A, representative images of gastrocnemius muscle cross sections of WB, HS, RE and REM rats immunostained for dystrophin (green). Scale bar = 50 μm. B and C, quantification of muscle fibre CSA of gastrocnemius from WB (n = 8), HS (n = 7), RE (n = 8) and REM (n = 8) rats (B), and frequency distribution of CSA in RE (n = 8) and REM (n = 8) rats only (C). Values are means ± SEM. One‐way ANOVA followed by Tukey's post hoc test was used to determine statistical significance: *different from WB, †different from HS, ‡difference from RE, P < 0.05.