The myosin and actin fractionation methods were conducted, with slight modifications, as described by Roberts et al. (54 (link)). In brief, 20 mg of dorsal muscle tissue was dissected and immediately submerged in 500 µL of homogenization buffer (98% RIPA lysis extraction buffer (ThermoFisher #89900), 1% Halt protease/phosphatase inhibitor cocktail (Thermo Scientific #78442), 1% EDTA). The tissue was homogenized with triple pure M-Bio grade high-impact zirconium beads in a Beadbug 6 microtube homogenizer bead beater at 4,900 rpm for 60 s followed by gentle agitation at 4 °C for 60 min. The sample was centrifuged at 4 °C at 3,000 × g for 30 min. The supernatant (cytosolic fraction) was removed and frozen at −80 °C. The pellet was resuspended with 500 µL of homogenization buffer, centrifuged for 10 min at 3,000 × g, and the supernatant was removed followed by two additional washes. The remaining myofibrillar pellet was then immediately frozen and placed at −80 °C until further processing. Electrophoresis of the sarcoplasmic and myofibrillar fractions is detailed in SI Appendix, Supplementary Methods.