Although simultaneous measurements of pulmonary oxygen uptake (VO2) and Phosphorus-31 magnetic resonance spectroscopy ((31)P MRS) is attractive to investigate muscular metabolism during exercise, the superconducting magnet requires the design of specific gas exchange analyser (GEA). Thus, this study aimed to assess the validity of a commercial GEA system (ZAN600) compatible with (31)P MRS measurements. Using nonmagnetic pneumotachograph and prolonged sampling line (from 2m, control condition, to 6.5m) did not alter the proper synchronisation between flow and gas concentration signals. Also, end-expiratory fraction of O2 (FETO2) and CO(2) (FETCO2), and finally the values of steady-state ventilation (V(E)), carbon dioxide production (VCO2) and VO2 kinetics during moderate knee-extension exercise were not significantly different between 2m and 6.5m conditions and between 6.5m condition inside and outside the magnet. These results showed that a prolonged sampling line used inside the superconducting magnet did not affect the accuracy of VO2 measurements of a commercial GEA system; the latter appears suitable for simultaneous measurements of VO2 and (31)P MRS.