Because an old injury broke up I did not finish Ironman Frankfurt on Sunday.
I had to quit after 20 km on the run.
I ran the 20 km in about 9:30 min/mile instead of the planned and realistic 8:00-8:30 min/miles (realistic pace for my current fitness based on my experience of 12 Ironman finishes, including 3:30 IM run times)
The bike was not very hard neither.

Can anybody please explain to me why my leg muscles are so sore after the race?

Was it the heat (100+ degrees)?
Too less fluids?
Too less carbohydrates?
Not enough volume during the preparation (only easy running because of injury and not more than 35 miles/week)?
No long transition runs in preparation?

I was always sore after I finished an IM but I dedicated that to the full marathon..but after slow 20 km..I have no clue.

All ideas are very welcome.

Andy