A Critical Evaluation of Work Capacity Assessments and Their Applications to Structural Firefighting

By Jim Spengler, MTI Contributor 

Structural firefighting is unarguably a physically demanding task. Stretching a hose line into a building, search, victim rescue, laddering, to name a few, all require high levels of work capacity. Work capacity from MTI’s own definition is “ high intensity, variable, relatively short physical efforts…where it all comes together-relative strength, cardio, strength endurance, and mental toughness.” I would argue that no matter what assignment you have on the fireground, the above definition of work capacity would describe the demands placed on the body. Simple and direct assessment of work capacity is integral to evaluating overall firefighter readiness.

MTI’s Tactical Work Capacity Assessment offers greater applicability than “traditional” fire service assessments. However, there is still more development needed to account for the specific demands of a fire-rescue athlete.

Physiological Implications of Work Capacity

A 2013 study concluded that there were four significant factors that could predict successful firefighter physical performance: capacity to carry extra load, percent body fat, age, and overall work capacity level (3). In addition, cardiovascular ability and oxygen consumption are important concepts for present day fire suppression. To illustrate, one room in a single-family home will reach untenable, flashover conditions between three to five minutes (12). This results in shorter times for victim survival, interior operations for firefighters, and structural collapse. 

Compressed time windows demand hard, quick and effective work without being forced to exit because of SCBA air supply. Performing high-output tasks with poor work capacity would not be ideal. For example, average heart rates can go above 80 percent of maximum during a structure fire (4). Difficulty performing in this upper range would most likely result in respirations increasing. 

For every nine percent increase in cardiorespiratory demand, SCBA service time will decrease by 4 minutes (4). Similarly, being “on-air” with SCBA can reduce performance measures close to 20 percent through increased cardiorespiratory strain (1, 11). Individuals with poor work capacity would most likely deplete their SCBA at a faster rate. 

Also, the thermal and moisture barriers in turnout gear obliterates the ability to thermoregulate. Wearing turnouts in ambient conditions alone will elevate heart rate, respiratory rate, increase recovery time, and decrease time to exhaustion (5, 6, 7). Adding thermal stress from activity and the environment compounds the physiological response. 

Taken together, SCBA and turnout gear lowers the work capacity ceiling regardless of individual fitness levels. Broadly, higher work capacity individuals complete fireground tasks in less time, with less air consumption than less fit individuals (10).

 

Cognitive Implications of Work Capacity

Physical performance is not the only domain that can improve from work capacity ability. Decision making, a central tenet to fireground tactics, also benefits. High work capacity serves as a buffer between physical performance and the performance deficits induced by gear/SCBA and the environment. Cognitive performance has a similar buffering effect via high work capacity levels. 

A 2020 study sought to show the effect of rapid heat stress in turnout gear on decision making. Researchers found that subjects wearing gear made significantly more incorrect decisions and had slower reaction time compared to subjects not in gear (9). Both groups experienced equal rises in ambient temperature. Poor cognitive performance was attributed wholly to increases in core temperature as a result of wearing turnout gear. 

Researchers also studied the effect of exercise intensity on decision making. As power output increased during a 6.5 minute bout, cognitive performance decreased. However, this performance decrease was moderated by individual fitness levels. Higher fit individuals performed significantly better on decision making tasks when their power output was 60 to 80 percent of max compared to lower fit individuals (8). 

Poor work capacity could indicate impaired decision making ability when adding thermal stress to high-output physical work in a structure fire. This is especially crucial when faced with scenarios that demand a quick decision to solve a complex problem. Problems could range from falling through a floor, SCBA malfunction, or finding egress after a deterioration in interior conditions.

Fire/Rescue Work Capacity Assessments: Pros and Cons

The NFPA standard for Comprehensive Occupational Medical Programs for Fire Departments lists fitness domains that should be tested annually. None come close to assessing a high-intensity, variable domain such as work capacity. Some departments do go beyond the NFPA recommendation and conduct more job-related testing, which approximates a work capacity assessment. These types of events are done in full protective equipment/SCBA. A typical assessment might be:

As fast as possible, in full turnout gear and SCBA, complete:

  • 24’ ladder carry 20 meters, throw to a target, raise fly section to full extension
  • Rotary saw carry, 20 meters
  • Forcible entry with 10 lb sledgehammer, 5 strikes
  • Stair climb with “high-rise” hose bundle, 50 flights up and down
  • Hose advancement 20 meters
  • Victim drag 20 meters
  • Ceiling breach and pull, 5 up, 5 down, 3 rounds

These types of assessments have their place to indicate overall work preparedness. But, the gear, the types of tasks, and skill differentials person to person introduce too many confounding variables. Yes, it is crucial to regularly train in full structural gear. But, assessing a “true” work capacity value, without confounders, is just as important as assessing a true aerobic capacity value or relative strength value. Additionally, there is no clear, evidenced-based standard to follow with the above test. Would we assess completion time, air consumption, or task efficiency? 

