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.
Level three efforts should be continuous and should range from at least 30 minutes to about an hour. The pace, as I wrote above, is somewhere between 30 km and 50 km race pace, and is also the fastest pace you can sustain without feeling lactic acid start to accumulate in your muscles. Personally, I find it to be the most psychologically challenging pace to maintain; it is fast enough that you want to slow down, but at any point you also have the ability to sustain a significantly faster pace.
One way to ease yourself in to long level three sessions is to break them up. If it sounds like I am waffling about level three intervals, well, maybe I am. I find it useful, early in the season, to make only half of my level three sessions continuous efforts. The other days I use five or ten minute intervals with 20% (one or two minutes) recovery. The shorter blocks of going hard are much easier to manage psychologically, and the very short recovery prevents going too hard. I must emphasize that while I find this a very useful tool, I consider it as a crutch that helps an athlete transition to “real” level three training, which includes only longer unbroken efforts.
I would like to say a word about training modality and technique. Level five training, since it is primarily neuromuscular and therefore motion specific, is only effective if it is done in a skiing motion (skiing, rollerskiing, possibly bounding). Level three training can include running, and perhaps even cycling or other activities. But level three provides another opportunity to work on efficiency. You are moving close enough to race pace to really work on race technique, and you have plenty of time to try out new variations. Perhaps your climbing V-2 is weak; a level three session is the best time to push a V-2 farther up every hill than you want before switching to V-1 (on a level one day you might go too hard this way; on a level four day you are focused on skiing fast, not just skiing right).
Finally, as I suggested with level five training: go out there and do some level three. Level three efforts are a great way to satisfy that late spring urge to train fast. They also teach patience, practice the primary pace for master skiers who focus on marathons, and can help build efficient technique.