The runners who ran slower than their personal best times are those with positive values in the "Time compared to personal best" column.
Let's analyze the times:
- Gregor: +5.6 (slower than personal best)
- Hiroki: -11.6 (faster than personal best)
- Isabelle: +3.2 (slower than personal best)
- Juan: 0 (equal to personal best)
- Karen: -5.2 (faster than personal best)
Based on this:
- Gregor and Isabelle ran slower than their personal best times.
So the correct answer is: Gregor and Isabelle.
However, this option is not provided. To clarify based on only the provided choices, the correct response would then be:
- Hiroki and Karen.
However, they actually ran faster than their personal bests and thus are not part of the answer regarding runners who ran slower.
There's some confusion here with the phrasing of responses available. The best conclusion from the information given is that Gregor and Isabelle are indeed the runners who ran slower in context, leading to an inconsistency in the answer choices provided.