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Training and Racing
The Art and Science of Interval Training for Sports and Fitness
By Roy Stevenson
July/August 2009
For the Washington Running Report
Interval training is an extremely potent training technique that will improve your endurance racing performances. It is also widely avoided by recreational endurance athletes because many consider it too complex or too hard. This should not be the case, and endurance athletes, runners, cyclists, and swimmers of all levels can utilize this mode of training to significantly improve their fitness and competition performances.
Defined as "repeated bouts of high intensity activity, each followed by a limited rest period," interval training involves running, swimming, or cycling a short distance repeatedly, at a speed that is always greater than could be sustained continuously for the full session.
In other words, you swim, run, or cycle shorter bursts faster than you would race, with much slower recovery intervals between these fast bursts. This is how it gets the name "intervals." And by manipulating the length and speed of the recovery interval we create the desired training effect, e.g. short recovery intervals create an oxygen debt, enabling us to tolerate more lactic acid, so we are better prepared for races.
Key Guidelines to Using Intervals Successfully
1. It is critical that you recover completely between interval workouts so your energy reserves are replenished and your muscle tissue has time to recover and rebuild.
2. Adjust your recovery interval distance to get the desired training effect for your racing distance. You should be able to complete your workout feeling like it was a challenge, but attainable.
3. Interval workouts should not become the focal point of your weekly training program--avoid becoming over competitive with yourself.
The Devil Is in the Details
Figuring out the details of your interval training workouts can be tricky; you will need to use the acronym DIRT to help, where . . .
D = Distance of each fast burst
I = Interval, or length of recovery (jog, walk, swim, or cycle) between fast bursts
R = Repetitions. How many fast bursts we do in one session.
T = Time for each fast burst.
This is an especially appropriate acronym-you will feel like dirt if you miscalculate any of these factors.
We will use distance running to illustrate the physiology of interval training. And for general fitness buffs, the "Table of Suggested Workouts for Beginners" can be used for good results.
D = Distance: The Length of Your Interval Bursts
The fast bursts in an interval workout need to be long enough to dip into the aerobic system--that is, they should be three to ten minutes long. Because of the precise nature of the distances and times you will be running, interval training is best done on the 400-meter track.
I = Interval: What to Do in the Recovery Intervals
Walking or jogging, or a combination, is recommended in the interval between fast bursts. Your goal is to adapt to the interval workouts by attaining the maximum number of repetitions over these distances. Then, for continued improvement, speed up the fast burst, or decrease the recovery interval between them.
Decreasing the length of the recovery interval between fast bursts achieves great results. Your body eventually adapts by generating smaller amounts of lactic acid at the same pace, enabling you to cruise at a "higher wattage," or a much faster pace, with less lactic acid building up.
R = Repetitions: How Many Fast Bursts Should You Do in an Interval Workout?
The cumulative distance of the fast bursts in your interval workouts should add up to one and one-half to two miles for beginners, three miles for experienced runners.
For example, a session of 8 x 400 meters should be the absolute maximum number prescribed. You might start with 4 repeats of 400 meters, adding two to that workout next time you do it. Once you reach 8 or 10 x 400 meter repeats comfortably, for example, you can pick up your pace by about two to three seconds for following sessions.
T = Time: How to Estimate the Speed of Your Fast Interval Bursts
The longer the fast bursts, the slower they need to be because of our limited ability to supply oxygen to the working muscles and to disperse fatiguing byproducts (such as lactic acid) as they build up. If you do mile repeats for example, they should be done 10 to 25 seconds faster than your average 10K race pace, or slightly faster than your average 5K race pace.
Putting it All Together
An Example: Sub 40-Minute 10K
Let's look at a runner trying to break 40 minutes for a 10K race. He or she needs to average less than 6:27 mile pace, so 1600 meter (one mile) repeats should be done at around 6:10 pace. Start with one of these and build to two, then three.
How Much Time Do You Need to Recover From an Interval Workout?
Because of the high risk of illness or injury it is critical for you to adapt to your interval workouts, rather than let them flatten you. Allow at least 48 hours between these high intensity workouts, and if you are over 30 years old, one interval workout a week is sufficient.
Moving Up to a Higher Level of Interval Training
If you are running faster than your previous times for two to three consecutive workouts, it is time to ramp up your pace. When you can comfortably perform the workout, it is time to increase the pace or decrease the recovery interval.
Warm-Up
A good warm-up is critical before interval workouts. A solid 15 to 25 minute jog with stretching and some fast "stride-outs" of up to 50 meters should be included in the warm-up. With these "stride-outs," you pick your tempo up to a medium-paced sprint to prepare you for the fast interval bursts.
Recovering from Interval Training Sessions
Your interval workout should not be so exhausting you cannot recover for the next day's training, which should be a slow recovery jog on a soft surface. Most important of all is that you have an adequate aerobic conditioning base before attempting interval training. I suggest eight to ten weeks of steady state, aerobic running to prepare you for the rigors of interval speed work.
Interval Workouts for Swimmers and Cyclists?
Interval training is an integral part of swimmers' and cyclists' preparation for racing. For D.I.R.T. guidelines for these sports, find a good local coach to help you establish these workouts.
Good luck with this fast training, and remember, when in doubt, slow down the pace, or consult with your coach or a runner who is experienced in using interval training.
Roy Stevenson has a master's degree in coaching and exercise physiology from Ohio University. He has coached hundreds of serious and recreational runners in the Seattle area. His articles on running have been published in more than 30 regional, national, and international running magazines in the U.S.A., Australia, and U.K. Roy teaches exercise science at Seattle Pacific University and Highline Community College in the Puget Sound, Seattle area.