CLCN1 and Myotonia: Interestingly, despite the 3-minute rest interval, the myotonia in CaV1.1Δe29 ClC-1–/–, but not in ClC-1–/–, muscle demonstrated warm-up, showing a 42% decrease over successive stimulations (Figure 4F, red), without any corresponding drop in peak specific force (Supplemental Figure 8).