Tapering for important competitions is both an art and a science. There has been much research in the last 5 years on this subject and some applicable information has begun to emerge.
Before we begin a discussion about the most effective ways to taper, let's get a few ground rules on the record:
1) It is possible to taper for only two (or with exceptional planning, three) events per competition season. This is not something you do for each race on your calender (although a rest day 2 days pre-race can be helpful). Save your tapers for the big ones, whether those are the Birkie, the Boulder Mountain Tour, Masters Nationals or World Cup Finals.
2) Tapering is very individual. The findings sited below are general. Only by trying different types and durations of taper will you discover the method that works best for you.
3) Tapering is not the same as resting. You will continue to train during your taper, although the time spent training and the focus of that training will be quite different than your normal routine.
Tapering is effective.The most in-depth research in this field has been conducted by the Spaniard, Dr. Inigo Mujika. I've been lucky enough to see him speak at US Olympic Training Centers on several occasions. His book, Tapering and Peaking for Optimal Performance is a great resource. His findings with elite athletes from a broad range of sports has been that a well executed taper can yield performance increases of 3-5%, which, while it may not sound significant at first, could equate to an advantage of 3 minutes per hour of race time. In a race like the Birkie, depending on your pace, this can mean a difference of 12-20+ minutes and hundreds of places.
The essential considerations in a taper include duration of the taper, volume of training during the taper, distribution of training during the taper and type of training during the taper.
According to Mujika, the duration of an effective taper can be anywhere from 5-21 days. This depends on several athlete-specific parameters, including fast to slow twitch muscle ratio, length of event, general fitness level, etc. Without extensive testing, we usually use a 10-day taper, which has been shown to be effective in most people.
The volume of training during a taper is generally quite low. Again, research indicates a range of approaches for different athletes. Values anywhere from 10-40% of the hours one would normally train during a certain period have proven effective (ie. If you normally train an average of 15 hours over the course of 10 days, your 10-day taper could call for as little at 1.5 hours (10%) or as much as 6 hours (40%)). In lab studies and in my work in the field, the number that has proven most effective for the greatest number of people was a reduction to about 30% of your "average" training volume. This will feel like a big reduction! You may feel a little restless and be chomping at the bit to get out on a long ski, but don't do it! This heightened state of energy is precisely what we are looking for.
The distribution of training during this 10 day period is not flat. We are interested in creating a plan with what we call a "fast decay" of volume, meaning that the volume at the start of the taper (the first day or two) will be considerable higher than the volume during the last 3-4 days.
The type of training that we utilize during a taper is quite different than the type of training used at other times in our training cycle. About 50% of the workouts during this period should be quite intense. Generally, we try to do some type of speed or interval work every second day during a taper. As we move through a taper, the intensity sessions change from longer Lactate Threshold Intervals (Level 3) in the first few days to mid-length Anaerobic Threshold Intervals (Level 4) in the middle of the taper, then finally to Anaerobic Speed work (Level 5) in the last few pre-competition sessions. We increase the intensity of training during the taper because, in its' rested state, our body is more prepared to absorb this training. Intensity work is essential to sharpening up for a top performance.
Here's an example of how all this might come together: If your average training volume for a 10 day period is 20 hours, we would plan for a taper that allowed for 6 hours (30% of 20 hours) of training during the tapers' 10-day duration. We would then distribute the training using the "fast-decay" mentioned above, and plan intensity sessions accordingly, giving us something that looks like this:
Day 1: 70 minutes, including 3 x 12 min @ Lactate Threshold (LT)
Day 2: 60 minutes, easy ski
Day 3: 50 minutes, Including 3 x 7 min @ LT
Day 4: 40 minutes, easy ski
Day 5: 30 minutes, including 4 x 4 min @ Anaerobic Threshold (AT)
Day 6: 30 minutes, easy ski or jog
Day 7: OFF
Day 8: 30 minutes, including 2 x 3 min @ AT and 4 x 15 sec SPEED
Day 9: 25 minutes, easy ski or jog
Day 10: 25 minutes including 4 x 10 sec SPEED
(total of 360 minutes)
Day 11 - Race!
Again, the only way to find the tapering solution that works best for you is to experiment over a few seasons. The example above is just a combination of the taper types that have proven effective for the greatest percentage of test subjects.
Hope this helps, and best of luck out on the trails.