Performing a threshold workout

Performing a threshold workout

For the past dozen years, my early season XTERRA calendar has always included courses with lots of twists and turns, but limited elevation gain or sustained climbing (think Alabama and Richmond).

The second half of the season shifts to mountainous courses with long sustained climbs on the bike and the run.  XTERRA Beaver Creek, the XTERRA USA Championship in Ogden, and the XTERRA World Championship in Maui all fit this mold.  Success in these events depends on your ability to climb continuously.  Specifically, your output relative to your body weight at anaerobic threshold is the discriminating factor.  The answer to increasing your performance is to raise your output (power, speed, VO2) at anaerobic threshold.

Threshold training is very demanding physically and psychologically.  Compared to VO2 max interval training (Performing an Interval Session), the interval lengths are much longer. Most athletes avoid this type of training even though a race demands it.  Few have the focus and attention span to suffer in the most effective way.

There was an interesting study that examined the physiological effects of different interval lengths.  There were three well-trained groups, each performing two quality sessions per week for 7 weeks.  The hard workout for group 1 was 4 x 4 min at maximal tolerable intensity.  Group 2 performed 4 x 8 min at maximal tolerable intensity.  Group 3 performed 4 x 16 min at maximal tolerable intensity.  As the interval length went up, naturally the average intensity was lower.  I would classify group 1 as VO2 max intervals, group 2 performed threshold Intervals, and group 3 performed tempo bouts.  This was by no means the perfect study, but the group that increased all physiological parameters of performance more than the others was group 2, which performed the 4 x 8 minutes.  To achieve the proper peripheral adaptations, the bouts need to be well paced, performed at a steady-state intensity very close to anaerobic threshold, and sustained for a period of time.  Rest and repeat as long as quality can be maintained.

How to perform a threshold workout
Let’s simplify.  Ideal interval lengths for threshold training should range from 6-12 minutes.  Recovery time between bouts should be about 50% of the work, so for an 8 minute effort, use 4 minutes for recovery.  Intensity for cycling should be right around your threshold power or around your 1-hour race intensity.  For runners you can use your 10k race intensity or slightly slower as a starting point.  Total volume of hard work should be 30-40 minutes.  So 5 x 6 minutes gets you to 30 minutes of total work, or 4 x 10 minutes puts you at 40 minutes.  The goal is repeatability so don’t confuse yourself with too much variation.  You want to be able to see if you can maintain the same power, or cover the same distance at a steady pace each time.  Remember that variety is for the weak minded:)

Make it specific
If you are lucky enough to live in the mountains, you can perform these intervals uphill, repeating the same climb each time to ensure the quality and recovering on the downhill.  I find I get more consistent power and heart rate if the climb is smooth and a steady grade.   On the CompuTrainer, you can block up your front wheel and use smaller gears at threshold power to simulate climbing.
For running you can either find a long hill or use the treadmill with incline.  For 10% grade try backing off the speed 2.5-3 mph from your flat running pace.  To be prepared for the speed of the downhills, you can perform some of the intervals at uphill and some flat.

Fine points

  • Typically I usually use slightly shorter interval lengths for running and less total volume compared to cycling.
  • It is important to evenly pace each effort to achieve a steady state.  If you use heart rate alone, allow it to ramp throughout each bout.
  • Try holding back a bit on your first effort, make a line in the dirt, and see if you can repeat or surpass the mark each time.
  • For advanced athletes you can try going beyond the 40-minute mark on the bike as long as power can be maintained.  Another advanced option is to perform 30-40 minutes of hard work on the bike, followed by 15-20 minutes of hard work running.
  • To make a measurable change, it works best to focus on threshold workouts for a block of training with 2 or 3 of these types of workouts per week.  Keep total minutes of threshold training under 20% of your total training volume.

Intuitively threshold training makes sense.  Essentially you are asking yourself to train at intensities similar to what you will experience in a race.  After a solid block of threshold training I find that even if threshold power does not increase much, I am able to sustain that power longer with less fade late in a race.  Threshold training has been my bread and butter for many years and I hope it works for you.

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Example:  Cycling workout 4 x 9 min at 100% threshold power.  Notice the steady ramp in heart rate as power stays the same.

Reference
Seiler, S. (2013). Adaptations to aerobic interval training: Interactive effects of exercise intensity and total work duration. Scand J Med Sci Sports, 23(1), 74-83.

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