My run today was a series of Fartleks. As Wikipedia says, the word Fartlek is Swedish for "speed play". In running, this involves a series of time spans at different intensities (or speeds) that incorporates both aerobic and anaerobic exercise into the workout. These varying intervals could be fast running, slow running, walking, sprinting, or even hills in a repeating cycle for the desired amount of time.
Some Fartlek workouts are rather structured - more like tempo runs, really - such as run 4 minutes fast, run 1 minute easy, and repeat 4 times. Other Fartleks are fun and free and random - truly at the whim of the runner at any given moment. I picture playing soccer or flag football or doing Parkour. (Not that I can do Parkour... I'm just saying.)
In any case, the benefits of Fartlek workouts are many. They can be fun and freeing. They teach your body what it feels like to give a surge of speed. They get your body used to maintaining a harder effort when you're tired. They simulate varying terrain or even obstacles.
For my workout today, I gave the more structured version of Fartleks a try: 4 minutes fast, 1 minute slow for 20 minutes. I really focused on maintaining the fast pace during those 4-minute periods, and let me tell you...it was a hard workout! This is how you get stronger and faster in running - pushing outside of your comfort zone.
The feeling that I worked hard today was encouraging. I'm still doing low mileage in only week 2 of my training plan, but I feel that I'm doing the right work to improve my endurance for the longer runs to come.
3 miles total of Fartleks
Warm up, 4 minutes hard/1 minute easy for 20 minutes, cool down