Evaluation of a treadmill test for predicting the aerobic capacity of firefighters

Background As part of a comprehensive occupational medical program for fire departments in the USA, the National Fire Protection Association and The Fire Service Joint Labor Management Wellness/Fitness Initiative endorse a standardized submaximal test that uses the Gerkin treadmill protocol for predicting the maximal oxygen uptake (VO2max) of firefighters. Aims To test the validity of the Gerkin treadmill protocol in healthy men and women. Methods Fifty-four healthy men and women (age range 19-58 years) performed the Gerkin test and a treadmill run test to maximal exhaustion. Their heart rates were monitored continuously with an electrocardiogram during each test. During the VO2max test, the subjects' VO2 was measured continuously using indirect calorimetry. Results Although the predicted and observed VO2max values correlated (r = 0.70, P < 0.001 and standard error of estimate = 5.98 ml/kg/min), the mean values differed (49.8 +/- 8.3 and 41.8 +/- 5.8 ml/kg/min, respectively) (P < 0.001). The VO2max value was overestimated in 50 (93%) participants. The overestimation was >25% in 18 (33%) participants. Gender, age and VO2max did not affect the Gerkin protocol's predictability of VO2max. Conclusions 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.