If men can keep up a faster pace for over 100 kms, then they can sustain exertion for more than long enough.
The paper someone else posted showed that women start to lose pace in a marathon later than men, but men start out so much faster, and over the course of an ultra-marathon men still keep up a faster pace the whole distance.
Given how insanely vast the universe is it is still a near statistical certainty their is currently other sapient life out there. The is also an extremely high chance that other sapient civilization lived and went extinct in many different parts of the universe already.