We here at ShrinkGeek are clearly not the only folks excited about the latest fitness game for the Nintendo Wii, EA SPORTS Active. Nintendo announced on Monday that the game sold more than 600,000 units in the first two weeks of being on the market.

With numbers like that it shouldn’t be much of a surprise to learn that Nintendo is already planning to roll out the first expansion for the game in time for the holiday shopping season.

The expansion will introduce several new elements to the game, including a heavy focus on core exercises (a feature I noted as being a glaring omission in the original product) and the addition of new warm up and cool down routines. Another new feature in the game will be the inclusion of new tropical locations as a backdrop for your daily exercise. While that may not seem like such an interesting feature at this point, I’m betting that if we continue to use the product regularly for the next six months we’ll be ready for a change of scenery.

I am, perhaps, most intrigued by the inclusion of new Six Week Challenge feature. The current 30 Day Challenge seems primarily designed for someone who is just getting into a workout routine to jump start their workout schedule, but this new challenge sounds like it is going to be perfect for those of us who will be looking to take our workouts with the game to the next level. With this new challenge users will check in with their virtual trainer every week to track calorie, weight and workout goals while slowly increasing the intensity of their workout over a six week period.

It is encouraging to see new content for EA SPORTS Active being announced so soon after the original release of the game. Repeating the same workouts over and over again gets tiresome very quickly, so the prospect of regular updates to keep the workouts interesting is yet another in what I see as along list of features that make EA SPORTS Active the most exciting and comprehensive console based personal trainer on the market today.