The Chester step test—a simple yet effective tool for the prediction of aerobic capacity

Objectives The assessment of cardiorespiratory fitness is becoming more commonplace in both community and occupational health settings. This study investigates the reliability and validity of the Chester step test, a submaximal test for the prediction of aerobic capacity, when compared to maximal oxygen uptake (V̇O2Max) measured during a treadmill test.

Design Participants completed a V̇O2Max Treadmill Test using a standardised fast incremental ramp protocol designed to elicit exhaustion in 8–12 minutes. Following this, on separate days, subjects then completed the Chester step test (CST) on two occasions (CST1 and CST2). During the submaximal step test, subjects were asked to step on to and off a 30-cm step at a rate set by the metronome beat on an audio cassette. The initial step rate was 15 steps per minute and every 2 minutes the tempo increased by 5 steps per minute. The subject continued stepping until he/she reached 80% of their maximum predicted heart rate, or reported a rating of perceived exertion of 15 (hard) on the Borg scale, or reached the end of the 10-minutes 5-stage test.

Setting Human Performance Laboratory, University College Chester

Participants Sixty-eight subjects (mean age 30.6±9.7 years; range 18–52 years) with a wide range of ages and abilities

Main outcome measures Gas exchange and heart rate were measured continuously using a Polar heart rate monitor. Heart rate and rating of perceived exertion were recorded after each 2-minute stage.

Results Results revealed a high correlation (r=0.92) between V̇O2Max and CST1 (P<0.001) and a standard error of the estimate of 3.9mlO2/kg/min, thus confirming the face validity of CST as a predictor of V̇O2Max. Using the method of analysis recommended by Bland and Altman (1986) [Lancet 5 (1986) 307] the mean difference between repeated predicted measures using CST was −0.7mlO2/kg/min. The limits of agreement analysis also demonstrated that a measurement repeated on a separate day was within 4.5mlO2/kg/min of the original predicted measurement. The Chester step test is therefore appropriate for use in situations where a change in aerobic capacity is expected to be more than 3.8mlO2/kg/min higher or more than 5.2mlO2/kg/min lower than the baseline measurement.

Conclusions The Chester step test was shown to be a valid test for the estimation of aerobic capacity within this group. The error of measurement is sufficiently small and suggests that this method is well suited to monitoring changes in aerobic capacity in rehabilitation settings.