Table 2

Comparison of CPET results with two techniques, the lower section of the table presents data available only from the step test

Cycle CPETStep test CPETMD (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)**
RER1.07 (1.04 to 1.09)0.86 (0.84 to 0.88)−0.21 (−0.45 to 0.03) ****
Absolute desaturation3 (2 to 4)5 (4 to 7)−2 (4 to −9)****
Steps/min19 (18 to 20)
Total energy (kJ)3.35 (2.84 to 3.95)
Climb index2.77 (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 deviation0.6 (0.0 to 2.4)
Desaturation area48 (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.