I think it is normal. I sometimes feel that my eyes are out of focus after doing some exercises, too. I think perhaps we have such symptom due to the change of the blood sugar levels. After doing exercises, we consume much calorie and our blood pressure alters, and our eyes cannot get enough energy to sustain their normal work. Also, the reason can be that the muscles which control eye movement are strained. As long as we have a rest, the eyes recover themselves again.
It is not normal reaction of doing exercises. Exercises might get your mind focus out, yet as to blurry vision, although it might be some simple and common eye condition, it might indicate certain healthy problem, which needs your immediate attention. Normally it is accompanied with dizziness, nausea, difficulty of concentration and breathing, and especially fatigue and thirst. The most common cause of blurry vision during or after exercises is low blood pressure, hypotension in medical term. I am suffering from hypotension so that I am easily tired, and sometimes I feel giddy and faint. Dehydration, allergy or nutrition deficiency might bring these uncomfortable feelings to you. People with pigmentary glaucoma might experience the blurred vision brought from exercises too. You can sit down to have a rest. Drink a cup of water slowly and take a small snack to relieve the symptom. If you have any allergic reaction, then get fresh air and be away from the allergens.
It is abnormal for your eyes not to be able to focus. Your eyes may get infection. The invisible bacterium may come into your eyes. You need to use the eye drops with anti-inflammation to make the eyes get clear and bright. In addition, you could also use the warm compress to make the eyes feel better.