Many runners have an idea of what interval training is. I run for a specific distance or time, rest for a specific distance or time, and then repeat for certain number of times. With all these variables (time, distance, rest, total volume), the options for interval workouts seem endless. How do you know what kind of interval training is right for you?
WHO SHOULD BE DOING INTERVAL TRAINING IN THE FIRST PLACE
The tendency is to think that ALL runners should be doing interval work, but it’s just not true. For someone with a tight schedule or is just beginning (less than 20 miles/week), their time would be better spent with aerobic running. Honestly, the growth just won’t happen unless there is a sufficient aerobic base built up.
INTERVAL TRAINING FOR A 5k RUNNER
Interval training is crucial for a 5k runner because VO2 max is the key factor in this type of running. VO2 max is the primary adaptation that is focused on in interval training.
Once a sufficient base phase of aerobic running has been completed, a 5k runner should start building interval training into his or her weekly schedule. The RRCA’s suggestion for the base phase is currently 500 miles. Naturally, for shorter races like the 5k, the speeds of the intervals should be done faster. I like the 3K to 5k race pace best and it is supported by authors like Pete Pfitzinger in his book, “Advanced Marathoning”.
Distances of the intervals can range anywhere from 400m to 1600m (1 mile). Total volume, or time spent on the intervals themselves can range from 2-5 miles.
An example workout might be 6×800 at 5k race pace with a 2 minute light jog in between intervals. That’s 4800m, or 3 miles, of total volume – well within our 2-5 mile range. The key with every interval workout is finding the balance. You want to stress the athlete enough to elicit some gain but not so much so that the athlete cannot recover for the next hard workout. If this example workout is too difficult to recover from, it should not be attempted. It would be more detrimental than helpful.
HOW TO ADJUST THE INTERVALS
Wherever the athlete’s starting point is, it is important to know how to adjust the workout in order to keep the athlete adapting. As Steve Magness points out in his book, “The Science of Running”, we want to “embarrass” the body in the direction that you want it to go. In other words, if you want to improve speed, it makes sense to tax the body by making it go faster.
Let’s look at some of the more common ways to adjust an interval workout and why you might want to use them. The following applies no matter what distance you are racing.
SPEED
It might sound like a simple task – “Run it FASTER next time, DUH!”. So instead of a 3 minute 800m interval, aim for 2:57. This is a logical next step if you are focused on improving pure speed and increasing the body’s ability to handle fatigue. This should make sense. If you are fatigued the same amount after running 2:57 intervals as you were with 3:00 intervals, then your body is learning to tolerate fatigue better.
VOLUME
Instead of doing the intervals faster, we could increase the stimulus by doing MORE of them and make it 7×800 at 5k race pace with a 2 minute recovery. This sort of change is geared toward helping the body adapt to a bigger load. It will increase the athlete’s general endurance, but not necessarily his or her specific endurance.
LENGTH
Another option in advancing this workout would be to increase the length of the intervals. 6×800 at 5k race pace with 2 minute recovery might turn into 6×500 or 6×600, keeping all other variables constant. This helps to increase race-specific endurance, or the ability to last longer at race pace. I like this sort of adjustment especially once the athlete has built up to running at least the target pace of their goal race.
RECOVERY
Let’s say you’re not quite ready to lengthen the interval yet. An intermediate step could be to reduce the amount of rest. In our example, the athlete could change to jogs of 90 seconds rather than 2 minutes. An adjustment like this helps the body learn to clear out fatiguing waste by-products that build up in the muscles. Unsurprisingly, the adaptation gained from this adjustment is the improved ability to recover.
INTERVAL TRAINING FOR A MARATHON RUNNER
Contrary to the 5k, interval training is much less important for the marathon. The key adaptations for the marathon are the ability to run faster at lactate threshold, to have endurance at race pace, and to store a lot of glycogen in the body. None of these are improved with interval training as we’ve defined it here.
Distances of the intervals are naturally longer for the marathoners when compared to 5k runners. I would suggest something between 800m and 1600m. A shorter rest is preferred since it does not allow the anaerobic system to recharge. This makes the workout more aerobic. Total volume of running should be longer as well, somewhere between 4 and 7 miles, with speeds ranging from 5k to 10k pace.
We could even start with the same example workout as mentioned above. The focus, however, is very different for the marathoner.
WHERE’S THE FOCUS
As mentioned earlier, the key in any training plan is balancing stress and recovery. For the marathoner, whose key workouts will be tempo runs (to improve lactate threshold) and long runs (to improve glycogen storing capability). These should be the focus of the training week, NOT intervals which improve VO2 max.
What does this mean? Marathoners should resist the urge to crush their interval workouts. Though it may seem counter-intuitive, they should make sure there is always something left in the tank. This enables ample recovery before the tougher key workouts later in the week.
So what interval training is right for you? It all comes back to the distance and adaptation on which you are focusing. Running intervals isn’t always fun, but they can be a very effective tool for getting you to race day ready to crush your goals.
