Once you are comfortable with strides, you can add fartleks (Swedish for "speed play") or short repeats to your training. A typical (but structured) fartlek might be 1 minute on/1 minute off for 10 sets, where the faster minutes are run at 5K (hard) effort while the rest minutes are run at an easy recovery pace. An appropriate repeat workout might be eight sets of 200-meter repeats on the track with 100m to 200m recovery jog in between. These repeats would also be done at 5K effort.
Half Marathon Training Tip #4: Head For The Hills
Recent research has indicated that hill training has significant benefits for runners, regardless of the specific nature of such training. Therefore, make running hills a big part of your training, and you are bound to see gains.
Hill training can be short: 10- to 15-second sprints up a steep hill. These intervals are similar to strides because they can be added to workouts regularly without making them hard. Or they can be more structured repeats, such as 6 x 200m up the hill, with a downhill recovery jog back to the start. They can even be executed as fartlek-type workouts, where you surge up every hill in a medium-length run, and then cruise or run easy on the downhills and flat portions. And if your half marathon has a lot of downhills, you should consider running downhill repeats to practice proper form, and strengthen your quads for the eccentric loading that they will experience.
Half Marathon Training Tip #5: Push Your Threshold
Besides your aerobic capacity, the next important physiological variable that influences your half marathon performance is your lactate threshold pace, or the pace at which your blood is no longer able to clear lactate effectively from your muscles. This pace falls somewhere between your 10K and half marathon pace, so it's easy to see that improving this pace can bring your half marathon time down with it.
The best way to improve your threshold pace is to train at or near it, and this is the purpose of most types of tempo runs. Depending on the length or time, tempo runs can be performed just above, right at, or just below your threshold pace, and this gets your body used to managing the lactate buildup.
Half Marathon Training Tip #6: Dial in Your Pacing
Gaining a sense of your race pace, and being able to find it early in the event is critical at all race distances, and this is especially true for the half marathon. Go out a bit too fast, and you hit that lactate threshold pace, from which it can be difficult to recover over the length of a half marathon. Go out too slowly, and you leave time on the table, which can also be difficult to make up late in the race.
The best way to get used to race pace is to run at race pace in a range of situations, from fresh legs to tired legs. For the former, workouts such as longer repeats (1000m or more) with short recoveries (like 1 minute) get you used to restraining yourself to a pace that's slower than you may be used to running for repeats or short races. For the latter, finish some of your long runs with 3 or 4 miles at race pace.
Half Marathon Training Tip #7: Build Your Strength
Strength training for runners serves two major purposes. The first is to help keep you healthy, which can allow you to train consistently. The second is to help improve your running form and economy by balancing your strength among necessary muscle groups, such as your hips, glutes and core.
This doesn't have to involve lifting weights or going to the gym. There are plenty of options for bodyweight-based strength routines for runners that target typical weaknesses. Just 15 to 30 minutes 2 to 3 times a week is often enough for you to feel a difference, especially if strength training has not been part of your routine to date.