It looks like Suunto has revamped their math a bit according to their product Q&A page. Here is their response to someone questioning why they were seeing a 25% reduction in PTE and burned Calories in the Ambit vs. the T3.
"The differences are due to different algorithms. The Suunto Ambit uses an updated algorithm compared to the t3 to calculate the results."
I think for the formula Suunto is using to be accurate it is dependent on accurate MaxHR and Activity Levels settings. I think that is what they are using along with Weight and Heart Rate to calculate the VO2 and Energy numbers. (Compare by overlay the ‘VO2’ and ‘Energy’ graphs on Movescount… same graph different numbers)
I’m not so sure the other programs I’ve used in the past use Activity Levels (a way to determine approx. VO2Max #) and I’m pretty sure if they used MaxHR it was derived by the old ‘220 – Age’ formula, which is crap for a lot of folks me including. So I think we may have been conditioned to expect bigger numbers by lumping folks together in big buckets. So maybe a swing of 40% is not out of line when people are group as such.
Their numbers did and do look suspect, but I can’t say that they are wrong because I just don’t know. I can only make comparisons at this point. I'm certainly not an expert so...
Anyway, the ‘Activity Level’, is just their way of getting a MET value and for a A.L. of 7 I believe they use 12.7 METs in their formula (as seen on the same page you set the slider on) or 44.45 VO2Max [MET= VO2max (ml/kg/min)/3.5].
So what this tells me is, if you know your VO2Max or MET number, bump the Activity Level indicator up or down to match your number and not worry with their definitions, and you might be closer to actual. Their Activity Level definitions are there because most people do not know what a MET or VO2Max is.
Of course all this depends on their mathematical model being correct too. I was just hoping that someone in the know could shed some light on this so we could feel a little better about grabbing that 2nd or 3rd beer!!!