Justin Freeman is a US Olympian in cross-country skiing. He races for the Saab Salomon Factory Team – http://www.enjoywinter.com This article first appeared in Ski Post – http://www.skipost.com
Level five, which I wrote about in my last article, is about improving race performance by working at a higher pace. Level three, which improves racing by working at a lower pace, is the natural complement to this training. Physiologically, the major goal of level three training is to improve lactate threshold.
Your lactate threshold is the point at which lactic acid starts rapidly accumulating in your muscles. If you can do a treadmill test and plot speed versus lactate, your threshold is the point where the curve suddenly becomes steeper – the graph’s inflection point. Improvement in lactate threshold can take several forms. You can increase the speed at which lactic acid starts to build, or you can increase the heart rate at which lactic acid starts to build. These improvements could either increase or decrease the concentration of lactic acid in your blood at the inflection point.
I explain the various effects training can have on our lactate curve to emphasize that a little knowledge can be a dangerous thing. Just assuming that your lactate threshold occurs at, say, 85% of max heart rate, or at a lactate concentration of 4 mmol/liter, can lead you to train too hard or too easy. This doesn’t mean that using heart rate monitors or lactate monitors is a bad idea, but it should remind you that information from external monitors is only so useful. Finding level three means combining this information with your own perceptions of how hard you are going.
When describing level five I tried to avoid the word interval. With level three, talking about intervals is completely inappropriate. One of the most annoying and contradictory phrases people use to talk about training is “level three intervals.” Level three is a pace that you can maintain for 30 to 50 km; aiming for such a pace for only a minute or two at a time will inevitably lead you to go too hard, and in the event that you avoid this pitfall you likely won’t get much benefit. Level three is also not something to be done when coming off of a cold: you are either healthy enough to train hard, say 30 minutes level three or 4 by 5 minutes level four, or you should stick to easy distance with a few unstructured pick-ups.

