I had a normal bowel movement this morning then ran on the elliptical for 75 min. towards the end of my workout i felt a sudden urge to poop & it was diarrhea. this happens after i run on the elliptical for a long time. is this normal? what is wrong?

I don't think you have any intestinal pathology. Vigorous exercise, with its release of adrenaline & other hormones are stimulating your intestinal tract with resultant urgent&loose BM's. For prevention of this reaction you could try taking an intestinal sedative like dicyclomine an hour before your workout. Your MD may be willing to give you a prescription.