Prolonged trabecula isometric stress duration. (A) The durations of isometric twitch “rise” (time from 5% rise to peak stress) and “fall” (time from peak stress to 95% relaxation) were quantified and presented as relations of active stress (relative to peak stress at L_o). (B) The rates of rise and fall of isometric twitch denote, respectively, the maximum slopes of the ascending (+dS/dt) and descending (−dS/dt) portions of the twitch, and are presented as relations of active stress (relative to peak stress at L_o). In both panels, the SEM for each relation is shown at peak active stress obtained at L_o. Control rat (solid lines), hypertrophic rat (broken lines), n = 12 trabeculae. The difference between regression lines was analyzed by the random coefficient model; *, P < 0.05. In the inset, data from an exemplar trabecula are shown, and fitted using linear regression.