Interval Training - How to Get the Most out of Suffering

The three main variables to consider when designing a training plan for yourself are frequency—the number of times you ride per week, duration—how long each ride lasts, and intensity—how fast you go. Many athletes have work and family responsibilities that largely dictate the frequency and duration components. This is “volume”—how many miles or hours you ride in a week. The hard part to figure out is the intensity component. What intensity should you ride to make the highest intensity workouts—intervals—contribute to making you a faster cyclist?

Everybody knows that simply training hard every day will lead to overtraining and burnout. Finding the right intensity for intervals is highly individual. When it comes to deciding how hard to ride, what works for one of your teammates may not necessarily be best for you. Appropriate training intensity also varies according to your goal race. Long distance athletes such as Ironman racers are not limited by VO2 and should focus on longer duration force and endurance type intervals for success. Olympic distance athletes need a high lactate threshold and VO2max. Sprint distance athletes are limited by VO2max and power.

The French Doctor Dr. Veronique Billat, a professor of Sport Sciences at the University of Lille in France, has researched various interval training methodologies to optimize VO2max training. She has produced some simple protocols and demonstrated improvements of three to six percent in elite athletes with only four weeks of training. While three to six percent may not seem like a lot to you, for an elite this represents a huge improvement. And if an elite rider can improve that much, what about the rest of us? “Carrying out excellent training is not hard to do,” says Billat. “You simply have to have reliable reference points around which to structure your workouts.”

Billat has shown that these reference points are your velocity at VO2max (vVO2max) and how long you can ride at VO2max velocity (tlimVO2max). See a Science Primer for definitions. VO2max, by itself, is a poor predictor of performance. Using vVO2max and tlimVO2max will provide a better indication of performance. This will also help you decide how hard and how long your intervals should be.

But let’s make sure you understand this point before going into this any further. It’s not how great your VO2max is, but how fast you can ride and how long you can last when at VO2max that are most important in building race fitness.

Why Intervals Many studies, including Billats’, have shown interval training produces greater fitness benefits than steady state training for sprint through olympic distance athletes. Billat found runners alternating 30 seconds at their vVO2max pace with 30 seconds at 50 percent of their vVO2max pace were able to accumulate three times the volume of VO2max pace running in one session than athletes running continuously at their vVO2max pace.

The problem with doing interval training is determining how fast to ride them, how long each interval should last, and how many intervals to do.  Each cyclist has his or her own individual VO2max, vVO2max, and tlimVO2max. Billat found a variation in these numbers between elite athletes of 130 percent. This again proves that the “one size fits all” approach to intervals is not the way to go. She constructed her protocols to individualize the training for each athlete based on his or her own vVO2max and tlimVO2max.

Thankfully, her protocols are easy to follow and apply in the “real world”. You can follow them, design your own personalized intervals, and reap the sizeable fitness benefits she demonstrated in her research.

The Tests The first thing you need to do is determine your reference points for vVO2max and tlimVO2max. These are both simple field tests. What you need is a reliable bike computer that displays current speed, and a flat, stop-free course to test on. This can be a long straightaway or an out-and-back.

The test may also be done indoors on a trainer if you have a rear-wheel pick-up for your handlebar computer. Indoors is the best venue if you live in a hilly or windy region. It’s best to use a powermeter when doing this test as wind is eliminated as a factor (another good reason to have a powermeter). If outside, choose a day with as little wind as possible. Pump up your tires, make sure your brakes are not rubbing, and consider anything else that will affect your bike speed. Take a couple of easy days training prior to the test so your legs are fresh.

Warm-up well for 30 minutes. Start the test riding in an aero position at 20 km/h (12.5 mph) for two minutes. Every two minutes increase your speed by two km/h (1.2 mph) or your power by 10 watts. Continue until you cannot accelerate or have to slow down. Your vVO2max is the speed or power you maintained during your final, successful two minutes.

Rest for 48 hours before the next test. Some light easy spinning on your bike is fine during this time.

Next you will determine your tlimVO2max. Warm-up well for 30 minutes. Start the test, on the same course, at the vVO2max speed or power you found 48 hours earlier. A rolling start is recommended. Time how long you can maintain your vVO2max speed/power. This will be your tlimVO2max. Billat found that, on average, cyclists have a tlimVO2max of four minutes.

Now, armed with these two numbers you can customize your interval training so you get the most out of your suffering. Here are two of Billat’s workouts to do this.

30-30 Sessions Alternate 30 seconds at 100 percent vVO2max with 30 seconds at 50 percent vVO2max. Repeat this for a total time including recoveries of two to two-and-one-half times your tlimVO2max.

For example, take a cyclist with a vVO2max of 40 km/h and a tlimVO2max of four minutes. After a good warm-up he/she will ride alternating 40 km/h (25 mph) for 30 seconds with 20 km/h (12.5 mph) for 30 seconds, repeating this eight to ten times for a total of eight to ten minutes.

2km Intervals Another classic interval workout you can customize for yourself is two-km (1.2 miles) intervals. Again, Billats’ work will tell you how fast to ride each two km interval, how fast to ride the recoveries, and how many intervals you should do.

After a good warm-up, ride two km at 100 percent vVO2max speed/power. Recover for the same time duration as the two-km interval took, but at 50 percent of vVO2max. The total combined time of the work intervals (not counting the recovery time) should be twice your tlimVO2max.

Take our above cyclist again as an example. At 40 km/h, two km will take three minutes. The optimum workout would be:

• 3 x 2km in 3 minutes with recoveries of 1 km in 3 minutes.

These are intense training sessions and a little bit goes a long way. Billat has shown that there is no increased benefit to doing them more than once per week. Doing more than one such workout weekly may increase your chance of overtraining, but not provide additional fitness.

As you will be continually improving, you should retest your vVO2max and tlimVO2max every six to eight weeks. Fitness should improve dramatically following this training method with your performance gains evident in your vVO2max, tlimVO2max—and in your race results.

This article was first published in Velo News in 2002.