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·m162±50137±44104±32ns
 Protocol length min12±210±310±2ns
 Maximal % MVIC achieved58.5±1352.5±1550.0±10ns
 Total work performed J6328±25154911±22113368±13300.006#
 Start SpO2 %97±197±298±2ns
 End SpO2 %97±195±395±4ns
 End HR beats per min90±1292±9101±140.03#
 End dyspnoea1.6±11.5±13.3±10.005#
 End leg fatigue4±23±13.5± 1ns
Elbow-flexor loading
 Peak torque N·m60±1957±1840±18ns
 Protocol length min10.5±18.8±27.2±20.0003
 Maximal % MVIC achieved52.3±744.1±1136.2±10ns
 Total work performed J3003±12122514±9111446±8110.001
 Start SpO2 %97±297±298±2ns
 End SpO2 %97±196±297±2ns
 End HR beats per min85±1188±894±11ns
 End dyspnoea1.5±11.5±13.2±10.01
 End arm fatigue4±22.5±23.5±1ns

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.