Fig. 1

Change of relative tetanic force during contraction protocols. Force normalized to initial (100%) denotes the average of first and last 5 contractions of sets 1, 5, and 10 from 0.2-ms pulse duration condition (closed circles) and 4-ms pulse duration condition (open circles). Values are means ± SE (0.2 ms: n = 5; 4 ms: n = 4). Significance compared with initial value for each condition: *P < 0.01