Commonly used reference values underestimate oxygen uptake in healthy, 50‐year‐old Swedish women

Summary Cardiopulmonary exercise testing ( CPET ) is the gold standard among clinical exercise tests. It combines a conventional stress test with measurement of oxygen uptake ( V O 2 ) and CO 2 production. No validated Swedish reference values exist, and reference values in women are generally understudied. Moreover, the importance of achieved respiratory exchange ratio ( RER ) and the significance of breathing reserve ( BR ) at peak exercise in healthy individuals are poorly understood. We compared V O 2 at maximal load (peak V O 2 ) and anaerobic threshold ( V O 2@ AT ) in healthy Swedish individuals with commonly used reference values, taking gender into account. Further, we analysed maximal workload and peak V O 2 with regard to peak RER and BR . In all, 181 healthy, 50‐year‐old individuals (91 women) performed CPET . Peak V O 2 was best predicted using Jones et al . (100·5%). Furthermore, underestimation of peak V O 2 in women was found for all studied reference values ( P <0·001) and was largest for Hansen‐Wasserman: women had 115% of predicted peak V O 2 , while men had 103%. Peak V O 2 was similar in subjects with peak RER of 1–1·1 and RER  > 1·1 (2 328·7 versus 2 176·7 ml min −1 , P  = 0·11). Lower BR (≤30%) related to significantly higher peak V O 2 ( P <0·001). In conclusion, peak V O 2 was best predicted by Jones. All studied reference values underestimated oxygen uptake in women. No evidence for demanding RER  > 1·1 in healthy individuals was found. A lowered BR is probably a normal response to higher workloads in healthy individuals.