Final answer:
If a single stimulus is applied to a muscle after complete relaxation from a previous twitch, the size of the second twitch curve on a myogram typically does not change significantly. However, if wave summation occurs due to overlapping twitches, the second curve would be larger.
Step-by-step explanation:
When a single stimulus is applied to a muscle, a curve representing a muscle twitch is observed, which consists of a latent period, a contraction phase, and a relaxation phase.
In a real-life scenario, if the same strength stimulus is applied to the muscle again post-complete relaxation, the size of the second curve typically would not be altered significantly. However, if the second stimulus is applied before the muscle has completely relaxed from the first twitch (during the relaxation phase), the phenomenon of wave summation may occur.
This results in a greater contraction for the second twitch because more Ca++ ions are released and available to activate additional sarcomeres while the muscle is still contracting from the first stimulus. The myogram, capturing these events, would show an increased peak on the second curve if wave summation occurs.