Background: Cardiorespiratory fitness (CRF) is an important aspect of the overall health of an individual and its monitoring must be promoted in the general population. Thus, the aim of the study was to cross-validate and improve CRF estimation based on quarter-mile Rockport Fitness Walking Test.
Methods: Thirty participants (31.4±7.99 years) were randomized in either a four-week aerobic training group (10 men and 10 women) or a control group (eight men and two women). CRF was assessed via VO2max test and estimated via quarter-mile Rockport Fitness and Ebbeling treadmill tests, before and after the training intervention. The original quarter-mile Rockport VO2max estimation was found to greatly overestimate CRF by 22 mL/kg/min. When its coefficient was updated according to our data, it largely improved (by 6.8 mL/kg/min). Furthermore, a new algorithm for predicting VO2max was designed using multi-linear regression analysis.
Results: The original quarter-mile Rockport Fitness Walking Test was not sensitive to CRF changes. It showed changes in VO2max, which were significantly different from the actual observed changes (-1.1±4.08 vs. 1.61±2.84, P=0.02, respectively). The Ebbeling treadmill test appeared to systematically overestimate CRF changes. Our new algorithm showed improved sensitivity for detecting CRF changes and stability.
Conclusions: The original quarter-mile Rockport Fitness Walking Test equation for predicting VO2max was neither accurate nor sensitive to changes in CRF, most likely due to cardiovascular drift. Our new algorithm, based on the same brisk walking test, can provide a more accurate estimate of CRF, which is also sensitive to VO2max changes, in a broad age range (18 to 50 years).