Fartlek. It's a funny word I know. It's actually a Swedish word that means "speed play". And it's an effective way of increasing your running speed or improving your endurance. Fartlek is a form of interval training but is mostly for advanced runners. The basic concept of interval training is that the runner will do short bursts of fast running alternating with slower bouts of mild jogging or "recovery" intervals. The thing that makes Fartlek different than conventional interval training is that there is no set format, it completely unstructured. Fartlek is also intended for road, path or trail "distance" running (as opposed to going back and forth over the same part of a path over and over, as is the case in most forms of interval training). Fartlek training is a great way to increase both your aerobic and anaerobic capabilities as well as your lactic thresholds. It's a very flexible way of incorporating interval training into distance running. In Fartlek training, the runner increases or decreases their running speed for short amounts of time. However, determining when they should increase or decrease speeds is decided solely by the runner themselves, in the moment. The runner can be in touch with their own feelings and responses to the harder intervals and decide for themselves when it is time to take a slower interval. The runner is also in charge of when they've had enough 'recovery' and should start a harder, fast run interval again. Fartlek is intended mostly for advanced runners because as mentioned, there is no set format to follow, so this requires some honesty by the runner to ensure they're actually getting a hard workout. There's no timer telling them to go fast or slow 鈥? no coach or specified distance that determines the speed changes, only the runner determines it for themselves as they go. Another interesting thing about Fartlek is that it allows for more experimentation than traditional timed intervals. The runner can change their pace whenever they feel like it, which allows for much more freedom with trying intervals of varying lengths and speeds. But just because Fartlek is designed for advanced runners doesn't mean that the average runner can't take advantage of this technique. An average runner can incorporate Fartlek into their routines by choosing random items along their path as 'goal-posts' where they promise themselves they will change their pace. The runner might choose a tree that's up in the distance or a bend in the road, or another jogger up ahead and tell themselves "When I reach that marker, I will increase my pace until I hit that next marker, then I can go slow again", and continue choosing markers along their path as they go (this eliminates the need for the " total honesty" that advanced runners must have when they're doing Fartlek without markers). As well, average runners can use this technique to become more in touch with themselves as a runner. It can help them notice things like how long it takes their breathing to become more difficult at higher paces, or how much faster their pace needs to be in order to get a harder cardiovascular workout. They can also experiment and learn things like how wide their stride is at certain paces as well as other physical changes that occur at different speeds, lengths of intervals, etc. This new-found knowledge can then help them become more advanced runners. Fartlek training is a fun and easy way to incorporate interval training into your running routines as well as getting you a harder and more beneficial workout on your regular long endurance runs. For lots of great lean-body advice check out Jackie's interview with Mike Geary, author of Truth About Abs. He shares loads of valuable information about how you can get ripped too. Jackie Burgmann is a Registered Weight Trainer and Registered Personal Trainer who also runs a popular fitness-oriented video blog using the pseudonym Girlwithnoname at her blog Girlwithnoname - Fitness At Home where she provides inspiration, motivation and Online Fitness Coaching.