Threshold intervals are a term often used by runners who have already calculated their individual training zones. Training zones are defined (preferably) on the basis of thresholds - more specifically the first and second thresholds. The thresholds have several different names dependent upon several different circumstances, but if we have to boil it down to the most essential, then we have:
- First threshold, otherwise defined as:
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First ventilatory threshold (VT1)
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First lactate threshold (LT1)
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Aerobic Threshold (AeT)
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- Second threshold, otherwise defined as:
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Second ventilatory threshold (VT2)
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Second lactate threshold (VT2)
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Anaerobic threshold (AnT or AT)
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If you want to read more about the thresholds, as well as the concepts 'aerobic' and 'anaerobic', then take a look at this article: "Aerobic and anaerobic training - what is the difference"
When engaging in threshold training, the idea is to run at a set intensity between the two thresholds - that is, at an intensity which makes you work hard, though not too hard that it means you lose your control and running rhythm. Your breathing won't have become a heavy pant just yet.
Why choose interval threshold training?
There are various reasons why it can be a good idea to engage in threshold running - the most common argument is no doubt training your competition pace; if you are preparing for a half marathon (or 10 km, if you are still slightly inexperienced), then the pace of the competition will lie between the two thresholds!
The more you run at a given pace, the better you will become at maintaing that pace - elite runners are a good example of this, since they often do threshold workouts in the period before long races. In all makes perfect sense to assume that the more you train at something, the better you will become. And if you keep your intensity below the 2nd threshold, you will be able to run significantly longer (no. meters) each time you train.
In addition, over time I have read a number of studies which have demonstrated how runners, who have taken part in experiments and been asked to only run at a very high intensity, have in fact experienced a deterioration in their running efficiency. My bet is that this can be explained by the fact that the runners have simply been running at too high an intensity, meaning they have not been running at an efficient pace.
How many thresholds, and how to do it?
Threshold intervals usually consist of long interval training sessions. The length of each interval can range from between 3 minutes to 15 minutes, depending on the pace. Since the pace can also vary quite a lot, it is also difficult to say how many intervals you will need to complete.
The guideline I like to follow is that there should be an obvious sense of uniformity and flow in all the interval sessions I complete - after all, the idea behind this type of training is to run relaxed and efficiently, whilst simultaneously maintaining a high intensity pace.
Examples of training sessions:
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10-12 x 1000 m at around the 10 km pace (or close to 2nd threshold) with 1 minute break
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6-8 x 2000 m at around the 15 km pace with 2 minutes break
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3-4 x 5000 m at around half marathon pace (halfway between the two thresholds in zone 3) with a 1000 m jogging break
References
- Shaw, Andrew J. The reliability, validity and trainability of running economy in trained distance runners. Diss. Loughborough University, 2016.
