Threshold training is one of the best means by which to improve running economy and speed endurance. Most of us however, fall victim to either ego, where we force the pace and go well beyond threshold, or, do the opposite and don’t push enough. Getting the pace right is a very hard thing to manage without the use of a heart rate monitor. But sometimes this too is not the ideal measure. Firstly, there are two ways of using them in training. The first is to do a threshold as part of an interval session. In this instance you either run an effort prior to a series of shorter repeats, or at the end of the session. The duration of the threshold should be around 20 minutes. The purpose of it is to stimulate some fatigue while you run in a manner that’s fast, yet relaxed. It should feel comfortable and upon completion you should have a sense of tiredness but be confident that you could have easily gone a lot faster. In terms of pace it should be around 90% of your marathon pace.
The second alternative is to make the threshold the sole effort in a given session. In this instance the threshold should be much longer than the former example. A good duration is in the range 40 to 80 minutes. Those training for marathons or longer will be at the longer end of the spectrum, while 5km runners should target the shorter. The pace should be much the same as for the first option, with the focus being on good technique and rhythm. Once again, you need to finish confident in the fact that you could have done more or gone faster.
This type of training is great year round. In the build phase of your training, the longer alternative is the better of the two. Then as you move closer to racing, introduce the shorter threshold coupled with intervals/hills. The other great thing about them is they become a nice way to measure your fitness outside of doing a maximal exertion. The fitter you get, the easier the speed will come!