TABLE 2.
Cardiopulmonary exercise test confounder adjusted (age, sex, ethnicity, & BMI) results for healthy controls versus long COVID cases.
| Cardiopulmonary exercise test | n | Potential outcome means (95% CI) | The difference in long COVID versus HC | ||
|---|---|---|---|---|---|
| Adj. for age, sex, ethnicity & BMI | M1: Adj. for age, sex, ethnicity & BMI | ||||
| Healthy controls | Long COVID | Δ (95% CI) | p‐value | ||
| Peak V̇O2 [mL/kg/min] during exercise | 45 | 23.3 (21.4, 25.2) | 18.3 (16.6, 19.7) | −5.0 (−7.1, −3.0) | <0.001 |
| Extrapolated V̇O2 max [mL/kg/min] | 45 | 33.0 (30.7, 35.3) | 30.5 (28.1, 32.8) | −2.5 (−5.2, 0.2) | 0.064 |
| OUES [mL/min] | 45 | 2175.8 (1978.3, 2373.3) | 1847.4 (1678.5, 2016.4) | −328.3 (−534.4, −122.3) | 0.002 |
| V̇O2 at AT [mL/kg/min] | 44 | 15.6 (14.4, 17.2) | 13.2 (12.2, 14.3) | −2.4 (−3.7, −1.1) | <0.001 |
| VAT [% of predicted] | 44 | 56.7 (53.3, 60.0) | 47.8 (44.1, 51.6) | −8.8 (−13.3, −4.4) | <0.001 |
| V̇E/V̇CO2 slope | 45 | 25.7 (24.5, 26.8) | 28.0 (26.9, 29.2) | 2.4 (0.9, 3.8) | 0.001 |
| Peak HR [min−1] | 45 | 146 (143, 149) | 130 (119, 140) | −16 (−27, −5) | 0.003 |
| Peak HR [% predicted] | 45 | 82 (81, 84) | 73 (68, 79) | −9 (−15, −3) | 0.002 |
| Highest V̇O2/HR (O2 pulse) [mL/beat] | 45 | 12.0 (10.8, 13.1) | 10.5 (9.6, 11.3) | −1.5 (−2.5, −0.5) | 0.002 |
| V̇O2/WR [mL/min/W] | 45 | 9.3 (8.9, 9.8) | 8.7 (8.2, 9.1) | −0.7 (−1.3, −0.1) | 0.027 |
| Peak power [W] | 45 | 170.5 (154.5, 186.4) | 128.2 (112.9, 143.4) | −42.3 (−56.6, −28.0) | <0.001 |
| Peak ventilation [L/min] | 45 | 58 (52, 64) | 48 (41, 54) | −11 (−18, −4) | 0.001 |
| Peak breathing reserve [%] | 45 | 57 (52, 63) | 59 (53, 66) | 2 (−6, 11) | 0.607 |
| Peak RER | 45 | 1.18 (1.15, 1.21) | 1.11 (1.06, 1.17) | −0.07 (−0.13, −0.01) | 0.024 |
| No. of participants RER ≥1.1 | 22 (85%) | 17 (90%) | ‐ | ‐ | |
| Lactate [Δmmol/L] | 36 | 4.5 (3.5, 5.5) | 2.6 (1.5, 3.7) | −1.9 (−3.2, −0.6) | 0.003 |
| Borg CR10 dyspnoea | 44 | 5 (5, 6) | 6 (5, 6) | 0 (−1, 1) | 0.500 |
| Borg CR10 leg fatigue | 45 | 6 (4, 7) | 7 (6, 8) | 1 (−0, 3) | 0.139 |
Abbreviations: AT, Anaerobic threshold; OUES, oxygen uptake efficiency slope; RER, respiratory exchange ratio; V̇E/V̇CO2, ventilation/carbon dioxide production; V̇O2, oxygen uptake; V̇O2WR, oxygen uptake work rate.