In comparison, MTI’s Tactical Athlete Work Capacity Assessment is as follows:

Load: In PT gear with 25# weight vest, IBA or Ruck

Warm Up:

4 Rounds (unloaded)

    • 5x Push Ups
    • 5x Walking Lunges
    • Run 25m
    • Instep Stretch

Assessment – wearing 25# weight vest, IBA or Ruck

    • 3 Minutes 25m shuttle sprints for reps – with a drop to prone at each end
    • Rest 1 minute
    • 3 Minutes 25m shuttle sprints for reps – with a drop to prone at each end
    • Rest 1 minute
    • 3 Minutes 25m shuttle sprints for reps – with a drop to prone at each end

1x Rep = 1x 25m length. Tally the total reps for each round. A sum of reps from all 3 rounds is the athlete’s final score. See scoring below:

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The MTI assessment comes closer to achieving a true work capacity value. It importantly limits confounders, lists clear standards, and has an appropriate cardiovascular demand. It it also quick and not equipment intensive-two groups could be done in 25 minutes. But, this assessment falls short for firefighters in several ways: movement demands, loading, and work/rest intervals. 

Fire suppression is usually one continuous work interval under a 70+ pound load, with upper body push/pull demands. Also, moving from a standing position to a squat/lunge position is much more common than standing to prone. An argument could also be made that movement demands will vary significantly between engine and truck companies. 

Lastly, covering distance on foot with quick direction changes, does not mimic fireground demands. But, given that MTI’s assessment is a valid work capacity test for other tactical athletes, it could be assumed a good score would correlate with faster times of the first assessment. Similarly, poor performers on the MTI assessment might complete the “standard” fire-service test slower. Completing both could offer useful feedback of physical and cognitive capabilities.

It is beyond the scope of this article to offer an improved fire service work capacity assessment, but future work could address the issue. Nevertheless, accurate self-assessment, with clear understanding of job related demands, is integral to improvement. 

Ownership of one’s fitness is a professional responsibility for firefighters. Due to modern building materials, firefighters have less time on their side prior to untenable conditions. This abbreviated window, compared to previous decades, demands that firefighters work quickly, guided by undistracted decision making. Having a testable work capacity standard, serves as a benchmark, so firefighters can be confident in their fitness, training approach, and mental attitude.

Jim Spengler is a career firefighter for a department in the DC metropolitan area. Jim completed a M.S. in Exercise Science in 2013.

References

  1. The Impact of Firefighter Physical Fitness on Job Performance: A Review of The Factors That Influence Fire Suppression Safety and Success. Morris, et al. Safety, 2018.
  2. Physical work capacity of firemen: With special reference to demands during fire fighting. Kilbom. Scandinavian Journal of Work and Environmental Health, 1980.
  3. A simple method to analyze overall individual physical fitness in firefighters. Calavalle, et al. Journal of Strength and Conditioning Research, 2013.
  4. Physiological demand on firefighters crawling during a search exercise. Davis, et al. International Journal of Industrial Ergonomics, 2014.
  5. Physiological Responses to Firefighting in Extreme Temperatures Do Not Compare to Firefighting in Temperate Conditions. Windisch, et al. Frontiers in Physiology, 2017.
  6. The Effect of Various Hot Environments on Physiological Responses and Information Processing Performance Following Firefighting Activities in a Smoke-Diving Room. Hemmatjo, et al. Safety and Health at Work, 2017.
  7. Psychological, Physical, and Heat Stress Indicators Prior to and after a 15-Minute Structural Firefighting Task. Canetti, et al. Biology, 2022
  8. Decline in executive control during acute bouts of exercise as a function of exercise intensity and fitness level. Labelle, et al. Brain and Cognition, 2012.
  9. Firefighter neural function and decision-making following rapid heat stress. Coehoorn, et al. Fire Safety Journal, 2020.
  10.  Development and evaluation of a test drill for assessing physical work capacity of firefighters. International Journal of Industrial Ergonomics. Sothmann, et al, 1994.
  11. Cardiorespiratory effects of respiratory protective devices during exercise in well trained men. European Journal of Applied Physiology. Louhevaara, et al, 1984.
  12. Analysis of changing residential fire dynamics and its implications on firefighter operational timeframes. Underwriter’s Laboratory. Kerber, 2014.

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