Is there a primer that can cover up large pores?

I am concerned because it seems my pores have widened due to the hot weather and excessive sweating. They seem to have gotten noticeably larger recently. I am worried, though I am not sure if it is because my skin is being irritated while exercising. What is a good primer that can shrink pores? I would be grateful to try any recommendations. It seems that shrinking pores becomes difficult as skin loses elasticity with age.