What is fartlek training, and why is it such a great way to condition for athletes? Fartlek is a Swedish word meaning “speed play,” and that’s essentially what this type of workout is built upon. (See also STACK Science: Developing Slow- and Fast-Twitch Muscle Fibers.)

Sound familiar? That’s because fartlek training is more commonly known as interval training, in which you alternate periods of high-intensity exercise with shorter periods of low-intensity work. This mimics the start-and-stop rhythm needed to dominate in most sports. Plus, the formula is key for losing fat, because it keeps the body burning calories long after the workout ends.

In general, fartlek training should be performed once or twice a week, alternating with other types of activity during the rest of the week. A fartlek training session can be made easier by reducing the number of intervals or the total time of the workout—or by reducing the duration of the high intensity periods and increasing the low intensity periods.

Athletic Benefits of Fartlek Training

• Reduces overuse injuries by varying the periods of  high intensity and low intensity exercise
• Offers an efficient way to incorporate high intensity and low intensity workouts into one routine
• Improves athletic performance by mimicking the intensity and flow of competition
• Helps prevent boredom

Want to create your own program? Base it off the following sample programs. You don’t have to use running as the cardio component. You can tailor your workouts by substituting biking, swimming or lifting.

Standard Interval

• Start by warming up for five to 10 minutes with a brisk walk or light jog
• Progress to a faster pace, pushing exertion to maximum effort for a full minute
• Follow up with a normal pace walk or light jog for a minute
• Repeat the cycle six to eight times
• Cool down with aerobic movements for five minutes, then stretch

Interval Progressions

• Start by warming up for five to 10 minutes with a brisk walk or light jog
• Sprint full-out for one minute, then walk for one minute
• Sprint full-out for 45 seconds, then walk for one minute
• Repeat cycle, reducing times by 15 seconds, until you are sprinting for 15 seconds, then progress back up by adding 15 seconds to each internal
• Repeat cycle six to eight times
• Cool down with aerobic movements for five minutes, then stretch

Advanced Interval Progressions

• Start by warming up for five to 10 minutes with a brisk walk or light jog
• Jog for 50 seconds at a challenging pace (but not too intense)
• For the the last 10 seconds, burst into a full-out sprint
• Jog for 40 seconds at a challenging pace
• For the last 20 seconds, go into a full-out sprint
• Repeat cycle, reducing jog times by 10 seconds and increasing sprint times, until you are jogging for 10 seconds and sprinting for 50 seconds, then progress back up by adding 10 seconds to each jogging interval and subtracting 10 seconds from each sprinting interval
• Repeat cycle six to eight times
• Cool down with aerobic movements for five minutes, then stretch

Track Intervals

• Start by warming up for five to 10 minutes with a brisk walk or light jog
• Run or jog one lap around a track, followed by a fast sprint for 100 yards
• Repeat interval for a total of 15 to 45 minutes
• Cool down with aerobic movements for five minutes, then stretch

Interval Mix-Up

• Start by warming up for five to 10 minutes with a brisk walk or light jog
• Sprint full-out for two minutes, then jog for two minutes
• Repeat one or two times
• Sprint full-out for 30 seconds, then jog for two minutes
• Repeat one or two times
• Spring full-out for one minute, then jog for one minute
• Repeat one or two times
• Progress to 60-yard sprints followed by one minute rest
• Repeat six to 10 times
• Repeat cycle six to eight times
• Cool down with aerobic movements for five minutes, then stretch

See also Boost Sport-Specific Conditioning With Interval Training.