Controlled L4 - PeRformance Vo2

In the NTS training plans we use the term CONTROLLED to describe a specific desired intensity. Controlled L4 intervals are also somtimes refered to as L4B. This pace should feel challenging but managable, 2-3 heart beats above lactic threshold. 

It is a common misconception that the harder we do our L4 intervals the better. New science however indicates that athletes are unlikely to see substantial gains in Vo2max from interval training, but we can see gains in Performance Vo2. 

Here's the difference: An athlete might have a massive Vo2max but because of technique or efficiency limitations they might not come close to accessing their aerobic capacity during a ski race. Performance Vo2 is a more realistic measurement of how fit a skier is while moving at their race pace. (in the case we are generally talking about 10-50km ski races) 

There is still a need for maximal L4 interval training at times, but what tends to happen is the interval quality diminishes greatly as fatigue and lactic acid in the muscles prevents quality skiing. This is where L4B fits in. We want to ski at a pace that is above L3 (lactate threshold) but not so hard that our muscles flood with lactic acid. This will allow for a session where skiers can log more L4 on-time than if the pace were maximal. More on-time = more opportunity to improve performance Vo2. 

L4 is typically categorized as 90% - 96% of max heart rate. L4B breaks things down even further and really focuses on the 90% - 92% range (or the 5-7 mmol of lactic acid range). This is an effective training model because by isolating the very bottom of our L4 heart rate zone we are able to do sessions with slightly longer intervals and potentially MORE of them.

Terrain: Rolling but with plenty of climbing 

5 minutes L2

5 minutes easy with accelerations

3 min L3

5 minutes dynamic stretching 

(can also use morning mechanics skate or classic as part of your warm-up routine) 

3 x 4 min w/ 3 min rec. 

Elite atheltges logging more interval time can increase reps. 5 x 4 min, or we recommend 2 sets of 3 x 4 min w/ 3 min rec. 10 min set break. 

Having a good feeling of where your lactate threshold is will make finding your L4 B pace a bit easier. If you don’t have a heart rate monitor, no stress. I like to focus on easing into each interval so my heart rate elevates naturally to threshold during the first minute. Once at threshold I increase the pace just a touch to bump my heart rate up a few beats. It’s not an all out race-pace, but comfortable and fast. Easy enough to maintain for the next 4 minutes of each interval. 

For most individuals a good L4B pace is just 2-3 heart beats above their L3 pace

Log more L4 on-time than an all our hammer L4 session. Logging 20 – 30 minutes of L4B can have a big impact increasing performance Vo2 and efficiency at race pace. 

Lactic acid goal: 4-7 mmol