Instead of doing my usual 10-12K steady effort run, this morning I had my first interval training. Doing it on the treadmill made it easier to monitor the time and set the speed to where I wanted. This is how the intervals looked like:

1. 6:00 Warm-up @ 8.5 km/h (5.3 mph)
2. 1:00 High effort run @ 12 km/h (7.5 mph)
3. 2:00 Slow paced jog @ 8 km/h (5 mph)
4. Repeat 2-3 11x for a total of 12 intervals
6. 10:00 Cool down @ 9 km/h (5.6 mph)

The result was about 52 minutes and 8km (5 miles), very close to my regular steady runs. During the intervals, my heat rate went up by 20 bpm at first during the intervals, then the difference was more like 10 bpm as I became fatigued. Even the average HR was close to that of a steady run. Here is the HR graph from runnigahead.com (unfortunately, it displayes the graph averaged, but click on it, then you can turn it off):

Why Interval Training?

There are several sources on the internet that’ll tell you it helps you lose weight quicker and helps you fight the plateaus. It also makes long(er) boring runs a little bit more eventful. It all comes down to confusing the body by changing the intensity of the workout, so it won’t get used to (and become very effective at) a specific type of workload. I think it also helps getting my feet used to higher speeds.  I want to do an interval training once a week for a while and see what happens.