Interval Training Question
First, what's the real difference between doing "natural intervals" & repeat intervals other than being able to see if you are fatiguing too much if you see yourself slowing down? Like, the difference between doing 5K that has 3 nice hills that all take about 3 min. each, verses going up & down the same hill that takes about 3 min.
Second, how should one decide between doing 9, 1 min. intervals, verses 3, 3 min. intervals, or some other combination? And, let's say my questions have to do mainly with a casual master trainer - who doesn't follow a strict schedule like a college athlete might, but one who has a rough plan to do intervals 1-2 times per week for 45-60 min.
From intervals in Ironwood, MI
I don't think that there really isn't too much difference between doing intervals naturally vs. in a specific location. The team I coach (CXC Team) sort of does a mix of these two approaches. For some sessions, we use a specific section of trail just because it lends itself well to the workout (e.g., hill bounding on Telemark Resort's alpine hill), and others through varied terrain because ... well, because doing the same section is a) boring and b) doesn't force you to change make the technique and pacing you need to practice for racing.
For "a casual master trainer," if you are talking doing "natural intervals" (keeping a steady pace despite terrain), I don't think it's a big deal. When we have athletes who are tracking training loads and working on certain intensities/speeds, it's nice to break things down to specifics. Ultimately, if you're getting appropriate intensity accomplished and enjoying yourself, that's what's important.
Your second question lends itself to the first. We meet with athletes and try to figure out where they need to improve the most, and build training from there.* If someone can hang with the group for the majority of the race but consistently gets out-kicked, we work more on speed (so maybe those 9 X 1 min. @ L4-5 with 3-4 min. recovery). If general racing fitness is looking pretty good, 5 X 3 min. @ L4 with 3 min. recovery is a fairly common workout. In general, you need to figure that the more intense the workout, the less the total time "on"
needs to be. My rule of thumb is that 20-40 min. of L3 will elicit a training response, as will 10-20 min. of L4, as will 2-4 min. of L5.
We will do more than that from time to time, but generally, this is enough. How you break that total time depends on what you need to improve on. For example:
+ 8 X 5 min. @ L3 if you have trouble starting races too fast and
blowing up vs. 2 X 20 min. @ L3 if you need to work on being comfortable skiing fast
+ 5 X 3 min. @ L4/15km pace as a mid-week workout in race season if
you are racing well and want to keep the system primed vs. 10 X 1:30 @ L4/5km pace if you are trying to generate more speed endurance
+ 6 X 30 sec. @ L5 pace with 1 min. recovery if you are working on finishing speed and lactate tolerance vs. 12 X 15 sec. @ L5 pace scattered throughout an OD session with complete recovery for general speed development;
*Note: We're talking about structured intensity here, but sometimes skiers -- especially juniors -- need to learn how to ski and build a base before getting too focused.
Hope that helps
Jason Cork- CXC Team more at more or comment here