physical activity, faster FEV1 decline and worse prognosis [37, 38], which supports its clinical importance.
The 6MWT is more sensitive for identifying exercise-induced desaturation than cycle testing [39].
Measurements of SpO2 during the 6MWT are reliable [1], provided that an adequate pulse signal is obtained.
However, change in SpO2 may be more variable in people with systemic sclerosis-associated ILD (SSc-ILD)
than in other lung conditions (ICCs ranging 0.24–0.64 in SSc-ILD, compared to 0.80–0.97 in CF and
COPD) [1], perhaps due to cutaneous involvement in SSc-ILD. The 6MWT may be safe without
continuous monitoring of SpO2 [36]. However, constant monitoring of SpO2 during the 6MWT is needed to
obtain an accurate measure of exercise-induced desaturation, as the lowest SpO2 often does not occur at the
end of the test