Tuesday, July 13, 2010

Analysis of an Intervals Workout

Tonight was my first intervals workout for this new training cycle. This was a 2x400 meter interval workout.

Here's basically how the workout went:

.6 mile easy run

400 meter fast run;
2 min walking

400 meter fast run;
2 min walking

.6 mile easy run

I'll add additional intervals every one to three weeks.

Tonight, the main goal was to get a couple of interval runs in and see how my pace looks. I basically ran by feel tonight, with a goal of running the 400m fast intervals at about 1:50 each. I wore my Garmin Forerunner 305 and heart-rate monitor so I could collect data on my pace and heart rate during the fast runs.

The overall goal of running intervals is to improve my race pace (by improving my LT). Ideally, my heart rate should be in an anaerobic training zone, which is between 80% and 90% of my max heart rate during the fast interval runs. So, I need to run a pace that gets my heart rate in that training zone.

So tonight my intervals looked like this:
Interval I: 400m in 1:51 (7:24min/mile pace)
Interval II: 400m in 1:48 (7:12min/mile pace)

Here's what my heart rate looked like:

The first hill is my warm-up run, and the second two hills are the two intervals.  My anaerobic zone is between 159 and 170 beats per minute (bpm).  It looks like my pace was about right for the first interval, maybe a bit high on the second.  During the second interval, my heart rate briefly exceeded 90%, which is sometimes referred to as red-line zone.  For short intervals like this, the red-line zone can be okay if you're healthy enough to withstand the intensity. 

So, moving forward, I now know that a good minimum interval pace for me right now is close to the pace I ran for the first interval: about 7:24min/mi.  

This information also gives me a good baseline for future comparison.  In a couple of months, I can repeat this analysis and hopefully I'll have a lower heart rate for the same pace (or the same heart rate for a faster pace).

Incidentally, my warm-up run should be in my aerobic zone, between 70% and 80% max heart rate (between about 148 and 159 bpm for me).  It looks like I hit it about right (but a bit on the fast side) with an average pace of about 10:30-10:45 min/mile.

I'm not an expert on any of this.  I'm just learning about many of the topics discussed above, so the above analysis is based on my very amateurish understanding. There is a ton of info on the internet about speed workouts and heart rate zones.

p.s. - just ran across this:  3 Ways to Take Your Run to the Next Level | Active.com

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