I experience this occasionally too (including today). I went for a quick 6k run, was fine for 1hr afterwards and then after having a cup of tea had the symptoms described here (blurry vision, squiggly lines, then headache) and can almost certainly say with me it is a combination of a hot workout with not enough water and/or too much tea/coffee. I will check out my blood pressure but I recommend keeping hydrated and keeping off the teas and coffees as a starter.
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Thomas Woods
