The benefits of interval training are anything but secret, so I'm wondering why so few runners take advantage?
More on that later, but today I wanted to share a piece of advice that I think is important when it comes to running intervals- how do you know you've done enough?
This morning I did 6 x 800 meters in 2:54, 2:55, 2:52, 2:54, 2:51, 2:57 with 90 seconds recovery. Intervals 2,4, and 6 were run into a slight headwind, so no surprise they were slower.
Why only 6? My general rule of thumb on intervals is when times drop off by more than 3 seconds, it's time to shut it down. While I was pretty confident I could squeeze out another low 2:50s on number 7 with the tailwind, I certainly was NOT keen on finding out what I had left for number 8 (I don't know why this is but I NEVER run an uneven number of intervals- it's always 4,6,8, 10, or more).
I like to compare each workout with a recent similar effort. Last week I did an interrupted 9 x 800 and averaged 3:04 (I know I said I never do an uneven number but this was one screwed up workout!). Today I ran 10 seconds faster (2:53.8 ave)! That's a huge improvement for 800s, and in terms of progression, a good reason in my mind NOT to incease volume. If I'd done those 9 all under 3 min last week, then perhaps I'd reconsider.
Another key indicator for me is this- if I can't jog the cool-down, that's a sign that I overextended in the workout. Today I was close- walking back to the apartment sure felt a lot better than slow jogging, so I split it and did a little of both. Clearly any more than 6 would have put me over the edge.
Other thoughts floating around in my head include an upcoming 10K race in just 4 days and the idea that I'd like to go out for an evening jog to pad my weekly miles. Another 2 intervals run to exhausion may affect both.
One other note- stopping at 6 leaves me 2 good options for my next interval workout- adding 2 more or cutting the rest to 60 seconds. If I was gearing up for a 5K, I'd probably cut the rest and keep it at 6, but with a half marathon as my primary goal, next time out I'll go for 8 and leave the recovery at 90 sec.