Isometric Ankle Dorsiflexion Torque Measurement

In vivo peak isometric torque of the ankle dorsiflexors was assessed as previously described (Baltgalvis, Call, Nikas, & Lowe, 2009 (link)). Briefly, anaesthesia was induced using an induction chamber and 5% isoflurane in oxygen. Anaesthesia was maintained using 1.5% isoflurane at an oxygen flow rate of 0.4 l min⁻¹. The left hindlimb was depilated and aseptically prepared and the foot placed in a foot-plate attached to a servomotor (Model 300C-LR; Aurora Scientific, Aurora, Ontario, Canada). Platinum–iridium needles (Model E2–12; Grass Technologies, West Warwick, RI, USA) were placed on either side of the left common peroneal nerve to elicit contraction of the dorsi-flexors muscles. Peak isometric torque was defined as the greatest torque measured by a 300B-LR servomotor (Aurora Scientific) during a 200 ms stimulation using 1 ms square-wave pulses at 300 Hz and increasing voltage from 3.0 to 9.0 V (models S48 and SIU5; Grass Technologies). All torque values were normalized by mouse body mass.