As we know that running is an exercise. There are certain forms of exercise, such as lifting weights and running require straining and cause momentary spikes in your heart rate. Then the strain and increase in blood flow builds up pressure in your head, which causes blood vessels to expand, including those in your eyes. If the pressure is too great, the tiny blood vessels in your eye can burst and make the white part of your eye appear red. You should also know that the more strenuous the exercise is, the greater the amount of pressure that builds in your head. And it will make your eyes redder. For the treatment, after you have a rest, it will disappear, so you don't have to worry about it. Besides, you can also use eye drops to relieve from it. If you still feel bad, you should go and see a doctor so that you can make sure if there are other diseases in your eyes.