TY - JOUR T1 - What the 4-metre gait speed measures and why it cannot replace functional capacity tests JF - European Respiratory Journal JO - Eur Respir J SP - 1819 LP - 1820 DO - 10.1183/09031936.00207913 VL - 43 IS - 6 AU - Matteo Cesari AU - Simone Scarlata Y1 - 2014/06/01 UR - http://erj.ersjournals.com/content/43/6/1819.abstract N2 - To the Editor:In a recent issue of the European Respiratory Journal, Kon et al. [1] explored the responsiveness of the 4-m gait speed (4MGS) test to pulmonary rehabilitation and provided its longitudinal modifications in a sample of chronic obstructive pulmonary disease (COPD) patients. That article may be considered complementary to a previous one published by the same group of authors a few months ago, in which the reliability and validity of the physical performance test were determined in older persons referred to an outpatient respiratory clinic [2]. Consistent with previous evidence from different medical specialties and settings [3], the 4MGS was confirmed to be a robust, clinically friendly instrument capable of improving the patient’s assessment and monitoring over time. We strongly believe that both studies by Kon and co-workers [1, 2] are extremely interesting and meritorious for proposing the widely studied 4MGS test in the field of respiratory medicine. Nevertheless, in both contributions, the authors tend to present the 4MGS … ER -