Table 2– Clinical characteristics of chronic obstructive pulmonary disease patients stratified by upper and lower quartile of percentage intramuscular fat.
| Lower quartile | Upper quartile | p-value | |
| Subjects | 25 | 25 | |
| Males/females | 17/8 | 15/10 | 0.38 |
| Age years | 63.4±7.3 | 66.4±6.3 | 0.14 |
| Height cm | 169±8 | 168.2±8.7 | 0.60 |
| Weight kg | 63.9±15.2 | 75.9±15.5 | 0.01 |
| Body mass index kg·m−2 | 22.0±4.2 | 26.7±5.2 | 0.001 |
| Fat mass kg | 16.1±6.4 | 26.0±9.5 | 0.001 |
| Fat-free mass kg | 47.7±10.5 | 49.8±8.0 | 0.43 |
| Fat-free mass index kg·m−2 | 16.7±2.6 | 17.1±2.6 | 0.61 |
| Smoking pack-years | 49±19 | 57±29 | 0.32 |
| FEV1 L | 1.16±0.62 | 0.98±0.43 | 0.25 |
| FEV1 % predicted | 42±21 | 37±15 | 0.42 |
| VC L | 3.37±0.84 | 2.83±0.85 | 0.03 |
| VC % predicted | 94±18 | 85±17 | 0.08 |
| FEV1/VC | 32.6±13.4 | 35.2±11.8 | 0.49 |
| TLC L | 7.98±1.5 | 6.97±1.73 | 0.04 |
| TLC % predicted | 129±14 | 116±16 | 0.005 |
| RV L | 4.54±1.25 | 4.09±1.17 | 0.21 |
| RV % predicted | 201±58 | 179±42 | 0.14 |
| RV/TLC | 52±15 | 59±7 | 0.08 |
| TLCO L | 3.66±1.72 | 2.98±1.49 | 0.18 |
| TLCO % predicted | 42±18 | 37±18 | 0.35 |
| PCO2 kPa | 5.21±0.43 | 5.27±0.92 | 0.76 |
| PO2 kPa | 10.25±1.38 | 9.11±1.72 | 0.02 |
| GOLD stage I/II/III/IV | 1/7/6/11 | 0/5/13/7 | 0.19 |
| GOLD grade A/B/C/D | 2/2/3/18 | 1/0/2/17 | 0.27 |
| Exacerbations in the past year | 1 (0–2) | 1 (0–2) | 0.45 |
| Medication n (%) | |||
| Long-acting β-agonist | 21 (84) | 22 (88) | 0.46 |
| Inhaled corticosteroid | 21 (84) | 22 (88) | 0.20 |
| Oral steroid >5 mg·day−1 | 3 (12) | 2 (8) | 0.50 |
| Oxygen | 4 (16) | 8 (32) | 0.16 |
| Nocturnal NIV | 0 (0) | 4 (16) | 0.03 |
| SGRQ | 47.2±21.2 | 56.5±13.5 | 0.09 |
| QMVC kg | 25.4±8.2 | 26.1±7.6 | 0.76 |
| Quadriceps twitch force kg | 10.3±3.0 | 9.0±2.7 | 0.21 |
| Body composition (both thighs) | |||
| MTCSA cm2 | 190.9±49.2 | 188.2±50.4 | 0.85 |
| Lean tissue cross-sectional area cm2 | 185.0±48.4 | 167.1±45.0 | 0.19 |
| Lean tissue HU | 44.9±4.7 | 37.6±4.9 | <0.001 |
| Intramuscular fat cm2 | 5.8±2.1 | 21.1±7.1 | <0.001 |
| Intramuscular fat % | 2.94±0.80 | 11.22±2.20 | <0.001 |
| Fibre type %# | |||
| I | 29.3±13.3 | 21.8±10.5 | 0.14 |
| IIa | 60.9±16.3 | 59.3±11.6 | 0.79 |
| IIx | 8.4±8.7 | 21.0±18.4 | 0.04 |
| II | 69.3±14.1 | 76.8±11.4 | 0.68 |
| Exercise capacity# | |||
| 6MWD m | 404±166 | 188±83 | 0.03 |
| ISWT m | 295±138 | 172±88 | 0.003 |
| Physical activity# | |||
| Wear time h per day | 23.7±0.4 | 23.7±0.3 | 0.87 |
| Wear time % | 98.7±1.6 | 98.8±1.1 | 0.81 |
| TEE kcal per day | 1961±412 | 1925±296 | 0.76 |
| Steps per day | 4632±3407 | 3073±2167 | 0.11 |
| PAL | 1.44±0.17 | 1.33±0.12 | 0.04 |
Data are presented as n, mean±sd or median (interquartile range), unless otherwise stated. FEV1: forced expiratory volume in 1 s; VC: vital capacity; TLC: total lung capacity; RV: residual volume; TLCO: transfer factor of the lung for carbon monoxide; PCO2: carbon dioxide tension; PO2: oxygen tension; GOLD: Global Initiative for Chronic Obstructive Lung Disease; NIV: noninvasive ventilation; SGRQ: St George’s respiratory questionnaire; QMVC: quadriceps maximum voluntary contraction; MTCSA: mid-thigh cross-sectional area; 6MWD: 6-min walking distance; ISWT: incremental shuttle walk test; TEE: total energy expenditure; PAL: physical activity level. #: comparison limited to n = 14 versus n = 11 for fibre type, n = 6 versus n = 5 for 6MWD and n = 19 versus n = 18 for ISWT and physical activity measures.