Interesting. Do you do much, if any, endurance exercise at sea-level (the kind that would regularly bring your heart rate to 150 or so)? Do you have any idea what your pulse was when you were starting to get light-headed?
Maybe I should get one of those pulse oximeters next time I get back into the Sierras. I want to see if I can day-hike Langley in 10 hours round trip. Is Old Army Pass snow-free already?
BTW, it's not widely known, but Diamox hinders your athletic performance. At the typical 250 mg 2x/day dosage it makes you 10-15% slower than if you were hiking without it.
