The goal of the workout is to serve as a transition from one training staple to another - the first being early season threshold-type work, the second being mid-season race pace intervals. Running 600s at 5k pace is not terribly challenging in and of itself, especially with a recovery interval that isn’t too much shorter, but by pushing the rest down, we can turn this session into a mix of race specificity and general conditioning. There was an excellent article done a few months ago in Running Times, by Steve Magness, which addresses this same subject. For a more scientifically oriented view of why such workouts work, I can’t do the topic more justice.
But on to specifics. Emily did the workout, which is a total of 8k in distance, in 29:49. Her 600s ranged from 1:57 to 2:00, averaging around 1:59. Her recoveries were all right around 1:44 to 1:45 for 400, so about 7 minute per mile pace. Here’s a little workout video I made of it:
We can take two things from this:
1. She was able to get in 4800 meters of quality work at her 5k PR pace (16:33).
2. She was able to get in 8000 meters of total running at sub 6 minute pace.
Now if you told me either one of these individually was the outcome of a workout, I would say, “Great! Sounds like we got some good work in!” But the beauty of the alternation workout is that we were able to get both in simultaneously. As I said, these workouts are a bridge from one type of training to another. We might be coming from workouts like a 10 mile progressive run, or a 6 mile tempo run, which while great, don’t by themselves allow someone to race a great 5k. To do that, we want to move towards workouts like 6x1k or 4x1600 at 5k race pace, but when it’s still February, and you want to compete well into April, May, and beyond, jumping into truly difficult interval training means sacrificing something else. With mixed workouts like the alternation session above, you don’t have to.
The only downside: these workouts are really, really hard if you do them correctly. They don’t have the lactic burn of race specific type sessions, but they require a lot of toughness to continue running quickly when you’re really starting to get tired. Running 5:59 minute pace for Emily, or 5:27 pace for me, is an entirely different thing when you’re alternating between 5:20 and 7:00 pace, or 4:50 and 6:35 pace, respectively. But if it was an easy workout, it probably wouldn’t work nearly as well, would it?