Characteristics of the study population
| Above LT | Below LT | |||
| Controls (n=10) | COPD (n=11) | Controls (n=7) | COPD (n=7) | |
| Clinical data | ||||
| Age (years) | 66.5±4.3 | 67.2±8.4 | 56.7±8.9 | 65.0±6.5 |
| BMI (kg/m2) | 26.2±2.4 | 24.8±3.2 | 27.3±7.0 | 25.7±2.5 |
| FFMI (kg/m2) | 21.0±2.6 | 19.2±1.4 | 22.4±5.3 | 19.3±1.8 |
| Lung function and peak exercise data | ||||
| FEV1 (l) | 2.9±0.4 | 1.4±0.3*** | 2.8±0.5 | 1.6±0.3*** |
| FEV1 (% ref) | 90.3±6.8 | 44.8±7.7*** | 92.5±5.6 | 49.9±3.8*** |
| Tlco (% ref) | 89.1±12.4 | 56.7±16.1** | 91.4±6.5 | 63.9±8.7** |
| Pao2 at rest (mm Hg) | 77±7 | 67±7** | 83±3 | 66±5*** |
| V′o2peak (l/min) | 1.67±0.23 | 1.23±0.18** | 1.73±0.34 | 1.34±0.29* |
| V′o2peak (% ref) | 91±3.3 | 68±10.4*** | 90±2.3 | 71±11.9** |
| V′o2 at LT (l/min) | 1.03±0.13 | 0.73±0.15** | 0.82±0.10 | 1.06±0.26** |
| Work rate peak (W) | 132 ±23 | 88±17** | 143±35 | 99±27* |
| V′epeak (l/min) | 64.9±9.3 | 48.1±4.1*** | 74.9±16.2 | 53.8±16.5** |
| Skeletal muscle results at rest | ||||
| mtDNA/nDNA | 1241±184 | 1104±183 | 1227±210 | 1082±229 |
| PGC-1α mRNA (arbitrary units) | 1.02±0.12 | 0.86±0.44 | 0.99±0.24 | 0.76±0.16 |
| MnSOD (U/mg) | 1.10±0.37 | 1.53±0.51* | 0.9±0.2 | 1.33±0.39* |
| Constant work load exercise data | ||||
| Work rate (W) | 86±14 | 57±25*** | 72±20 | 50±14** |
| V′o2peak (l/min) | 1.55±0.14 | 1.13±0.26** | 0.83±0.19 | 0.65±0.15* |
| V′epeak (l/min) | 61.3±5.7 | 44.6±5.9** | 36.7±9.1 | 27.9±8.5* |
| End exercise dyspnoea, CR10 | 5.0±2.2 | 4.1±1.4 | 3.6±1.8 | 2.0±1.0 |
| End exercise leg fatigue, CR10 | 7.5±1.8 | 6.8±1.6 | 4.7±2.1 | 2.4±1.5* |
| Total V′o2 (mmol) | 2122±280 | 1515±227*** | 1113±223 | 865±187*** |
| Estimated ROS production (mmol/kg) | 0.76±0.15 | 1.45±0.24*** | 0.4±0.1 | 0.81±0.16*** |
| Pao2 peak exercise (mm Hg) | 80±4 | 66±6*** | 87±5 | 67±7*** |
| Lactate end (mEq/l) | 5.4±0.7 | 5.0±0.6 | 2.4±0.3 | 2.8±0.5 |
Values shown are mean±SD.
*p<0.05; **p<0.01; ***p<0.001 vs controls.
BMI, body mass index; CR10, Borg CR10 scale; FEV1, forced expiratory volume in 1 s; FFMI, fat-free mass index; LT, lactate threshold; MnSOD, manganese superoxide dismutase; mtDNA, mitochondrial DNA; nDNA, nuclear DNA; Pao2, arterial oxygen tension; % ref, percentage of predicted values; PGC-1α, peroxisome proliferator-activated receptor-γcoactivator-1α; ROS, reactive oxygen species; Tlco, carbon monoxide transfer factor; V′o2 oxygen uptake; V′e, minute ventilation.