Table 2.
Comparison of CPET results with two techniques, the lower section of the table presents data available only from the step test
| Cycle CPET | Step test CPET | MD (step cycle) | |
| Exercise time (s) | 307 (285 to 329) | 114 (98 to 130) | −194 (−380 to −9)**** |
| Work rate (W) | 63 (58 to 69) | 38 (35 to 41) | NA |
| VO2 (mL/kg/min) | 11.9 (11.2 to 12.7) | 12.8 (11.9 to 13.7) | 0.9 (−3.6 to 5.4)*** |
| VO2 (% predicted) | 54 (50 to 57) | 58 (54 to 62) | 5 (−17 to 26)*** |
| Heart rate (bpm) | 115 (111 to 120) | 114 (109 to 118) | −2 (−32 to 28) |
| Cardiac reserve (%) | 71 (69 to 74) | 68 (64 to 72) | 4 (−35 to 28)* |
| O2 pulse (mL/beat) | 7.5 (7.0 to 8.0) | 8.1 (7.5 to 8.7) | 0.7 (− 2.7 to 4.1)*** |
| VE (L/min) | 35.2 (32.7 to 37.8) | 32.8 (30.3 to 35.5) | −2.2 (−16.4 to 11.9)** |
| Breathing reserve (%) | 63 (60 to 67) | 60 (56 to 64) | −3 (−25 to 19)** |
| RER | 1.07 (1.04 to 1.09) | 0.86 (0.84 to 0.88) | −0.21 (−0.45 to 0.03) **** |
| Absolute desaturation | 3 (2 to 4) | 5 (4 to 7) | −2 (4 to −9)**** |
| Steps/min | 19 (18 to 20) | ||
| Total energy (kJ) | 3.35 (2.84 to 3.95) | ||
| Climb index | 2.77 (2.60 to 2.95) | ||
| Height gained (m) | 4.72 (4.04 to 5.52) | ||
| Velocity (m/min) | 3.19 (3.01 to 3.35) | ||
| Saturation deviation | 0.6 (0.0 to 2.4) | ||
| Desaturation area | 48 (0 to 356) | ||
| Resaturation time (s) | 39 (13.5 to 70.0) |
Data presented as mean (95% CI) or median (IQR). Mean difference (MD) between the groups is calculated by the Bland-Altman technique.
Differences in work rate are not compared since the step oximetry system calculates only ascending work.
Significant difference between results in paired t-test:
*P<0.05; **P<0.01; ***P<0.001; ****P<0.0001.
CPET, cardiopulmonary exercise testing; NA, not applicable; RER, respiratory exchange ratio; VE, minute ventilation; VO2, peak oxygen uptake.