Authors

1. Grazzi, Giovanni MD
2. Conconi, Francesco MD, PhD
3. Myers, Jonathan PhD
4. Mazzoni, Gianni MD
5. Uliari, Simone MD
6. Fucili, Alessandro MD
7. Ceconi, Claudio MD

Abstract

PURPOSE: Cardiopulmonary exercise testing is widely used in clinical assessment and exercise prescription. However, significant differences in physiological responses can occur depending on testing protocol. The aim of this study was to evaluate the cardiopulmonary responses to different incremental cycle pedaling cadences in cardiac patients.

METHODS: Eleven men with coronary artery disease (CAD) and 12 men with chronic heart failure (CHF) performed 2 maximal cycle tests at constant cadence (60-70 rpm, at fixed cadence) and at progressive cadence. Peak values for oxygen uptake (VO_2peak), workload (W_peak), and heart rate (HR_peak); ventilatory threshold (VT); and the oxygen uptake (VO₂) per unit work rate (WR) increment ([DELTA]VO₂/[DELTA]WR) obtained using 2 protocols were determined.

RESULTS: Vo_2peak and W_peak, respectively, were higher during increasing cadence (INCR) compared with fixed cadence (FIX) protocol both in patients with CAD (32.7 +/- 5.4 vs 28.1 +/- 7.0 mL [middle dot] kg^-1 [middle dot] min^-1, P = .01; 214 +/- 42 vs 150 +/- 28 W, P = .001) and in patients with CHF (20.3 +/- 7.4 vs 17.2 +/- 5.5 mL [middle dot] kg^-1 [middle dot] min^-1, P = .006; 133 +/- 45 vs 104 +/- 33 W, P = .005). No differences were seen in HR_peak. Both in patients with CAD and in patients with CHF, VO₂ (21.7 +/- 5.5 vs 16.8 +/- 5.3 and 12.3 +/- 7.4 vs 9.3 +/- 2.8 mL [middle dot] kg^-1 [middle dot] min^-1) and HR (114 +/- 14 vs 98 +/- 13 and 92 +/- 17 vs 80 +/- 17 bpm) at VT were significantly higher in INCR than in FIX protocol. No differences were seen in workload at VT. [DELTA]Vo₂/[DELTA]WR during INCR protocol were higher in patients with CAD (13.4 +/- 1.8 vs 9.5 +/- 2.6 mL [middle dot] kg^-1 [middle dot] W^-1, P = .006) and patients with CHF (13.6 +/- 4.1 vs 8.7 +/- 1.9 mL [middle dot] kg^-1 [middle dot] W^-1, P = .006).

DISCUSSION: These findings indicate that in tests at fixed cadence, there occurs an earlier activation of the anaerobic mechanisms leading to a premature exhaustion before a cardiopulmonary endpoint has been achieved.