A, fatigue protocols. All fatigue bouts were elicited with one tetanic contraction every second for 3 min. ‘×’ indicates the end of an experiment. FAT1 and FAT2 were elicited under control conditions (Con) or in the presence of 1 μm verapamil (Ver) added 30 min prior to and removed immediately after FAT1-Ver. B and C, tetanic force(B) and, unstimulated force (C) are expressed as a percentage of the pre-FAT1 tetanic force. Vertical bars represent the s.e.m. of 5 FDB bundles. *Tetanic force and unstimulated force significantly different from FAT1, ANOVA and LSD, P < 0.05.