In Reply To:
Have people used these formulae for whole triathlons, not just swimming or running?
-Colin
Not as far as I'm aware.
Exponential formulas are the way to go as regards predicting performance based on results at a different distance, but you can't apply them across three different sports at the same time, all which require ratios raising to different powers due to the nature of the fluid you're moving through in the sport.
Those same factors also dictate that one should NOT be applying the same effort throughout a triathlon, but rather should be applying less than the mean effort during disciplines where you are constrained by a more viscous fluid (e.g. swimming), simply because the effort required to gain, say a minute, is a lot more than the effort that would be required to gain a minute later in a discipline where you're not constrained by the fluid (e.g. running, where power is almost proportional to speed).
Those are the rules I go by, I used to try to maintain the same effort throughout a triathlon, but now I realise that you can go faster on less total effort by goofing the swim, going steady on the bike, then running hard. I also try to negative split slightly within each discipline, which is also very effective but for different reasons.