Posted: 14/05/2016 at 10:39
Well on the treadmill you won't be making the same effort for the same pace on the road so that might explain it if it is a blood pressure issue. But also on the treadmill your horizon and surroundings are fixed. outside you will be making many subconscious adjustments to your balance based on your surroundings.
Mrs puffy has the heartrate of a fish and very low blood pressure. She will go dizzy on standing occasionally but has never got dizzy running even at the end of a long race.