Why is a greater tension developed during tetanus than that during a single twitch?

A greater tension during tetanus compared to a single twitch is primarily due to the increased frequency of stimulation. In tetanus, rapid successive stimuli prevent the muscle from fully relaxing between contractions, leading to a cumulative effect of calcium ions in the muscle fibers that enhances contraction strength. This sustained release of calcium allows for a more prolonged interaction between actin and myosin filaments, resulting in stronger and more sustained muscle contractions. Thus, the overlapping contractions lead to a greater overall force than a single twitch can generate.