce protocol. Pearson’s correlation coefficients showed the submaximal test to be moderately correlated in its ability to accurately predict the true V_ O2max of firefighters. Although the estimated sample mean values for the submaximal V_ O2 and Bruce V_ O2max values were similar, the submaximal V_ O2 treadmill test underestimated the true V_ O2max in the majority (72.4%) of individual firefighters by as much as 21.1% and overestimated the true V_ O2max by as much 30.6% in the remainder of the firefighters. Firefighters with over-predicted V_ O2max values from the WFI test were significantly more likely to have a higher skin fold body fat percentage than those who were under-predicted by the WFI test. This finding is concerning given one of the purposes for using this test is to identify firefighters who have substandard cardiorespiratory fitness and may not be able to safely perform on-duty activities. A test over-predicting the true V_ O2max of firefighters with relatively higher body fat percentages may not identify those who cannot safely perform on-duty activities, especially the tasks that are most associated with CVD event, and thus preclude the opportunity to intervene. The range of mean V_ O2max values and SDs produced from the WFI and Bruce protocols varied greatly (35.4– 50.9 vs. 28.6–58.4 ml$kg21$min21, and SD of 3.91 vs. 7.22, respectively). The prediction formula for the submaximal test compresses the V_ O2max values into a narrower range than the range of V_ O2max values produced from the Bruce protocol. Thus, in the context of our results, firefighters in

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Journal of Strength and Conditioning Research the low range of true V_ O2max values are likely to produce a higher predicted V_ O2max value on the WFI submaximal test then what is actually true, and thus may limit the ability of the WFI test to identify firefighters who may have a substandard V_ O2max. True V_ O2max values were found to be significantly and strongly correlated with percentage body fat (r = 20.7353; p = 0.0001), and moderately correlated with diastolic blood pressure (r = 20.541; p = 0.0035), BMI (r = 20.5445; p = 0.0033), 1-minute recovery HR (r = 0.537; p = 0.0038), and body composition (r = 20.5178; p = 0.008). These findings may be useful for improving the accuracy of the WFI submaximal test to predict the true V_ O2max of firefighters if these physiological measures can be incorporated into the current WFI formula. Furthermore, taking into account indicators such as percentage body fat, resting diastolic blood pressure, and 1-minute recovery heart rate in conjunction with the current WFI submaximal test may be helpful in identifying less-fit firefighters who may be producing overestimated V_ O2max values. Based on our findings, the current WFI V_ O2 test has improved in its ability to predict the true V_ O2max of firefighters when compared with the previous WFI V_ O2 test (16). Improvements for the current WFI test may be due to the change on how HRmax is estimated to set the 85% HRmax limit for when the WFI test is to be terminated. The previous WFI test used an age-predicted estimation of 85% HRmax = (220 2 age) 3 0.85; whereas the current WFI test uses 85% HRmax = 208 2 (0.7 3 age) 3 0.85. Age-estimated HRmax = 220 2 age has been shown to vary from true HRmax by 610 to 12 b$min21 among individuals (1,16). Although our findings suggest that the WFI test has improved, our results also show that further improvements might be needed because this test tends to overpredict the true V_ O2max in firefighters with a relatively higher percentage of body fat and under-predicts the true V_ O2max in firefighters with lower-body fat percentages. One explanation for the impact body fat percentage has on estimated V_ O2max values may be due to the variances in metabolic characteristics of individual body composition. A valid V_ O2 test is critical because cardiorespiratory fitness is essential in the performance of on-duty activities most associated with CVD events in firefighters (6,7,17). In addition to its cardiovascular benefits, aerobic fitness is now shown to be a significant predictor for the likelihood of on-duty injuries in firefighters (19). A recent epidemiological study found firefighters with a V_ O2max less than 43 ml$kg21$min21 were 2.2 times more likely to sustain injury than those with a V_ O2max greater than 48 ml$kg21$min21 (19). The findings from this study further underscores the need for a valid V_ O2 test to identify firefighters who do not possess the aerobic fitness believed necessary to safely perform on-duty tasks. Furthermore, this study highlights the discrepancy among researchers and professional firefighters regarding a healthy V_ O2max standard for

