When it comes to training, the analogy of baking a cake is often used and it’s a really good one. You should spend several weeks working on your endurance and building a solid base (the sponge), before layering on the speed work (think of that as the icing and the decorations). For a lot of runners the dilemma is often working out how to sharpen their speed for 13.1 miles (21km). With that in mind, here are some suggested workouts.
Three-minute intervals are a favoured workout for many athletes because they are long enough to gain the physiological adaptations from running at a higher intensity, but not so long that you cannot maintain the pace. The idea of this workout is that you try to run at faster than half marathon race pace. Start with 6 x 3 minutes with a 90 second jog recovery at your 10k race pace. Doing it this way means you can gradually build up the number of intervals as you get fitter and stronger.
'In and out ' kilometres/miles
The idea of this workout is to run a faster segment followed by an active recovery, where you still maintain a good pace. The thinking behind this is that it teaches your body to ‘recover’ and buffer any lactate in your blood at faster speeds. In addition it’s also a great workout for simulating the surges that often happen in a race.
You can run to distance (or the equivalent time) and adjust the length of the segments. So you could start with 5 x 1k on/1k fast recovery for example, and build from there. However, be warned, this workout can be quite evil if you misjudge your pacing.
Speed work sandwich
In training it can sometimes be tricky to simulate the fatigue that you may feel towards the end of a half marathon, but this workout should do the trick nicely. The idea is that during the second half of the workout you are asking your body to run at a sustained pace, even though you already have higher levels of lactate in your blood. This feeling is very similar to the latter part of a half marathon when it can start to hurt.
Run 2 miles (3.2km) at your 'tempo' pace. This should be a pace that is not eyeballs out gasping for breath, but is 'comfortably hard'. Another way of characterizing it is to think of the pace as one at which you can say three or four words but will be unable to talk in full sentences.
Take 3 minutes recovery. Run 3 x 5 minute intervals with a 2-minute jog recovery. Take 3 minutes recovery. Repeat the 2-mile (3.2km) tempo run.
400m repetitions with diminishing recoveries
This workout is a toughie, but it is also a great way to build strength and speed endurance, both of which you will certainly need for the half marathon distance. You can do this session on the track or you can run to the equivalent time or distance on the grass, road or trails.
Run three sets of 4 x 400m.Take 60 seconds recovery after the first rep, 45 seconds after the second, and 30 seconds after the third. Then take three to four minutes jog recovery between each set.