Interval

Warm-up: 10min

Workout:
2x2000m zone 3 with 2min rest in between
8min rest
2x800m zone 4, with 3min rest in between
5min rest
2x200m zone 4, with 1min rest in between

Cool down: 10min zone 1

What is the goal of this workout?

1. Improve your speed endurance: Unlike an all-out 100-metre sprint, you run a 1500m/5km/10km/half-marathon below your maximum speed. However, you should still be able to sustain a high pace for a long time. This is called speed endurance. This workout helps you improve running at a high pace over a long period of time.​
2. Improving your VO2max: Running at these high paces will challenge your body to be more efficient in its oxygen transport and consumption, thereby improving your VO2max.
3. Become mentally stronger: During your race, the tough feeling at the end will be nothing new for you. On the contrary, having experienced the same feeling at the end of this workout, you will be able to push just as hard or even harder during your race performance.

Guidelines

1. Don't run the 2000m too hard. They should feel comfortable, as these are zone 3 (threshold) efforts. The goal of these 2000m repetitions are (1) to increase the aerobic stimulus of your training (otherwise the training volume at higher pace is too low), and (2) induce pre-fatigue before your faster repetitions, which simulates racing conditions.
2. Run the 800m and 200m progressively. The first 800m and 200m should be fatser than the second one. And you can run your last 200m all-out.