More tension is developed during twitch summation than during a single twitch because the duration of elevated cytosolic Ca²⁺ concentration increases during summation, thus increasing the availability of cross-bridge binding sites.

Question

Quizplus · Accepted Answer

During twitch summation, the frequency of action potentials increases, leading to prolonged calcium release from the sarcoplasmic reticulum. This results in a longer duration of elevated cytosolic Ca²⁺ concentration, which increases the availability of cross-bridge binding sites. As a result, more cross-bridges can form, leading to increased muscle tension.

More Tension Is Developed During Twitch Summation Than During a Single