At the end of this workout are you 'smoked'? If so, then these are 'anaerobic endurance' intervals. Some training plans suggest just starting these 6-8 weeks before your first "A race"

Some plans suggest you work on "muscular endurance" first with long fairly hard efforts = 10m plus - then 6-8 weeks prior add anaerobic endurance intervals. The two biggest abilities for MTB are said to be muscular and anaerobic endurance.

http://www.joefrielsblog.com/2011/01/build-period-overview.html

Is my interval training routine effective for mountain bike training?
I'm writing trying to build a calendar right from scratch. I'm using the function written by David Walsh (see link) and it's great. 
He does a query for each day's cell.
But, I'm afraid that when the script's gonna have to run 30 queries in each render, it's gonna be sloooow. 

So, I was trying to think in another logic, for example, make a big query from X date to Y date at the begining of the script and then, at each day, check if that particular day has an event in the previous query. But I have no idea of how to do this...
So, if anyone can help, please shout!

Thanks.
