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:Pre- and post-test1 both included measurements of the S-reflex, M-wave, and H-reflex, followed by an MVC. S-reflex testing was performed at 0 , as in the study by Avela et al. (1999).
Category: