Incremental exercise using progressive versus constant pedaling rates: a study in cardiac patients
Giovanni Grazzi1, Francesco Conconi, Jonathan Myers
1Center of Biomedical Studies Applied to Sport, University of Ferrara, Ferrara, Italy. giovanni.grazzi@unife.it
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 (V(O(2)peak)), workload (W(peak)), and heart rate (HR(peak)); ventilatory threshold (VT); and the oxygen uptake (VO2) per unit work rate (WR) increment (ΔV(O(2))/ΔWR) obtained using 2 protocols were determined.
Results:
V(O(2)peak) 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 · kg(-1) · 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 · kg(-1) · 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, V(O(2)) (21.7 ± 5.5 vs 16.8 ± 5.3 and 12.3 ± 7.4 vs 9.3 ± 2.8 mL · kg(-1) · 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. ΔV(O(2))/ΔWR during INCR protocol were higher in patients with CAD (13.4 ± 1.8 vs 9.5 ± 2.6 mL · kg(-1) · W(-1), P = .006) and patients with CHF (13.6 ± 4.1 vs 8.7 ± 1.9 mL · kg(-1) · 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.
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