Effect of the E258K cMyBP-C on twitch force production. (A and B) Absolute (A) and normalized (B) averaged force traces of KO adWT (blue line) and KO ad258 (red line). (C) F_Max produced. (D) Contraction time from electrical stimulus to F_Max (CT₁₀₀). (E) Relaxation RT₅₀. (F) Relaxation RT_50–90. Blue bars, KO adWT mECT; red bars, KO ad258 mECT. *, P < 0.05 vs. WT (Student’s t test; KO adWT n = 11, KO ad258 n = 13). Error bars indicate SEM.