Figures
- FIGURE 1
End-exercise (task failure) muscle oxygen saturation (SmO2) over total workload (n=36). a) Knee-extensor loading (KEL); b) elbow-flexor loading (EFL). ILD: interstitial lung disease.
- FIGURE 2
Change in a) muscle oxygen saturation (SmO2), b) oxygenated haemoglobin (O2Hb), c) deoxygenated haemoglobin (HHb) and d) haemoglobin difference (Hb-diff) during incremental knee-extensor limb loading. ILD: interstitial lung disease. *: p≤0.05 for healthy subjects; #: p≤0.05 for severe ILD.
- FIGURE 3
Change in a) muscle oxygen saturation (SmO2), b) oxygenated haemoglobin (O2Hb), c) deoxygenated haemoglobin (HHb) and d) haemoglobin difference (Hb-diff) during incremental elbow-flexor limb loading. ILD: interstitial lung disease. *: p≤0.05 for healthy subjects; #: p≤0.05 for mild ILD; ¶: p≤0.05 for severe ILD.
- FIGURE 4
Change in total haemoglobin (tHb), an estimate of regional blood volume during incremental limb loading. a) Knee-extensor loading; b) elbow-flexor loading. ILD: interstitial lung disease. *: p≤0.05 for healthy subjects; #: p≤0.05 for mild ILD.
- FIGURE 5
Relationship between muscle oxygen saturation (SmO2) and arterial oxygen saturation measured by pulse oximetry (SpO2) at task failure following incremental limb loading. a) Knee-extensor loading (KEL); b) elbow-flexor loading (EFL). ILD: interstitial lung disease.
Tables
- TABLE 1
Participant characteristics (n=36)
Healthy Mild ILD Severe ILD Participants n 13 10 13 Males/females (% females) 8/5 (38.5%) 6/4 (40%) 8/5 (38.5%) Age years 60±9 60±9 65±5 BMI kg·m−2 25±3 27±4 26±3 FVC % predicted 101±14 81±17 59±20* DLCO % predicted 69 ±14 48 ±15* 6MWD m 558±107 397±71* 6MWD % predicted 83±15 62±13* Hb g·L−1 148±11 136±19 Hct L·L−1 0.43±0.02 0.41±0.05 Estimated FIO2 0.45±0.1# Diagnosis IPF 3 4 NSIP 1 3 IPF/COPD 2 DIP 1 COP 1 NYD 1 1 Hypersensitivity pneumonia 2 LAM 1 Sjogren's 2 RA-ILD 1 Data are presented as mean±sd unless otherwise stated. ILD: interstitial lung disease; BMI: body mass index; FVC: forced vital capacity; DLCO: diffusing capacity of the lung for carbon monoxide; 6MWD: 6-min walking distance; Hb: haemoglobin; Hct: haematocrit; FIO2: inspiratory oxygen fraction; IPF: idiopathic pulmonary fibrosis; NSIP: nonspecific interstitial pneumonia; DIP: desquamative interstitial pneumonia; COP: cryptogenic organising pneumonia; NYD: not yet diagnosed; LAM: lymphangioleiomyomatosis; RA: rheumatoid arthritis. #: during testing, determined from [7]; nasal cannulae regular 3–4 L·min−1 (n=5), nasal cannulae high flow 6–15 L·min−1 (n=5), Oxymizer 4–10 L·min−1 (n=3). *: p≤0.05 for differences between groups.
- TABLE 2
Incremental limb-loading characteristics (n=36)
Healthy (n=13) Mild ILD (n=10) Severe ILD (n=13) p-value Knee-extensor loading Peak torque N·m 162±50 137±44 104±32 ns Protocol length min 12±2 10±3 10±2 ns Maximal % MVIC achieved 58.5±13 52.5±15 50.0±10 ns Total work performed J 6328±2515 4911±2211 3368±1330 0.006# Start SpO2 % 97±1 97±2 98±2 ns End SpO2 % 97±1 95±3 95±4 ns End HR beats per min 90±12 92±9 101±14 0.03# End dyspnoea 1.6±1 1.5±1 3.3±1 0.005# End leg fatigue 4±2 3±1 3.5± 1 ns Elbow-flexor loading Peak torque N·m 60±19 57±18 40±18 ns Protocol length min 10.5±1 8.8±2 7.2±2 0.0003¶ Maximal % MVIC achieved 52.3±7 44.1±11 36.2±10 ns Total work performed J 3003±1212 2514±911 1446±811 0.001¶ Start SpO2 % 97±2 97±2 98±2 ns End SpO2 % 97±1 96±2 97±2 ns End HR beats per min 85±11 88±8 94±11 ns End dyspnoea 1.5±1 1.5±1 3.2±1 0.01¶ End arm fatigue 4±2 2.5±2 3.5±1 ns Data are presented as mean±sd unless otherwise stated. ILD: interstitial lung disease; MVIC: maximal voluntary isometric contraction; SpO2: arterial oxygen saturation measured by pulse oximetry; HR: heart rate; ns: not significant. #: knee-extensor loading: the healthy group had a higher total work than the mild and severe ILD groups; the severe ILD group had a higher end HR and Borg dyspnoea score than the healthy and mild ILD groups. ¶: elbow-flexor loading: the severe ILD group had a lower protocol length and total work than the mild ILD and healthy groups, and a higher end Borg dyspnoea score.
