well, not sure if it was just because of riding but I never had a labor longer than 20 minutes and my shortest was one single contraction - almost had that one on the floor! I kid you not…when my old OB retired he sent me my medical records and in HUGE red letters it said “precipitous labors” across the top page.
I have the same problem, but I thought it was just “fat thighs”. Much better to be able to claim it is a muscle.