Muscle metabolites, during exercise standardized by muscle CSA and MVC, did not differ between non-hypoxaemic COPD patients and control subjects. MVC, CSA or both, are assumed to be closely related to muscle metabolism, as no difference in high energy phosphate metabolites was observed for COPD patients compared to control subjects when the load was standardized for MVC and CSA. This suggests that high energy metabolites are consumed to a similar extent in the same muscle volume in non-hypoxaemic COPD patients and control subjects.