I stayed on the elliptical machine 65 minutes ( i usually do 45 min) when i got off one of my eyes was blood shot red. what caused this redness?

Blood: You probably have a subconjunctival hemorrhage. This is a bleed from a vein in the conjunctiva which directs itself to the space between this transparent tissue and the white of the eye. It looks dramatic but is harmless and will absorb in 3-10 days. It is due to a weak place in a vein, subject to pressure like coughing, rubbing, sneezing, straining, etc.

Broken blood vessel: A sudden appearance of a red spot after heavy exertion is usually a broken blood vessel (vein). It is like a bruise.....Doesn't look to nice, but does not really cause any problems.