Time to go anaerobic

AE intervals can be some of the most difficult yet rewarding workouts you can do
Ah, the sweet pain of anaerobic endurance (AE) intervals. If you are a road or mountain cyclist beginning your Build phases you are entering a time when AE work will be among your most important workouts. While incredibly difficult and stressful, these workouts will provide some of the best preparation for your important races.

AE intervals stress the anaerobic glycolytic energy system, otherwise known as the lactic acid system. This system becomes the primary source of energy production when exercise intensity increases beyond the level that the aerobic system can handle. During these intense efforts many different reactions are going on inside the body. One of these reactions is the production of lactic acid. When more lactic acid begins to accumulate in the muscles (more is being produced than can be removed or resynthesized) you enter a state called lactic acidosis. By doing intervals that put the body into this state, several positive training adaptations can occur.

The most important training effect from these workouts is a higher power output at VO2 max. Another benefit may include an increased lactic acid tolerance (the ability to sustain a workload as lactic acid is accumulating).

Most of these workouts use incomplete recovery to help attain the desired training effect. This is when not all of the lactic acid has been cleared from the muscles before the next work interval is commenced. In general a work to rest ratio of 1:1 or less is used. With this in mind it is almost inevitable that the power output or pace sustained in each successive work interval will decrease. This is OK. Unlike some sprint workouts that call for you to desist when the power fades, for these workouts you should continue regardless of decreasing power or speed.

Anaerobic endurance workouts

Classic VO2 max intervals: Do 3-4 x 3-4 minutes building to heart rate zone 5b or sustained CP6 power. 3-minute recoveries. Do not stop the efforts if pace or power fades. These can be done on the flats, on various grade climbs or any combination. Do them on the terrain that challenges your limiters and that mimics your important races. Intervals on climbs can be done seated for some sessions and standing for others.

Attack the top: On a 6-8% hill that "tops out" do 4-5 x 1.5-3 minute efforts. Stay seated for the first part of the effort, then stand and attack all-out over the crest of the hill for the last 30 seconds. HR should reach zone 5c by the top. Power for the first part of the effort should be CP6, and whatever you can muster for the last 30 seconds. This is a great race-specific workout.

Hill attacks #1: On a 6-8% hill do 6-7 x 2 minutes building to the heart rate 5b zone. At 30, 60 and 90 seconds "attack" for 10 pedal strokes. Recover for 3 minutes between efforts. The attacks should be practiced both seated and standing. For those using power, the intervals should start at CP6. The attacks should be all-out.

Hill attacks #2: On a sustained 3-5% climb do 2-3 x 10-15 minutes in HR zone 4-5a or at CP30 power. Every 2 minutes "attack" for 20 pedal strokes. After each attack sit and allow yourself to recover only to HR zone 4 or CP30 power. Try to maintain a steady pace while not attacking. Attacks should be practiced both seated and standing. This workout should be done in a situation that you will likely see in one of your important races. It should enable you to follow surges or attacks on longer climbs or help you make the winning move yourself.

5 x 5km time trial efforts: Do 5 x 5km building to heart rate 5a-5b zone or sustain CP12 power. 5-minute recovery intervals. Flat course. Increase gear size for first 3 efforts. Use your time trial bike set-up. 85-100 rpm. While this workout definitely pushes the length of what is considered an AE workout, it is still mostly anaerobic and is very useful for riders working toward short TTs or power for breakaway efforts.

Hill anaerobic endurance + threshold: On a 4-6% hill do 4-5 x 3 minutes to heart rate 5b zone (CP6 power) with 3-minute recoveries between efforts. Stay seated on each. 60-70 rpm. Immediately following your last effort ride 20 minutes in the heart rate 4-5a zones (CP30 power) on a mostly flat course.

Descending intervals: Do 3 sets of 2, 1.5, 1, 0.5 minutes in the heart rate/effort 5b-c zones (CP6 power for all but the 30-second interval which is CP1 power). Each recovery is the same as the preceding interval. For example: 2 on, 2 off, 1.5 on, 1.5 off. Recover 3 minutes between sets. 100+ rpm.

These are just a few ideas for workouts that target this energy system. Before putting any of these workouts into your training schedule, it is advisable that you have developed a significant aerobic fitness base and have done some muscular endurance (lactate threshold) type training. All of the workouts listed above are very difficult and you will most likely need at least 48 hours of recovery after any of them before attempting another difficult workout. No more than two AE workouts per week should be attempted.

Some common mistakes when doing AE workouts are:

  • Going into the workout not fully recovered from the previous hard workout or race.
  • Starting the interval too hard and "blowing up" before the end of the effort.
  • Taking too long of a recovery interval. Remember: incomplete recovery.
  • Not going hard enough for the duration of the interval: They are supposed to hurt!
  • Giving up on the number of efforts if power or pace fades. Stick with it!
  • Remember that heart rate responds relatively slowly. Use perceived exertion along with HR or power to gauge your efforts.

Along with muscular endurance work, AE intervals can be some of the most difficult yet rewarding workouts you can do as a cyclist. The pain level during these workouts will be high, but the benefits will be great.


Andy Applegate heads a2 coaching and is an elite-level road, cyclo-cross and mountain bike racer. He is also a USA Cycling and Ultrafit-certified coach. He may be reached at aapplegate@ultrafit.com. For more information check out www.a2coaching.com.

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