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:Baseline VO2 max estimates using treadmill protocols are comparable to bike tests and
our results, and ranging from 26 ml/kg/min and 33.2 ml/kg/min (Cade, Fantry, Nabar, Shaw, & Keyser,
2003; MacArthur et al., 1993).
Category: