All forms of exercise equipment require a period of habituation in which individuals adapt to the novel movement required in operating the device and reach a point of physiological stability. During this adaptation period, physiological variables which indicate cardiopulmonary demand typically will change. In general, such changes are expected with devices that require complex movements. The influence of this habituation on physical performance is vital for establishing research methodology in which precise control of power output is necessary. The StairMaster® corporation has recently introduced the CrossRobics™ 2650UE (2650UE), an ergometer which simulates the kayak stroke pattern. In contrast to bicycle and arm crank ergometers, with which the user follows a set motion, the 2650UE allows the user to adopt a variety of movement patterns. To determine responses during habituation to the 2650UE, 14 female and 12 male subjects (18-32 years of age) were monitored during their first four exercise trials. Each session was 10 min long at a constant load of 0.36 watts/kg ± 0.02SD and 0.55 watt/kg ±0.02SD for female and male subjects, respectively. Significant differences (p<O.OOI) were found for V02, -.vO₂, -.vE, HR and RPE across the four trials, with decreases of 6.3% to 9.5% from the mean values in trial 1 to trial 2. Post hoc analysis indicates that a minimum of two 10 min practice trials are required for measures of oxygen consumption to stabilize, whereas one 10 min practice trial is required for measures of-.v E, HP and RPE to stabilize.