Evaluate the collective function of references cited together in a given text segment.
Classify their combined role into one of the following categories: 'method', 'background', or 'result'.

Text:…characterized by a mono-exponential function following steady-state exercise at “moderate” and “heavy” exercise intensities (Ozyener et al. 2001; rossiter et al. 2002). the starting point of the curve was made to equal the average VO2 over the final 3 min of exercise to minimize the…
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