Fitness Tips

Just how fit are you?

One way to determine your overall fitness is to take a Gerkin Fitness Test. Named after the Arizona researcher who designed this test, this submaximal treadmill test (submaximal means the athlete works below maximum effort) is used to predict VO2 max - the volume of oxygen you can consume while exercising at your maximum capacity. The particular test has gained great popularity in the firefighter community. Like most fitness tests, it is classified as a graded exercise test (GXT). The test is stopped at the point the subject's heart rate reaches 85% of their age-predicted maximum.

The Gerkin Protocol Explained
The Gerkin protocol (procedure) starts at 4.5 miles per hour at a 0% incline. It will then increase in speed or incline every 60 seconds. For example, at the seven-minute mark, the speed will increase to 6 miles per hour while the incline is raised to 8%. Other treadmill fitness test protocols are usually based on maximal tests (maximal is when the subject must run or walk to the maximum effort and exhaustion). This type of fitness test is considered unsafe without proper supervision. Two fitness tests based on maximal exertion are Bruce and modified Bruce. Both of these tests require inclines far in excess of 15%. Balke is another maximal fitness test but uses normal treadmill inclines.

The version of the Gerkin Protocol that TRUE Fitness uses in its exercise machines is the new equation of 205.8 - 0.685*age. To better understand why we selected this method over the outdated "220 - age" maximal heart rate equation, you can review the scientific paper in Journal of Exercise Physiology, a PDF document located at http://www.asep.org/Documents/Robergs2.pdf.

The Accuracy of the Gerkin Protocol
The scientific journal Occupational Medicine published a study on the accuracy of the Gerkin test in 2004. The conclusion:

"The Gerkin treadmill protocol overpredicts VO2max in healthy men and women and, therefore, should not be used for predicting VO2max in individual firefighters, particularly if VO2max is a criterion for inclusion or exclusion from duty. At this time, a valid treadmill running test is needed for predicting the VO2max value of individual firefighters."

However, for the fitness enthusiast who is interested in monitoring their fitness level, this program can be used to see how long they can go before the session stops and measure progress over time.