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firefighters. Recommended V_ O2max values for firefighters from previous research vary greatly and range from 33.5 to 51.0 ml$kg21$min21 (9,12,16,24,26,31). The inconsistency for a recommended V_ O2max standard from previous research may be largely due to these studies using various V_ O2 protocols to measure V_ O2max (2,9,11,16,24,25,30). For instance, previous methods for determining healthy V_ O2max values for firefighters have evolved over time and include such tests as the Gerkin and Balke treadmill protocols (16,26). A validated and universally accepted V_ O2max protocol that can be feasibly administered in the field may help to address the discrepancies among the recommendations for a safe V_ O2max standard for firefighters. Caution should be used in the interpretation of these results because there are several limitations to this research. First, the sample size in this study was small (n = 29). In light of this limitation, to the best of our knowledge, this is the only V_ O2max cross-validation study using a sample entirely comprised active-duty firefighters. Typically, firefighters only make up a portion of the sample in V_ O2max validation studies, wherein all or the majority of the sample is often comprised non-firefighters. The sample of female firefighters was also small. However, the sample size of females in our study (15%) is larger than the national average of females in the firefighter profession (6%) (29). Furthermore, to the best of our knowledge, this is the first study to sample active duty female firefighters in the validation of any V_ O2max test used for firefighters. Another demographic limitation is the average age of the sample was lower than the department average. This was in part due to study exclusion criteria for ages .54 years old due to concerns with the intensity of the Bruce maximal aerobic test potentially triggering a cardiac event during testing. Another limitation is our sample comprised relatively physically fit firefighters and may have limited generalizability to less-fit firefighters. The majority of firefighters who participated in our study had a slightly higher estimated V_ O2max than the average V_ O2max from the fire department they were sampled. Additionally, the sample reported an average of 4.6 days per week of moderate to strenuous physical activity, averaging 40 minutes per session (Table 1). No incentives were offered when recruiting firefighters into the study, so most firefighters who voluntarily participated were generally fitness-conscious and more inclined in knowing their level of physical fitness in terms of true V_ O2max. Offering incentives in future studies may help increase recruitment and participation of less-fit firefighters. Another limitation was not alternating the order in which participants took the V_ O2 tests. In our study, each participant completed the WFI test first, followed by the Bruce protocol within 1-week time. Future studies should alternate the order in which participants complete the 2 V_ O2max protocols to account for the potential of performance differences due to the practicing of V_ O2max testing. To the best of our knowledge, this is the first study to test the accuracy of the current WFI submaximal V_ O2 protocol in VOLUME 28 | NUMBER 10 | OCTOBER 2014 |

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Fitness Assessment for Firefighters a pure firefighter sample. Our results indicate that the current WFI V_ O2 test is an improvement over previous WFI protocols. However, our results also show that the accuracy of the WFI submaximal test in predicting the true V_ O2max of individual firefighters is questionable and may not identify firefighters who possess substandard cardiorespiratory fitness, particularly in those with a higher percentage of body fat. Thus, the results of this study indicate improvements to the current WFI V_ O2 assessment are still needed to accurately reflect the true V_ O2max of firefighters. In light of our results, further research is needed to test the accuracy of the current WFI submaximal V_ O2 test in a larger sample of demographically diverse firefighters with varying physical fitness levels.

PRACTICAL APPLICATIONS Increasingly, professionals in the exercise and sports medicine fields are collaborating with fire departments in efforts to assess and improve the physical fitness of firefighters. Professionals in these fields play a critical role in assessing the cardiorespiratory fitness firefighters. Professional organizations (like the Tactical Strength & Conditioning [TSAC] program and the National Strength & Conditioning Association [NSCA]) working with firefighters who are using this WFI test to assess cardiorespiratory fitness should interpret the results of this test with caution. This caution should particularly be taken into account if firefighter’s who have relatively lower-body fat percentages and _ O2 valare aerobically fit are producing lower than expected V ues; and if firefighter’s who have relatively higher percentages of body fat, are not aerobically fit, and are producing a higher _ O2 value. Exercise and sport science professiothan expected V nals working with fire departments who require fit for duty _ O2 test should voice their concern about standards and use the V the accuracy of this test. A valid, universally accepted, test is needed. This would allow for large-scale analyses regarding cardiorespiratory fitness in firefighters; and provide a standard for the industry for improving the accuracy and comparing across fire departments and firefighters. Perhaps, in the near future, such a vocation-specific test can be devised to predict _ O2 in firefighters; and this would have quite an impact the true V on the field. We recommend that the TSAC/NSCA and other professionals in the field work to develop such a test, especially if the test is based on firefighter specific tasks. If adopted and endorsed by WFI, this could impact the practice of how firefighter cardiorespiratory fitness is assessed throughout the nation.

ACKNOWLEDGMENTS None of the authors in this study have any professional relationships with companies or manufacturers who will benefit from the results of this study; therefore, there is no conflict of interest. Funding was not provided for this study. Results of this study do not constitute endorsement by the American College of Sports Medicine (ACSM). Our efforts to evaluate the validity of cardiorespiratory assessments in firefighters would not have been possible without the contributions of numerous people

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and agencies. The authors thank Gainesville Fire Rescue and the Peer Fitness Firefighters for being proactive in their willingness to collaborate. The authors especially acknowledge Chief William Northcutt for his significant contributions toward this project. The authors also like to thank Drs. Beth Chaney, Morgan Pigg, John Dobson, and Mildred Maldonado-Molina, as well as our research assistants, including Jordan Miller, Jeffrey Parr, Nick Abt, Maxwell Ottis, Krishna Dipnarine, Janelle Garcia, and Veronica Novosad.

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