Physiological and Metabolic Responses to Constant-Load Exercise on an Inclined Stepper and Treadmill

This study evaluated oxygen uptake (VO2), heart rate (HR), and lactate [HLa] responses between the treadmill (TM) and the CardiosquatTM 1650 LETM inclined stepper by StairMasterTM (SM) during constant-load exercise. The slow component of VO2 (SC) was a central variable assessed during exercise. Twenty-two healthy college-aged (18-30) subjects completed an incremental TM and SM exercise test to establish a workload equivalent to 70% VO2peak. Following each incremental test, a 20-minute constant-load exercise bout was performed . Incremental and instant-load exercise bouts were separated by at least 48 hours. The order of the tests were randomized. VO2, HR, and [HLa] were evaluated at 5, 10, 15, and 20-minutes of exercise. Expired gases were analyzed using a Med Graphics CPX/D metabolic cart.

Blood samples were analyzed immediately for lactate concentration with an automated lactate analyzer (Yellow Springs Instrument Model 1500 Sport ). A two-way ANOVA with repeated measures was performed on the rate of change between the treadmill and stepper for VO2, HR, and [HLa]. No significant differences were found for any of the response variables (P>0.05). These results suggest at that the same relative workload, the SM does not elicit a more pronounced SC than the TM.

Based on these findings, the SM appears to be an appropriate modality of exercise for various clinical populations.