Peripheral vision

After doing twelve miles this morning my periperal vision went a bit hazy. I'd hydrated well but I'd possibly let my sugar levels drop.

Is this normal or am I about to die?


  • I would guess sugar levels. I have had this happen to me too, with a bit of light headedness thrown in too but am still here.
    What did you eat before going out?
  • You have probably experienced what is known as "blowing up" or in cycling circles "bonking".
    Carry a gel sachet with you and get it down your neck before you start to feel "iffy"
    I know the feeling well - it happened to me after about 11hrs in an Ironman event.
    Flat coke helps - instant sugar hit !
  • Thought i was the only one to suffer from this! Thank goodness for the forum. I usually find in the last mile of a race when i speed up, i have tunnel vision, then when i cross the line and come to a stop, i go dizzy. It takes about 10 minutes for me to return to normal. I usually have a good gulp of water, then sports drink or squash at the end of a race which presumably helps to sort it out. Having hubby handy on the finish line to keep me walking also helps to prevent me from standing still and keeling over.
  • Chief suspect has to be your blood sugar falling below your comfort zone as you suspect, Dragon Breath. The other possibility is a rapid fall in your blood pressure caused by the effort of running leading to complicated nervous system adjustments.

    If the former, top of my list of "how to avoid this in future" is to keep doing those long runs so that you become more efficient at using fat as fuel early before you run out of glycogen. Second from top is a good dinner and a carb-rich bedtime snack the night before the run and as much breakfast as you can cope with before running.
  • Thanks all. I'd had the pasta dinner the night before but I couldn't stomach the porridge in the morning (too early to eat). Had merely drunk tea and water before going out. Better try the old Lucozade Sport next Saturday morning.
  • Vrap, would a rapid fall in blood pressure also leads to numbness in the body (all of it) and mental confusion? This has happened to me twice whilst running now and despite numerous tests on my heart no one has found the cause yet. My blood sugar levels have been fine...
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