What is VO2 Max?
VO2 max is also referred to as cardiopulmonary capacity or aerobic fitness. When you exercise, your cells need an increased supply of oxygen. Oxygen uptake, designated by the abbreviation “VO2,” is a measurement of how well the respiratory and circulatory systems deliver oxygen to the tissues. The rate of oxygen uptake during maximum exercise intensity is called “VO2max.” It is usually stated in terms of ml of oxygen per kilogram body weight per minute (ml/kgmin).
Why It’s Important?
There are two answers to this question.
The first and foremost deals with what is a healthy value. The number one killer in the US is cardiovascular disease. This is the same for firefighters. According to the US Fire Administration, 83 firefighters died in 2011. Heart attacks were responsible for the deaths of 50 firefighters, nearly the same proportion of firefighter deaths from heart attack or stroke recorded in 2010. Often the quick response to stress is considered the cause. However this is complicated by the low fitness levels among firefighters. Increasing cardiovascular fitness is the biggest change that an individual can do to decrease this risk.
This has been documented by Dr. Steven Blair, a professor at the University of South Carolina and a leading epidemiologist on the relationship of aerobic fitness to health. His research has proven that low “cardiorespiratory fitness (VO2max)” is a greater risk factor for cardiovascular mortality than any of the more traditional risk factors that our medical profession typically focuses on. (eg., obesity, hypertension, diabetes, high cholesterol, smoking). (Blair SN. 2009).
According to a 1999 article by the American Journal of Clinical Nutrition, “Unfit, lean men had twice the risk of all-cause mortality as did fit, lean men and also had higher risk of all-cause mortality when compared with fit, obese men. For long-term health benefits we should focus on improving fitness by increasing physical activity rather than relying only on diet for weight control.”
“If the height/weight charts say you are five pounds too heavy, or even 50 pounds or more too heavy, it is of little or no consequence health wise-as long as you are physically fit. On the other hand, if you are a couch potato, being thin provides absolutely no assurance of good health, and does nothing to increase your chances of living a long life,” according to Steven Blair, P.E.D., Cooper Institute for Aerobics Research, 1997.
Often firefighters are overweight and have low fitness levels. This is a double whammy. See the chart below to understand how fitness protects even if overweight but notice as a person becomes overweight, if they are unfit their risk increases very fast.
So what is the value that has been shown through research to protect against cardiovascular disease? Values in the low fitness category (VO2 max< 27) place an individual at greater risk than than those at intermediate category (VO2 max 28-38) with the greatest protection at highest fitness level (VO2 max > 38). — Lowry,Prevention 2009
The second reason to increase VO2max is job specific. Determinants of a successful CPAT were evaluated by Andrew Kirkham Sheaff in 2009. He divided subjects into those that passed and those that did not pass. Passing as defined by International Association of Firefighters (IAFF) is less than 10 minutes 20 seconds. The data looked at upper body strength, lower body strength, VO2 max and anaerobic fatigue. Upper body was strength a better predictor than lower body strength, however VO2 max and anaerobic fatigue were the best predictors. These findings complement findings by Williams-Bell that observed VO2 values in excess of 38 during simulated firefighter duties.
A joint task force of the IAFF and International Association of Fire Chiefs developed the Fire Service Joint Labor Management Wellness-Fitness Initiative (WFI) in 1997. Revisions in the 1999 and 2008 WFI recognize the firefighter as the “most important asset” in the fire service, and its intent is to improve firefighter function, on-duty effectiveness, and overall quality of life, while reducing morbidity and mortality related to fire fighting. The WFI mandates that firefighters have a maximal exercise test at age 40 and every other year thereafter. The maximal exercise test is intended to measure max VO2. Proposed for firefighting range a max VO2 range of 33.6 ml/kg-1 min-1·to 49 ml/kg-1·min-1). R
Recent analysis of physical aptitude tests among firefighter recruits demonstrated that male recruits’ average VO2 requirement was 38.5. Measurement of functional capacity in 23 firefighters suggested that a mean of 41.54 is required to complete standard fire suppression tasks while wearing personal protective equipment. — Nord-Drew,Journal of Occup Med Drew, 2011
Testing firefighters over the last 20 years, I have seen a new interest in changing the culture of the fire service to encourage firefighters to be fit. In summary, cardiorespiratory fitness helps you perform your job better and is just good medicine.
Karen Leatherman is President/Owner of Fitness Forum Occupational Testing Services. She received a BS in Biology from Francis Marion University and a MS in Exercise Physiology from the University of South Carolina. She started the first hospital based fitness center in S.C. where she started cardiac and pulmonary rehab programs. She has 28 plus years performing exercise stress testing and has been testing firefighters for over 20 years. In addition, she was on the American College of Sports Medicine (ACSM), Health and Fitness Certification Committee where she travelled with a team from the US to India and Hong Kong to teach and administer ACSM exams.