Fiber typing followed the methods described in (69 (link)). Frozen muscle sections (10μm) of the gastrocnemius muscle were fixed in ice cold acetone for 5 minutes, rinsed in PBS, and then blocked in 1% bovine serum albumin and 10% fetal bovine serum in PBS for 1 hr. For fiber typing, sections were incubated with primary antibodies BA-F8 (1:10), SC-71 (1:30), and BF-F3 (1:10); all from Developmental Studies Hybridoma Bank, Iowa City, IA) overnight at 4°C. Sections were rinsed in PBS plus 1% bovine serum albumin and then incubated with secondary antibodies AlexaFluor350 anti-IgG2b, AlexaFluor488 anti-IgG1, and AlexaFluor594 anti-IgM (A21140, A21121, and 1010111, respectively; Life Technologies) (all used at 1:500) for 1 hr. Following secondary incubation, sections were again rinsed in PBS plus 1% bovine serum albumin. All primary and secondary antibodies were diluted in a 1% bovine serum albumin PBS solution. All steps were carried out at room temperature using room temperature reagents except where noted. All samples were fixed in ProLong® Gold Antifade Mountant (P36930; Thermo Fisher Scientific, Waltham, MA) and imaged on a Keyance microscope. Type 2B, Type 2A, and Type 1 fibers were quantified and expressed as the % of total myofibers per muscle section.