Rationale: Evaluation of functional exercise capacity is an important outcome measure in outpatient cardiac rehabilitation programs (CRP). Conventionally functional capacity is evaluated either by METS achieved in training (METStr) or by the 6-minute walk (6MW). The NuStep recumbent stepper offers an alternative to both METStr & 6MW, which may solve problems associated with handrail support and peak walking speed, respectively.

Objectives: This study was designed to test the hypothesis that a 6-minute NuStep test would provide a better reflection of improvements in functional capacity during CRP than METtr & 6MW.

Methods: Forty consecutively enrolled patients in a Phase II CRP (aged 36-88, referring diagnosis: CABG = 18, Valve = 5, PTCA = 4, MI = 2, stable AP=2, Combined=9) performed randomly ordered 6MW, 6-minute NuStep and METtr during the first week of CRP and during the last week (range = 15-31 exercise sessions). All results were normalized to METs to allow comparison of indices of exercise performance.

Results: Functional capacity in METs improved during CRP based on METStr (2.7 + 0.8 vs 4.3 + 1.8), 6MW (2.9 + 0.4 vs 3.1 + 0.4), and 6-minute NuStep (2.8 + 0.7 vs 3.5 + 0.9). The estimated improvement in METStr was significantly (P < .05) larger than the improvement estimated from 6MW & 6-minute NuStep and the estimated change in 6-minute NuStep was larger than 6MW. Correlations between indices of improvement during CRP were very low amongst all markers of functional capacity (METStr vs 6MW = 0.23, METtr vs 6-minute NuStep = 0.28, 6MW vs 6-minute NuStep = -0.12).

Conclusions: The lack of agreement between markers of improved functional capacity with CRP suggests the need for further study to define a gold standard outcome measure.