If you take a snapshot of your fitness at any given time, your body can produce a particular pace for a given energy cost, or intensity. Think of this as your speed spectrum, with lactate threshold as one limit. At this limit, if you are conditioned, you have some 60 to 90 minutes of top threshold speed.
If you are a relatively new athlete that has not yet reached your metabolic limits, you can use threshold workouts to move lactate threshold to a greater percentage of VO2 max; thereby improving the metabolic limit as well as speed at threshold. Experienced athletes that are already near their metabolic limit for improving lactate threshold use threshold workouts to improve speed at threshold.
In this column, I'd like to share a few of my favorite bike threshold workouts. Though the workouts can be strategically used in a number of training plans, they are particularly useful for Olympic distance triathletes and cyclists aiming to improve their 40k time trial ability.
For all the workouts listed below, be sure to include a good warm-up of at least 20 to 30 minutes and a cool down of at least 15 minutes.
Cruise IntervalsPart 1 1 of 7
On a mostly flat course or indoor trainer, do 5-7 x 3 minutes, allowing heart rate to rise into Zones 4 to 5a over the course of the interval. Take 1 minute of easy spinning in Zone 1 between work intervals to recover. For the work intervals, begin the first one at the low end Zone 4 and end your last interval at the high end of Zone 5a. This strategy keeps your average power output and speed high for the entire session.
Cruise IntervalsPart 2 2 of 7
Begin timing the work interval as soon as you increase your effort. It may take a while for heart rate to respond, and that's okay. It will also take a while for your heart rate to respond within the recovery time. Recovery time begins as soon as you reduce effort.
If you are using lactate threshold power for the session, you will notice your heart rate will begin relatively low and end higher for the same power output. This is known as heart rate creep.
Cruise IntervalsVariations 3 of 7
As you gain fitness over the course of several weeks, you can use the following variations:
4-7 x 4 minutes (1 minute recovery between each)
3-5 x 6 minutes (2 minutes recovery between each)
2-5 x 8 minutes (2 minutes recovery between each)
Select the number of intervals based on your fitness level, race goals and training plan.
I prefer to use broken intervals rather than a steady 20 minutes at threshold because I find athletes can produce higher average speeds and power outputs.
Criss-Cross ThresholdPart 1 4 of 7
Right after I've told you I prefer broken intervals, I'm going to give you a 20-minute threshold workout. After you've completed several broken interval sessions, this criss-cross session is nice because it works on mental toughness and pace control, as well as threshold speed.
Criss-Cross ThresholdPart 2 5 of 7
Do the session on a mostly flat or rolling course. After your warm-up, slowly increase heart rate to Zone 4. Once Zone 4 is attained, begin timing. Gradually build speed until the top of Zone 5a is achieved. Then, gradually reduce speed until the bottom of Zone 4 is achieved. The build and reduction time segments should take about two minutes. Continue the criss-cross from low Zone 4 to high Zone 5a for 20 minutes.
Improvement6 of 7
By including threshold workouts once per week at the right time in your training, and including the proper recovery, you should see an improvement in your 40K bike time trial speed.