3. In General, Avoid "Middle of The Chart" Intensities.

This should not be taken too dogmatically. Sometimes the intensity climbs during a steady state workout as a function of the terrain, or getting chased by a dog! And even the top skiers say that sometimes it is a nice variation to pick up the pace just a bit on the long tours. However, the main point is important:

 "Train too hard on the easy days, and soon you will be training too easy on the hard days!"

Ok, after reading so far, two questions might be swirling about in your brain:

1. "If interval training is so important, why not do more?"

and

2. "Why not do more of the low intensity distance training at higher intensity, or in other words, what is wrong with the "pretty tough" medium intensity workout?" Whatever happened to "No Pain, No Gain?"

I think answering both requires not only a knowledge of muscle and heart physiology, but an understanding of the "whole athlete". Historically, many people have made the mistake of thinking of training one-dimensionally. By this I mean they only think of training as a means to induce the positive physiological changes that result in better performance. This type of thinking rapidly leads to the "more intensity is better" or, more precisely, "more intervals are better" mentality. In the lab, numerous sport scientists have designed short training studies with untrained subjects and demonstrated that those who train at higher intensity improve more in the short run. I have done it myself, having made rats run hard intervals 5 days a week before! Clearly, intensity is a critical determinant of the training response. BUT, pushing intensity too far, too often leads to big problems when we try to extrapolate to the long term development of the elite endurance athlete.

Training must be thought of "two-dimensionally." The first dimension is training as inducer of positive change. The second dimension is training as a stress that does cellular damage, alters brain chemistry, and disturbs hormone levels, negative consequences all in all. When we realize that the training sword cuts both ways, then the "magic" of ensuring the long term progress of the elite athlete can be understood as an exercise in maximizing the "Benefits to Risk ratio," both from week to week and over the long haul.

The answer to both "why not more interval sessions?" and "why so much low intensity steady state work?" is similar I think. I call it avoiding regression towards the mean. If we try to do hard/interval training (read: high lactate accumulation over many minutes) too frequently, we either break down completely or we end up performing many of the interval sessions at inadequate intensity. It can be either the head or the body that cracks, but the result is the same. If we instead try to turn up the intensity on those "long tour sessions," they become too stressful and too limited by glycogen availability, and we shorten them.

As a related point, one of the best ways to end up overtraining is to have too little variation in training intensity (coined "training monotony" in some nice research on speedskaters and cyclists by Dr. Carl Foster). Athletes can eventually handle high workloads if they successfully avoid letting all the workouts drift towards a middle of the road intensity.

Is this training structure unique to XC skiing?

I would have to say YES and NO right now. In general terms, I would say no. This philosophy of training is generally consistent with observations in rowing, cycling and running (though perhaps less so with running as it relates to the Kenyans). It looks very similar to the current pattern in international rowing. However, some might argue that the high volume of low intensity work is particularly evident in rowing and XC skiing. If that is true, I propose that these sports ARE unique in an important way. They require the simultaneous work of all four limbs. This is an exercise situation that humans have evolved away from. The human cardiovascular system was not designed to support the energy demands of quadrapedal movement. We just don't have the big pumps like sled dogs and race-horses. So, when the upper limbs are added to the mix, the sympathetic stress load is higher at any given absolute work load. This may mean that higher volumes of low intensity work are a better way to train the upper limbs and lower limbs simultaneously while avoiding overtraining. Another approach is to spend more time isolating the upper-body during endurance training. This is an issue I will discuss more in other articles!

A SUMMARY of the "UNIFIED FIELD THEORY" for XC ski endurance training.

1.  Build the the typical training week around 2 hard/high intensity training sessions.

2. Increase the total volume of training with primarily low intensity work at not more than 70-75% % or so of HR max. Don't view these long, low intensity sessions as valueless, and don't adopt a "harder must be better" approach!

3. Avoid a training condition in which each session begins to take on the same medium intensity.

Copyright Stephen Seiler