Submaximal VO2 Prediction Formula

A mouthful of words that do not mean much to people outside my fire department. The IAFC (International Association of Fire Chiefs) and IAFF (International Association of Fire Fighters) have established a great program to help the fire service get into shape.

I will readily admit that I am not in the best of shape. According to the handy BMI (Body Mass Index) chart, I am a 39. I won’t go into the details, but many physicians and experts are saying that the BMI is not accurate.  Baylor College of Medicine & Michigan State University have both done studies on the BMI’s accuracy. I digress however.

I am not trying to say that I am not overweight. I am, as is my father & his mother. I really want to get into shape. I have paid for a personal trainer, taken the advice from a nutritionist, and I have lost 20 lbs. I pay for a membership to a workout facility in the area, I workout every shift at the fire station. I want to be in shape.

My Fire Chief decided to switch to a sub-maximal VO2 test in lieu of a mile and a half run as a test for aerobic fitness level. Last year around this time we ran our annual Physical Agility Test (PAT) and began the VO2 test. I can complete the PAT in the required time, but I have not yet met the minimum standard that my department has adopted for the VO2, yet.

According to the firefighters who have taken the Peer Fitness Trainer, the intention is to encourage fire fighters to get in shape by using weight training and aerobic exercise. The whole program is non punitive. We all know that negative reinforcement is not a good motivator.

Three weeks ago my chief sent an email to the entire department. He stated that if an individual could not pass the VO2 with a minimal score of 38.5 then they will receive a “not fit for duty” letter by the chief and would not be allowed to work. The individual would be sent home immediately and have to take personal and sick time until it runs out or until they pass the VO2 test. Sounds like negative reinforcement to me, and very punitive. Reminder, I am not opposed to getting in shape, I want to get into shape. There are many ways to fool the math. We have officers that take prescribed beta blockers who can pass the test but never work out. Here is the formula for the Sub-maximal Stepmill VO2 prediction.

  • VO2 max = 57.775 +(1.757 x TT) – (0.904 x BMI)

TT = Test time. The test begins with 2 minutes of warm up. Then you keep increasing the difficulty (level) on the stair mill until your heart rate exceeds the target rate for more that 15 seconds.  BMI = Body Mass Index. So theoretically if I take the blood pressure medication my doctor wants to prescribe (that was last year) I could keep my heart rate below the target and not have to workout at all. Is this really a test of aerobic fitness? It’s what we have so I’m stuck with imperfection.

Now I have three months worth of time to workout and consider my options (and my future). Has any other fire department adopted the Peer Fitness Initiative? Just curious. Today is my last shift, Tuesday I will take the test and I doubt I’ll pass (I’ve been required to test monthly and I haven’t passed yet). I will be sent home, and I will go to work for F&B Ambulance while I consider my options.


Read more about the Sub-Maximal VO2 Prediction Formula from the IAFF/IAFC and ACE


About Joel

I am a paramedic, firefighter and I work for an organ procurement organization. All stories related to work have been altered to HIPPA standards and for the protection of those involved. The personal stories are different. Photography, flying, aviation, hiking, camping, travel, geocaching, amateur radio are a few of my hobbies.
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2 Responses to Submaximal VO2 Prediction Formula

  1. Rich says:

    Did you still take the sub vo2 max test while on beta blockers? Or what was your departments answer for those taking the meds since your HR doesn’t / will not reach 85% of THR?

  2. Kevin says:

    We found that step mill tests are usually a lot lower as far as submax vo2 prediction. And also remember submax testing isn’t very accurate.

    Has the stepmill been calibrated?

    I’d ask to take the treadmill test. It’s more accurate and less taxing on the lower body.

    You might try requesting a max vo2 test from a doctor?

    With the results from a submax vo2 assessment having so much of wide margin for error, with out research I remember it to be as much as 6 to 10% plus or minus. I don’t know how the chief can use it for justification of your job.

    I’ve been a PFT for a few years and have performed a lot of assessments. Some newer treadmills have the WFI protocol pre loaded in them. We also found that using the formula provided by the WFI program gave different results rather then letting the treadmill to automatically calculate it after the assessment.

    Not sure how old this article is. Stay safe!!!!

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