Understanding aerobic capacity as it relates to fire fighting tasks

What do you want from your annual firefighter physicals?

CarolinaFireJournal - Charles F. Turner, R.N.
Charles F. Turner, R.N.
07/15/2014 -

As more and more companies are offering annual firefighter physicals it is important to determine exactly what it is you want from the physicals offered to your department. This is a very costly expenditure so there are things to consider when making this determination.

Heart Disease
As you probably already know, heart disease is still the number one killer of firefighters in the country. If you are concerned about screening for heart disease in your department, of course you should choose a company offering 12 lead ECG stress tests. Resting ECGs only show abnormalities when the heart is at rest. This will not help much in screening for heart disease which typically presents when the heart is stressed.

Aerobic Capacity
Another point to consider is the importance of aerobic capacity. Most companies offering occupational health screens will give each participant an estimated aerobic capacity. Aerobic capacity (or VO2) is a measurement of physical fitness determined by bicycle ergometer. Aerobic capacity is expressed in ml/kg/min. This unit estimates how many milliliters of oxygen can be used by the body per minute of exercise per kilogram of body weight. The higher this number is the greater the fitness level. A higher VO2 shows the body can utilize more oxygen at greater workloads indicating a well conditioned cardiovascular system.

There have been many research articles published showing the importance of aerobic capacity to fire fighting operations. “Age of a Bona Fide Occupational Qualification for Fire Fighting” from the January 1992 edition of the “Journal of Occupational Medicine” shows the importance of aerobic capacity and fire fighting. The article cites many studies that relate the importance of aerobic capacity to fire fighting.

The article states that “numerous studies have shown a VO2 of 25 to 35 ml/kg/min during fire suppression. Based on these observations, 38 to 42 ml/kg/min have been most frequently cited as the most desirable VO2 max level.” Studies have also indicated that “firefighters below 33.5 ml/kg/min had a high probability of not being able to sustain the performance of critical and routine fire-suppression tasks.” Given this information it is not only important to know what your firefighter’s aerobic capacities are but also what method is used to derive that information.

Of course every company will say their method (which there are many) of determining aerobic capacity is the best. The advantages and disadvantages to each of these methods are too many to list here. Some methods over-estimate aerobic capacity and some under-estimate. The Gerkin protocol used by some companies has been proven to be inaccurate. The article also stated that, “the Gerkin treadmill protocol over predicts VO2max in healthy men and women and, therefore, should not be used for predicting VO2max values in individual firefighters, particularly if VO2max is a criterion for inclusion or exclusion from duty.”

The only way to determine a “true” aerobic capacity is in the exercise physiology labs at universities. Exercise lab testing is the only method that gives a truly accurate VO2 as it measures the actual intake of oxygen while the body is under maximal workloads. It is unlikely that a company offering health screens can bring exercise physiology lab equipment to a mobile/field setting. Unless a company offers a true oxygen intake method, their aerobic capacity determination is merely an estimate.

Do your research and determine which company offers the physical that is right for your department. You spend a lot of time and money researching the equipment you buy for your department; you should take the same considerations into account when researching physicals that determine the wellness and physical capabilities of your firefighters.


“Age as a Bona Fide Occupational Qualification for Fire Fighting,” “Journal of Occupational Medicine,” January 1992.

“Evaluation of a treadmill test for predicting the aerobic capacity of firefighters,” “Society of Occupational Medicine,” 2004.

Charles F. Turner, R.N. is President/Director and founder of North Greenville Fitness and Cardiac Rehabilitation Clinic. He’s a graduate of Furman University with a B.S. in Business Administration. He received is RN certification at Greenville Technical College, Cardiac Certification from Colorado State University and the Medical University of South Carolina. Since 1979 he has performed over 120,000 Stress Tests and Health Screenings. He can be reached at 888-348-8911.
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