Fig. (5).

At an average cycle rate of 125 ms (8 Hz), a variation in inter-beat duration of 40% was applied. The correlation between the developed calcium transient and peak active force development (Fdev) is shown in panel A (R² = 0.57, p=0.03) . Panel B demonstrates the positive correlation between the variations in cycle length and the developed calcium transients (R² = 0.72, p=0.0006). In panel C, the top and bottom panel show the resulting intracellular calcium transients and twitch contractions respectively. The variation in inter-beat duration is associated with variations in the calcium transients.