Clinical characteristics of study subjects
| Controls (n=14) | COPD (n=31) | Significance (p value) | |
| Sex (F:M) | 6:8 | 11:21 | |
| Age | 68±8 | 65±7 | 0.192 (T) |
| Height (cm) | 171±8 | 169±9 | >0.5 (T) |
| Weight (kg) | 79.8±18.4 | 70.9±16.5 | 0.114 (T) |
| BMI (kg/m2) | 26.9±4.5 | 24.5±4.7 | 0.109 (T) |
| FFMI (kg/m2) | 17.8±2.3 | 15.7±2.2 | 0.006 (T) |
| Pack-years* | 4.1 (0–10) | 45 (34–69) | <0.001 (MW) |
| FEV1 (% pred)* | 110 (103.6–112.6) | 32 (25.1–47.1) | <0.001 (MW) |
| RV/TLC (%) | 37.1±4.7 | 58.6±9.9 | <0.001 (T) |
| Tlco (% pred)* | 86 (82.5–91.8) | 33 (26.2–52.2) | <0.001 (MW) |
| Paco2 (kPa)* | 5.33 (4.80–5.42) | 5.18 (4.96–5.74) | >0.5 (MW) |
| Pao2 (kPa) | 10.37±1.55 | 9.25±1.34 | 0.017 (T) |
| 6MW (m) | 623±89 | 378±134 | <0.001 (T) |
| 6MW (% pred) | 125±15 | 72±24 | <0.001 (T) |
| Locomotion time (min/12 h)* | 86 (61–122) | 45.5 (23–81) | 0.006 (MW) |
| Mt (%)* | 20.6±7.2 | 15.7±6.2 | 0.03 (T) |
| MI (m/s2)* | 2.1 (1.7–2.4) | 1.6 (1.4–2.0) | 0.017 (MW) |
| SGRQ* | 5 (1–8) | 52 (41–61) | <0.001 (MW) |
| Best MVC | 36.84±7.78 | 29.21±9.11 | 0.009 (T) |
| Best TwQ | 9.58±3.04 | 7.89±2.41 | 0.077 (T) |
| MVC/BMI | 1.4±0.3 | 1.2±0.3 | 0.075 (T) |
| Quadriceps endurance T80(s)* | 110 (70–160) | 80 (60–105) | 0.121 (MW) |
| MHCI mRNA (AU)* | 28.0 (19.2–39.9) | 7.0 (4.8–14.0) | <0.001 (MW) |
| MHCIIA mRNA (AU)* | 1.5 (0.8–2.2) | 2.6 (1.3–3.6) | 0.105 (MW |
| Type I CSA (μm2) | 5786±1371 | 4909±1327 | 0.048 (T) |
| Type IIA CSA (μm2)* | 4593.5 (2946−6105) | 3784 (2964−4615) | 0.141 (MW) |
| Type IIX CSA (μm2) | 6187±1868 | 3231±1403 | <0.001 (T) |
| % Type I fibres* | 52 (39–62) | 25 (17–30) | <0.001 (MW) |
| % Type I/II fibres* | 1.5 (0–3) | 3 (0–11) | 0.088 (MW) |
| % Type II fibres | 47±14 | 69±15 | <0.001 (T) |
| % Type IIA fibres | 44±13 | 60±15 | 0.002 (T) |
| % Type IIX fibres* | 2.6 (0–4.0) | 8.9 (3.0–13.0) | 0.006 (MW) |
Values are mean±SEM for normally distributed data or median (IQR) for non-normally distributed data.
p values were calculated by t test (normally distributed data), indicated by (T), or the Mann–Whitney test (non-normally distributed data), indicated by (MW), and are shown in bold when p<0.05.
MHC RNAs were determined by qPCR and normalised to the expression of RPLPO in the same samples as described in the online supplement.
↵* Not normally distributed.
BMI, body mass index; CSA, cross-sectional area; FFMI, fat-free mass index; FEV1, forced expiratory volume in 1 s; MVC, maximal voluntary contraction; MI, movement intensity; Mt, movement time; Pao2, arterial oxygen tension; Paco2, arterial carbon dioxide tension; pred, predicted; RV, residual volume; TLC, total lung capacity; Tlco, transfer factor of the lung for carbon monoxide; TwQ, twitch force in the quadriceps.