Demographic and cardiopulmonary characteristics
| All | Significant cardiopulmonary pathology | No significant cardiopulmonary pathology | Significance (pathology vs no pathology) | |
| No of patients | 113 | 7 | 106 | – |
| Age (years) | 40 (33–47) | 50 (45–54) | 39 (31–46) | * |
| Male (%) | 95 (84.3) | 7 (100) | 88 (83.0) | ns |
| BMI mean | 29 (±4.2) | 31 (±3.9) | 29 (±4.3) | ns |
| BMI >30 (%) | 40 (35) | 4 (57) | 40 (38) | ns |
| BMI >35 (%) | 12 (9) | 0 (–) | 12 (11) | ns |
| No (%) of +ve PCR/AB test | 57 (50.4) | 5 (71) | 52 (49) | ns |
| Weeks from acute illness to assessment | 29 (23–34) | 22 (21–25) | 29 (23–35.5) | ns |
| RER | 1.17 (±0.06) | 1.20 (±0.05) | 1.17 (±0.06) | ns |
| Peak lactate (mmol/L) | 12.4 (±2.8) | 9.4 (±1.8) | 12.7 (±2.7) | ns |
| V̇O2 peak (mL/kg/min) | 34.1 (±7.2) | 26.7 (±5.1) | 34.6 (±7.0) | ** |
| V̇O2 % peak predicted | 112 (±20) | 95 (±15) | 113% (±20) | * |
| Peak workload (W) | 244 (±55) | 200 (±36) | 247 (±55) | * |
| Peak workload % predicted | 101 (±22) | 82 (±16) | 102 (±22) | * |
| V̇O2 at AT (mL/kg/min) | 13.8 (±2.9) | 11.8 (±1.8) | 14.0 (±2.9) | ** |
| V̇E/V̇CO2 slope | 28.2 (±5.9) | 37.0 (±8.0) | 27.6 (±5.3) | *** |
| V̇E/V̇CO2 at AT | 27.0 (±3.7) | 32.8 (±4.1) | 26.6 (±3.35) | *** |
| % Breathing reserve† | 15 (±13) | 7 (±18) | 17% (±17) | ns |
| Alveolar–arterial gradient rest (kPa) | 2.5 (±2.0) | 3.8 (±2.0) | 2.4 (±2.0) | ns |
| Alveolar–arterial gradient stress (kPa) | 2.5 (±2.0) | 4.6 (±1.5) | 2.3 (±2.0) | ** |
| Resting heart rate (bpm) | 85 (±14) | 82 (±8.6) | 85 (±14) | ns |
| Peak heart rate (bpm) | 173 (±16) | 156 (±19) | 174 (±15) | ** |
| Peak heart rate % predicted | 108 (±9) | 103 (±13) | 108 (±9) | ns |
| Heart rate recovery (bpm fall in 60 s) | 27 (±13) | 28 (±12) | 27 (±14) | ns |
| V̇O2/HR% peak predicted | 104 (±22) | 92 (±7.4) | 105 (±22) | ns |
| Six-min walk test distance (m) | 614 (±110) | 621 (±122) | 613 (±110) | ns |
Mean values are presented (±SD); median values are presented with IQR (first to third quartile). Significant differences were tested between seven patients with significant disease and 106 patients with no significant disease. Level of significance for group comparison: ns; *p<0.05; **p<0.01; ***p<0.001.
*p<0.05; **p<0.01; ***p<0.001.
†Breathing reserve: predicted peak minute ventilation−actual peak minute ventilation (L/min).
AT, anaerobic threshold; BMI, body mass index; bpm, beats per minute; HR, heart rate; ns, not significant; RER, respiratory exchange ratio (>1.10 implies excellent maximal effort); VCO2, carbon dioxide elimination; VE, minute ventilation (L/min); V̇O2, oxygen uptake.