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:The measured torque (TQ) during isometric knee extension and plantar flexion were converted to muscle force (Fm) by the following equations (Kubo et al. 2007, 2009):
Fm ¼ k TQ MA 1
where k is the relative contribution of the physiological cross sectional area in each of vastus lateralis muscle…
Category: