Table 3.
Cardiopulmonary function parameters
| Variable | H-SA | H-RB | C-SC | C-RD | CON E | F Score | P Value | A vs. D | A vs. E | B vs. D | B vs. E | C vs D | C vs. E |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| CPET | |||||||||||||
| V̇o2 at rest, mL/kg/min | 4.9 ± 1.0 | 4.8 ± 0.7 | 4.9 ± 1.0 | 5.5 ± 1.2 | 5.5 ± 1.8 | 1.930 | 0.111 | ||||||
| V̇o2 at VT1, mL/kg/min | 12.1 ± 1.7 | 12.9 ± 2.5 | 14.5 ± 3.9 | 17.2 ± 3.0 | 18.2 ± 5.6 | 10.995 | <0.001 | *** | *** | ** | ** | ||
| V̇o2 at peak (mL/kg/min) | 29.9 ± 5.0 | 32.6 ± 6.6 | 34.4 ± 7.2 | 44.3 ± 7.4 | 43.9 ± 13.1 | 13.448 | <0.001 | *** | *** | * | * | ** | *** |
| V̇o2 at VT1 (% peak predicted) | 43 ± 5 | 46 ± 10 | 47 ± 13 | 47 ± 7 | 56 ± 17 | 4.628 | 0.002 | ** | * | ||||
| V̇o2 at peak (% predicted) | 105 ± 13 | 116 ± 24 | 111 ± 19 | 122 ± 19 | 133 ± 25 | 7.701 | <0.001 | * | *** | ** | |||
| Work rate, W/kg, at VT1 | 0.70 ± 0.16 | 0.87 ± 0.18 | 0.92 ± 0.36 | 1.20 ± 0.29 | 1.38 ± 0.38 | 19.566 | <0.001 | *** | *** | ** | * | *** | |
| Work rate, W/kg, at peak | 2.40 ± 0.45 | 2.56 ± 0.55 | 2.77 ± 0.68 | 3.73 ± 0.67 | 3.89 ± 0.82 | 24.076 | <0.001 | *** | *** | ** | *** | *** | *** |
| Δ V̇o2, L/min/Δ work, W | 10.8 ± 1.0 | 11.3 ± 0.94 | 11.2 ± 2.2 | 11.2 ± 0.9 | 11.5 ± 0.7 | 1.855 | 0.124 | ||||||
| Lactate at rest, mmol/L | 1.2 ± 0.4 | 1.67 ± 0.5 | 1.3 ± 0.5 | 1.4 ± 0.4 | 1.2 ± 0.4 | 2.019 | 0.097 | ||||||
| Lactate at peak, mmol/L | 11.5 ± 2.3 | 14.0 ± 2.5 | 13.1 ± 2.3 | 14.1 ± 2.4 | 14.2 ± 1.5 | 6.119 | <0.001 | ** | *** | ||||
| O2 pulse at peak | 16.2 ± 4.0 | 18.4 ± 2.0 | 18.5 ± 4.7 | 21.1 ± 3.7 | 21.1 ± 4.7 | 5.785 | <0.001 | ** | *** | ||||
| O2 pulse (% predicted at peak) | 95 ± 21 | 104 ± 15 | 105 ± 20 | 119 ± 17 | 126 ± 22 | 9.377 | <0.001 | ** | *** | ** | |||
| RPE at peak (scored 6–20) | 18 ± 2 | 17 ± 2 | 17 ± 2 | 18 ± 2 | 17 ± 2 | 0.975 | 0.425 | ||||||
| SoB at peak (rated 0–10) | 7 ± 2 | 7 ± 3 | 6 ± 3 | 7 ± 2 | 7 ± 2 | 1.004 | 0.409 | ||||||
| Heart rate profile | |||||||||||||
| HR at rest, beats/min | 81 ± 11 | 82 ± 12 | 84 ± 13 | 77 ± 15 | 73 ± 8 | 3.566 | 0.009 | ** | |||||
| HR at peak, beats/min | 173 ± 15 | 169 ± 15 | 175 ± 16 | 178 ± 7 | 175 ± 8 | 0.792 | 0.533 | ||||||
| Ventilation | |||||||||||||
| V̇e/V̇co2 at rest | 30.7 ± 4.8 | 31.2 ± 5.2 | 30.5 ± 5.3 | 28.1 ± 2.0 | 28.0 ± 3.1 | 2.591 | 0.041 | ||||||
| V̇e/V̇co2 at VT1 | 28.1 ± 3.9 | 26.7 ± 4.6 | 26.7 ± 4.0 | 24.1 ± 1.7 | 24.3 ± 2.0 | 6.124 | <0.001 | ** | ** | ||||
| V̇e/V̇co2 at peak | 34.7 ± 5.6 | 33.1 ± 5.3 | 33.2 ± 4.0 | 30.5 ± 3.1 | 31.3 ± 3.3 | 3.525 | 0.010 | * | * | ||||
| V̇e/V̇co2 slope | 30.5 ± 5.3 | 26.5 ± 3.1 | 27.9 ± 5.3 | 24.1 ± 6.0 | 25.5 ± 2.6 | 6.012 | <0.001 | *** | ** | ||||
| OUES | 3.00 ± 0.57 | 3.16 ± 0.63 | 3.34 ± 0.96 | 4.88 ± 1.11 | 3.79 ± 0.93 | 4.135 | 0.004 | * | ** | ||||
| RER at peak | 1.18 ± 0.05 | 1.20 ± 0.05 | 1.18 ± 0.07 | 1.20 ± 0.06 | 1.22 ± 0.07 | 1.879 | 0.119 |
Values are means ± SD. The oxygen uptake efficiency slope (OUES) is a regression-derived parameter. It is the gradient of the slope (δy/δx) of the relationship between oxygen uptake (V̇o2) (y-axis) and log-transformed minute ventilation (V̇e) (x-axis) from 1 min after the onset of exercise until the second ventilatory threshold (VT2; also known as the respiratory compensation point). There were no significant differences between H-S vs. C-S, H-R vs. C-S, and C-R vs. CON for any CPET parameter. BF, breathing frequency; BP, blood pressure; CON, control population; CPET, cardiopulmonary exercise testing; C-R, community-recovered; C-S, community-symptomatic; FEV1, forced expiratory volume in the first second; FVC, forced vital capacity; H-R, hospitalized-recovered; HR, heart rate; HRR, heart rate recovery; H-S, hospitalized-symptomatic; OUES, oxygen uptake efficiency slope; RER, respiratory exchange ratio; RPE, rate of perceived exertion; SoB, shortness of breath; VT1, 1st ventilatory threshold. Level of significance: *P < 0.05, **P < 0.01, ***P < 0.001.