The benefits of threshold training

Get back to your best with a touch of threshold work

Threshold running

When you’re new to running, big gains can be seen fast! But as you become more of a regular runner, sticking to the same training sessions each week, and running similar times at your Sunday races, you slowly see your gains level off and, with it, the excitement and passion you felt when you first became acquainted with running. If you want to get back on your best form, get those butterflies back, and take your training to the next level, it’s worth trying your hand at threshold training. With just one session per week, you’ll see improvements. Here’s how and why.

What is threshold training?

If you’ve ever explored advanced training plans for 10K races and upwards, you will have seen references to threshold training. As the name suggests, it involves training at (or slightly below) your threshold – we’re not talking about a pain threshold or a patience threshold, but specifically your lactate threshold (LT) or anaerobic threshold (AT).The lactate threshold is, in the simplest terms, the point at which your body produces lactic acid faster than it can be removed from the muscles, so it starts to build up in the bloodstream. Lactic acid is a normal by-product of the energy release system that allows you to exercise hard, and at lower intensity levels your body simply removes it as a waste product. When you’re working harder and lactic acid starts to build up, the effect you’ll notice is that you fatigue much quicker and you start to feel a burning sensation in your working muscles, making it harder to push on through.

Why do it?

Unless you’re a recreational sprinter, most of your runs and races are probably longer than that sprint for the bus. That means if you want to run at your very limit, without crashing out and seeing your speed drop off dramatically at the end of your race, you need to introduce some threshold training. The great thing about your lactate threshold is that you can raise it over time with the right training, which means you’re able to run harder and faster for longer. The end result? A personal best.

Where’s my threshold?

There is one downside to threshold training: first of all, you need to find out what your lactate threshold is. The only way to truly know your lactate threshold is to visit a sport science lab and have a test carried out. In the lab, the best type of testing involves running on a treadmill at increasing intensity (to exhaustion) while a technician takes blood samples from your finger or earlobe at regular intervals. These blood samples are analysed to determine your blood lactate levels, and the point at which your concentration levels reach 4mm/litre is deemed to be your threshold. You’ll be told your heart rate and speed at this point so that you can then go away and train at this level. Usually, you’d be re-tested six to eight weeks later to look for changes in your threshold, as over time you should take longer to reach it and hit a higher heart rate. Less invasive lab tests use a gas exchange measurement on a treadmill test: you perform a similar increasing intensity test, but wearing a special mask to analyse gases you breathe out (unfortunately this isn’t much more fun than the blood tests, though).

If you don’t have the money or access to testing, then there are ways you can estimate your lactate threshold. In terms of speed, it is usually the highest speed you can maintain for 30-60 minutes, so is somewhere between your 10K and half-marathon PB pace. However, a more accurate test might be to use rate of perceived exertion (RPE) to gauge your threshold. Research has shown that already-fit runners are quite good at predicting their threshold pace this way. You’ll need to calibrate your own RPE scale, from nought to 10 where nought is zero effort and 10 is an all-out sprint with your mind and body screaming at you to stop: lactate threshold is between six and seven on this scale.

How do I use it?

One session per week of threshold training is enough to see improvements. The pace should feel relatively easy, especially if you’ve been used to doing quick intervals.
Start by adding two five-minute threshold intervals to a 30 or 40-minute run, with a two-minute break in between. You can gradually increase the length of the intervals. If you’re training for a half-marathon or marathon, adding 10 to 20-minute stretches at threshold to a long run is a brilliant way to improve fitness. Ideally, measure your effort with a heart-rate monitor. During your threshold intervals you’re not aiming to run above your LT, as that will wear you out too quickly. Instead, aim to be at or within 5bpm below your threshold. If you’re using RPE, just practice ‘calibrating’ your scale so that you know when you’re running at threshold.


Jenny Bozon

Written by Jenny Bozon | 298 articles | View profile

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