Table 2. Main characteristics of vastus lateralis muscle fibers.
| Healthy controls | COPD | COPDND | COPDD | |
| Type I proportion, % | 62.7 (55.3, 68.3) | 39.7 (35.3, 48.6)*** | 40.3 (35.5, 62.3)* | 39.7 (29.8, 47.4)*** |
| Type I/IIa proportion, % | 8.1 (4.6, 11.0) | 5.6 (2.2, 9.5) | 5.3 (3.5, 9.0) | 6.4 (1.2, 12.7) |
| Type IIa proportion, % | 25.5 (16.8, 32.4) | 40.5 (25.9, 48.9)** | 32.0 (24.5, 46.1)* | 45.4 (39.7, 55.2)*** |
| Type IIa/IIx proportion, % | 1.0 (0.3, 3.4) | 3.6 (1.1, 8.1) | 4.3 (1.0, 9.4) | 3.6 (0.7, 7.4) |
| Type IIx proportion, % | 0.5 (0.0, 2.7) | 2.3 (0.5, 9.4)* | 2.2 (0.2, 8.8) | 3.2 (0.6, 11.0) |
| Type I fiber CSA, µm2 | 8703±1858 | 8154±2460 | 8524±2655 | 7756±2268 |
| Type I/IIa fiber CSA, µm2 | 6540±2048 | 6073±2742 | 6274±2810 | 5838±2766 |
| Type IIa fiber CSA, µm2 | 7107±2580 | 7016±2309 | 7030±2533 | 7001±2144 |
| Type IIa/IIx fiber CSA, µm2 | 7214±3139 | 5760±2795 | 6082±3124 | 5341±2396 |
| Type IIx fiber CSA, µm2 | 4694±2613 | 3792±2032 | 4375±2192 | 3257±1799 |
| CS activity, µmol/min/g protein | 63±37 | 54±22 | 52±24 | 56±21 |
| HADH activity, µmol/min/g protein | 22±9 | 19±7 | 19±7 | 19±6 |
| OXPHOS complex I subunit content, AU | 2.0 (1.2, 3.9) | 1.5 (0.8, 2.1) | 1.6 (1.0, 1.9) | 1.2 (0.3, 2.4) |
| OXPHOS complex II subunit content, AU | 2.8 (1.7, 4.3) | 2.2 (1.5, 3.6) | 2.3 (1.6, 2.5) | 2.2 (1.2, 4.2) |
| OXPHOS complex III subunit content, AU | 1.5 (0.7, 2.0) | 1.2 (0.8, 1.7) | 1.2 (0.9, 1.4) | 1.4 (0.7, 1.8) |
| OXPHOS complex IV subunit content, AU | 4.1 (2.8, 8.1) | 2.4 (1.1, 3.6)* | 2.9 (1.3, 4.1) | 1.9 (0.6, 3.3)* |
| OXPHOS complex V subunit content, AU | 0.7 (0.4, 1.1) | 0.5 (0.3, 0.7)* | 0.5 (0.3, 0.8) | 0.6 (0.3, 0.7) |
Values are expressed as mean±SD or median (25th percentile, 75th percentile). Abbreviations: CSA, cross-sectional area; CS, citrate synthase; HADH, 3-hydroxyacyl-CoA dehydrogenase; OXPHOS, oxidative phosphorylation; AU, arbitrary units. Significance of difference compared to controls: * p<0.05, ** p<0.01, *** p≤0.001.